WorldWideScience

Sample records for deformation mechanism map

  1. -Deformed nonlinear maps

    Indian Academy of Sciences (India)

    Ramaswamy Jaganathan; Sudeshna Sinha

    2005-03-01

    Motivated by studies on -deformed physical systems related to quantum group structures, and by the elements of Tsallis statistical mechanics, the concept of -deformed nonlinear maps is introduced. As a specific example, a -deformation procedure is applied to the logistic map. Compared to the canonical logistic map, the resulting family of -logistic maps is shown to have a wider spectrum of interesting behaviours, including the co-existence of attractors – a phenomenon rare in one-dimensional maps.

  2. Deformation mechanism maps of magnesium lithium alloy and their experimental application

    Institute of Scientific and Technical Information of China (English)

    曹富荣; 崔建忠; 温景林

    2002-01-01

    Deformation mechanism maps for binary Mg-(8~9)Li(mass fraction, %) alloy at 423~623K were constructed in order to elucidate the internal meaning of mechanical experimental data at elevated temperatures. The models and data source used for constructing maps and constructed results are presented. It is determined through comparison of mechanical experimental data with constructed deformation mechanism maps that the dominant deformation mechanism for such alloy at 423~623K is lattice diffusion controlled grain boundary sliding. The difference of such deformation mechanism maps from former ones is that dislocation quantity inside the grains participates in the model calculation, which reveals the dislocation features of different deformation mechanisms.

  3. Understanding creep in sandstone reservoirs - theoretical deformation mechanism maps for pressure solution in granular materials

    Science.gov (United States)

    Hangx, Suzanne; Spiers, Christopher

    2014-05-01

    -boundary diffusion and precipitation on pore walls. As a first step to better describe creep in sands and sandstones, we have derived a simple model for intergranular pressure solution (IPS) within an ordered pack of spherical grains, employing existing IPS rate models, such as those derived by Renard et al. (1999) and Spiers et al. (2004). This universal model is able to predict the conditions under which each of the respective pressure solution serial processes, i.e. diffusion, precipitation or dissolution, is dominant. In essence, this creates generic deformation mechanism maps for any granular material. We have used our model to predict the amount and rate of compaction for sandstone reservoirs, and compared our predictions to known subsidence rates for reservoirs around the world. This gives a first order-comparison to verify whether or not IPS is an important mechanism in controlling reservoir compaction.

  4. Geometrical and mechanical properties of the fractures and brittle deformation zones based on the ONKALO tunnel mapping, 2400 - 4390 m tunnel chainage

    Energy Technology Data Exchange (ETDEWEB)

    Moenkkoenen, H.; Rantanen, T.; Kuula, H. [WSP Finland Oy, Helsinki (Finland)

    2012-05-15

    In this report, the rock mechanics parameters of fractures and brittle deformation zones have been estimated in the vicinity of the ONKALO area at the Olkiluoto site, western Finland. This report is an extension of the previously published report: Geometrical and Mechanical properties if the fractures and brittle deformation zones based on ONKALO tunnel mapping, 0-2400 m tunnel chainage (Kuula 2010). In this updated report, mapping data are from 2400-4390 m tunnel chainage. Defined rock mechanics parameters of the fractures are associated with the rock engineering classification quality index, Q', which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. There are no new data from laboratory joint shear and normal tests. The fracture wall compressive strength (JCS) data are available from the chainage range 1280-2400 m. Estimation of the mechanics properties of the 24 brittle deformation zones (BDZ) is based on the mapped Q' value, which is transformed to the GSI value in order to estimate strength and deformability properties. A component of the mapped Q' values is from the ONKALO and another component is from the drill cores. In this study, 24 BDZs have been parameterized. The location and size of the brittle deformation are based on the latest interpretation. New data for intact rock strength of the brittle deformation zones are not available. (orig.)

  5. 变形机理图的研究进展及发展趋势%Development and Prospect for Deformation Mechanism Map

    Institute of Scientific and Technical Information of China (English)

    周舸; 曹富荣; 丁桦

    2011-01-01

    变形机理图又称为塑性变形的相图,它对材料变形过程的预报对于材料成形科学基础研究具有重要的意义.文中分别对Ashby、Langdon-Mohamed、Ruano-Wadsworth-Sherby、含位错数量的R-W-S变形机理图的构建方法、使用条件及特点进行了介绍.为变形机理图在实际生产中的应用提供了理论基础.%Deformation mechanism map, I.e. Plastic deformation map, is effective to predict the material deformation during processing, which is very important for basic research on material processing. The constructing method, applying conditions and characteristics for the four deformation mechanism maps are introduced, for example, Ashby, Langdon-Mohamed, Ruano-Wadsworth-Sherby and dislocation R-W-S, respectively. The deformation mechanism map is the basic theory for application on production.

  6. Nanoscale deformation mechanisms in bone.

    Science.gov (United States)

    Gupta, Himadri S; Wagermaier, Wolfgang; Zickler, Gerald A; Raz-Ben Aroush, D; Funari, Sérgio S; Roschger, Paul; Wagner, H Daniel; Fratzl, Peter

    2005-10-01

    Deformation mechanisms in bone matrix at the nanoscale control its exceptional mechanical properties, but the detailed nature of these processes is as yet unknown. In situ tensile testing with synchrotron X-ray scattering allowed us to study directly and quantitatively the deformation mechanisms at the nanometer level. We find that bone deformation is not homogeneous but distributed between a tensile deformation of the fibrils and a shearing in the interfibrillar matrix between them.

  7. Near real-time skin deformation mapping

    Science.gov (United States)

    Kacenjar, Steve; Chen, Suzie; Jafri, Madiha; Wall, Brian; Pedersen, Richard; Bezozo, Richard

    2013-02-01

    A novel in vivo approach is described that provides large area mapping of the mechanical properties of the skin in human patients. Such information is important in the understanding of skin health, cosmetic surgery[1], aging, and impacts of sun exposure. Currently, several methods have been developed to estimate the local biomechanical properties of the skin, including the use of a physical biopsy of local areas of the skin (in vitro methods) [2, 3, and 4], and also the use of non-invasive methods (in vivo) [5, 6, and 7]. All such methods examine localized areas of the skin. Our approach examines the local elastic properties via the generation of field displacement maps of the skin created using time-sequence imaging [9] with 2D digital imaging correlation (DIC) [10]. In this approach, large areas of the skin are reviewed rapidly, and skin displacement maps are generated showing the contour maps of skin deformation. These maps are then used to precisely register skin images for purposes of diagnostic comparison. This paper reports on our mapping and registration approach, and demonstrates its ability to accurately measure the skin deformation through a described nulling interpolation process. The result of local translational DIC alignment is compared using this interpolation process. The effectiveness of the approach is reported in terms of residual RMS, image entropy measures, and differential segmented regional errors.

  8. Deformation mechanisms in experimentally deformed Boom Clay

    Science.gov (United States)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  9. A deformation mechanism map for polycrystals modeled using strain gradient plasticity and interfaces that slide and separate

    DEFF Research Database (Denmark)

    Dahlberg, Carl F.O.; Faleskog, Jonas; Niordson, Christian Frithiof

    2013-01-01

    Small scale strain gradient plasticity is coupled with a model of grain boundaries that take into account the energetic state of a plastically strained boundary and the slip and separation between neighboring grains. A microstructure of hexagonal grains is investigated using a plane strain finite...... element model. The results show that three different microstructural deformation mechanisms can be identified. The standard plasticity case in which the material behaves as expected from coarse grained experiments, the nonlocal plasticity region where size of the microstructure compared to some intrinsic...

  10. Supersymmetric q-deformed quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Traikia, M. H.; Mebarki, N. [Laboratoire de Physique Mathematique et Subatomique, Mentouri University, Constantine (Algeria)

    2012-06-27

    A supersymmetric q-deformed quantum mechanics is studied in the weak deformation approximation of the Weyl-Heisenberg algebra. The corresponding supersymmetric q-deformed hamiltonians and charges are constructed explicitly.

  11. Deformation quantization and Nambu mechanics

    CERN Document Server

    Dito, G; Sternheimer, D; Takhtajan, L A; Dito, Giuseppe; Flato, Moshe; Sternheimer, Daniel; Takhtajan, Leon

    1996-01-01

    Starting from deformation quantization (star-products), the quantization problem of Nambu Mechanics is investigated. After considering some impossibilities and pushing some analogies with field quantization, a solution to the quantization problem is presented in what we call the Zariski quantization of fields (observables, functions, in this case polynomials). This quantization is based on the factorization over {\\Bbb R} of polynomials in several real variables. We quantize the algebra of fields generated by the polynomials by defining a deformation of this algebra which is Abelian, associative and distributive. This procedure is then adapted to derivatives (needed for the Nambu brackets), which ensures the validity of the Fundamental Identity of Nambu Mechanics also at the quantum level. Our construction is in fact more general than the particular case considered here: it can be utilized for quite general defining identities and for much more general star-products.

  12. The character map in deformation quantization

    CERN Document Server

    Cattaneo, Alberto S; Willwacher, Thomas

    2009-01-01

    The third author recently proved that the Shoikhet-Dolgushev L-infinity-morphism from Hochschild chains of the algebra of smooth functions on manifold to differential forms extends to cyclic chains. Localization at a solution of the Maurer-Cartan equation gives an isomorphism, which we call character map, from the periodic cyclic homology of a formal associative deformation of the algebra of functions to de Rham cohomology. We prove that the character map is compatible with the Gauss-Manin connection, extending a result of Calaque and Rossi on the compatibility with the cap product. As a consequence, the image of the periodic cyclic cycle 1 is independent of the deformation parameter and we compute it to be the A-roof genus of the manifold. Our results also imply the Tamarkin-Tsygan index Theorem.

  13. Deformation of noncommutative quantum mechanics

    Science.gov (United States)

    Jiang, Jian-Jian; Chowdhury, S. Hasibul Hassan

    2016-09-01

    In this paper, the Lie group GNC α , β , γ , of which the kinematical symmetry group GNC of noncommutative quantum mechanics (NCQM) is a special case due to fixed nonzero α, β, and γ, is three-parameter deformation quantized using the method suggested by Ballesteros and Musso [J. Phys. A: Math. Theor. 46, 195203 (2013)]. A certain family of QUE algebras, corresponding to GNC α , β , γ with two of the deformation parameters approaching zero, is found to be in agreement with the existing results of the literature on quantum Heisenberg group. Finally, we dualize the underlying QUE algebra to obtain an expression for the underlying star-product between smooth functions on GNC α , β , γ .

  14. Mechanical Deformation of Ship Stern-Shaft Mechanical Face Seals

    Institute of Scientific and Technical Information of China (English)

    朱汉华; 刘正林; 温诗铸; 严新平

    2004-01-01

    In ship propeller shaft systems, the shaft seal is a mechanical face seal, which includes a stationary metal seal ring and a rotating ring.The seal faces are deformed with different loads.The deformation of the seal faces affects the performance of mechanical face seals, which leads to water leakage, so the seal face deformation must be analyzed.A mechanics model with deformation equations was developed to describe ship stern-shaft seals.An example was given to verify the deformation equations.The solution of the deformation equations gives a theoretical basis for the analysis of seal leakage and improvements of seal structures.

  15. UAV for landslide mapping and deformation analysis

    Science.gov (United States)

    Shi, Beiqi; Liu, Chun

    2015-12-01

    Unmanned aerial vehicle (UAV) can be a flexible, cost-effective, and accurate method to monitor landslides with high resolution aerial images. Images acquired on 05 May 2013 and 13 December 2014 of the Xishan landslide, China, have been used to produce a high-resolution ortho-mosaic of the entire landslide and digital elevation model (DEM). The UAV capability for imaging detection and displacements on the landslide surface has been evaluated, and the subsequent image processing approaches for suitably georectifying the data have been assessed. Objects derived from the segmentation of a multispectral image were used as classifying units for landslide object-oriented analysis. Spectral information together with various morphometric characteristics was applied for recognizing landslides from false positives. Digital image correlation technique was evaluated to quantify and map terrain displacements. The magnitude and direction of the displacement vectors derived from correlating two temporal UAV images corresponded to a visual interpretation of landslide change. Therefore, the UAV can demonstrate its capability for producing valuable landslide mapping data and deformation information.

  16. Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

    Science.gov (United States)

    Kaercher, P. M.; Zepeda-Alarcon, E.; Prakapenka, V.; Kanitpanyacharoen, W.; Smith, J.; Sinogeikin, S. V.; Wenk, H. R.

    2014-12-01

    The crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, yet little is known about its deformation mechanisms. Information about how stishovite deforms under stress is important for understanding subduction of quartz-bearing crustal rocks into the mantle. Particularly, stishovite is elastically anisotropic and thus development of crystallographic preferred orientation (CPO) during deformation may contribute to seismic anomalies in the mantle. We converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. Diffraction patterns were collected in situ in radial geometry at the Advanced Light Source (ALS) and the Advanced Photon Source (APS) to examine development of CPO during deformation. We find that (001) poles preferentially align with the compression direction and infer deformation mechanisms leading to the observed CPO with visco-plastic self consistent (VPSC) polycrystal plasticity models. Our results show pyramidal and basal slip are most likely active at high pressure and ambient temperature, in agreement with transmission electron microscopy (TEM) studies of rutile (TiO2) and paratellurite (TeO2), which are isostructural to stishovite. Conversely other TEM studies of stishovite done at higher temperature suggest dominant prismatic slip. This indicates that a variety of slip systems may be active in stishovite, depending on conditions. As a result, stishovite's contribution to the seismic signature in the mantle may vary as a function of pressure and temperature and thus depth.

  17. Deformation mechanisms of plasticized starch materials.

    Science.gov (United States)

    Mikus, P-Y; Alix, S; Soulestin, J; Lacrampe, M F; Krawczak, P; Coqueret, X; Dole, P

    2014-12-19

    The aim of this paper is to understand the influence of plasticizer and plasticizer amount on the mechanical and deformation behaviors of plasticized starch. Glycerol, sorbitol and mannitol have been used as plasticizers. After extrusion of the various samples, dynamic mechanical analyses and video-controlled tensile tests have been performed. It was found that the nature of plasticizer, its amount as well as the aging of the material has an impact on the involved deformation mechanism. The variations of volume deformation could be explained by an antiplasticization effect (low plasticizer amount), a phase-separation phenomenon (excess of plasticizer) and/or by the retrogradation of starch.

  18. Molecular deformation mechanisms in polyethylene

    CERN Document Server

    Coutry, S

    2001-01-01

    adjacent labelled stems is significantly larger when the DPE guest is a copolymer molecule. Our comparative studies on various types of polyethylene lead to the conclusion that their deformation behaviour under drawing has the same basis, with additional effects imputed to the presence of tie-molecules and branches. Three major points were identified in this thesis. The changes produced by drawing imply (1) the crystallisation of some of the amorphous polymer and the subsequent orientation of the newly formed crystals, (2) the re-orientation of the crystalline ribbons and (3) the beginning of crystallite break-up. However, additional effects were observed for the high molecular weight linear sample and the copolymer sample and were attributed, respectively, to the presence of tie-molecules and of branches. It was concluded that both the tie-molecules and the branches are restricting the molecular movement during deformation, and that the branches may be acting as 'anchors'. This work is concerned with details...

  19. Constructal Hypothesis for Mechanical Deformation

    Directory of Open Access Journals (Sweden)

    Atanu Chatterjee

    2012-08-01

    Full Text Available Mild Steel specimen, when subjected to tensile forces shows considerable plastic deformation before fracture. A cross-section of the fractured specimen has the familiar cup – cone form and shows traces of a three – dimensional parabolic geometry. The morphing of the steel specimen from a volume to a point as a spontaneous, entropy producing or energy dispersing process is analysed using the Constructal law.

  20. Dislocations: 75 years of Deformation Mechanisms

    Science.gov (United States)

    Schneider, Judy

    2009-01-01

    The selection of papers presented in this section reflect on themes to be explored at the "Dislocations: 75 years of Deformation Mechanisms" Symposium to be held at the Annual 2009 TMS meeting. The symposium was sponsored by the Mechanical Behavior of Materials Committee to give tribute to the evolution of a concept that has formed the basis of our mechanistic understanding of how crystalline solids plastically deform and how they fail.

  1. Atomistic deformation mechanisms in twinned copper nanospheres.

    Science.gov (United States)

    Bian, Jianjun; Niu, Xinrui; Zhang, Hao; Wang, Gangfeng

    2014-01-01

    In the present study, we perform molecular dynamic simulations to investigate the compression response and atomistic deformation mechanisms of twinned nanospheres. The relationship between load and compression depth is calculated for various twin spacing and loading directions. Then, the overall elastic properties and the underlying plastic deformation mechanisms are illuminated. Twin boundaries (TBs) act as obstacles to dislocation motion and lead to strengthening. As the loading direction varies, the plastic deformation transfers from dislocations intersecting with TBs, slipping parallel to TBs, and then to being restrained by TBs. The strengthening of TBs depends strongly on the twin spacing.

  2. Highly deformable bones: unusual deformation mechanisms of seahorse armor.

    Science.gov (United States)

    Porter, Michael M; Novitskaya, Ekaterina; Castro-Ceseña, Ana Bertha; Meyers, Marc A; McKittrick, Joanna

    2013-06-01

    Multifunctional materials and devices found in nature serve as inspiration for advanced synthetic materials, structures and robotics. Here, we elucidate the architecture and unusual deformation mechanisms of seahorse tails that provide prehension as well as protection against predators. The seahorse tail is composed of subdermal bony plates arranged in articulating ring-like segments that overlap for controlled ventral bending and twisting. The bony plates are highly deformable materials designed to slide past one another and buckle when compressed. This complex plate and segment motion, along with the unique hardness distribution and structural hierarchy of each plate, provide seahorses with joint flexibility while shielding them against impact and crushing. Mimicking seahorse armor may lead to novel bio-inspired technologies, such as flexible armor, fracture-resistant structures or prehensile robotics.

  3. Preliminary deformation model for National Seismic Hazard map of Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Meilano, Irwan; Gunawan, Endra; Sarsito, Dina; Prijatna, Kosasih; Abidin, Hasanuddin Z. [Geodesy Research Division, Faculty of Earth Science and Technology, Institute of Technology Bandung (Indonesia); Susilo,; Efendi, Joni [Agency for Geospatial Information (BIG) (Indonesia)

    2015-04-24

    Preliminary deformation model for the Indonesia’s National Seismic Hazard (NSH) map is constructed as the block rotation and strain accumulation function at the elastic half-space. Deformation due to rigid body motion is estimated by rotating six tectonic blocks in Indonesia. The interseismic deformation due to subduction is estimated by assuming coupling on subduction interface while deformation at active fault is calculated by assuming each of the fault‘s segment slips beneath a locking depth or in combination with creeping in a shallower part. This research shows that rigid body motion dominates the deformation pattern with magnitude more than 15 mm/year, except in the narrow area near subduction zones and active faults where significant deformation reach to 25 mm/year.

  4. Mechanical deformation mechanisms and properties of amyloid fibrils.

    Science.gov (United States)

    Choi, Bumjoon; Yoon, Gwonchan; Lee, Sang Woo; Eom, Kilho

    2015-01-14

    Amyloid fibrils have recently received attention due to their remarkable mechanical properties, which are highly correlated with their biological functions. We have studied the mechanical deformation mechanisms and properties of amyloid fibrils as a function of their length scales by using atomistic simulations. It is shown that the length of amyloid fibrils plays a role in their deformation and fracture mechanisms in such a way that the competition between shear and bending deformations is highly dependent on the fibril length, and that as the fibril length increases, so does the bending strength of the fibril while its shear strength decreases. The dependence of rupture force for amyloid fibrils on their length is elucidated using the Bell model, which suggests that the rupture force of the fibril is determined from the hydrogen bond rupture mechanism that critically depends on the fibril length. We have measured the toughness of amyloid fibrils, which is shown to depend on the fibril length. In particular, the toughness of the fibril with its length of ∼3 nm is estimated to be ∼30 kcal mol(-1) nm(-3), comparable to that of a spider silk crystal with its length of ∼2 nm. Moreover, we have shown the important effect of the pulling rate on the mechanical deformation mechanisms and properties of amyloid fibril. It is found that as the pulling rate increases, so does the contribution of the shear effect to the elastic deformation of the amyloid fibril with its length of deformation mechanism of the amyloid fibril with its length of >15 nm is almost independent of the pulling rate. Our study sheds light on the role of the length scale of amyloid fibrils and the pulling rate in their mechanical behaviors and properties, which may provide insights into how the excellent mechanical properties of protein fibrils can be determined.

  5. Hydroxyl induced eclogite fabric and deformation mechanism

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junfeng; JIN Zhenmin; Harry W. Green II

    2005-01-01

    Eclogites from orogens often show strong plastic deformation and high hydroxyl content. We have studied the correlation between crystallographic preferred orientations of garnet and omphacite from natural eclogites with their hydroxyl contents using the electron back-scat- tered diffraction technique. The results show: 1) Omphacite has typical L-type or SL-type crystrallographic preferred orientations, that is, [001] is distributed in a girdle in the foliation plane with a maximum parallel to lineation; (010) is distributed in a girdle normal to the lineation with a maximum parallel to the foliation plane, suggesting a shear dominant deformation regime. Omphacite fabrics do not vary significantly with hydroxyl content, although the hydrous component may cause lower flow strength. 2) Hydroxyl can influence significantly flow properties of garnet in eclogite. Garnets behave as rigid bodies under low temperature and dry conditions. Grain boundary processes will dominate the deformation and lower the flow strength of garnet under high water fugacity conditions. Garnets show no crystallographic preferred orientation in both cases. These results may have important implications for a better understanding of deformation mechanisms and associated fluid activities during deep subduction and exhumation processes.

  6. Deformed Coherent State for Multiparticle Production Mechanism

    Science.gov (United States)

    Wang, W. Y.; Leong, Q.; Ng, W. K.; Dewanto, A.; Chan, A. H.; Oh, C. H.

    2014-04-01

    The deformation structure function describing the Generalised Multiplicities Distribution (GMD), Negative Binomial Distribution (NBD), Furry-Yule Distribution (FYD), and their corresponding deformed coherent states and second order correlation function g(2) are derived. A superposition model of the GMD and NBD states is then proposed as a general description of the mechanism that gives rise to the double NBD model first proposed by Giovannini. The model is applied to LHC multiplicity data at |η| ≤ 2.4 and 0.9, 2.36 and 7 TeV, from the CMS collaboration at CERN, and the second order correlation g(2) of the model is then compared with the normalised second factorial moment {F_2}/F_1^2 of the multiplicity.

  7. Deformation Mechanisms of Gum Metals Under Nanoindentation

    Science.gov (United States)

    Sankaran, Rohini Priya

    Gum Metal is a set of multi-component beta-Ti alloys designed and developed by Toyota Central R&D Labs in 2003 to have a nearly zero shear modulus in the direction. After significant amounts of cold-work (>90%), these alloys were found to have yield strengths at a significant fraction of the predicted ideal strengths and exhibited very little work hardening. It has been speculated that this mechanical behavior may be realized through an ideal shear mechanism as opposed to conventional plastic deformation mechanisms, such as slip, and that such a mechanism may be realized through a defect structure termed "nanodisturbance". It is furthermore theorized that for near ideal strength to be attained, dislocations need to be pinned at sufficiently high stresses. It is the search for these defects and pinning points that motivates the present study. However, the mechanism of plastic deformation and the true origin of specific defect structures unique to gum metals is still controversial, mainly due to the complexity of the beta-Ti alloy system and the heavily distorted lattice exhibited in cold worked gum metals, rendering interpretation of images difficult. Accordingly, the first aim of this study is to clarify the starting as-received microstructures of gum metal alloys through conventional transmission electron microscopy (TEM) and aberration-corrected high resolution scanning transmission electron microscopy with high-angle annular dark field detector (HAADF-HRSTEM) imaging. To elucidate the effects of beta-stability and starting microstructure on the deformation behavior of gum metals and thus to provide adequate context for potentially novel deformation structures, we investigate three alloy conditions: gum metal that has undergone solution heat treatment (STGM), gum metal that has been heavily cold worked (CWGM), and a solution treated alloy of nominal gum metal composition, but leaner in beta-stabilizing content (ST Ref-1). In order to directly relate observed

  8. Mechanical behaviour of nanoparticles: Elasticity and plastic deformation mechanisms

    Indian Academy of Sciences (India)

    Celine Gerard; Laurent Pizzagalli

    2015-06-01

    Nano-objects often exhibit drastically different properties compared to their bulk counterpart, opening avenues for new applications in many fields, such as in advanced composite materials, nanomanufacturing, nanoelectromechanical systems etc. As such, related research topics have become increasingly prominent in recent years. In this review on the mechanical behaviour of nanoparticles, the main investigation approaches are first briefly presented. The main results in terms of elasticity and plastic deformation mechanisms are then reported and discussed.

  9. Development of regional liquefaction-induced deformation hazard maps

    Science.gov (United States)

    Rosinski, A.; Knudsen, K.-L.; Wu, J.; Seed, R.B.; Real, C.R.; ,

    2004-01-01

    This paper describes part of a project to assess the feasibility of producing regional (1:24,000-scale) liquefaction hazard maps that are based-on potential liquefaction-induced deformation. The study area is the central Santa Clara Valley, at the south end of San Francisco Bay in Central California. The information collected and used includes: a) detailed Quaternary geological mapping, b) over 650 geotechnical borings, c) probabilistic earthquake shaking information, and d) ground-water levels. Predictions of strain can be made using either empirical formulations or numerical simulations. In this project lateral spread displacements are estimated and new empirical relations to estimate future volumetric and shear strain are used. Geotechnical boring data to are used to: (a) develop isopach maps showing the thickness of sediment thatis likely to liquefy and deform under earthquake shaking; and (b) assess the variability in engineering properties within and between geologic map units. Preliminary results reveal that late Holocene deposits are likely to experience the greatest liquefaction-induced strains, while Holocene and late Pleistocene deposits are likely to experience significantly less horizontal and vertical strain in future earthquakes. Development of maps based on these analyses is feasible.

  10. The Neighbor Switching Mechanism of Superplastic Deformation

    Science.gov (United States)

    Sherwood, David John

    At one time the notion that crystal plasticity resulted from the simultaneous motion of lattice planes over one another was entertained. This idea was displaced by the concept that relative atomic motions occur sequentially when dislocations move through the crystal. Similarly, McLean suggested that grains switch neighbors sequentially in a polycrystalline material undergoing superplastic flow. Morral and Ashby observed that the neighbor switching reactions in a froth occurred at irregular cells, and that these irregularities were associated with dislocations in the cellular array. They introduced cellular dislocation glide as a model for superplastic flow, and suggested that if the concentration of these defects required to make the froth flow increased with the flow stress, then the froth would have a non-Newtonian viscosity, like many superplastic materials. Cahn and Padawer pointed out that cellular dislocation climb was used as a model for grain growth by Hillert; this process results in the elimination of cells from the froth. Sato, Kuribayashi and Horiuchi used cellular dislocation climb to model both grain motion and the deformation-enhanced grain growth which can accompany superplastic flow. Here, the neighbor switching mechanism of superplastic deformation is developed as a topic in dislocation theory. The compatibility theory of dislocations is developed at an introductory level with exterior calculus. "Compatibility" of a cellular array corresponds to statements, a la Rivier, about the distribution of edges amongst the cells. The theory of dislocation motion, or crystal plasticity, is also developed with exterior calculus. Morral and Ashby's constitutive relationship for superplastic flow is analyzed and two models for deformation-enhanced grain growth are developed. The constitutive relationship and grain growth kinetics for superplastic flow are illustrated by modelling the behavior exhibited by single phase (Sn-1% Bi) and quasi -single phase (7475 Al

  11. Coordinated Mapping of Sea Ice Deformation Features with Autonomous Vehicles

    Science.gov (United States)

    Maksym, T.; Williams, G. D.; Singh, H.; Weissling, B.; Anderson, J.; Maki, T.; Ackley, S. F.

    2016-12-01

    Decreases in summer sea ice extent in the Beaufort and Chukchi Seas has lead to a transition from a largely perennial ice cover, to a seasonal ice cover. This drives shifts in sea ice production, dynamics, ice types, and thickness distribution. To examine how the processes driving ice advance might also impact the morphology of the ice cover, a coordinated ice mapping effort was undertaken during a field campaign in the Beaufort Sea in October, 2015. Here, we present observations of sea ice draft topography from six missions of an Autonomous Underwater Vehicle run under different ice types and deformation features observed during autumn freeze-up. Ice surface features were also mapped during coordinated drone photogrammetric missions over each site. We present preliminary results of a comparison between sea ice surface topography and ice underside morphology for a range of sample ice types, including hummocked multiyear ice, rubble fields, young ice ridges and rafts, and consolidated pancake ice. These data are compared to prior observations of ice morphological features from deformed Antarctic sea ice. Such data will be useful for improving parameterizations of sea ice redistribution during deformation, and for better constraining estimates of airborne or satellite sea ice thickness.

  12. Deformation mechanisms in nanotwinned metal nanopillars.

    Science.gov (United States)

    Jang, Dongchan; Li, Xiaoyan; Gao, Huajian; Greer, Julia R

    2012-09-01

    Nanotwinned metals are attractive in many applications because they simultaneously demonstrate high strength and high ductility, characteristics that are usually thought to be mutually exclusive. However, most nanotwinned metals are produced in polycrystalline forms and therefore contain randomly oriented twin and grain boundaries making it difficult to determine the origins of their useful mechanical properties. Here, we report the fabrication of arrays of vertically aligned copper nanopillars that contain a very high density of periodic twin boundaries and no grain boundaries or other microstructural features. We use tension experiments, transmission electron microscopy and atomistic simulations to investigate the influence of diameter, twin-boundary spacing and twin-boundary orientation on the mechanical responses of individual nanopillars. We observe a brittle-to-ductile transition in samples with orthogonally oriented twin boundaries as the twin-boundary spacing decreases below a critical value (∼3-4 nm for copper). We also find that nanopillars with slanted twin boundaries deform via shear offsets and significant detwinning. The ability to decouple nanotwins from other microstructural features should lead to an improved understanding of the mechanical properties of nanotwinned metals.

  13. A mechanism for tectonic deformation on Venus

    Science.gov (United States)

    Phillips, Roger J.

    1986-01-01

    In the absence of identifiable physiographic features directly associated with plate tectonics, alternate mechanisms are sought for the intense tectonic deformation observed in radar images of Venus. One possible mechanism is direct coupling into an elastic lithosphere of the stresses associated with convective flow in the interior. Spectral Green's function solutions have been obtained for stresses in an elastic lithosphere overlying a Newtonian interior with an exponential depth dependence of viscosity, and a specified surface-density distribution driving the flow. At long wavelengths and for a rigid elastic/fluid boundary condition, horizontal normal stresses in the elastic lid are controlled by the vertical shear stress gradient and are directly proportional to the depth of the density disturbance in the underlying fluid. The depth and strength of density anomalies in the Venusian interior inferred by analyses of long wavelength gravity data suggest that stresses in excess of 100 MPa would be generated in a 10 km thick elastic lid unless a low viscosity channel occurring beneath the lid or a positive viscosity gradient uncouples the flow stresses. The great apparent depth of compensation of topographic features argues against this, however, thus supporting the importance of the coupling mechanism. If there is no elastic lid, stresses will also be very high near the surface, providing also that the viscosity gradient is negative.

  14. Mapping deformation method and its application to nonlinear equations

    Institute of Scientific and Technical Information of China (English)

    李画眉

    2002-01-01

    An extended mapping deformation method is proposed for finding new exact travelling wave solutions of nonlinearpartial differential equations (PDEs). The key idea of this method is to take full advantage of the simple algebraicmapping relation between the solutions of the PDEs and those of the cubic nonlinear Klein-Gordon equation. This isapplied to solve a system of variant Boussinesq equations. As a result, many explicit and exact solutions are obtained,including solitary wave solutions, periodic wave solutions, Jacobian elliptic function solutions and other exact solutions.

  15. Mechanics of deformable bodies lectures on theoretical physics

    CERN Document Server

    Sommerfeld, Arnold

    1950-01-01

    Mechanics of Deformable Bodies: Lectures on Theoretical Physics, Volume II covers topics on the mechanics of deformable bodies. The book discusses the kinematics, statics, and dynamics of deformable bodies; the vortex theory; as well as the theory of waves. The text also describes the flow with given boundaries. Supplementary notes on selected hydrodynamic problems and supplements to the theory of elasticity are provided. Physicists, mathematicians, and students taking related courses will find the book useful.

  16. Hot Deformation Behavior and Processing Maps of 2099 Al-Li Alloy

    Science.gov (United States)

    Chen, Bin; Tian, Xiao-lin; Li, Xiao-ling; Lu, Chen

    2014-06-01

    Hot deformation behavior and processing maps of the 2099 Al-Li alloy are investigated by tensile test at the temperature range from 250 to 450 °C and the strain rate range from 0.001 to 5.0 s-1. The typical true stress-true strain curves show that the flow stress increases with increasing the strain rate and decreasing the deforming temperature. All curves exhibit rapid work hardening at an initial stage of strain followed by remarkable dynamic softening. Based on the flow stress behavior, the processing maps are calculated and analyzed according to the dynamic materials model (DMM). The processing maps exhibit an instability domain in the temperature and strain rate ranges: T = 250-260 °C and = 0.1-0.5 s-1. The maps also exhibit an optimum hot working condition in the stability domain that occurs in the temperature of 400 °C for a strain rate of 0.001 s-1 and having a maximum efficiency of 60%. The microstructural examinations exhibit the occurrence of dynamic recovery (DRV) during hot deformation of the 2099 alloy which is the dominant softening mechanism in the alloy. The fracture behavior changes from a brittle fracture to a ductile fracture as strain rate decreases and temperature increases.

  17. Polypropylene–rubber blends: 5. Deformation mechanism during fracture

    NARCIS (Netherlands)

    Wal, van der A.; Gaymans, R.J.

    1999-01-01

    The deformation mechanism of polypropylene–EPDM rubber blends during fracture was studied by post-mortem SEM fractography. The deformation mechanism was determined for various blend morphologies and test conditions. Brittle fracture merely gives rise to voids, which are caused by voiding of the rubb

  18. Structural refinement and deformation mechanisms in nanostructured metals

    DEFF Research Database (Denmark)

    Lu, K.; Hansen, Niels

    2009-01-01

    Deformation mechanisms in metals deformed to ultrahigh strains are analyzed based on a general pattern of grain subdivision down to structural scales 10 nm. The materials analyzed are medium- to high-stacking fault energy face-centered cubic and body-centered cubic metals with different loading...... conditions. The analysis points to dislocation glide as the dominant deformation mechanism at different length scales supplemented by a limited amount of twinning at the finest scales. With decreasing deformation temperature and increasing strain rate, the contribution of twinning increases...

  19. Transition in Deformation Mechanism of AZ31 Magnesium Alloy during High-Temperature Tensile Deformation

    Directory of Open Access Journals (Sweden)

    Masafumi Noda

    2011-01-01

    Full Text Available Magnesium alloys can be used for reducing the weight of various structural products, because of their high specific strength. They have attracted considerable attention as materials with a reduced environmental load, since they help to save both resources and energy. In order to use Mg alloys for manufacturing vehicles, it is important to investigate the deformation mechanism and transition point for optimizing the material and vehicle design. In this study, we investigated the transition of the deformation mechanism during the high-temperature uniaxial tensile deformation of the AZ31 Mg alloy. At a test temperature of 523 K and an initial strain rate of 3×10−3 s-1, the AZ31 Mg alloy (mean grain size: ~5 μm exhibited stable deformation behavior and the deformation mechanism changed to one dominated by grain boundary sliding.

  20. Plastic mechanism of deformation of garnet-- Water weakening

    Institute of Scientific and Technical Information of China (English)

    SU; Wen(苏文); CONG; Bolin(从柏林); YOU; Zhendong(游振东); ZHONG; Zengqiu(钟增球); CHEN; Daizhang(陈代章)

    2002-01-01

    The strongly deformed eclogites are well developed in ultra-high pressure jadeite-quartzite zone of the Dabie Mountains, Eastern China, and garnets had been deformed strongly. Observations by transmission electron microscopy identified not only structure of plastic deformation occurring as free dislocation, dislocation loops and dislocation walls, but also clusters of water molecules present in the deformed garnet. Using infrared spectroscopy, two types of hydrous components are identified as the hydroxyl and free-water in the garnet. Based on analysis of microstructure mechanism of deformation in garnets, and experimental data of petrology, the clusters of water molecules were considered to lead strong plastic deformation of garnet by dislocations because of mechanical weakening.

  1. Inelastic deformation mechanisms in a transverse MMC lamina under compression

    Science.gov (United States)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1992-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Both mechanical behavior and microstructural evaluation were undertaken at room temperature, 538 and 650 C. Results indicate that mechanical response and deformation characteristics are significantly different in monotonic tension and compression. The inelastic deformation mechanisms in compression are controlled by radial fiber fracture, matrix plasticity and fiber-matrix debonding. The radial fiber fracture is a new damage mode observed for metal-matrix composites (MMC).

  2. Mechanisms of crustal deformation in the western US

    Science.gov (United States)

    Turcotte, Donald L.

    1986-01-01

    The deformation processes in the western United States were studied, considering both deterministic models and random or statistical models. The role of the intracrustal delamination and mechanisms of crustal thinning were also examined. The application of fractal techniques to understand how the crust is deforming was studied in complex regions. Work continued on the development of a fractal based model for deformation in the western United States. Fractal studies were also extended to the study of topography and the geoid.

  3. Mechanisms of plastic deformation for powder materials in cold working

    Institute of Scientific and Technical Information of China (English)

    张连洪; 李双义

    2003-01-01

    To deal with the discontinuity of particulate media and subsequent uncertainty of stress, based on the probability theory for mechanics of particulate media, Mohr-Coulomb yield criterion of particulate media, and the theory of crystal deformation, we put forward the statistical mechanisms of deformation of powder materials in cold working and mechanism of texture development of the high temperature superconducting wire/tape. A new yield criterion of powder materials is proposed.

  4. Deformation and failure mechanisms in metal matrix composites

    Science.gov (United States)

    Newaz, G.; Majumdar, B. S.

    1991-01-01

    An investigation was undertaken to determine the key deformation mechanisms and their interaction leading to failure of both 0 degree and 90 degree Ti 15-3/SCS-6 laminae under monotonic loading. The experimental results suggest that inelastic deformation in the 0-degree lamina is dominated by plastic deformation and that in the 90-degree lamina is dominated by both fiber-matrix debonding and plasticity. The loading-unloading response, monitoring of Poisson's ratio and microscopy were utilized to identify the key deformation mechanisms. The sequence of deformation mechanisms leading to failure are identified for both the 0 and the 90-degree specimens. The threshold strains for plasticity or damage which are referred to as 'microdeformation' in the 0 deg and 90 deg laminae are approximately 0.004 and 0.002, respectively, at room temperature. These strain levels may be considered critical in initiation based structural design with these composites.

  5. Deformation behavior and mechanisms of Ti- 1023 alloy

    Institute of Scientific and Technical Information of China (English)

    BAO Ru-qiang; HUANG Xu; CAO Chun-xiao

    2006-01-01

    The deformation behavior and mechanisms of Ti-1023 alloy were studied in the temperature range of 650-900 ℃ and strain rate range of 0.001-10 s-1 by compression and tensile tests. The results show that in a limited strain rate range of 0.001-0.1 s-1,the kinetic rate equation is obeyed and a linear fit is obtained at all the temperatures. The apparent activation energy is 322 kJ/mol in the α-β region and 160 kJ/mol in the β region, respectively. Power dissipation maps of this alloy developed by using Gleeble test data show three domains in the tested range. Superplasticity, marked by abnormal elongation at 700 ℃, occurs in the temperature range of 650-750 ℃ and at strain rates below about 0.03 s-1 Large grain superplasticity takes place in the temperature range of 750-850℃ and strain rates range of 0.001-0.03 s-1. Dynamic recrystallization occurs in the temperature range of 850-900 ℃ and at strain rates below about 1 s-1. The instability maps of this alloy were also developed.

  6. Identification of deformation mechanisms in ice core samples

    OpenAIRE

    Kuiper, E.N.; Weikusat, I.; Drury, M.R.; Pennock, G.M.; de Winter, Matthijs

    2014-01-01

    To determine active deformation mechanisms in polar ice. We use LM and Electron BackScattered Diffraction to identify possible slip systems of subgrain boundaries in EDML (Antarctica) and NEEM (Greenland) ice cores.

  7. RECENT PROGRESS OF NANO-MECHANICAL MAPPING

    Institute of Scientific and Technical Information of China (English)

    Toshio Nishi; Sac Nagai; So Fujinami; Ken Nakajima

    2009-01-01

    Nano-mechanical mapping by atomic force microscopy has been developed as an useful application to measure mechanical properties of soft materials at nanometer scale.To date,the Hertzian theory was used for analyzing forcedistance curves as the simplest model among several contact mechanics between elastic bodies.However,the preexisting methods based on this theory do not consider the adhesive interaction in principle,which cannot be neglected in the ambient condition.A new analytical method was introduced to estimate the elasticity and the adhesive energy simultaneously by means of the JKR theory,describing adhesive contact between elastic materials.Poly(dimethylsiloxane) (PDMS) and isobutylene-co-isoprene rubber (IIR) were analyzed to verify the applicable limit of the JKR analysis.For elastic samples such as PDMS,the force-deformation plots obtained experimentally were consistent with JKR theoretical curves.Meanwhile,for viscoelastic samples,especially for IIR,the experimental plots revealed large deviations from JKR curves depending on scanning velocity and maximum loading force.Some nano-rheological arguments were employed based on the difference between these specimens.

  8. Deformation mechanism of cryorolled Fe-36%Ni strip steel

    Directory of Open Access Journals (Sweden)

    Li Changsheng

    2015-01-01

    Full Text Available The deformation mechanism of cryogenic rolled Fe-36%Ni steel is investigated with rolling strain of ε = 0.24–0.92. Experimental results show that both dislocation slip and twinning are activated at cryogenic temperature as strain ε = 0.24, and the mean thickness of deformation twins is about 200 nm. When the rolling strain increases to 0.53, the mean thickness of deformation twins reduces to 50 nm and some curved deformation twins exists. As the rolling strain increases to 0.92, the thickness of deformation twins is no longer changed and the micro shear bands exist due to the concentration of work hardening, which suggests that twinning is activated at the early stage of cryogenic rolling (CR process. It is assumed that more deformation twins will be fragmented by shear bands during the following CR. The dislocation slip becomes the dominated mechanism again during the following deformation. The mechanism of the Fe-36%Ni steel following CR was analyzed quantitatively.

  9. Visual Encoding of Dissimilarity Data via Topology-Preserving Map Deformation.

    Science.gov (United States)

    Bouts, Quirijn W; Dwyer, Tim; Dykes, Jason; Speckmann, Bettina; Goodwin, Sarah; Riche, Nathalie Henry; Carpendale, Sheelagh; Liebman, Ariel

    2016-09-01

    We present an efficient technique for topology-preserving map deformation and apply it to the visualization of dissimilarity data in a geographic context. Map deformation techniques such as value-by-area cartograms are well studied. However, using deformation to highlight (dis)similarity between locations on a map in terms of their underlying data attributes is novel. We also identify an alternative way to represent dissimilarities on a map through the use of visual overlays. These overlays are complementary to deformation techniques and enable us to assess the quality of the deformation as well as to explore the design space of blending the two methods. Finally, we demonstrate how these techniques can be useful in several-quite different-applied contexts: travel-time visualization, social demographics research and understanding energy flowing in a wide-area power-grid.

  10. Application of the Deformation Information System for automated analysis and mapping of mining terrain deformations - case study from SW Poland

    Science.gov (United States)

    Blachowski, Jan; Grzempowski, Piotr; Milczarek, Wojciech; Nowacka, Anna

    2015-04-01

    Monitoring, mapping and modelling of mining induced terrain deformations are important tasks for quantifying and minimising threats that arise from underground extraction of useful minerals and affect surface infrastructure, human safety, the environment and security of the mining operation itself. The number of methods and techniques used for monitoring and analysis of mining terrain deformations is wide and expanding with the progress in geographical information technologies. These include for example: terrestrial geodetic measurements, Global Navigation Satellite Systems, remote sensing, GIS based modelling and spatial statistics, finite element method modelling, geological modelling, empirical modelling using e.g. the Knothe theory, artificial neural networks, fuzzy logic calculations and other. The presentation shows the results of numerical modelling and mapping of mining terrain deformations for two cases of underground mining sites in SW Poland, hard coal one (abandoned) and copper ore (active) using the functionalities of the Deformation Information System (DIS) (Blachowski et al, 2014 @ http://meetingorganizer.copernicus.org/EGU2014/EGU2014-7949.pdf). The functionalities of the spatial data modelling module of DIS have been presented and its applications in modelling, mapping and visualising mining terrain deformations based on processing of measurement data (geodetic and GNSS) for these two cases have been characterised and compared. These include, self-developed and implemented in DIS, automation procedures for calculating mining terrain subsidence with different interpolation techniques, calculation of other mining deformation parameters (i.e. tilt, horizontal displacement, horizontal strain and curvature), as well as mapping mining terrain categories based on classification of the values of these parameters as used in Poland. Acknowledgments. This work has been financed from the National Science Centre Project "Development of a numerical method of

  11. Impact of mechanical deformation on space charge in XLPE

    OpenAIRE

    Chen, G; Kamaruzzaman, M. R.

    2007-01-01

    In this paper we report the effect of mechanical deformation on space charge dynamics in crosslinked polyethylene. Thin films were peeled from a 66 kV commercial XLPE cable. Space charge measurements under dc electric fields have been monitored using the pulsed electroacoustic (PEA) technique. It has been found that charge dynamics in deformed XLPE are different from that from undeformed XLPE at lower voltages. At low applied electric field, space charge is dominated by heterocharge in the de...

  12. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles.

    Directory of Open Access Journals (Sweden)

    Olga Kononova

    2016-01-01

    Full Text Available The mechanical properties of virus capsids correlate with local conformational dynamics in the capsid structure. They also reflect the required stability needed to withstand high internal pressures generated upon genome loading and contribute to the success of important events in viral infectivity, such as capsid maturation, genome uncoating and receptor binding. The mechanical properties of biological nanoparticles are often determined from monitoring their dynamic deformations in Atomic Force Microscopy nanoindentation experiments; but a comprehensive theory describing the full range of observed deformation behaviors has not previously been described. We present a new theory for modeling dynamic deformations of biological nanoparticles, which considers the non-linear Hertzian deformation, resulting from an indenter-particle physical contact, and the bending of curved elements (beams modeling the particle structure. The beams' deformation beyond the critical point triggers a dynamic transition of the particle to the collapsed state. This extreme event is accompanied by a catastrophic force drop as observed in the experimental or simulated force (F-deformation (X spectra. The theory interprets fine features of the spectra, including the nonlinear components of the FX-curves, in terms of the Young's moduli for Hertzian and bending deformations, and the structural damage dependent beams' survival probability, in terms of the maximum strength and the cooperativity parameter. The theory is exemplified by successfully describing the deformation dynamics of natural nanoparticles through comparing theoretical curves with experimental force-deformation spectra for several virus particles. This approach provides a comprehensive description of the dynamic structural transitions in biological and artificial nanoparticles, which is essential for their optimal use in nanotechnology and nanomedicine applications.

  13. Deformation and Failure Mechanisms of Shape Memory Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Daly, Samantha Hayes [Univ. of Michigan, Ann Arbor, MI (United States)

    2015-04-15

    The goal of this research was to understand the fundamental mechanics that drive the deformation and failure of shape memory alloys (SMAs). SMAs are difficult materials to characterize because of the complex phase transformations that give rise to their unique properties, including shape memory and superelasticity. These phase transformations occur across multiple length scales (one example being the martensite-austenite twinning that underlies macroscopic strain localization) and result in a large hysteresis. In order to optimize the use of this hysteretic behavior in energy storage and damping applications, we must first have a quantitative understanding of this transformation behavior. Prior results on shape memory alloys have been largely qualitative (i.e., mapping phase transformations through cracked oxide coatings or surface morphology). The PI developed and utilized new approaches to provide a quantitative, full-field characterization of phase transformation, conducting a comprehensive suite of experiments across multiple length scales and tying these results to theoretical and computational analysis. The research funded by this award utilized new combinations of scanning electron microscopy, diffraction, digital image correlation, and custom testing equipment and procedures to study phase transformation processes at a wide range of length scales, with a focus at small length scales with spatial resolution on the order of 1 nanometer. These experiments probe the basic connections between length scales during phase transformation. In addition to the insights gained on the fundamental mechanisms driving transformations in shape memory alloys, the unique experimental methodologies developed under this award are applicable to a wide range of solid-to-solid phase transformations and other strain localization mechanisms.

  14. Analysis of Deformation Mechanisms Associated with Biaxially Oriented Polypropylene Films

    Science.gov (United States)

    Wang, Yong; Hsu, Shaw Ling

    1998-03-01

    Biaxially oriented samples can be prepared either by simultaneous or sequential deformation along two orthogonal directions. Generally speaking the orientation achieved in the plane of the film is independent of the method. In this study, we demonstrate that for sequential deformation, the degree of orientation achieved in the two orthogonal directions is dependent on initial sample morphology and deformation parameters. The achievable orientation is strongly dependent on the degree of crystallinity and initial crystallite dimensions. Samples containing small crystallites can achieve significantly higher orientation in the transverse direction (restretching step). The ultimate morphology is dictated by the temperature at which second drawing occurs. At lower deformation temperature, rotation of stacked crystalline lamellae can be accomplished to form biaxially oriented films. At higher temperatures, the dominant mechanism is unfolding of crystalline chain segments followed by recrystallization into units aligned with the restretching direction. X-ray diffraction, polarized infrared and Raman spectroscopy, and calorimetric techniques were employed to analyze these structural transformations.

  15. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles

    CERN Document Server

    Kononova, Olga; Marx, Kenneth A; Wuite, Gijs J L; Roos, Wouter H; Barsegov, Valeri

    2015-01-01

    We present a new theory for modeling forced indentation spectral lineshapes of biological particles, which considers non-linear Hertzian deformation due to an indenter-particle physical contact and bending deformations of curved beams modeling the particle structure. The bending of beams beyond the critical point triggers the particle dynamic transition to the collapsed state, an extreme event leading to the catastrophic force drop as observed in the force (F)-deformation (X) spectra. The theory interprets fine features of the spectra: the slope of the FX curves and the position of force-peak signal, in terms of mechanical characteristics --- the Young's moduli for Hertzian and bending deformations E_H and E_b, and the probability distribution of the maximum strength with the strength of the strongest beam F_b^* and the beams' failure rate m. The theory is applied to successfully characterize the $FX$ curves for spherical virus particles --- CCMV, TrV, and AdV.

  16. Inference of postseismic deformation mechanisms of the 1923 Kanto earthquake

    Science.gov (United States)

    Pollitz, F.F.; Nyst, M.; Nishimura, T.; Thatcher, W.

    2006-01-01

    Coseismic slip associated with the M7.9, 1923 Kanto earthquake is fairly well understood, involving slip of up to 8 m along the Philippine Sea-Honshu interplate boundary under Sagami Bay and its onland extension. Postseismic deformation after the 1923 earthquake, however, is relatively poorly understood. We revisit the available deformation data in order to constrain possible mechanisms of postseismic deformation and to examine the consequences for associated stress changes in the surrounding crust. Data from two leveling lines and one tide gage station over the first 7-8 years postseismic period are of much greater amplitude than the corresponding expected interseismic deformation during the same period, making these data suitable for isolating the signal from postseismic deformation. We consider both viscoelastic models of asthenosphere relaxation and afterslip models. A distributed coseismic slip model presented by Pollitz et al. (2005), combined with prescribed parameters of a viscoelastic Earth model, yields predicted postseismic deformation that agrees with observed deformation on mainland Honshu from Tokyo to the Izu peninsula. Elsewhere (southern Miura peninsula; Boso peninsula), the considered viscoelastic models fail to predict observed deformation, and a model of ???1 in shallow afterslip in the offshore region south of the Boso peninsula, with equivalent moment magnitude Mw = 7.0, adequately accounts for the observed deformation. Using the distributed coseismic slip model, layered viscoelastic structure, and a model of interseismic strain accumulation, we evaluate the post-1923 stress evolution, including both the coseismic and accumulated postseismic stress changes and those stresses contributed by interseismic loading. We find that if account is made for the varying tectonic regime in the region, the occurrence of both immediate (first month) post-1923 crustal aftershocks as well as recent regional crustal seismicity is consistent with the predicted

  17. Scattering and Bound States of a Deformed Quantum Mechanics

    CERN Document Server

    Ching, Chee-Leong

    2012-01-01

    We construct the exact position representation of a deformed quantum mechanics which exhibits an intrinsic maximum momentum and use it to study problems such as a particle in a box and scattering from a step potential, among others. In particular, we show that unlike usual quantum mechanics, the present deformed case delays the formation of bound states in a finite potential well. In the process we also highlight some limitations and pit-falls of low-momentum or perturbative treatments and thus resolve two puzzles occurring in the literature.

  18. Nanoscale Deformation and Toughening Mechanisms of Nacre

    Science.gov (United States)

    2011-03-31

    dental implant. Biomaterials 2005;26:6229-32. [6] A. Sellinger, P.M. Weiss, A. Nguyen, Y. Lu, R.A. Assink, W. Gong, C.J. Brinker, Nature 1998, 394, 252...Editorial Board, International Journal of Applied Mechanics Editorial Board, Journal of Biomaterials and Nanobiotechnology Editorial Board, Journal of...A. Guetted, R. Naslaind, and X. Bourrat, Biomaterials 26, 6254 (2005). [8] X. D. Li, Z. H. Xu, and R. Z. Wang, Nano Lett. 6, 2301 (2006). [9] K. Wada

  19. Dynamic tensile behaviour and deformational mechanism of C5191 phosphor bronze under high strain rates deformation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Dao-chun [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Taizhou Vocational & Technical College, Taizhou 318000 (China); Chen, Ming-he, E-mail: meemhchen@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Lei; Cheng, Hu [College of Mechanical Engineering, Taizhou University, Taizhou 318000 (China)

    2016-01-01

    High speed stamping process is used to high strength and high electrical conductivity phosphor bronze with extremely high strain rates more than 10{sup 3} s{sup −1}. This study on the dynamic tensile behaviour and deformational mechanism is to optimise the high speed stamping processes and improve geometrical precision in finished products. Thus, the tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s{sup −1} by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s{sup −1} by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the deformation mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 11.07% respectively compared with quasi-static condition, the strain hardening index increases from 0.075 to 0.251, and the strength of the material strain rates sensitivity index change from 0.005 to 0.022, which presented a clear sensitive to strain rates. Therefore, it is claimed that the dominant deformation mechanism was changed by the dislocation motion under different strain rates, and the ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s{sup −1}.

  20. Analysis of soft rock roadway deformation mechanism in Zhangshuanglou Mine

    Institute of Scientific and Technical Information of China (English)

    顾士亮

    2003-01-01

    On basis of ground stress surveying and analysis of physical nature and mechanics character of rock, the deformation mechanism of west main roadway in Zhangshuanglou Mine is studied. It is put forward that engineering mechanics nature, infiltration of water and concentrated stress on pillar are the main factors to affect stability of the west main roadway. The overall thinking used to restore the roadway is raised.

  1. Hot deformation of spray formed nickel-base superalloy using processing maps

    Institute of Scientific and Technical Information of China (English)

    KANG Fu-wei; ZHANG Guo-qing; LI Zhou; SUN Jian-fei

    2008-01-01

    The hot compression testing of hot isostatically pressed (HIPed) spray formed (SF) nickel-base superalloy was carried out by thermal mechanical simulator in the temperature range of 1050-1140℃ at strain rates of 0.01-10 S-1 and engineering strain of 50%. A processing map was developed on the basis of these data by using the principles of dynamic materials modeling. The microstructural evolution of deformed samples was also examined on the basis of optical and electron microscopic observations. The map exhibits two domains: the instability domain at the temperatures of 1050℃-1110℃ and strain rate of 0.01 S-1, the stability domain at the temperatures of 1110℃-1140℃ and strain rates of 1s-1-10 S-1, with a peak efficiency of about 40%. The dynamic recrystallization(DRX) is observed in the stability domain and the deformed specimens are no cracking or instabilities. However, there is no DRX in the instability domain and the alloy exhibits flow instability with cracks due to poor workability. The optimum hot working condition Was determined in the stability domain.

  2. Angularly Deformed Special Relativity and its Results for Quantum Mechanics

    CERN Document Server

    Glinka, Lukasz Andrzej

    2015-01-01

    In this paper, the deformed Special Relativity, which leads to an essentially new theoretical context of quantum mechanics, is presented. The formulation of the theory arises from a straightforward analogy with the Special Relativity, but its foundations are laid through the hypothesis on breakdown of the velocity-momentum parallelism which affects onto the Einstein equivalence principle between mass and energy of a relativistic particle. Furthermore, the derivation is based on the technique of an eikonal equation whose well-confirmed physical role lays the foundations of both optics and quantum mechanics. As a result, we receive the angular deformation of Special Relativity which clearly depicts the new deformation-based theoretical foundations of physics, and, moreover, offers both constructive and consistent phenomenological discussion of the theoretical issues such like imaginary mass and formal superluminal motion predicted in Special Relativity for this case. In the context of the relativistic theory, p...

  3. Transformation from slip to plastic flow deformation mechanism during tensile deformation of zirconium nanocontacts

    Science.gov (United States)

    Yamada, Kohei; Kizuka, Tokushi

    2017-01-01

    Various types of nanometer-sized structures have been applied to advanced functional and structural devices. Inherent structures, thermal stability, and properties of such nanostructures are emphasized when their size is decreased to several nanometers, especially, to several atoms. In this study, we observed the atomistic tensile deformation process of zirconium nanocontacts, which are typical nanostructures used in connection of nanometer-sized wires, transistors, and diodes, memory devices, and sensors, by in situ transmission electron microscopy. It was found that the contact was deformed via a plastic flow mechanism, which differs from the slip on lattice planes frequently observed in metals, and that the crystallinity became disordered. The various irregular relaxed structures formed during the deformation process affected the conductance. PMID:28218244

  4. Grain Refinement and Deformation Mechanisms in Room Temperature Severe Plastic Deformed Mg-AZ31

    Directory of Open Access Journals (Sweden)

    Ludwig Schultz

    2013-07-01

    Full Text Available A Ti-AZ31 composite was severely plastically deformed by rotary swaging at room temperature up to a logarithmic deformation strain of 2.98. A value far beyond the forming limit of pure AZ31 when being equivalently deformed. It is observed, that the microstructure evolution in Mg-AZ31 is strongly influenced by twinning. At low strains the {̅1011} (10̅12 and the {̅1012} (10̅11 twin systems lead to fragmentation of the initial grains. Inside the primary twins, grain refinement takes place by dynamic recrystallization, dynamic recovery and twinning. These mechanisms lead to a final grain size of ≈1 μm, while a strong centered ring fibre texture is evolved.

  5. Transformation from slip to plastic flow deformation mechanism during tensile deformation of zirconium nanocontacts

    Science.gov (United States)

    Yamada, Kohei; Kizuka, Tokushi

    2017-02-01

    Various types of nanometer-sized structures have been applied to advanced functional and structural devices. Inherent structures, thermal stability, and properties of such nanostructures are emphasized when their size is decreased to several nanometers, especially, to several atoms. In this study, we observed the atomistic tensile deformation process of zirconium nanocontacts, which are typical nanostructures used in connection of nanometer-sized wires, transistors, and diodes, memory devices, and sensors, by in situ transmission electron microscopy. It was found that the contact was deformed via a plastic flow mechanism, which differs from the slip on lattice planes frequently observed in metals, and that the crystallinity became disordered. The various irregular relaxed structures formed during the deformation process affected the conductance.

  6. Molecular deformation mechanisms of the wood cell wall material.

    Science.gov (United States)

    Jin, Kai; Qin, Zhao; Buehler, Markus J

    2015-02-01

    Wood is a biological material with outstanding mechanical properties resulting from its hierarchical structure across different scales. Although earlier work has shown that the cellular structure of wood is a key factor that renders it excellent mechanical properties at light weight, the mechanical properties of the wood cell wall material itself still needs to be understood comprehensively. The wood cell wall material features a fiber reinforced composite structure, where cellulose fibrils act as stiff fibers, and hemicellulose and lignin molecules act as soft matrix. The angle between the fiber direction and the loading direction has been found to be the key factor controlling the mechanical properties. However, how the interactions between theses constitutive molecules contribute to the overall properties is still unclear, although the shearing between fibers has been proposed as a primary deformation mechanism. Here we report a molecular model of the wood cell wall material with atomistic resolution, used to assess the mechanical behavior under shear loading in order to understand the deformation mechanisms at the molecular level. The model includes an explicit description of cellulose crystals, hemicellulose, as well as lignin molecules arranged in a layered nanocomposite. The results obtained using this model show that the wood cell wall material under shear loading deforms in an elastic and then plastic manner. The plastic regime can be divided into two parts according to the different deformation mechanisms: yielding of the matrix and sliding of matrix along the cellulose surface. Our molecular dynamics study provides insights of the mechanical behavior of wood cell wall material at the molecular level, and paves a way for the multi-scale understanding of the mechanical properties of wood.

  7. High-Resolution Reciprocal Space Mapping for Characterizing Deformation Structures

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, Bo

    2014-01-01

    each subgrain, but larger variations between different subgrains. On average, subgrains experience backward strains, whereas dislocation walls are strained in a forward direction. Based on these observations the necessary revision of the classical composite model is outlined. Additionally, subgrain...... relaxation occurs, but no changes in number, size and orientation of the subgrains are observed. The radial profile asymmetry becomes reversed, when pre-deformed specimens are deformed in tension along a perpendicular axis....

  8. Quantum Tunneling In Deformed Quantum Mechanics with Minimal Length

    CERN Document Server

    Guo, Xiaobo; Tao, Jun; Wang, Peng

    2016-01-01

    In the deformed quantum mechanics with a minimal length, one WKB connection formula through a turning point is derived. We then use it to calculate tunnelling rates through potential barriers under the WKB approximation. Finally, the minimal length effects on two examples of quantum tunneling in nuclear and atomic physics are discussed

  9. Mechanical deformations of boron nitride nanotubes in crossed junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yadong; Chen, Xiaoming; Ke, Changhong, E-mail: cke@binghamton.edu [Department of Mechanical Engineering, State University of New York at Binghamton, Binghamton, New York 13902 (United States); Park, Cheol [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Fay, Catharine C. [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Stupkiewicz, Stanislaw [Institute of Fundamental Technological Research, Warsaw (Poland)

    2014-04-28

    We present a study of the mechanical deformations of boron nitride nanotubes (BNNTs) in crossed junctions. The structure and deformation of the crossed tubes in the junction are characterized by using atomic force microscopy. Our results show that the total tube heights are reduced by 20%–33% at the crossed junctions formed by double-walled BNNTs with outer diameters in the range of 2.21–4.67 nm. The measured tube height reduction is found to be in a nearly linear relationship with the summation of the outer diameters of the two tubes forming the junction. The contact force between the two tubes in the junction is estimated based on contact mechanics theories and found to be within the range of 4.2–7.6 nN. The Young's modulus of BNNTs and their binding strengths with the substrate are quantified, based on the deformation profile of the upper tube in the junction, and are found to be 1.07 ± 0.11 TPa and 0.18–0.29 nJ/m, respectively. Finally, we perform finite element simulations on the mechanical deformations of the crossed BNNT junctions. The numerical simulation results are consistent with both the experimental measurements and the analytical analysis. The results reported in this paper contribute to a better understanding of the structural and mechanical properties of BNNTs and to the pursuit of their applications.

  10. Accardi complementarity in $\\mu$-deformed quantum mechanics

    OpenAIRE

    Pita-Ruiz, Claudio; Sontz, Stephen B.

    2005-01-01

    In this note we show that the momentum and position operators of $\\mu$-deformed quantum mechanics for $\\mu > 0$ are not Accardi complementary in a sense that we will define. We conjecture that this is also true if $-1/2 < \\mu < 0$.

  11. Conformal mapping modeling of metal plastic deformation and die cavity in special-shaped extrusion

    Institute of Scientific and Technical Information of China (English)

    齐红元; 朱衡君; 杜凤山; 刘才

    2002-01-01

    With the help of Complex Function Mapping studied results, the analysis function of Conformal Mapping is set up. Since the complicated three dimension's deformation problems are transferred into two dimension problems, both the stream function and strain ratio field are analyzed in the metal plastic deformation. Using the upper-bound principles, the theory of metal deformation and die cavity optimized modeling is established for random special-shaped product extrusion. As a result, this enables the realization of intelligent technique target in the die cavity of CAD/CAM integration.

  12. Deformation of supersymmetric and conformal quantum mechanics through affine transformations

    Science.gov (United States)

    Spiridonov, Vyacheslav

    1993-01-01

    Affine transformations (dilatations and translations) are used to define a deformation of one-dimensional N = 2 supersymmetric quantum mechanics. Resulting physical systems do not have conserved charges and degeneracies in the spectra. Instead, superpartner Hamiltonians are q-isospectral, i.e. the spectrum of one can be obtained from another (with possible exception of the lowest level) by q(sup 2)-factor scaling. This construction allows easily to rederive a special self-similar potential found by Shabat and to show that for the latter a q-deformed harmonic oscillator algebra of Biedenharn and Macfarlane serves as the spectrum generating algebra. A general class of potentials related to the quantum conformal algebra su(sub q)(1,1) is described. Further possibilities for q-deformation of known solvable potentials are outlined.

  13. 3D brain mapping using a deformable neuroanatomy

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, G.E.; Rabbitt, R.D.; Miller, M.I. (Washington Univ., St. Louis, MO (United States))

    1994-03-01

    This paper presents two different mathematical methods that can be used separately or in conjunction to accommodate shape variabilities between normal human neuroanatomies. Both methods use a digitized textbook to represent the complex structure of a typical normal neuroanatomy. Probabilistic transformations on the textbook coordinate system are defined to accommodate shape differences between the textbook and images of other normal neuroanatomies. The transformations are constrained to be consistent with the physical properties of deformable elastic solids in the first method and those of viscous fluids in the second. Results presented in this paper demonstrate how a single deformable textbook can be used to accommodate normal shape variability. (Author).

  14. Deformation Mechanism and Stability of a Rocky Slope

    Institute of Scientific and Technical Information of China (English)

    Huang Runqiu; Xiao Huabo; Ju Nengpan; Zhao Jianjun

    2007-01-01

    A high slope is located on the side of the spillway at a hydropower station in Southwest China, which has some weak inter-layers inclining outwards. Parts of the slope show heavy weathering and unloading. There appeared deformation and tensile crack either on the surface or on the afteredge of the slope during excavation, and under a platform (elev. 488 m), two levels of slopes collapsed on the downriver side. Based on the investigation in situ and the analysis of the geological structure, the conceptual model of deformation and failure mechanism was erected for this slope. Furthermore, the deformation characteristics were studied with FLAC3D numerical simulation. Comprehensive analysis shows that the whole deformation of the slope is unloading rebound in certain depth scope and the whole body does not slide along any weak interlayer. In addition, two parts with prominent local deformation in the shallow layer of the slope show the models of "creep sliding-tensile cracking" and "sliding-tensile cracking", respectively. Based on the above analysis, the corresponding project of support and reinforcement is proposed to make the slope more stable.

  15. Identifying deformation mechanisms in the NEEM ice core using EBSD measurements

    Science.gov (United States)

    Kuiper, Ernst-Jan; Weikusat, Ilka; Drury, Martyn R.; Pennock, Gill M.; de Winter, Matthijs D. A.

    2015-04-01

    Deformation of ice in continental sized ice sheets determines the flow behavior of ice towards the sea. Basal dislocation glide is assumed to be the dominant deformation mechanism in the creep deformation of natural ice, but non-basal glide is active as well. Knowledge of what types of deformation mechanisms are active in polar ice is critical in predicting the response of ice sheets in future warmer climates and its contribution to sea level rise, because the activity of deformation mechanisms depends critically on deformation conditions (such as temperature) as well as on the material properties (such as grain size). One of the methods to study the deformation mechanisms in natural materials is Electron Backscattered Diffraction (EBSD). We obtained ca. 50 EBSD maps of five different depths from a Greenlandic ice core (NEEM). The step size varied between 8 and 25 micron depending on the size of the deformation features. The size of the maps varied from 2000 to 10000 grid point. Indexing rates were up to 95%, partially by saving and reanalyzing the EBSP patterns. With this method we can characterize subgrain boundaries and determine the lattice rotation configurations of each individual subgrain. Combining these observations with arrangement/geometry of subgrain boundaries the dislocation types can be determined, which form these boundaries. Three main types of subgrain boundaries have been recognized in Antarctic (EDML) ice core¹². Here, we present the first results obtained from EBSD measurements performed on the NEEM ice core samples from the last glacial period, focusing on the relevance of dislocation activity of the possible slip systems. Preliminary results show that all three subgrain types, recognized in the EDML core, occur in the NEEM samples. In addition to the classical boundaries made up of basal dislocations, subgrain boundaries made of non-basal dislocations are also common. ¹Weikusat, I.; de Winter, D. A. M.; Pennock, G. M.; Hayles, M

  16. Nanoparticle mechanics: deformation detection via nanopore resistive pulse sensing

    Science.gov (United States)

    Darvish, Armin; Goyal, Gaurav; Aneja, Rachna; Sundaram, Ramalingam V. K.; Lee, Kidan; Ahn, Chi Won; Kim, Ki-Bum; Vlahovska, Petia M.; Kim, Min Jun

    2016-07-01

    Solid-state nanopores have been widely used in the past for single-particle analysis of nanoparticles, liposomes, exosomes and viruses. The shape of soft particles, particularly liposomes with a bilayer membrane, can greatly differ inside the nanopore compared to bulk solution as the electric field inside the nanopores can cause liposome electrodeformation. Such deformations can compromise size measurement and characterization of particles, but are often neglected in nanopore resistive pulse sensing. In this paper, we investigated the deformation of various liposomes inside nanopores. We observed a significant difference in resistive pulse characteristics between soft liposomes and rigid polystyrene nanoparticles especially at higher applied voltages. We used theoretical simulations to demonstrate that the difference can be explained by shape deformation of liposomes as they translocate through the nanopores. Comparing our results with the findings from electrodeformation experiments, we demonstrated that the rigidity of liposomes can be qualitatively compared using resistive pulse characteristics. This application of nanopores can provide new opportunities to study the mechanics at the nanoscale, to investigate properties of great value in fundamental biophysics and cellular mechanobiology, such as virus deformability and fusogenicity, and in applied sciences for designing novel drug/gene delivery systems.Solid-state nanopores have been widely used in the past for single-particle analysis of nanoparticles, liposomes, exosomes and viruses. The shape of soft particles, particularly liposomes with a bilayer membrane, can greatly differ inside the nanopore compared to bulk solution as the electric field inside the nanopores can cause liposome electrodeformation. Such deformations can compromise size measurement and characterization of particles, but are often neglected in nanopore resistive pulse sensing. In this paper, we investigated the deformation of various

  17. Deformation Behavior of Severely Deformed Al and Related Mechanisms Through Warm Tensile Test

    Science.gov (United States)

    Charkhesht, V.; Kazeminezhad, M.

    2017-01-01

    Flow stress and ductility behaviors of the annealed and severely deformed Al were investigated at warm deformation temperatures. Constrained groove pressing (CGP) method as a severe plastic deformation process was used. The tensile test was carried out at the temperature range of the 298-573 K and strain rate range of 0.001-0.1 s-1 to present the elevated temperature deformation behavior utilizing hyperbolic sine constitutive equation. The flow stress of the CGPed sample is increased with the number of CGP passes and decreased with temperature. Dynamic recovery and strain softening are found as main restoration mechanisms. Flow stress amounts are not remarkably affected by the strain rate. Values of the elongation are decreased with the number of CGP passes. Values of the calculated strain rate sensitivity are utilized to justify the elongation behavior. Shear bands created by CGP remarkably decrease the fracture elongation values. Temperature interval of 298-473 K cannot remarkably affect the flow stress and ductility. The interval of 473-573 K is chosen as critical temperature interval in which the values of flow stress and elongation are remarkably decreased and increased, respectively. Increasing the temperature up to 573 K causes recrystallization in shear bands. Scanning electron microscope was used to study fracture surface which can truly predict the elongation behavior. With increasing the temperature, the shear decohesion area is gradually replaced with fully dimpled structures. Finally, hot deformation activation energy for CGPed samples was calculated about 85 kJ/mol which is close to the grain boundary diffusion activation energy in pure Al.

  18. Tectonophysics map of discontinuous deformation of Rybnik region

    Directory of Open Access Journals (Sweden)

    Głogowska Magdalena

    2016-06-01

    Full Text Available In this paper, a Tectonophysics map of Rybnik region is presented which is based on the method of determining the direction of the trajectory of the principal stresses in the rock mass and axis orientation of these stresses. This method is used in tectonophysics and is based on the character and parameters of faults. The whole map of Rybnik region encompasses an area of active mines: Rydułtowy-Anna, Marcel, Chwałowice, Jankowice as well as closed ones: Rymer and 1 May of Marcel mine. The paper presents only some fragments of the maps made for the four fault systems and a collective map of tectonophysic, i.e., showing chart areas of compaction for all the systems. The tectonophysics map was made to a scale of 1:20 000. Before the proper work which was the reconstruction of the compaction zone, preparatory work was done. This consisted of updates in 2013 of the tectonics of this area. As a result, tectonic maps were obtained where faults were projected on one level to get their proper azimuth and their inclination. So, a map was made which was used to separate four fault systems arising in similar conditions of stress. Next followed the reconstruction of the main stress fields, which was the cause of faults. On the map there are plotted trajectories showing minimum stress (σ3 and areas of compaction. The maps thus constructed will be used for further studies on the stress spreading and the impact of these areas for geomechanical properties.

  19. Modeling adsorption properties of structurally deformed metal-organic frameworks using structure-property map.

    Science.gov (United States)

    Jeong, WooSeok; Lim, Dae-Woon; Kim, Sungjune; Harale, Aadesh; Yoon, Minyoung; Suh, Myunghyun Paik; Kim, Jihan

    2017-07-25

    Structural deformation and collapse in metal-organic frameworks (MOFs) can lead to loss of long-range order, making it a challenge to model these amorphous materials using conventional computational methods. In this work, we show that a structure-property map consisting of simulated data for crystalline MOFs can be used to indirectly obtain adsorption properties of structurally deformed MOFs. The structure-property map (with dimensions such as Henry coefficient, heat of adsorption, and pore volume) was constructed using a large data set of over 12000 crystalline MOFs from molecular simulations. By mapping the experimental data points of deformed SNU-200, MOF-5, and Ni-MOF-74 onto this structure-property map, we show that the experimentally deformed MOFs share similar adsorption properties with their nearest neighbor crystalline structures. Once the nearest neighbor crystalline MOFs for a deformed MOF are selected from a structure-property map at a specific condition, then the adsorption properties of these MOFs can be successfully transformed onto the degraded MOFs, leading to a new way to obtain properties of materials whose structural information is lost.

  20. Size-dependent deformation mechanisms in hollow silicon nanoparticles

    Directory of Open Access Journals (Sweden)

    L. Yang

    2015-07-01

    Full Text Available Even inherently brittle hollow silicon nanoparticles (NPs can withstand larger strain to failure than solid NPs. However, the influence of wall thickness on the mechanical behavior of hollow Si NPs is not fully understood. Using molecular dynamics simulations, we investigate the compressive behavior of hollow Si NPs. Three distinct failure mechanisms of hollow NPs are uncovered, and their strength and deformability are analyzed quantitatively. For extra-thick-walled NPs, dislocations will nucleate below the contact area and cut through the particles till failure. For mid-thick-walled NPs, however, dislocations will emit from the inner surface and slip towards the outer surface. For thin-walled NPs, elastic buckling is the cause of failure. Compared to solid NPs, hollow NPs with wall thickness being around half of its outer radius can achieve significant improvement in both strength and deformability.

  1. Carbon nanotube heterojunctions: unusual deformations and mechanical vibration properties

    Science.gov (United States)

    Scarpa, F.; Narojczyk, J.; Wojciechowski, K. W.; Inman, D. J.

    2011-04-01

    The mechanical deformation and dynamics properties of single wall carbon nanotube heterojunctions (HJ) oscillators are investigated using an hybrid finite element atomistic-continuum approach. The nanotube HJs provide a peculiar deformation pattern, with combined bending and axial stretching of carbon nanotubes (CNTs), and a broad agreement of their axial stiffness with spring series continuum mechanics and existing molecular dynamics (MD) simulations. We show also peculiar distributions of the natural frequencies and modes of the hetero-junctions compared to classical single-wall nanotube configurations, and the mass-sensor capability of (5,5)-(10,10) SWCNT HJ structures, with frequency shifts highly depending on the heterojunction section subjected to the mass loading.

  2. Disclinations provide the missing mechanism for deforming olivine-rich rocks in the mantle.

    Science.gov (United States)

    Cordier, Patrick; Demouchy, Sylvie; Beausir, Benoît; Taupin, Vincent; Barou, Fabrice; Fressengeas, Claude

    2014-03-06

    Mantle flow involves large strains of polymineral aggregates. The strongly anisotropic plastic response of each individual grain in the aggregate results from the interactions between neighbouring grains and the continuity of material displacement across the grain boundaries. Orthorhombic olivine, which is the dominant mineral phase of the Earth's upper mantle, does not exhibit enough slip systems to accommodate a general deformation state by intracrystalline slip without inducing damage. Here we show that a more general description of the deformation process that includes the motion of rotational defects referred to as disclinations can solve the olivine deformation paradox. We use high-resolution electron backscattering diffraction (EBSD) maps of deformed olivine aggregates to resolve the disclinations. The disclinations are found to decorate grain boundaries in olivine samples deformed experimentally and in nature. We present a disclination-based model of a high-angle tilt boundary in olivine, which demonstrates that an applied shear induces grain-boundary migration through disclination motion. This new approach clarifies grain-boundary-mediated plasticity in polycrystalline aggregates. By providing the missing mechanism for describing plastic flow in olivine, this work will permit multiscale modelling of the rheology of the upper mantle, from the atomic scale to the scale of the flow.

  3. Magnetic and Mechanical Properties of Deformed Iron Nitride γ′-Fe4N

    Directory of Open Access Journals (Sweden)

    Chin-Hsiang Cheng

    2015-01-01

    Full Text Available The present study is aimed at magnetic and mechanical properties of iron nitride (γ′-Fe4N with elastic deformation. Electronic structure and thermal properties of the iron nitride are also studied to have a comprehensive understanding of the characteristics of γ′-Fe4N. This study is focused on the variation of the magnetic and the mechanical properties of iron nitride with a change in crystal size represented by lattice constant. As the lattice constant is altered with deformation, magnetic moment of Fe-II atoms is appreciably elevated, while that of Fe-I atoms is nearly unchanged. Dependence of the magnetic moment and the bulk modulus on the lattice constant is examined. Meanwhile, chemical bonds between Fe atoms and N atoms formed across the crystal have been visualized by delocalization of atomic charge density in electron density map, and thermodynamic properties, including entropy, enthalpy, free energy, and heat capacity, are evaluated.

  4. Bertram Hopkinson's pioneering work and the dislocation mechanics of high rate deformations and mechanically induced detonations.

    Science.gov (United States)

    Armstrong, Ronald W

    2014-05-13

    Bertram Hopkinson was prescient in writing of the importance of better measuring, albeit better understanding, the nature of high rate deformation of materials in general and, in particular, of the importance of heat in initiating detonation of explosives. This report deals with these subjects in terms of post-Hopkinson crystal dislocation mechanics applied to high rate deformations, including impact tests, Hopkinson pressure bar results, Zerilli-Armstrong-type constitutive relations, shock-induced deformations, isentropic compression experiments, mechanical initiation of explosive crystals and shear banding in metals.

  5. Temperature Dependent Cyclic Deformation Mechanisms in Haynes 188 Superalloy

    Science.gov (United States)

    Rao, K. Bhanu Sankara; Castelli, Michael G.; Allen, Gorden P.; Ellis, John R.

    1995-01-01

    The cyclic deformation behavior of a wrought cobalt-base superalloy, Haynes 188, has been investigated over a range of temperatures between 25 and 1000 C under isothermal and in-phase thermomechanical fatigue (TMF) conditions. Constant mechanical strain rates (epsilon-dot) of 10(exp -3)/s and 10(exp -4)/s were examined with a fully reversed strain range of 0.8%. Particular attention was given to the effects of dynamic strain aging (DSA) on the stress-strain response and low cycle fatigue life. A correlation between cyclic deformation behavior and microstructural substructure was made through detailed transmission electron microscopy. Although DSA was found to occur over a wide temperature range between approximately 300 and 750 C the microstructural characteristics and the deformation mechanisms responsible for DSA varied considerably and were dependent upon temperature. In general, the operation of DSA processes led to a maximum of the cyclic stress amplitude at 650 C and was accompanied by pronounced planar slip, relatively high dislocation density, and the generation of stacking faults. DSA was evidenced through a combination of phenomena, including serrated yielding, an inverse dependence of the maximum cyclic hardening with epsilon-dot, and an instantaneous inverse epsilon-dot sensitivity verified by specialized epsilon-dot -change tests. The TMF cyclic hardening behavior of the alloy appeared to be dictated by the substructural changes occuring at the maximum temperature in the TMF cycle.

  6. Deformable liposomes and ethosomes: mechanism of enhanced skin delivery.

    Science.gov (United States)

    Elsayed, Mustafa M A; Abdallah, Ossama Y; Naggar, Viviane F; Khalafallah, Nawal M

    2006-09-28

    Despite intensive research, the mechanisms by which vesicular systems deliver drugs into intact skin are not yet fully understood. In the current study, possible mechanisms by which deformable liposomes and ethosomes improve skin delivery of ketotifen under non-occlusive conditions were investigated. In vitro permeation and skin deposition behavior of deformable liposomes and ethosomes, having ketotifen both inside and outside the vesicles (no separation of free ketotifen), having ketotifen only inside the vesicles (free ketotifen separated) and having ketotifen only outside the vesicles (ketotifen solution added to empty vesicles), was studied using rabbit pinna skin. Results suggested that both the penetration enhancing effect and the intact vesicle permeation into the stratum corneum might play a role in improving skin delivery of drugs by deformable liposomes, under non-occlusive conditions, and that the penetration enhancing effect was of greater importance in case of ketotifen. Regarding ethosomes, results indicated that ketotifen should be incorporated in ethosomal vesicles for optimum skin delivery. Ethosomes were not able to improve skin delivery of non-entrapped ketotifen.

  7. Deformation mechanism in swollen radiation-grafted polyethylene

    Science.gov (United States)

    Ungar, G.; Dlugosz, J.; Ranogajec, F.

    Stress-strain behaviour of anisotropic polyethylene (PE) film radiation-grafted with styrene was studied with the samples immersed in xylene. The glassy polystyrene (PS) phase (1) is softened by swelling. Whereas the tensile modulus of dry graft increases somewhat with increasing PS content, for the swollen graft it decreases sharply. However the yield stress and the elongation at break remain fairly large. For highly grafted films (PS/PE > 1) deformation is almost fully reversible and proceeds without necking up to draw ratios as high as 5:1. With the aid of additional X-ray diffraction and transmission electron microscopy results the deformation mechanism is interpreted in terms of the known morphology of the copolymer.

  8. Deformation mechanism in swollen radiation-grafted polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Ungar, G.; Ranogajec, F. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Dlugosz, J. (Bristol Univ. (UK). H.H. Wills Physics Lab.)

    1981-01-01

    Stress-strain behaviour of anisotropic polyethylene (PE) film radiation-grafted with styrene was studied with the samples immersed in xylene. The glassy polystyrene (PS) phase is softened by swelling. Whereas the tensile modulus of dry graft increases somewhat with increasing PS content, for the swollen graft it decreases sharply. However the yield stress and the elongation at break remain fairly large. For highly grafted films (PS/PE > 1) deformation is almost fully reversible and proceeds without necking up to draw ratios as high as 5:1. With the aid of additional X-ray diffraction and transmission electron microscopy results the deformation mechanism is interpreted in terms of the known morphology of the copolymer.

  9. Warm deformation mechanism of hot-rolled Mg alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Tension attachment of high temperature microscopy was proposed to research the microstructure evolution and plastic behavior of AZ31 magnesium, alloy in a temperature range of 473-523 K and a load range of 80-160 N. Transmission electron microscopy(TEM) was utilized to observe the morphology of twins after deformation process. The results show that as ZenerHollomon parameter Z increases (temperature falls, strain rate rises), the peak stress obviously increases, while the ductility tends to become worse. A great amount of twins can be found at moderate temperatures. Therefore, basal slip, a+c non-basal slipping and twinning are considered the dominant mechanisms at moderate temperatures. Some DRXed grains can be observed in the twinned regions and grain boundaries, suggesting both twinning-induced DRX and continuous DRX occurs in the deformation process.

  10. Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

    Science.gov (United States)

    2005-01-01

    The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of

  11. Mapping soil deformation around plant roots using in vivo 4D X-ray Computed Tomography and Digital Volume Correlation.

    Science.gov (United States)

    Keyes, S D; Gillard, F; Soper, N; Mavrogordato, M N; Sinclair, I; Roose, T

    2016-06-14

    The mechanical impedance of soils inhibits the growth of plant roots, often being the most significant physical limitation to root system development. Non-invasive imaging techniques have recently been used to investigate the development of root system architecture over time, but the relationship with soil deformation is usually neglected. Correlative mapping approaches parameterised using 2D and 3D image data have recently gained prominence for quantifying physical deformation in composite materials including fibre-reinforced polymers and trabecular bone. Digital Image Correlation (DIC) and Digital Volume Correlation (DVC) are computational techniques which use the inherent material texture of surfaces and volumes, captured using imaging techniques, to map full-field deformation components in samples during physical loading. Here we develop an experimental assay and methodology for four-dimensional, in vivo X-ray Computed Tomography (XCT) and apply a Digital Volume Correlation (DVC) approach to the data to quantify deformation. The method is validated for a field-derived soil under conditions of uniaxial compression, and a calibration study is used to quantify thresholds of displacement and strain measurement. The validated and calibrated approach is then demonstrated for an in vivo test case in which an extending maize root in field-derived soil was imaged hourly using XCT over a growth period of 19h. This allowed full-field soil deformation data and 3D root tip dynamics to be quantified in parallel for the first time. This fusion of methods paves the way for comparative studies of contrasting soils and plant genotypes, improving our understanding of the fundamental mechanical processes which influence root system development.

  12. Evaluation of structural deformations of a mechanical connecting unit oxidizer supplies by thermo-mechanical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Woo [Dept. of Mechanical Engineering, Institute of Machine Convergence Technology, Hankyong National University, Anseong (Korea, Republic of)

    2016-10-15

    A Mechanical connecting unit (MCU) used in ground facilities for a Liquid propellant rocket (LPR) acts as a bridge between the onboard system and the ground oxidizer filling system. It should be resistant to structural deformations in order to guarantee successful supply of a cryogenic oxidizer and high pressure gases without reduction of sealing capability. The MCU consists of many components and linkages and operates under harsh conditions induced by a cryogenic oxidizer, high pressure gases and other mechanical forces. Thus, the evaluation of structural deformation of the MCU considering complex conditions is expensive and time consuming. The present study efficiently evaluates the structural deformations of the key components of the MCU by Thermo-mechanical simulation (TMS) based on the superposition principle. Deformations due to the mechanical loadings including weights, pressures, and spring forces are firstly evaluated by using a non-linear flexible body simulation module (FFlex) of Multi-body dynamics (MBD) software, RecurDyn. Then, thermal deformations for the deformed geometries obtained by RecurDyn were subsequently calculated. It was conducted by using a Finite element (FE) analysis software, ANSYS. The total deformations for the onboard plate and multi-channel plate in the connecting section due to the mechanical and thermal loadings were successfully evaluated. Moreover, the outer gaps at six points between two plates were calculated and verified by comparison to the measured data. Their values and tendencies showed a good agreement. The author concluded that the TMS using MBD software considering flexible bodies and an FE simulator can efficiently evaluate structural deformations of the MCU operating under the complex load and boundary conditions.

  13. Local deformation and processing maps of Ti-24Al-17Nb-0.5Mo alloy

    Institute of Scientific and Technical Information of China (English)

    Yong WANG; Bin LU; Rui YANG; Xiaodong HAN; Ping REN

    2012-01-01

    The processing maps were used to identify the optimal forging parameters of Ti-24Al-17Nb-0.5Mo alloy by evaluating the flow data according to the DMM model.The actual local strain rate and strain distribution in the samples were obtained by finite element calculations.The local microstructures of the deformed samples were related to the local deformation parameters and correlated with the processing maps at 0.3,0.4,0.5 and 0.6 of logarithmic strain.Flow regimes predicted by DMM analysis were then correlated with the local microstructural observations.Five domains of efficient coefficient could be distinguished.Unstable regions were microstructurally related to shear band formation within the α2+B2 phase deformation field,and to flow localization at grain boundaries of B2 phase in the near B2 phase deformation field.Stable flow regimes were shown to be associated with dynamic globularization of the platelike α2 in the α2+B2 phase deformation zone,and with dynamic recrystallization of B2 in the near B2 phase deformation zone.

  14. Investigation of deformation mechanisms of staggered nanocomposites using molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Mathiazhagan, S., E-mail: smathi.research@gmail.com; Anup, S., E-mail: anupiist@gmail.com

    2016-08-19

    Biological materials with nanostructure of regularly or stair-wise staggered arrangements of hard platelets reinforced in a soft protein matrix have superior mechanical properties. Applications of these nanostructures to ceramic matrix composites could enhance their toughness. Using molecular dynamics simulations, mechanical behaviour of the bio-inspired nanocomposites is studied. Regularly staggered model shows better flow behaviour compared to stair-wise staggered model due to the symmetrical crack propagation along the interface. Though higher stiffness and strength are obtained for stair-wise staggered models, rapid crack propagation reduces the toughness. Arresting this crack propagation could lead to superior mechanical properties in stair-wise staggered models. - Highlights: • The deformation behaviour of staggered nanocomposites is studied. • Stair-wise staggered model has high stiffness and strength, but low toughness. • Rapid crack growth in overlap region causes this low toughness. • Toughness could be enhanced by arresting interfacial crack in the overlap.

  15. Mechanical Design of Odin, an Extendable Heterogeneous Deformable Modular Robot

    DEFF Research Database (Denmark)

    Lyder, Andreas; Garcia, Ricardo Franco Mendoza; Støy, Kasper

    2008-01-01

    Highly sophisticated animals consist of a set of heterogenous modules decided by nature so that they can survive in a complex environment. In this paper we present a new modular robot inspired by biology called Odin. The Odin robot is based on a deformable lattice and consists of an extendable se...... of heterogeneous modules. We present the design and implementation of a cubic closed-packed (CCP) joint module, a telescoping link, and a flexible connection mechanism. The developed robot is highly versatile and opens up for a wide range of new research in modular robotics....

  16. Structural evolution of fault zones in sandstone by multiple deformation mechanisms: Moab fault, southeast Utah

    Science.gov (United States)

    Davatzes, N.C.; Eichhubl, P.; Aydin, A.

    2005-01-01

    Faults in sandstone are frequently composed of two classes of structures: (1) deformation bands and (2) joints and sheared joints. Whereas the former structures are associated with cataclastic deformation, the latter ones represent brittle fracturing, fragmentation, and brecciation. We investigated the distribution of these structures, their formation, and the underlying mechanical controls for their occurrence along the Moab normal fault in southeastern Utah through the use of structural mapping and numerical elastic boundary element modeling. We found that deformation bands occur everywhere along the fault, but with increased density in contractional relays. Joints and sheared joints only occur at intersections and extensional relays. In all locations , joints consistently overprint deformation bands. Localization of joints and sheared joints in extensional relays suggests that their distribution is controlled by local variations in stress state that are due to mechanical interaction between the fault segments. This interpretation is consistent with elastic boundary element models that predict a local reduction in mean stress and least compressive principal stress at intersections and extensional relays. The transition from deformation band to joint formation along these sections of the fault system likely resulted from the combined effects of changes in remote tectonic loading, burial depth, fluid pressure, and rock properties. In the case of the Moab fault, we conclude that the structural heterogeneity in the fault zone is systematically related to the geometric evolution of the fault, the local state of stress associated with fault slip , and the remote loading history. Because the type and distribution of structures affect fault permeability and strength, our results predict systematic variations in these parameters with fault evolution. ?? 2004 Geological Society of America.

  17. Deformation mechanisms of Cu nanowires with planar defects

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Xia, E-mail: tianxia@lsec.cc.ac.cn; Yang, Haixia; Wan, Rui [College of Mechanics and Materials, HoHai University, Nanjing 210098 (China); Cui, Junzhi [LSEC, ICMSEC, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, Beijing 100190 (China); Yu, Xingang [School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China)

    2015-01-21

    Molecular dynamics simulations are used to investigate the mechanical behavior of Cu nanowires (NWs) with planar defects such as grain boundaries (GBs), twin boundaries (TBs), stacking faults (SFs), etc. To investigate how the planar defects affect the deformation and fracture mechanisms of naowires, three types of nanowires are considered in this paper: (1) polycrystalline Cu nanowire; (2) single-crystalline Cu nanowire with twin boundaries; and (3) single-crystalline Cu nanowire with stacking faults. Because of the large fraction of atoms at grain boundaries, the energy of grain boundaries is higher than that of the grains. Thus, grain boundaries are proved to be the preferred sites for dislocations to nucleate. Moreover, necking and fracture prefer to occur at the grain boundary interface owing to the weakness of grain boundaries. For Cu nanowires in the presence of twin boundaries, it is found that twin boundaries can strength nanowires due to the restriction of the movement of dislocations. The pile up of dislocations on twin boundaries makes them rough, inducing high energy in twin boundaries. Hence, twin boundaries can emit dislocations, and necking initiates at twin boundaries. In the case of Cu nanowires with stacking faults, all pre-existing stacking faults in the nanowires are observed to disappear during deformation, giving rise to a fracture process resembling the samples without stacking fault.

  18. Mechanical deformation of atomic-scale metallic contacts: Structure and mechanisms

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Brandbyge, Mads; Jacobsen, Karsten Wedel

    1998-01-01

    We have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain using molecular dynamics and effective medium theory potentials. The evolution of the structure of the contacts and the underlying deformation mechanisms are described along with the calculated ele...... that the results measured in a nanocontact experiment depend significantly on the elastic stiffness of the experimental apparatus. For a soft setup, some of the atomic rearrangements might not be detected, whereas others are amplified.......We have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain using molecular dynamics and effective medium theory potentials. The evolution of the structure of the contacts and the underlying deformation mechanisms are described along with the calculated...... electronic conductance. Various defects such as intersecting stacking faults, local disorder, and vacancies are created during the deformation. Disordered regions act as weak spots that reduce the strength of the contacts. The disorder tends to anneal out again during the subsequent atomic rearrangements...

  19. Tensile deformation mechanisms of ABS/PMMA/EMA blends

    Science.gov (United States)

    Wang, S. H.; Gao, J.; Lin, S. X.; Zhang, P.; Huang, J.; Xu, L. L.

    2014-08-01

    The tensile deformation mechanisms of acrylonitrile - butadiene - styrene (ABS) / polymethyl methacrylate (PMMA) blends toughened by ethylene methacrylate (EMA) copolymer was investigated by analysing the fracture morphology. ABS/PMMA was blended with EMA copolymer by melt mixing technique using co-rotating twin extruder. Tensile tests show that the elongation at break of ABS/PMMA blends can be efficiently improved with the increase in EMA content. Fracture morphology of ABS/PMMA/EMA blends reveals that the material yield induced by hollowing-out of EMA particles and its propagation into yield zone is the main toughening mechanism. Moreover, the appearance that EMA particles in the central area are given priority to hollowing-out may be related to the skin-core structure of the injection moulded parts caused by the different cooling rate between surface and inside in the process of injection moulding.

  20. Engineering mechanics of deformable solids a presentation with exercises

    CERN Document Server

    Govindjee, Sanjay

    2013-01-01

    This book covers the essential elements of engineering mechanics of deformable bodies, including mechanical elements in tension-compression, torsion, and bending. It emphasizes a fundamental bottom up approach to the subject in a concise and uncluttered presentation. Of special interest are chapters dealing with potential energy as well as principle of virtual work methods for both exact and approximate solutions. The book places an emphasis on the underlying assumptions of the theories in order to encourage the reader to think more deeply about the subject matter. The book should be of special interest to undergraduate students looking for a streamlined presentation as well as those returning to the subject for a second time.

  1. In-situ electron microscopy studies on the tensile deformation mechanisms in aluminium 5083 alloy

    CSIR Research Space (South Africa)

    Motsi, G

    2014-10-01

    Full Text Available In this study tensile deformation mechanisms of aluminium alloy 5083 were investigated under observations made from SEM equipped with a tensile stage. Observations during tensile testing revealed a sequence of surface deformation events...

  2. Deformation mechanisms of NiAl cyclicly deformed near the brittle-to-ductile transformation temperature

    Science.gov (United States)

    Antolovich, Stephen D.; Saxena, Ashok; Cullers, Cheryl

    1992-01-01

    One of the ongoing challenges of the aerospace industry is to develop more efficient turbine engines. Greater efficiency entails reduced specific strength and larger temperature gradients, the latter of which means higher operating temperatures and increased thermal conductivity. Continued development of nickel-based superalloys has provided steady increases in engine efficiency and the limits of superalloys have probably not been realized. However, other material systems are under intense investigation for possible use in high temperature engines. Ceramic, intermetallic, and various composite systems are being explored in an effort to exploit the much higher melting temperatures of these systems. NiAl is considered a potential alternative to conventional superalloys due to its excellent oxidation resistance, low density, and high melting temperature. The fact that NiAl is the most common coating for current superalloy turbine blades is a tribute to its oxidation resistance. Its density is one-third that of typical superalloys and in most temperature ranges its thermal conductivity is twice that of common superalloys. Despite these many advantages, NiAl requires more investigation before it is ready to be used in engines. Binary NiAl in general has poor high-temperature strength and low-temperature ductility. On-going research in alloy design continues to make improvements in the high-temperature strength of NiAl. The factors controlling low temperature ductility have been identified in the last few years. Small, but reproducible ductility can now be achieved at room temperature through careful control of chemical purity and processing. But the mechanisms controlling the transition from brittle to ductile behavior are not fully understood. Research in the area of fatigue deformation can aid the development of the NiAl system in two ways. Fatigue properties must be documented and optimized before NiAl can be applied to engineering systems. More importantly though

  3. Investigating Deformation and Failure Mechanisms in Nanoscale Multilayer Metallic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Zbib, Hussein M. [Washington State Univ., Pullman, WA (United States); Bahr, David F. [Purdue Univ., West Lafayette, IN (United States)

    2014-10-22

    Over the history of materials science there are many examples of materials discoveries that have made superlative materials; the strongest, lightest, or toughest material is almost always a goal when we invent new materials. However, often these have been a result of enormous trial and error approaches. A new methodology, one in which researchers design, from the atoms up, new ultra-strong materials for use in energy applications, is taking hold within the science and engineering community. This project focused on one particular new classification of materials; nanolaminate metallic composites. These materials, where two metallic materials are intimately bonded and layered over and over to form sheets or coatings, have been shown over the past decade to reach strengths over 10 times that of their constituents. However, they are not yet widely used in part because while extremely strong (they don’t permanently bend), they are also not particularly tough (they break relatively easily when notched). Our program took a coupled approach to investigating new materials systems within the laminate field. We used computational materials science to explore ways to institute new deformation mechanisms that occurred when a tri-layer, rather than the more common bi-layer system was created. Our predictions suggested that copper-nickel or copper-niobium composites (two very common bi-layer systems) with layer thicknesses on the order of 20 nm and then layered 100’s of times, would be less tough than a copper-nickel-niobium metallic composite of similar thicknesses. In particular, a particular mode of permanent deformation, cross-slip, could be activated only in the tri-layer system; the crystal structure of the other bi-layers would prohibit this particular mode of deformation. We then experimentally validated this predication using a wide range of tools. We utilized a DOE user facility, the Center for Integrated Nanotechnology (CINT), to fabricate, for the first time, these

  4. STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS

    Energy Technology Data Exchange (ETDEWEB)

    Anter El-Azab

    2013-04-08

    The research under this project focused on a theoretical and computational modeling of dislocation dynamics of mesoscale deformation of metal single crystals. Specifically, the work aimed to implement a continuum statistical theory of dislocations to understand strain hardening and cell structure formation under monotonic loading. These aspects of crystal deformation are manifestations of the evolution of the underlying dislocation system under mechanical loading. The project had three research tasks: 1) Investigating the statistical characteristics of dislocation systems in deformed crystals. 2) Formulating kinetic equations of dislocations and coupling these kinetics equations and crystal mechanics. 3) Computational solution of coupled crystal mechanics and dislocation kinetics. Comparison of dislocation dynamics predictions with experimental results in the area of statistical properties of dislocations and their field was also a part of the proposed effort. In the first research task, the dislocation dynamics simulation method was used to investigate the spatial, orientation, velocity, and temporal statistics of dynamical dislocation systems, and on the use of the results from this investigation to complete the kinetic description of dislocations. The second task focused on completing the formulation of a kinetic theory of dislocations that respects the discrete nature of crystallographic slip and the physics of dislocation motion and dislocation interaction in the crystal. Part of this effort also targeted the theoretical basis for establishing the connection between discrete and continuum representation of dislocations and the analysis of discrete dislocation simulation results within the continuum framework. This part of the research enables the enrichment of the kinetic description with information representing the discrete dislocation systems behavior. The third task focused on the development of physics-inspired numerical methods of solution of the coupled

  5. The relationships between deformation mechanisms and mechanical properties of additively manufactured porous biomaterials.

    Science.gov (United States)

    Kadkhodapour, J; Montazerian, H; Darabi, A Ch; Zargarian, A; Schmauder, S

    2016-09-16

    Modulating deformation mechanism through manipulating morphological parameters of scaffold internal pore architecture provides potential to tailor the overall mechanical properties under physiological loadings. Whereas cells sense local strains, cell differentiation is also impressed by the elastic deformations. In this paper, structure-property relations were developed for Ti6-Al-4V scaffolds designed based on triply periodic minimal surfaces. 10mm cubic scaffolds composed of 5×5×5 unit cells formed of F-RD (bending dominated) and I-WP (stretching dominated) architectures were additively manufactured at different volume fractions and subjected to compressive tests. The first stages of deformation for stretching dominated structure, was accompanied by bilateral layer-by-layer failure of unit cells owing to the buckling of micro-struts, while for bending dominated structure, namely F-RD, global shearing bands appeared since the shearing failure of struts in the internal architecture. Promoted mechanical properties were found for stretching dominated structure since the global orientation of struts were parallel to loading direction while inclination of struts diminished specific properties for bending dominated structure. Moreover, elastic-plastic deformation was computationally studied by applying Johnson-Cook damage model to the voxel-based models in FE analysis. Scaling analysis was performed for mechanical properties with respect to the relative density thereby failure mechanism was correlated to the constants of power law describing mechanical properties.

  6. Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian Margin

    Science.gov (United States)

    Schmiedel, Tobias; Kjoberg, Sigurd; Planke, Sverre; Magee, Craig; Schofield, Nick; Galland, Olivier; A-L Jackson, Christopher; Jerram, Dougal A.

    2017-04-01

    Accounting for igneous intrusions into sedimentary basins is important as they provide additional volume into the basin as well as a relatively rapid heat pulse. This is of particular importance to the petroleum industry because magmatism deforms the host rock and affects the thermal evolution of a basin, thereby influencing the potential hydrocarbon source and reservoir rocks (i.e. hydrocarbon generation, migration, and accumulation). Presently, numerous mechanisms concerning the syn-emplacement (i.e. elastic bending related active uplift/forced folding and aureole induced volume reduction) and post-emplacement (i.e. differential compaction) deformation of the host rock have been suggested. In this study, we investigate the relevance of the different existing syn- or post-emplacement related mechanical models of dome growth accommodating the emplacement of igneous sills. We use high-quality 3D seismic located in the western part of the Møre Basin (mid-Norwegian margin) to analyse the deformation of Cretaceous - Paleogene overburden associated with the emplacement of the Tulipan saucer-shaped sill. The sill is further constrained due to available well data drilled in the sill overburden and its emplacement is timing in between 55.8 and 54.9 Ma. Horizon interpretations and various thickness and attribute maps show a clear correlation between the saucer-shaped Tulipan sill and an observed overlying domed structure. Additionally, we observe in the shallow parts of the dome structure hydrothermal vent complexes connected by fractures only along the periphery of the underlying sill. We show that the Tulipan sill is responsible for the dome structure in the overburden of the study area. At the same time we demonstrate that not solely one of the different mechanisms of overburden deformation (e.g. elastic bending/forced folding, shear failure, differential compaction, etc.) can be responsible for the observed dome structure, but a combination of them.

  7. Expressway deformation mapping using high-resolution TerraSAR-X images

    KAUST Repository

    Shi, Xuguo

    2014-01-27

    Monitoring deformation of linear infrastructures such as expressway and railway caused by natural processes or anthropogenic activities is a vital task to ensure the safety of human lives and properties. Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized as an effective technology to carry out large-area surface deformation mapping. However, its application in linear infrastructure deformation monitoring has not been intensively studied till now. In this article, a modified Small BAseline Subset (SBAS) method is proposed to retrieve the deformation patterns of the expressway. In our method, only the point-like targets identified on the expressway were kept in our analysis, and two complementary subsets of interferograms were formed to better separate the signals of height error and deformation from inteferometric phase observations. We successfully applied this method with multitemporal high-resolution TerraSAR-X images to retrieve the spatialoral pattern of surface deformation along the Beian-Heihe expressway that is located in island-permafrost areas and threatened by geohazards. © 2014 Taylor & Francis.

  8. Deformation and failure mechanism of slope in three dimensions

    Directory of Open Access Journals (Sweden)

    Yingfa Lu

    2015-04-01

    Full Text Available Understanding three-dimensional (3D slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering. In this paper, the mechanisms of progressive failure with thrust-type and pull-type landslides are described in detail. It is considered that the post-failure stress state and the pre-peak stress state may occur at different regions of a landslide body with deformation development, and a critical stress state element (or the soil slice block exists between the post-failure stress state and the pre-peak stress state regions. In this regard, two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides, based on the characteristics of shear stress and strain (or tensile stress and strain. Accordingly, a new joint constitutive model (JCM is proposed based on the current stability analytical theories, and it can be used to describe the mechanical behaviors of geo-materials with softening properties. Five methods, i.e. CSRM (comprehensive sliding resistance method, MTM (main thrust method, CDM (comprehensive displacement method, SDM (surplus displacement method, and MPM (main pull method, for slope stability calculation are proposed. The S-shaped curve of monitored displacement vs. time is presented for different points on the sliding surface during progressive failure process of landslide, and the relationship between the displacement of different points on the sliding surface and height of landslide body is regarded as the parabolic curve. The comparisons between the predicted and observed load–displacement and displacement–time relations of the points on the sliding surface are conducted. The classification of stable/unstable displacement–time curves is proposed. The definition of the main sliding direction of a landslide is also suggested in such a way that the failure body of landslide (simplified as “collapse body” is only

  9. From chemical mapping to pressure temperature deformation micro-cartography: mineralogical evolution and mass transport in thermo-mechanic disequilibrium systems: application to meta-pelites and confinement nuclear waste materials; De l'imagerie chimique a la micro-cartographie Pression-Temperature-Deformation: evolution mineralogique et transport de matiere dans des systemes en desequilibre thermomecanique. Applications aux metapelites et aux materiaux de stockage de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, V. de

    2006-03-15

    The mineralogical composition of metamorphic rocks or industrial materials evolves when they are submitted to thermomechanical disequilibria, i.e. a spatial or temporal pressure and temperature evolution, or chemical disequilibria as variations in redox conditions, pH... For example, during low temperature metamorphic processes, rocks re-equilibrate only partially, and thus record locally thermodynamic equilibria increasing so the spatial chemical heterogeneities. Understanding the P-T evolution of such systems and deciphering modalities of their mineralogical transformation imply to recognize and characterize the size of these local 'paleo-equilibria', and so to have a spatial chemical information at least in 2 dimensions. In order to get this information, microprobe X-ray fluorescence maps have been used. Computer codes have been developed with Matlab to quantify these maps in view of thermo-barometric estimations. In this way, P-T maps of mineral crystallisation were produced using the multi-equilibria thermodynamic technique. Applications on two meta-pelites from the Sambagawa blue-schist belt (Japan) and from the Caledonian eclogitic zone in Spitsbergen, show that quantitative chemical maps are a powerful tool to retrieve the metamorphic history of rocks. From these chemical maps have been derived maps of P-T-time-redox-deformation that allow to characterize P-T conditions of minerals formation, and so, the P-T path of the sample, the oxidation state of iron in the chlorite phase. As a result, we underline the relation between deformation and crystallisation, and propose a relative chronology of minerals crystallisation and deformations. The Fe{sup 3+} content map in chlorite calculated by thermodynamic has also been validated by a {mu}-XANES mapping at the iron K-edge measured at the ESRF (ID24) using an innovative method. Another application relates to an experimental study of clay materials, main components of an analogical model of a nuclear

  10. Global rotation of mechanical metamaterials induced by their internal deformation

    Science.gov (United States)

    Dudek, K. K.; Gatt, R.; Mizzi, L.; Dudek, M. R.; Attard, D.; Grima, J. N.

    2017-09-01

    In this work, we propose the concept that a device based on mechanical metamaterials can be used to induce and control its own rotational motion as a result of internal deformations due to the conversion of translational degrees of freedom into rotational ones. The application of a linear force on the structural units of the system may be fine-tuned in order to obtain a desired type of rotation. In particular, we show, how it is possible to maximise the extent of rotation of the system through the alteration of the geometry of the system. We also show how a device based on this concept can be connected to an external body in order to rotate it which result may potentially prove to be very important in the case of applications such as telescopes employed in space.

  11. Pyrite deformation and connections to gold mobility: insight from micro-structural analysis and trace element mapping

    Science.gov (United States)

    Dubosq, Renelle; Rogowitz, Anna; Lawley, Christopher; Schneider, David; Jackson, Simon

    2017-04-01

    Pyrite is an important and ubiquitous gold-bearing phase in many orogenic gold deposits making the study of its deformation behaviour under metamorphic conditions crucial to the understanding of gold (re)mobilization. However, pyrite deformation mechanisms and their influence on the retention or release of trace elements during deformation and metamorphism remain poorly understood. We propose a syn- to post-peak metamorphic and deformation driven gold upgrading model where gold is remobilized through deformation-induced diffusion pathways in the form of substructures in pyrite. The middle amphibolite facies assemblage (actinolite-biotite-plagioclase-almandine) of the Detour Lake deposit (Canada) makes it an ideal study area due to maximum temperatures reaching 550°C, exceeding the conditions for plastic deformation in pyrite (450°C). The world-class Detour Lake deposit, containing 16.4 Moz of Au at 1 g/t, is a Neoarchean orogenic gold ore body located in the northern Abitibi district within the Superior Province. The mine is situated along the high strain, sub-vertical ductile-brittle Sunday Lake Deformation Zone (SLDZ) parallel to the broadly E-W trending Abitibi greenstone belt. Herein we combine orientation contrast (OC) forescatter imaging, electron backscatter diffraction (EBSD) and 2D laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) trace element pyrite mapping to evaluate the influence of pyrite brittle and plastic deformation on the release of trace elements during syn-metamorphic gold remobilization. Local misorientation patterns in pyrite exhibit parallel bands that can be described by continuous rotation around one of the axes, whereas higher strain areas reveal more heterogeneous misorientation patterns and the development of low-angle grain boundaries with late fractures indicative of dislocation creep and strain hardening. These late fractures are an important micro-structural setting for gold and clusters of precious

  12. Hot-Deformation Behavior and Hot-Processing Maps of AISI 410 Martensitic Stainless Steel

    Science.gov (United States)

    Qi, Rong-Sheng; Jin, Miao; Guo, Bao-Feng; Liu, Xin-Gang; Chen, Lei

    2016-10-01

    The compressive deformation behaviors of 410 martensitic stainless steel were investigated on a Gleeble-1500 thermomechanical simulator, and the experimental stress-strain data were obtained. The measured flow stress was corrected for friction and temperature. A constitutive equation that accounts for the influence of strain was established, and the hot-processing maps at different strain were plotted. The microstructure evolution of the hot-deformation process was studied on the basis of microstructural observations at high temperatures. Phase-transformation experiments on 410 steel were conducted at high temperatures to elucidate the effects of temperature on the delta-ferrite content. The initial forging temperature and optimum process parameters were obtained on the basis of the processing map and the changes in the delta-ferrite content at high temperatures.

  13. Competing indentation deformation mechanisms in glass using different strengthening methods

    Science.gov (United States)

    Luo, Jian; Lezzi, Peter; Vargheese, K. Deenamma; Tandia, Adama; Harris, Jason; Mauro, John

    2016-11-01

    Chemical strengthening via ion exchange, thermal tempering, and lamination are proven techniques for strengthening of oxide glasses. For each of these techniques, the strengthening mechanism is conventionally ascribed to the linear superposition of the compressive stress profile on the glass surface. However, in this work we use molecular dynamics simulations to reveal the underlying indentation deformation mechanism beyond the simple linear superposition of compressive and indentation stresses. In particular, the plastic zone can be dramatically different from the commonly assumed hemispherical shape, which leads to a completely different stress field and resulting crack system. We show that the indentation-induced fracture is controlled by two competing mechanisms: the compressive stress itself and a potential reduction in free volume that can increase the driving force for crack formation. Chemical strengthening via ion exchange tends to escalate the competition between these two effects, while thermal tempering tends to reduce it. Lamination of glasses with differential thermal expansion falls in between. The crack system also depends on the indenter geometry and the loading stage, i.e., loading vs. after unloading. It is observed that combining thermal tempering or high free volume content with ion exchange or lamination can impart a relatively high compressive stress and reduce the driving force for crack formation. Therefore, such a combined approach might offer the best overall crack resistance for oxide glasses.

  14. Competing indentation deformation mechanisms in glass using different strengthening methods

    Directory of Open Access Journals (Sweden)

    Jian Luo

    2016-11-01

    Full Text Available Chemical strengthening via ion exchange, thermal tempering, and lamination are proven techniques for strengthening of oxide glasses. For each of these techniques, the strengthening mechanism is conventionally ascribed to the linear superposition of the compressive stress profile on the glass surface. However, in this work we use molecular dynamics simulations to reveal the underlying indentation deformation mechanism beyond the simple linear superposition of compressive and indentation stresses. In particular, the plastic zone can be dramatically different from the commonly assumed hemispherical shape, which leads to a completely different stress field and resulting crack system. We show that the indentation-induced fracture is controlled by two competing mechanisms: the compressive stress itself and a potential reduction in free volume that can increase the driving force for crack formation. Chemical strengthening via ion exchange tends to escalate the competition between these two effects, while thermal tempering tends to reduce it. Lamination of glasses with differential thermal expansion falls in between. The crack system also depends on the indenter geometry and the loading stage, i.e., loading vs. after unloading. It is observed that combining thermal tempering or high free volume content with ion exchange or lamination can impart a relatively high compressive stress and reduce the driving force for crack formation. Therefore, such a combined approach might offer the best overall crack resistance for oxide glasses.

  15. In situ monitoring of the deformation mechanisms in titanium with different oxygen contents

    Energy Technology Data Exchange (ETDEWEB)

    Barkia, B. [Laboratoire de Mécanique des Solides, UMR 7649, CNRS, École Polytechnique, Palaiseau (France); Institut de Chimie et des Matériaux Paris-Est (ICMPE), UMR 7182, CNRS/UPEC, Thiais (France); Doquet, V. [Laboratoire de Mécanique des Solides, UMR 7649, CNRS, École Polytechnique, Palaiseau (France); Couzinié, J.P., E-mail: couzinie@icmpe.cnrs.fr [Institut de Chimie et des Matériaux Paris-Est (ICMPE), UMR 7182, CNRS/UPEC, Thiais (France); Guillot, I. [Institut de Chimie et des Matériaux Paris-Est (ICMPE), UMR 7182, CNRS/UPEC, Thiais (France); Héripré, E. [Laboratoire de Mécanique des Solides, UMR 7649, CNRS, École Polytechnique, Palaiseau (France)

    2015-06-11

    The deformation mechanisms of two titanium batches with different oxygen contents were monitored during tensile tests performed along the rolling and transverse directions under an optical or scanning electron microscope, after EBSD mappings of grain orientations. Whereas the contribution of mechanical twinning was very limited, grain boundary sliding, sometimes leading to intergranular decohesion, as well as kink bands formation were observed. Based on the identification of the primary slip traces in a significant number of grains, the critical resolved shear stresses (CRSSs) for prismatic, basal and π{sub 1}〈a〉 were estimated. Transmission electron microscopy was used to identify unambiguously dislocations of π{sub 1}〈c+a〉 systems and to estimate the corresponding CRSS. The difference in oxygen content between T40 and T60 was found to modify the magnitude of the CRSSs, but to leave their relative values nearly unchanged. The evolutions in the work hardening rate were correlated with the active deformation mechanisms.

  16. Introduction to the Mechanics of Deformable Solids Bars and Beams

    CERN Document Server

    H Allen, David

    2013-01-01

    Introduction to the Mechanics of Deformable Solids: Bars and Beams introduces the theory of beams and bars, including axial, torsion, and bending loading and analysis of bars that are subjected to combined loadings, including resulting complex stress states using Mohr’s circle. The book  provides failure analysis based on maximum stress criteria and introduces design using models developed in the text. Throughout the book, the author emphasizes fundamentals, including consistent mathematical notation. The author also presents the fundamentals of the mechanics of solids in such a way that the beginning student is able to progress directly to a follow-up course that utilizes two- and three-dimensional finite element codes imbedded within modern software packages for structural design purposes. As such, excessive details included in the previous generation of textbooks on the subject are obviated due to their obsolescence with the availability of today’s finite element software packages. This book also:...

  17. Consistent Deformed Bosonic Algebra in Noncommutative Quantum Mechanics

    CERN Document Server

    Zhang, Jian-Zu

    2009-01-01

    In two-dimensional noncommutive space for the case of both position - position and momentum - momentum noncommuting, the consistent deformed bosonic algebra at the non-perturbation level described by the deformed annihilation and creation operators is investigated. A general relation between noncommutative parameters is fixed from the consistency of the deformed Heisenberg - Weyl algebra with the deformed bosonic algebra. A Fock space is found, in which all calculations can be similarly developed as if in commutative space and all effects of spatial noncommutativity are simply represented by parameters.

  18. Consistent Deformed Bosonic Algebra in Noncommutative Quantum Mechanics

    Science.gov (United States)

    Zhang, Jian-Zu

    In two-dimensional noncommutative space for the case of both position-position and momentum-momentum noncommuting, the consistent deformed bosonic algebra at the nonperturbation level described by the deformed annihilation and creation operators is investigated. A general relation between noncommutative parameters is fixed from the consistency of the deformed Heisenberg-Weyl algebra with the deformed bosonic algebra. A Fock space is found, in which all calculations can be similarly developed as if in commutative space and all effects of spatial noncommutativity are simply represented by parameters.

  19. On Advantages of the Kelvin Mapping in Finite Element Implementations of Deformation Processes

    CERN Document Server

    Nagel, Thomas; Moerman, Kevin M; Kolditz, Olaf

    2016-01-01

    Classical continuum mechanical theories operate on three-dimensional Eu-clidian space using scalar, vector, and tensor-valued quantities usually up to the order of four. For their numerical treatment, it is common practice to transform the relations into a matrix-vector format. This transformation is usually performed using the so-called Voigt mapping. This mapping does not preserve tensor character leaving significant room for error as stress and strain quantities follow from different mappings and thus have to be treated differently in certain mathematical operations. Despite its conceptual and notational difficulties having been pointed out, the Voigt mapping remains the foundation of most current finite element programmes. An alternative is the so-called Kelvin mapping which has recently gained recognition in studies of theoretical mechanics. This article is concerned with benefits of the Kelvin mapping in numerical modelling tools such as finite element software. The decisive difference to the Voigt mapp...

  20. Mapping cardiac surface mechanics with structured light imaging.

    Science.gov (United States)

    Laughner, Jacob I; Zhang, Song; Li, Hao; Shao, Connie C; Efimov, Igor R

    2012-09-15

    Cardiovascular disease often manifests as a combination of pathological electrical and structural heart remodeling. The relationship between mechanics and electrophysiology is crucial to our understanding of mechanisms of cardiac arrhythmias and the treatment of cardiac disease. While several technologies exist for describing whole heart electrophysiology, studies of cardiac mechanics are often limited to rhythmic patterns or small sections of tissue. Here, we present a comprehensive system based on ultrafast three-dimensional (3-D) structured light imaging to map surface dynamics of whole heart cardiac motion. Additionally, we introduce a novel nonrigid motion-tracking algorithm based on an isometry-maximizing optimization framework that forms correspondences between consecutive 3-D frames without the use of any fiducial markers. By combining our 3-D imaging system with nonrigid surface registration, we are able to measure cardiac surface mechanics at unprecedented spatial and temporal resolution. In conclusion, we demonstrate accurate cardiac deformation at over 200,000 surface points of a rabbit heart recorded at 200 frames/s and validate our results on highly contrasting heart motions during normal sinus rhythm, ventricular pacing, and ventricular fibrillation.

  1. Hot deformation mechanism and microstructure evolution of an ultra-high nitrogen austenitic steel containing Nb and V

    Institute of Scientific and Technical Information of China (English)

    Rong-hua Zhang; Ze-an Zhou; Ming-wei Guo; Jian-jun Qi; Shu-hua Sun; Wan-tang Fu

    2015-01-01

    The flow curves of an ultra-high nitrogen austenitic steel containing niobium (Nb) and vanadium (V) were obtained by hot com-pression deformation at temperatures ranging from 1000℃ to 1200℃ and strain rates ranging from 0.001 s?1 to 10 s?1. The mechanical be-havior during hot deformation was discussed on the basis of flow curves and hot processing maps. The microstructures were analyzed via scanning electron microscopy and electron backscatter diffraction. The relationship between deformation conditions and grain size after dy-namic recrystallization was obtained. The results show that the flow stress and peak strain both increase with decreasing temperature and in-creasing strain rate. The hot deformation activation energy is approximately 631 kJ/mol, and a hot deformation equation is proposed. (Nb,V)N precipitates with either round, square, or irregular shapes are observed at the grain boundaries and in the matrix after deformation. According to the discussion, the hot working should be processed in the temperature range of 1050℃ to 1150℃ and in the strain rate range of 0.01 to 1 s?1.

  2. Nonlinear microrheology and molecular imaging to map microscale deformations of entangled DNA networks

    Science.gov (United States)

    Wu, Tsai-Chin; Anderson, Rae

    We use active microrheology coupled to single-molecule fluorescence imaging to elucidate the microscale dynamics of entangled DNA. DNA naturally exists in a wide range of lengths and topologies, and is often confined in cell nucleui, forming highly concentrated and entangled biopolymer networks. Thus, DNA is the model polymer for understanding entangled polymer dynamics as well as the crowded environment of cells. These networks display complex viscoelastic properties that are not well understood, especially at the molecular-level and in response to nonlinear perturbations. Specifically, how microscopic stresses and strains propagate through entangled networks, and what molecular deformations lead to the network stress responses are unknown. To answer these important questions, we optically drive a microsphere through entangled DNA, perturbing the system far from equilibrium, while measuring the resistive force the DNA exerts on the bead during and after bead motion. We simultaneously image single fluorescent-labeled DNA molecules throughout the network to directly link the microscale stress response to molecular deformations. We characterize the deformation of the network from the molecular-level to the mesoscale, and map the stress propagation throughout the network. We further study the impact of DNA length (11 - 115 kbp) and topology (linear vs ring DNA) on deformation and propagation dynamics, exploring key nonlinear features such as tube dilation and power-law relaxation.

  3. High temperature deformation behavior and processing map for a nickel-titanium shape memory alloy

    Science.gov (United States)

    Yin, Xiang-Qian; Lee, Sang-Won; Li, Yan-Feng; Park, Chan-Hee; Mi, Xu-Jun; Yeom, Jong-Taek

    2017-09-01

    The hot deformation behavior of 49.2Ti-50.8Ni shape memory alloy was studied using hot compressive deformation testing in the temperature range of 1023-1323 K and at strain rates of 0.01-10 s-1. The work-hardening rate was induced to analyze the stress-strain curves, and the critical stress σc and the dynamic recovery saturation stress σsat were measured which can be specified approximately by the expressions: σsat-1.12σp and σc-0.86σp. An Arrhenius model was calculated to describe the relationship between peak stress and the Z parameter. The relationship between deformation activation energy, the deformation conditions and the effect of Ni component in a binary TiNi alloy on the activation energy were discussed in this work. With the help of electron backscattering diffraction, a connected mode dynamic recrystallization microstructure was confirmed in peak efficiency regimes (850 °C & 0.01 s-1 and 1050 °C & 10 s-1) of the processing map.

  4. Deformation mechanisms of carbon nanotube fibres under tensile loading by in situ Raman spectroscopy analysis.

    Science.gov (United States)

    Li, Qiu; Kang, Yi-Lan; Qiu, Wei; Li, Ya-Li; Huang, Gan-Yun; Guo, Jian-Gang; Deng, Wei-Lin; Zhong, Xiao-Hua

    2011-06-03

    Deformation mechanisms of carbon nanotube (CNT) fibres under tensile loading are studied by means of in situ Raman spectroscopy to detect the CNT deformation and stress distributions in the fibres. The G' band in the Raman spectrum responds distinctly to the tensile stress in Raman shift, width and intensity. The G' band changes with the tensile deformation of the fibre at different stages, namely elastic deformation, strengthening and damage-fracture. It is deduced that the individual CNTs only deform elastically without obvious damage or bond breaking. The yield and fracture of fibres can be due to the slippage among the CNTs.

  5. Nanoscale mapping of the three-dimensional deformation field within commercial nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Maqbool, Muhammad Salman; Hoxley, David; Phillips, Nicholas W.; Coughlan, Hannah D.; Darmanin, Connie; Johnson, Brett C.; Harder, Ross; Clark, Jesse N.; Balaur, Eugeniu; Abbey, Brian

    2017-01-01

    The unique properties of nanodiamonds make them suitable for use in a wide range of applications, including as biomarkers for cellular tracking in vivo at the molecular level. The sustained fluorescence of nanodiamonds containing nitrogen-vacancy (N-V) centres is related to their internal structure and strain state. Theoretical studies predict that the location of the N-V centre and the nanodiamonds' residual elastic strain state have a major influence on their photoluminescence properties. However, to date there have been no direct measurements made of their spatially resolved deformation fields owing to the challenges that such measurements present. Here we apply the recently developed technique of Bragg coherent diffractive imaging (BCDI) to map the three-dimensional deformation field within a single nanodiamond of approximately 0.5 µm diameter. The results indicate that there are high levels of residual elastic strain present in the nanodiamond which could have a critical influence on its optical and electronic properties.

  6. Time-slice maps showing age, distribution, and style of deformation in Alaska north of 60° N.

    Science.gov (United States)

    Moore, Thomas E.; Box, Stephen E.

    2016-08-29

    The structural architecture of Alaska is the product of a complex history of tectonism that occurred along the Cordilleran and Arctic margins of North America through interactions with ancient and modern ocean plates and with continental elements derived from Laurentia, Siberia, and Baltica. To unravel the tectonic history of Alaska, we constructed maps showing the age, distribution, structural style, and kinematics of contractional and penetrative extensional deformation in Alaska north of latitude 60° N. at a scale of 1:5,000,000. These maps use the Geologic Map of the Arctic (Harrison and others, 2011) as a base map and follow the guidelines in the Tectonic Map of the Arctic project (Petrov and others, 2013) for construction, including use of the International Commission on Stratigraphy time scale (Cohen and others, 2013) divided into 20 time intervals. We find evidence for deformation in 14 of the 20 time intervals and present maps showing the known or probable extent of deformation for each time interval. Maps and descriptions of deformational style, age constraints, kinematics, and information sources for each deformational episode are discussed in the text and are reported in tabular form. This report also contains maps showing the lithologies and structural geology of Alaska, a terrane map, and the distribution of tectonically important units including post-tectonic sedimentary basins, accretionary complexes, ophiolites, metamorphic rocks.These new maps show that most deformational belts in Alaska are relatively young features, having developed during the late Mesozoic and Cenozoic. The oldest episode of deformation recognized anywhere in Alaska is found in the basement of the Farewell terrane (~1.75 Ga). Paleozoic and early Mesozoic deformational events, including Devonian deformation in the Arctic Alaska terrane, Pennsylvanian deformation in the Alexander terrane, Permian deformation in the Yukon Composite (Klondike orogeny) and Farewell terranes (Browns

  7. Deformation mechanism of nanoporous materials upon water freezing and melting

    Science.gov (United States)

    Erko, Maxim; Wallacher, Dirk; Paris, Oskar

    2012-10-01

    Temperature-induced non-monotonous reversible deformation of water-filled nanoporous silica materials is investigated experimentally using in-situ small-angle x-ray scattering. The influence of freezing and melting in the nanopores on this deformation is treated quantitatively by introducing a simple model based on the Gibbs-Thomson equation and a generalized Laplace-pressure. The physical origin of the melting/freezing induced pore lattice deformation is found to be exactly the same as for capillary condensation/evaporation, namely the curved phase boundary due to the preferred wetting of the pore walls by the liquid phase. As a practical implication, elastic properties of the nanoporous framework can be determined from the temperature-deformation curves.

  8. Coordinate mapping of hyolaryngeal mechanics in swallowing.

    Science.gov (United States)

    Thompson, Thomas Z; Obeidin, Farres; Davidoff, Alisa A; Hightower, Cody L; Johnson, Christohper Z; Rice, Sonya L; Sokolove, Rebecca-Lyn; Taylor, Brandon K; Tuck, John M; Pearson, William G

    2014-05-06

    Characterizing hyolaryngeal movement is important to dysphagia research. Prior methods require multiple measurements to obtain one kinematic measurement whereas coordinate mapping of hyolaryngeal mechanics using Modified Barium Swallow (MBS) uses one set of coordinates to calculate multiple variables of interest. For demonstration purposes, ten kinematic measurements were generated from one set of coordinates to determine differences in swallowing two different bolus types. Calculations of hyoid excursion against the vertebrae and mandible are correlated to determine the importance of axes of reference. To demonstrate coordinate mapping methodology, 40 MBS studies were randomly selected from a dataset of healthy normal subjects with no known swallowing impairment. A 5 ml thin-liquid bolus and a 5 ml pudding swallows were measured from each subject. Nine coordinates, mapping the cranial base, mandible, vertebrae and elements of the hyolaryngeal complex, were recorded at the frames of minimum and maximum hyolaryngeal excursion. Coordinates were mathematically converted into ten variables of hyolaryngeal mechanics. Inter-rater reliability was evaluated by Intraclass correlation coefficients (ICC). Two-tailed t-tests were used to evaluate differences in kinematics by bolus viscosity. Hyoid excursion measurements against different axes of reference were correlated. Inter-rater reliability among six raters for the 18 coordinates ranged from ICC = 0.90 - 0.97. A slate of ten kinematic measurements was compared by subject between the six raters. One outlier was rejected, and the mean of the remaining reliability scores was ICC = 0.91, 0.84 - 0.96, 95% CI. Two-tailed t-tests with Bonferroni corrections comparing ten kinematic variables (5 ml thin-liquid vs. 5 ml pudding swallows) showed statistically significant differences in hyoid excursion, superior laryngeal movement, and pharyngeal shortening (p Pearson correlations of hyoid excursion measurements from two different

  9. Study and Simulation of Deformation Mechanics Modeling of Flexible Workpiece Processing by Rayleigh-Ritz Method

    Directory of Open Access Journals (Sweden)

    Yaohua Deng

    2015-01-01

    Full Text Available This paper discusses the calculation problems of bending deformation of FWP processing. Take three axis CNC machining as an example, to establish mechanics model of flexible workpiece processing process. The flexible workpiece balance equation is a two-dimensional partial differential equation, to solve the problem of flexible workpiece bending deformation using Rayleigh-Ritz method and designing the test function of bending deformation of flexible workpiece. By satisfying the minimum potential energy condition of FWP processing to work out the approximate solution of bending deformation of flexible workpiece, find out the relationship between material properties of flexible piece, acting force Fz, and deformation value. Finally, the rectangle flexible workpiece which is made up of polyurethane sponge is selected as an experiment subject. The results show that the average relative deviation between theoretical value and observed value is only 5.51%. It is proved that the bending deformation test function satisfies the actual deformation calculation requirements.

  10. MO-C-17A-08: Evaluation of Lung Deformation Using Three Dimensional Strain Maps

    Energy Technology Data Exchange (ETDEWEB)

    Cui, T [Duke University, Durham, NC (United States); Huang, Q [Duke Unversity, Durham, NC (United States); Miller, W [University of Virginia, Charlottesville, VA (United States); Zhong, X [Siemens Healthcare, Atlanta, GA (United States); Yin, F; Cai, J [Duke University Medical Center, Durham, NC (United States)

    2014-06-15

    Purpose: To develop a systematic approach to generate three dimensional (3D) strain maps of lung using the displacement vector field (DVF) during the respiratory deformation, and to demonstrate its application in evaluating deformable image registration (DIR). Methods: A DVF based strain tensor at each voxel of interest (VOI) was calculated from the relative displacements between the VOI and each of the six nearest neighbors. The maximum and minimum stretches of a VOI can be determined by the principal strains (E{sub 1}, E{sub 2} and E{sub 3}), which are the eigenvalues and the corresponding strain tensors. Two healthy volunteers enrolled in this study under IRB-approved protocol, each was scanned using 3D Hyperpolarized He-3 tagging-MRI and 3D proton-MRI with TrueFISP sequence at the endof- inhalation (EOI) and the end-of-exhalation (EOE) phases. 3D DVFs of tagging- and proton-MRI were obtained by the direct measurements of the tagging grid trajectory and by the DIR method implemented in commercial software. Results: 3D strain maps were successfully generated for all DVFs. The principal strain E1s were calculated as 0.43±0.05 and 0.17±0.25 for tagging-MRI and proton-MRI, respectively. The large values of E{sub 1} indicate the predominant lung motion in the superior-inferior (SI) direction. Given that the DVFs from the tagging images are considered as the ground truth, the discrepancies in the DIR-based strain maps suggest the inaccuracy of the DIR algorithm. In the E{sub 1} maps of tagging-MRI for subject 1, the fissures were distinguishable by the larger values (0.49±0.02) from the adjacent tissues (0.41±0.03) due to the larger relative displacement between the lung lobes. Conclusion: We have successfully developed a methodology to generate DVF-based 3D strain maps of lung. It can potentially enable us to better understand the pulmonary biomechanics and to evaluate and improve the DIR algorithms for the lung deformation. We are currently studying more

  11. Sentinel-1 Constellation for nationwide deformation mapping with InSAR -- From science to operations

    Science.gov (United States)

    Dehls, John; Larsen, Yngvar; Marinkovic, Petar

    2016-04-01

    For more than a decade, InSAR has been used in Norway study landslides and subsidence. Initial studies concentrated on understanding and validating the technique in various settings. During the last five years, however, we have moved towards using InSAR in operational settings. Of all the challenges we have faced, the largest has been regular access to SAR imagery. The Sentinel-1 constellation will bring a paradigm shift to the field with its operational characteristics: mission configuration, acquisition planning, and data distribution policy. For the first time, we will have nationwide acquisitions with an unprecedented temporal spacing. By the end of this year, we will have a sufficiently long time series of data to produce an initial version of a national deformation map. Within the ESA SEOM InSARap project, we have developed the necessary updates of interferometric processing tools necessary to handle the novel TOPS mode, and successfully demonstrated the performance of S1 InSAR in a number of scientific applications. However, to fully exploit the key advantages of the Sentinel-1 mission, we still face a number of scientific and operational challenges, due to the new and unique characteristics of the mission. Specifically, the large coverage and dense temporal sampling results in very large data sets with a vastly increased information content, which still needs new algorithmic development to extract. In the context of national mapping, optimal harmonization of deformation maps based on overlapping individual S1 stacks is the most prominent challenge. Urban areas in Norway face much the same problems as many other cities throughout the world; subsidence due to soil compaction and groundwater changes or excavation, and resulting damage to infrastructure. More unique to Norway is the threat to lives caused by large unstable rock slopes along the steep fjords. In the 20th century alone, catastrophic rock slope failures leading to tsunamis in fjords and large

  12. Simultaneous multi-scale registration using large deformation diffeomorphic metric mapping.

    Science.gov (United States)

    Risser, Laurent; Vialard, François-Xavier; Wolz, Robin; Murgasova, Maria; Holm, Darryl D; Rueckert, Daniel

    2011-10-01

    In the framework of large deformation diffeomorphic metric mapping (LDDMM), we present a practical methodology to integrate prior knowledge about the registered shapes in the regularizing metric. Our goal is to perform rich anatomical shape comparisons from volumetric images with the mathematical properties offered by the LDDMM framework. We first present the notion of characteristic scale at which image features are deformed. We then propose a methodology to compare anatomical shape variations in a multi-scale fashion, i.e., at several characteristic scales simultaneously. In this context, we propose a strategy to quantitatively measure the feature differences observed at each characteristic scale separately. After describing our methodology, we illustrate the performance of the method on phantom data. We then compare the ability of our method to segregate a group of subjects having Alzheimer's disease and a group of controls with a classical coarse to fine approach, on standard 3D MR longitudinal brain images. We finally apply the approach to quantify the anatomical development of the human brain from 3D MR longitudinal images of pre-term babies. Results show that our method registers accurately volumetric images containing feature differences at several scales simultaneously with smooth deformations.

  13. Continuum Mechanics Based Bi-linear Shear Deformable Shell Element Using Absolute Nodal Coordinate Formulation

    Science.gov (United States)

    2014-03-07

    the convergent solution in the case of the continuum mechanics based bi- linear shear deformable ANCF shell element. 5.3 Slit Annular Plate Subjected...UNCLASSIFIED: Distribution Statement A. Approved for public release. #24515 CONTINUUM MECHANICS BASED BI- LINEAR SHEAR DEFORMABLE SHELL ELEMENT...MAR 2014 2. REPORT TYPE Technical Report 3. DATES COVERED 07-01-2014 to 04-03-2014 4. TITLE AND SUBTITLE CONTINUUM MECHANICS BASED BI- LINEAR

  14. Mapping ground surface deformation using temporarily coherent point SAR interferometry: Application to Los Angeles Basin

    Science.gov (United States)

    Zhang, L.; Lu, Zhiming; Ding, X.; Jung, H.-S.; Feng, G.; Lee, C.-W.

    2012-01-01

    Multi-temporal interferometric synthetic aperture radar (InSAR) is an effective tool to detect long-term seismotectonic motions by reducing the atmospheric artifacts, thereby providing more precise deformation signal. The commonly used approaches such as persistent scatterer InSAR (PSInSAR) and small baseline subset (SBAS) algorithms need to resolve the phase ambiguities in interferogram stacks either by searching a predefined solution space or by sparse phase unwrapping methods; however the efficiency and the success of phase unwrapping cannot be guaranteed. We present here an alternative approach - temporarily coherent point (TCP) InSAR (TCPInSAR) - to estimate the long term deformation rate without the need of phase unwrapping. The proposed approach has a series of innovations including TCP identification, TCP network and TCP least squares estimator. We apply the proposed method to the Los Angeles Basin in southern California where structurally active faults are believed capable of generating damaging earthquakes. The analysis is based on 55 interferograms from 32 ERS-1/2 images acquired during Oct. 1995 and Dec. 2000. To evaluate the performance of TCPInSAR on a small set of observations, a test with half of interferometric pairs is also performed. The retrieved TCPInSAR measurements have been validated by a comparison with GPS observations from Southern California Integrated GPS Network. Our result presents a similar deformation pattern as shown in past InSAR studies but with a smaller average standard deviation (4.6. mm) compared with GPS observations, indicating that TCPInSAR is a promising alternative for efficiently mapping ground deformation even from a relatively smaller set of interferograms. ?? 2011.

  15. Microscale Mechanical Deformation Behaviors and Mechanisms in Bulk Metallic Glasses Investigated with Micropillar Compression Experiments

    Science.gov (United States)

    Ye, Jianchao

    2011-12-01

    Over the past years of my PhD study, the focused-ion-beam (FIB) based microcompression experiment has been thoroughly investigated with respect to the small-scale deformation in metallic glasses. It was then utilized to explore the elastic and plastic deformation mechanisms in metallic glasses. To this end, micropillars with varying sample sizes and aspect ratios were fabricated by the FIB technique and subsequently compressed on a modified nanoindentation system. An improved formula for the measurement of the Young's modulus was derived by adding a geometrical prefactor to the Sneddon's solution. Through the formula, geometry-independent Young's moduli were extracted from microcompression experiments, which are consistent with nanoindentation results. Furthermore, cyclic microcompression was developed, which revealed reversible inelastic deformation in the apparent elastic regime through high-frequency cyclic loading. The reversible inelastic deformation manifests as hysteric loops in cyclic microcompression and can be captured by the Kelvin-type viscoelastic model. The experimental results indicate that the free-volume zones behave essentially like supercooled liquids with an effective viscosity on the order of 1 x 108 Pas. The microscopic yield strengths were first extracted with a formula derived based on the Mohr-Coulomb law to account for the geometrical effects from the tapered micropillar and the results showed a weak size effect on the yield strengths of a variety of metallic-glass alloys, which can be attributed to Weibull statistics. The nature of the yielding phenomenon was explored with the cyclic micro-compression approach. Through cyclic microcompression of a Zr-based metallic glass, it can be demonstrated that its yielding stress increases at higher applied stress rate but its yielding strain is kept at a constant of ~ 2%. The room-temperature post-yielding deformation behavior of metallic glasses is characterized by flow serrations, which were

  16. Mechanism of Austenite Evolution During Deformation of Ultra-High Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-lan; SUN Xin-jun; DONG Han

    2008-01-01

    The mechanism of transformation of austenite to cementite and pearlite during the deformation of ultra-high carbon steel was discussed. The results indicate that the pearlite and cementite can be induced by deformation be-tween Acm to Arcm. The transformation during deformation is still considered as a diffusion-controlled process. With the increase of time and reduction, the pearlite fraction increased. At the beginning of the transformation, the pearli- te was lamelliform. When the rate of reduction was increased to 70%, some of the induced lamellar pearlite was bro-ken up under deformation.

  17. Mechanical properties of hot deformed Inconel 718 and X750

    Directory of Open Access Journals (Sweden)

    A. Nowotnik

    2012-02-01

    Full Text Available Purpose: Variations of a flow stress vs. true strain illustrate behavior of material during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloys of Inconel 718 and X750 at constant true strain rates of 10-4, 4x10-4s-1 within temperature through which precipitation hardening phases process occurred (720-1150°C using thermomechanical simulator Gleeble and dilatometer Baehr 850D/L equipped with compression unit. True stress-true strain curves analysis of hot deformed alloys were described.Findings: On the basis of received flow stress values activation energy of a high-temperature deformation process was estimated. Mathematical dependences (σpl -T i σpl - ε and compression data were used to determine material’s constants. These constants allow to derive a formula that describes the relationship between strain rate (ε, deformation temperature (T and flow stress σpl.Research limitations/implications: Study the flow stress will be continued on the samples after the aging process.Practical implications: The results of high-temperature deformation of the examined Inconel alloys may possibly find some practical use in the workshop practice to predict a flow stress values, but only within particular temperature and strain rate ranges. The results of the study can be used in the aerospace industry to produce blades for jet engines.Originality/value: The results of the study can be used in the aerospace industry to produce blades for jet engines.

  18. Failure mechanism and supporting measures for large deformation of Tertiary deep soft rock

    Institute of Scientific and Technical Information of China (English)

    Guo Zhibiao; Wang Jiong; Zhang Yuelin

    2015-01-01

    The Shenbei mining area in China contains typical soft rock from the Tertiary Period. As mining depths increase, deep soft rock roadways are damaged by large deformations and constantly need to be repaired to meet safety requirements, which is a great security risk. In this study, the characteristics of deformation and failure of typical roadway were analyzed, and the fundamental reason for the roadway deformation was that traditional support methods and materials cannot control the large deformation of deep soft rock. Deep soft rock support technology was developed based on constant resistance energy absorption using constant resistance large deformation bolts. The correlative deformation mechanisms of surrounding rock and bolt were analyzed to understand the principle of constant resistance energy absorption. The new technology works well on-site and provides a new method for the excavation of roadways in Tertiary deep soft rock.

  19. The Classical and Quantum Mechanics of lazy baker Maps

    CERN Document Server

    Lakshminarayan, A

    1993-01-01

    We introduce and study the classical and quantum mechanics of certain non hyperbolic maps on the unit square. These maps are modifications of the usual baker's map and their behaviour ranges from chaotic motion on the whole measure to chaos on a set of measure zero. Thus we have called these maps ``lazy baker maps.'' The aim of introducing these maps is to provide the simplest models of systems with a mixed phase space, in which there are both regular and chaotic motions. We find that despite the obviously contrived nature of these maps they provide a good model for the study of the quantum mechanics of such systems. We notice the effect of a classically chaotic fractal set of measure zero on the corresponding quantum maps, which leads to a transition in the spectral statistics. Some periodic orbits belonging to this fractal set are seen to scar several eigenfunctions.

  20. Single-step scanner-based digital image correlation (SB-DIC) method for large deformation mapping in rubber

    Science.gov (United States)

    Goh, C. P.; Ismail, H.; Yen, K. S.; Ratnam, M. M.

    2017-01-01

    The incremental digital image correlation (DIC) method has been applied in the past to determine strain in large deformation materials like rubber. This method is, however, prone to cumulative errors since the total displacement is determined by combining the displacements in numerous stages of the deformation. In this work, a method of mapping large strains in rubber using DIC in a single-step without the need for a series of deformation images is proposed. The reference subsets were deformed using deformation factors obtained from the fitted mean stress-axial stretch ratio curve obtained experimentally and the theoretical Poisson function. The deformed reference subsets were then correlated with the deformed image after loading. The recently developed scanner-based digital image correlation (SB-DIC) method was applied on dumbbell rubber specimens to obtain the in-plane displacement fields up to 350% axial strain. Comparison of the mean axial strains determined from the single-step SB-DIC method with those from the incremental SB-DIC method showed an average difference of 4.7%. Two rectangular rubber specimens containing circular and square holes were deformed and analysed using the proposed method. The resultant strain maps from the single-step SB-DIC method were compared with the results of finite element modeling (FEM). The comparison shows that the proposed single-step SB-DIC method can be used to map the strain distribution accurately in large deformation materials like rubber at much shorter time compared to the incremental DIC method.

  1. Integration of GPS and InSAR Data for Optimal 3-Dimensional Crustal Deformation Map

    Science.gov (United States)

    Shen, Z.; Liu, Z.

    2016-12-01

    GPS and InSAR are complementary to each other for crustal deformation monitoring, We develop an algorithm to integrate the two data sets for the production of 3-dimensional crustal motion map. In the algorithm point-based discrete GPS measurements are first interpolated to produce continuous 3-D vector map at chosen grids covered by the InSAR data. The interpolation is based on an algorithm of Shen et al. [2015], which takes into account of GPS station distance, network density and configuration for data weighting. A Gaussian distance weighting function and a Voronoi cell spatial weighting function are used in the interpolation. The amount of weighting and degree of smoothing can be spatially variable and optimally determined based on in situ data strength. This approach can effectively smooth out the incoherencies in discretized GPS velocity data. At the locations where both InSAR and interpolated GPS data are available, optimal 3-D components are solved for using a weighted least square method. The InSAR data are weighted by their LOS uncertainties. The GPS interpolated data are weighted by their re-estimated uncertainties assuming a uniform smoothing instead of variable smoothing used for data interpolation as mentioned above, to ensure that the uncertainty estimates reflect the in situ data strength consistently and not biased by uneven degree of smoothing. Including InSAR data from both ascending and descending viewing geometry, if available, provides improved constraint on the 3-D deformation when integrating with GPS data. We apply this algorithm to a test region in southern California covering most of the active faults in the region such as the San Andreas, San Jacinto, and Garlock. We use LOS rate data derived from 18 years of ERS-Envisat InSAR data, and a combination of continuous and campaign GPS data of more than two decades of time span. Our preliminary result shows that the GPS and InSAR data are generally consistent for the horizontal velocities at

  2. Macro-scale deformation behavior and characterization of deformation mechanisms below µm-scale in experimentally deformed Boom Clay by using the combination of triaxial compression, X-ray µ-CT imaging, DIC, BIB cross sectioning, and SEM

    Science.gov (United States)

    Oelker, Anne; Desbois, Guillaume; Urai, Janos L.; Bésuelle, Pierre; Viggiani, Gioacchino; Levasseur, Séverine

    2017-04-01

    Boom Clay is one formation being studied in Belgium as a potential host rock for deep geological disposal of radioactive waste. This poorly indurated clay presents in its natural state favorable properties against the migration of radionuclides: low permeability, low solute diffusion rates, good retention and sorption capacity for many radionuclides and good self-sealing capacity. During construction of disposal galleries, stress redistribution will lead to perturbation of the clay and the formation around galleries of the so-called "Excavation disturbed Zone" (EdZ). The study of deformation mechanisms and evolution of Boom Clay properties at macro but also micro scale allows to assess in a more mechanistic way the evolution of Boom Clay properties in this EdZ. In this work, we show microstructural investigations of Boom Clay deformed in undrained triaxial compression by linking conventional stress/strain curves with Digital Image Correlation (DIC) and scanning electron microscopy (SEM) imaging of broad-ion-beam (BIB) milled cross-sections to deduce deformation mechanisms based on microstructures at sub-micron resolution. Two specimens, collected in Mol (Belgium) at the European Underground Laboratories (URL) on HADES level, were analyzed: The major principal stress σ1 was applied parallel as well as perpendicular to the bedding direction with an initial mean normal effective stress of 4.5 MPa and an initial pore water pressure of 2.3 MPa, which are equal to the in-situ values. Linking the resulting DIC-derived maps of incremental strains with the corresponding stress/strain curve give not only information about the moment of the shear band development, but also on the way strain evolves within the specimen throughout the rest. Incremental DIC analysis of X-ray tomographic scans performed during loading tests give a time evolution of the strain field, and subsequently allow to detect strain localization which appears close to the stress peak. Regions with a

  3. Relationships between phase morphology and deformation mechanisms in polymer nanocomposite nanofibres prepared by an electrospinning process.

    Science.gov (United States)

    Kim, G M; Lach, R; Michler, G H; Pötschke, P; Albrecht, K

    2006-02-28

    Relationships between phase morphology and mechanical deformation processes in various electrospun polymer nanocomposite nanofibres (PNCNFs) containing different types of one-, two- and three-dimensional nanofiller have been investigated by transmission electron microscopy using in situ tensile techniques. From the study of the phase structure of electrospun PNCNFs, two morphological standard types are classified for the analysis of deformation mechanisms: the binary system (polymer matrix and nanofillers), and the ternary system (polymer matrix, nanofillers and nanopores on the fibres surface). According to these categories, deformation processes have been characterized, and different schematic models for these processes are proposed. The finding of importance in the present work is a brittle-to-ductile transition in polymer nanocomposite fibres during in situ tensile deformation processes. This unique feature in the deformation behaviour of electrospun PNCNFs provides an optimal balance of stiffness, strength and toughness for use as reinforcing elements in a polymer based composite of a new kind.

  4. Compression Deformation Mechanisms at the Nanoscale in Magnesium Single Crystal

    Institute of Scientific and Technical Information of China (English)

    Yafang GUO; Xiaozhi TANG; Yuesheng WANG; Zhengdao WANG; Sidney YIP

    2013-01-01

    The dominant deformation mode at low temperatures for magnesium and its alloys is generally regarded to be twinning because of the hcp crystal structure.More recently,the phenomenon of a "loss" of the twins has been reported in microcompression experiments of the magnesium single crystals.Molecular dynamics simulation of compression deformation shows that the pyramidal slip dominates compression behavior at the nanoscale.No compression twins are observed at different temperatures at different loadings and boundary conditions.This is explained by the analyses,that is,the {10(1-)2} and {101-1} twins can be activated under c-axis tension,while compression twins will not occur when the c/a ratio of the hcp metal is below (/)3.Our theoretical and simulation results are consistent with recent microcompression experiments of the magnesium (0001) single crystals.

  5. Deformation mechanisms in negative Poisson's ratio materials - Structural aspects

    Science.gov (United States)

    Lakes, R.

    1991-01-01

    Poisson's ratio in materials is governed by the following aspects of the microstructure: the presence of rotational degrees of freedom, non-affine deformation kinematics, or anisotropic structure. Several structural models are examined. The non-affine kinematics are seen to be essential for the production of negative Poisson's ratios for isotropic materials containing central force linkages of positive stiffness. Non-central forces combined with pre-load can also give rise to a negative Poisson's ratio in isotropic materials. A chiral microstructure with non-central force interaction or non-affine deformation can also exhibit a negative Poisson's ratio. Toughness and damage resistance in these materials may be affected by the Poisson's ratio itself, as well as by generalized continuum aspects associated with the microstructure.

  6. In vivo deformation of thin cartilage layers: Feasibility and applicability of T2* mapping.

    Science.gov (United States)

    Van Ginckel, Ans; Witvrouw, Erik E

    2016-05-01

    The objectives of this study were as follows: (i) to assess segmentation consistency and scan precision of T2* mapping of human tibio-talar cartilage, and (ii) to monitor changes in T2* relaxation times of ankle cartilage immediately following a clinically relevant in vivo exercise and during recovery. Using multi-echo gradient recalled echo sequences, averaged T2* values were calculated for tibio-talar cartilage layers in 10 healthy volunteers. Segmentation consistency and scan precision were determined from two repeated segmentations and two repeated acquisitions with repositioning, respectively. Subsequently, acute in vivo cartilage loading responses were monitored by calculating averaged tibio-talar T2* values at rest, immediately after (i.e., deformation) and at 15 min (i.e., recovery) following a 30-repetition knee bending exercise. Precision errors attained 4-6% with excellent segmentation consistency point estimates (i.e., intra-rater ICC of 0.95) and acceptable limits of confidence. At deformation, T2* values were increased in both layers [+16.1 (10.7)%, p = 0.004 and +17.3 (15.3)%, p = 0.023, for the talus and tibia, respectively] whereas during recovery no significant changes could be established when comparing to baseline [talar cartilage: +5.2 (8.2)%, p = 0.26 and tibial cartilage: +6.6 (10.4)%, p = 0.23]. T2* mapping is a viable method to monitor deformational behavior in thin cartilage layers such as ankle cartilage. Longitudinal changes in T2* can be reliably appraised and require at least 4-6% differences to ascertain statistical significance. The ability to detect considerable change even after non-strenuous loading events, endorses T2* mapping as an innovative method to evaluate the effects of therapeutic exercise on thin cartilage layers. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:771-778, 2016.

  7. Cyclic mechanical deformation stimulates human lung fibroblast proliferation and autocrine growth factor activity.

    Science.gov (United States)

    Bishop, J E; Mitchell, J J; Absher, P M; Baldor, L; Geller, H A; Woodcock-Mitchell, J; Hamblin, M J; Vacek, P; Low, R B

    1993-08-01

    Cellular hypertrophy and hyperplasia and increased extracellular matrix deposition are features of tissue hypertrophy resulting from increased work load. It is known, for example, that mechanical forces play a critical role in lung development, cardiovascular remodeling following pressure overload, and skeletal muscle growth. The mechanisms involved in these processes, however, remain unclear. Here we examined the effect of mechanical deformation on fibroblast function in vitro. IMR-90 human fetal lung fibroblasts grown on collagen-coated silastic membranes were subjected to cyclical mechanical deformation (10% increase in culture surface area; 1 Hz) for up to 5 days. Cell number was increased by 39% after 2 days of deformation (1.43 +/- .01 x 10(5) cells/membrane compared with control, 1.03 +/- 0.02 x 10(5) cells; mean +/- SEM; P < 0.02) increasing to 163% above control by 4 days (2.16 +/- 0.16 x 10(5) cells compared with 0.82 +/- 0.03 x 10(5) cells; P < 0.001). The medium from mechanically deformed cells was mitogenic for IMR-90 cells, with maximal activity in the medium from cells mechanically deformed for 2 days (stimulating cell replication by 35% compared with media control; P < 0.002). These data suggest that mechanical deformation stimulates human lung fibroblast replication and that this effect is mediated by the release of autocrine growth factors.

  8. Mechanical and microstructural characterization of 6061 aluminum alloy strips severely deformed by Dissimilar Channel Angular Pressing

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Evren, E-mail: etan@metu.edu.tr [Middle East Technical University, Metallurgical and Materials Eng. Dept., 06531, Ankara (Turkey); Kibar, Alp Aykut, E-mail: alpaykut@gmail.com [Scientific and Technological Research Council of Turkey, 06100, Ankara (Turkey); Guer, C. Hakan, E-mail: chgur@metu.edu.tr [Middle East Technical University, Metallurgical and Materials Eng. Dept., 06531, Ankara (Turkey)

    2011-04-15

    Dissimilar Channel Angular Pressing (DCAP) is a severe plastic deformation technique to improve the mechanical properties of flat products by producing ultrafine grains. In this study, the changes in the microstructure and mechanical properties of 6061 Al-alloy strips deformed by various numbers of DCAP passes were investigated. Some DCAPed samples were also held at 200 deg. C and 350 deg. C to investigate the effect of post-annealing. Mechanical properties were determined by hardness and tension tests; and microstructural changes were investigated by TEM analysis. Up to a critical level of plastic strain, remarkable improvements have been observed in the strength and hardness of the severely deformed strips; and the improvements have been explained by variations in grain size, dislocation structure, and formation of subgrains. - Research Highlights: {yields}Dissimilar Channel Angular Pressing (DCAP). {yields}Severe plastic deformation (SPD). {yields}Transmission Electron Microscopy of the 6061 Al alloy. {yields}Mechanical Properties of 6061 Al alloy.

  9. GIS multi-criteria decision analysis for assessment and mapping of neotectonic landscape deformation: A case study from Crete

    Science.gov (United States)

    Argyriou, Athanasios V.; Teeuw, Richard M.; Rust, Derek; Sarris, Apostolos

    2016-01-01

    This study of drainage systems in a tectonically active region is based on the Geographical Information Systems (GIS) integration of data from an analytic hierarchy process (AHP) and a weighted linear combination (WLC) procedure with multiple criteria data. A set of thematic maps were produced, based on existing geological maps and freely-available ASTER Global DEM elevation data, using various geological information (i.e. lineaments and lithologies), geomorphometric indices (i.e. slope gradient, drainage density, stream frequency, and the topographic wetness index) and morphotectonic indices (i.e. amplitude of relief and stream length gradient) that highlight areas of neotectonic landscape deformation. The weights of the factors were determined using AHP and WLC. A neotectonic landscape deformation index (NLDI) is computed as the sum of the various weighted factors to provide a map of NLDI distribution across the study region (western Crete). The main objective of this study was to analyse and map the intra-basin spatial variations in neotectonic landscape deformation: five classes, very low to very high, were determined. High to very high deformation zones are linked with known and newly detected active fault zones. The methodology could be developed into a low-cost technique for assessing seismic hazard, guiding disaster risk reduction activities. It can provide an alternative to the Interferometric Synthetic Aperture Radar (InSAR) approach for highlighting zones of neotectonic deformation, particularly in regions where dense vegetation or snow cover renders InSAR ineffective.

  10. Unobstructedness of deformations of holomorphic maps onto Fano manifolds of Picard number 1

    CERN Document Server

    Hwang, Jun-Muk

    2009-01-01

    We show that deformations of a surjective morphism onto a Fano manifold of Picard number 1 are unobstructed and rigid modulo the automorphisms of the target, if the variety of minimal rational tangents of the Fano manifold is non-linear or finite. The condition on the variety of minimal rational tangents holds for practically all known examples of Fano manifolds of Picard number 1, except the projective space. When the variety of minimal rational tangents is non-linear, the proof is based on an earlier result of N. Mok and the author on the birationality of the tangent map. When the varieties of minimal rational tangents of the Fano manifold is finite, the key idea is to factorize the given surjective morphism, after some transformation, through a universal morphism associated to the minimal rational curves.

  11. Thick and deformed Antarctic sea ice mapped with autonomous underwater vehicles

    Science.gov (United States)

    Williams, G.; Maksym, T.; Wilkinson, J.; Kunz, C.; Murphy, C.; Kimball, P.; Singh, H.

    2015-01-01

    Satellites have documented trends in Antarctic sea-ice extent and its variability for decades, but estimating sea-ice thickness in the Antarctic from remote sensing data remains challenging. In situ observations needed for validation of remote sensing data and sea-ice models are limited; most have been restricted to a few point measurements on selected ice floes, or to visual shipboard estimates. Here we present three-dimensional (3D) floe-scale maps of sea-ice draft for ten floes, compiled from two springtime expeditions by an autonomous underwater vehicle to the near-coastal regions of the Weddell, Bellingshausen, and Wilkes Land sectors of Antarctica. Mean drafts range from 1.4 to 5.5 m, with maxima up to 16 m. We also find that, on average, 76% of the ice volume is deformed ice. Our surveys indicate that the floes are much thicker and more deformed than reported by most drilling and ship-based measurements of Antarctic sea ice. We suggest that thick ice in the near-coastal and interior pack may be under-represented in existing in situ assessments of Antarctic sea ice and hence, on average, Antarctic sea ice may be thicker than previously thought.

  12. Microstructural Evolution and Dynamic Softening Mechanisms of Al-Zn-Mg-Cu Alloy during Hot Compressive Deformation

    Directory of Open Access Journals (Sweden)

    Cangji Shi

    2014-01-01

    Full Text Available The hot deformation behavior and microstructural evolution of an Al-Zn-Mg-Cu (7150 alloy was studied during hot compression at various temperatures (300 to 450 °C and strain rates (0.001 to 10 s−1. A decline ratio map of flow stresses was proposed and divided into five deformation domains, in which the flow stress behavior was correlated with different microstructures and dynamic softening mechanisms. The results reveal that the dynamic recovery is the sole softening mechanism at temperatures of 300 to 400 °C with various strain rates and at temperatures of 400 to 450 °C with strain rates between 1 and 10 s−1. The level of dynamic recovery increases with increasing temperature and with decreasing strain rate. At the high deformation temperature of 450 °C with strain rates of 0.001 to 0.1 s−1, a partially recrystallized microstructure was observed, and the dynamic recrystallization (DRX provided an alternative softening mechanism. Two kinds of DRX might operate at the high temperature, in which discontinuous dynamic recrystallization was involved at higher strain rates and continuous dynamic recrystallization was implied at lower strain rates.

  13. Mechanical spectroscopy of deformed WE43 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lambri, O.A. [Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Instituto de Fisica Rosario, CONICET, Avda Pellegrini 250, 2000 Rosario (Argentina); Laboratorio de Materiales, Esc. de Ing. Electrica, FCEIA, UNR (Argentina); Riehemann, W. [Institute of Materials Science and Technology, Clausthal University of Technology, Agricolastrasse 6, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: werner.riehemann@tu-clausthal.de; Lucioni, E.J. [Laboratorio de Materiales, Esc. de Ing. Electrica, FCEIA, UNR (Argentina); Bolmaro, R.E. [Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Instituto de Fisica Rosario, CONICET, Avda Pellegrini 250, 2000 Rosario (Argentina)

    2006-12-20

    Ageing commercial WE43 magnesium alloys at 643 K for various times up to 10,000 s promotes the development of P1 precipitates, which strengthen the matrix. However, overageing causes P2 precipitates, which soften the matrix, to develop. Room temperature plastic deformation of samples aged at 643 K causes (a) the generation of new dislocations and (b) the dissolution of the previously developed strengthening P1 precipitates. These effects are revealed by (a) the decreased micro yield stress, (b) the increased part of the measured internal friction which is independent of the amplitude, and (c) the decreased integrated intensity of the diffraction peak related to P1.

  14. Uncovering the deformation mechanisms of origami metamaterials by introducing generic degree-four vertices.

    Science.gov (United States)

    Fang, Hongbin; Li, Suyi; Ji, Huimin; Wang, K W

    2016-10-01

    Origami-based design holds promise for developing new mechanical metamaterials whose overall kinematic and mechanical properties can be programmed using purely geometric criteria. In this article, we demonstrate that the deformation of a generic degree-four vertex (4-vertex) origami cell is a combination of contracting, shearing, bending, and facet-binding. The last three deformation mechanisms are missing in the current rigid-origami metamaterial investigations, which focus mainly on conventional Miura-ori patterns. We show that these mechanisms provide the 4-vertex origami sheets and blocks with new deformation patterns as well as extraordinary kinematical and mechanical properties, including self-locking, tridirectional negative Poisson's ratios, flipping of stiffness profiles, and emerging shearing stiffness. This study reveals that the 4-vertex cells offer a better platform and greater design space for developing origami-based mechanical metamaterials than the conventional Miura-ori cell.

  15. Uncovering the deformation mechanisms of origami metamaterials by introducing generic degree-four vertices

    Science.gov (United States)

    Fang, Hongbin; Li, Suyi; Ji, Huimin; Wang, K. W.

    2016-10-01

    Origami-based design holds promise for developing new mechanical metamaterials whose overall kinematic and mechanical properties can be programmed using purely geometric criteria. In this article, we demonstrate that the deformation of a generic degree-four vertex (4-vertex) origami cell is a combination of contracting, shearing, bending, and facet-binding. The last three deformation mechanisms are missing in the current rigid-origami metamaterial investigations, which focus mainly on conventional Miura-ori patterns. We show that these mechanisms provide the 4-vertex origami sheets and blocks with new deformation patterns as well as extraordinary kinematical and mechanical properties, including self-locking, tridirectional negative Poisson's ratios, flipping of stiffness profiles, and emerging shearing stiffness. This study reveals that the 4-vertex cells offer a better platform and greater design space for developing origami-based mechanical metamaterials than the conventional Miura-ori cell.

  16. Deformation mechanisms of bent Si nanowires governed by the sign and magnitude of strain

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lihua, E-mail: wlh@bjut.edu.cn, E-mail: xdhan@bjut.edu.cn, E-mail: j.zou@uq.edu.au [Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Materials Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); Kong, Deli; Xin, Tianjiao; Shu, Xinyu; Zheng, Kun; Xiao, Lirong; Sha, Xuechao; Lu, Yan; Han, Xiaodong, E-mail: wlh@bjut.edu.cn, E-mail: xdhan@bjut.edu.cn, E-mail: j.zou@uq.edu.au [Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Zhang, Ze [Department of Materials Science, Zhejiang University, Hangzhou 310008 (China); Zou, Jin, E-mail: wlh@bjut.edu.cn, E-mail: xdhan@bjut.edu.cn, E-mail: j.zou@uq.edu.au [Materials Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2016-04-11

    In this study, the deformation mechanisms of bent Si nanowires are investigated at the atomic scale with bending strain up to 12.8%. The sign and magnitude of the applied strain are found to govern their deformation mechanisms, in which the dislocation types (full or partial dislocations) can be affected by the sign (tensile or compressive) and magnitude of the applied strain. In the early stages of bending, plastic deformation is controlled by 60° full dislocations. As the bending increases, Lomer dislocations can be frequently observed. When the strain increases to a significant level, 90° partial dislocations induced from the tensile surfaces of the bent nanowires are observed. This study provides a deeper understanding of the effect of the sign and magnitude of the bending strain on the deformation mechanisms in bent Si nanowires.

  17. Dynamic Crystallization: An Influence on Degree of Prior Deformation and Mechanical Strength of 6063 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Gbenebor, O.P

    2012-09-01

    Full Text Available This research is aimed at investigating the influence dynamic solidification of melts on degree of mechanical deformation and mechanical strength of 6063 aluminum alloy. Cylindrical samples of 14mm diameter and 140mm long were die cast following two techniques – vibration and static. Prior deformation via forging was imposed on each solidified sample to achieve 7%, 14%, 21% and 28% thickness reductions respectively for each casting technique. Average deformation load, average hammer velocities and the average energy absorbed were recorded. Tensile properties of each sample were studied via the use of Monsanto tensometer. Mechanical agitation of mould and its content increased the machinability of the alloy even at higer pre deformation. This was justified by the failure of the 28% reduction sample cast on static floor during machining to a tensile piece. The energy absorbed during deformation influences the tensile strength of the material. This increases with increase in percentage deformation except for 28% reduction whose magnitude was lower than that subjected to 21% reduction; vibrated samples possessed superior properties. From results obtained, vibrating a sample and subjecting to 21% pre-deformation possessed the best tensile strength.

  18. Deformation and failure mechanisms of 18650 battery cells under axial compression

    Science.gov (United States)

    Zhu, Juner; Zhang, Xiaowei; Sahraei, Elham; Wierzbicki, Tomasz

    2016-12-01

    An important deformation mode during ground impacts of battery packs made of cylindrical battery cells is axial compression. This type of loading subjects the cell to a complex deformation pattern and failure mechanism. The design of endcaps plays an important role in such deformations. To explore the sequence of deformation and the underlying failure mechanisms, a combined experimental/numerical study was carried out. Tests were conducted on 18650 cells, and the deformation of each component was carefully investigated and documented. There are four different stages in the force-displacement curve, corresponding with deformation of various components in the endcap assembly. A short circuit happens at a displacement of 4 mm. To clarify these observations, a detailed Finite Element model was set up, covering the geometry and the mechanical property of almost all the components of the cell. Using the simulation results, the sequence of the axial compression was revealed, which was subsequently validated by Micro CT scans as well as analytical solutions. Based on the precise analysis of the mechanical behavior, the cause of the short circuit during axial loading was clarified. Two failure mechanisms in the separator at the top section of the cell explain the possible causes of short circuit.

  19. Mechanical modelling of the Singoe deformation zone. Site descriptive modelling Forsmark stage 2.1

    Energy Technology Data Exchange (ETDEWEB)

    Glamheden, Rune; Maersk Hansen, Lars; Fredriksson, Anders; Bergkvist, Lars; Markstroem, Ingemar; Elfstroem, Mats [Golder Associates AB (Sweden)

    2007-02-15

    This project aims at demonstrating the theoretical approach developed by SKB for determination of mechanical properties of large deformation zones, in particular the Singoe deformation zone. Up to now, only bedrock and minor deformation zones have been characterized by means of this methodology, which has been modified for this project. The Singoe deformation zone is taken as a reference object to get a more comprehensive picture of the structure, which could be incorporated in a future version of the SDM of Forsmark. Furthermore, the Singoe Zone has been chosen because of available data from four tunnels. Scope of work has included compilation and analysis of geological information from site investigations and documentation of existing tunnels. Results have been analyzed and demonstrated by means of RVS-visualization. Numerical modelling has been used to obtain mechanical properties. Numerical modelling has also been carried out in order to verify the results by comparison of calculated and measured deformations. Compilation of various structures in the four tunnels coincides largely with a magnetic anomaly and also with the estimated width. Based on the study it is clear that the Singoe deformation zone has a heterogeneous nature. The number of fracture zones associated with the deformation zone varies on either side of the zone, as does the transition zone between host rock and the Singoe zone. The overall impression from the study is that the results demonstrate that the methodology used for simulating of equivalent mechanical properties is an applicable and adequate method, also in case of large deformation zones. Typical rock mechanical parameters of the Singoe deformations that can be used in the regional stress model considering the zone to be a single fracture are: 200 MPa/m in normal stiffness, 10-15 MPa/m in shear stiffness, 0.4 MPa in cohesion and 31.5 degrees in friction angle.

  20. Electric anisotropy in high density polyethylene + carbon black composites induced by mechanical deformation

    Energy Technology Data Exchange (ETDEWEB)

    Vigueras-Santiago, E; Hernandez-Lopez, S; Camacho-Lopez, M A; Lara-Sanjuan, O, E-mail: eviguerass@uaemex.m [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA), Facultad de Quimica, UAEM. Paseo Colon esq. con Paseo Tollocan, s/n. C.P. 50000, Toluca (Mexico)

    2009-05-01

    High density polyethylene + carbon black composites with electrical anisotropy was studied. Electrical anisotropy was induced by uniaxial mechanical deformation and injection moulding. We show that anisotropy depends on the carbon black concentration and percentage deformation. Resistivity had the highest anisotropy resistivity around the percolation threshold. Perpendicular resistivity showed two magnitude orders higher than parallel resistivity for injected samples, whereas resistivity showed an inverse behaviour for 100% tensile samples. Both directions were set respect to the deformation axe. Anisotropy could be explained in terms of the molecular deformation (alignment) of the polymer chains as a response of the deformation process originating a redistribution of the carbon black particles in both directions. Alignment of the polymer chains was evidenced by polarized Raman spectroscopy.

  1. Hot Deformation Characteristics of 13Cr-4Ni Stainless Steel Using Constitutive Equation and Processing Map

    Science.gov (United States)

    Kishor, Brij; Chaudhari, G. P.; Nath, S. K.

    2016-07-01

    Hot compression tests were performed to study the hot deformation characteristics of 13Cr-4Ni stainless steel. The tests were performed in the strain rate range of 0.001-10 s-1 and temperature range of 900-1100 °C using Gleeble® 3800 simulator. A constitutive equation of Arrhenius type was established based on the experimental data to calculate the different material constants, and average value of apparent activation energy was found to be 444 kJ/mol. Zener-Hollomon parameter, Z, was estimated in order to characterize the flow stress behavior. Power dissipation and instability maps developed on the basis of dynamic materials model for true strain of 0.5 show optimum hot working conditions corresponding to peak efficiency range of about 28-32%. These lie in the temperature range of 950-1025 °C and corresponding strain rate range of 0.001-0.01 s-1 and in the temperature range of 1050-1100 °C and corresponding strain rate range of 0.01-0.1 s-1. The flow characteristics in these conditions show dynamic recrystallization behavior. The microstructures are correlated to the different stability domains indicated in the processing map.

  2. Deformation mechanisms in the frontal Lesser Himalayan Duplex in Sikkim Himalaya, India

    Indian Academy of Sciences (India)

    Abdul Matin; Sweety Mazumdar

    2009-08-01

    Understanding deformation mechanisms in Himalayan rocks is a challenging proposition due to the complex nature of the deformed rocks and their genesis. Crustal deformation in the Himalayan thrust belt typically occurs in elastico-frictional (EF) or quasi-plastic (QP) regimes at depths controlled mainly by regional strain-rate and geothermal gradient. However, material property, grain-size and their progressive changes during deformation are also important controlling factors. We present evidence of EF deformation from Gondwana rocks developed during the emplacement of one of the frontal horses (Jorthang horse) in the Lesser Himalayan Duplex (LHD) structure associated with Lesser Himalayan rocks in the footwall of the Ramgarh thrust in the Rangit window near Jorthang in the Sikkim Himalaya. The rocks in the horse exhibit systematic changes in microand meso-structures from an undeformed protolith to cataclasite suggesting that it was emplaced under elastico-frictional conditions. Meso- to micro-scale shear fractures are seen developed in Gondwana sandstone and slate while intercalated fine-grained shale-coal-carbonates are deformed by cataclastic flow suggesting that material property and grain-size have played an important role in the deformation of the Jorthang horse. In contrast, the hanging wall schists and quartzites of the Ramgarh thrust exhibit quasi-plastic deformation structures. This suggests that the Jorthang horse was emplaced under shallower crustal conditions than the antiformally folded Ramgarh thrust sheet even though the Ramgarh sheet presently overlies the Jorthang horse.

  3. Representing Matrix Cracks Through Decomposition of the Deformation Gradient Tensor in Continuum Damage Mechanics Methods

    Science.gov (United States)

    Leone, Frank A., Jr.

    2015-01-01

    A method is presented to represent the large-deformation kinematics of intraply matrix cracks and delaminations in continuum damage mechanics (CDM) constitutive material models. The method involves the additive decomposition of the deformation gradient tensor into 'crack' and 'bulk material' components. The response of the intact bulk material is represented by a reduced deformation gradient tensor, and the opening of an embedded cohesive interface is represented by a normalized cohesive displacement-jump vector. The rotation of the embedded interface is tracked as the material deforms and as the crack opens. The distribution of the total local deformation between the bulk material and the cohesive interface components is determined by minimizing the difference between the cohesive stress and the bulk material stress projected onto the cohesive interface. The improvements to the accuracy of CDM models that incorporate the presented method over existing approaches are demonstrated for a single element subjected to simple shear deformation and for a finite element model of a unidirectional open-hole tension specimen. The material model is implemented as a VUMAT user subroutine for the Abaqus/Explicit finite element software. The presented deformation gradient decomposition method reduces the artificial load transfer across matrix cracks subjected to large shearing deformations, and avoids the spurious secondary failure modes that often occur in analyses based on conventional progressive damage models.

  4. Earthquake mechanism and seafloor deformation for tsunami generation

    Science.gov (United States)

    Geist, Eric L.; Oglesby, David D.; Beer, Michael; Kougioumtzoglou, Ioannis A.; Patelli, Edoardo; Siu-Kui Au, Ivan

    2014-01-01

    Tsunamis are generated in the ocean by rapidly displacing the entire water column over a significant area. The potential energy resulting from this disturbance is balanced with the kinetic energy of the waves during propagation. Only a handful of submarine geologic phenomena can generate tsunamis: large-magnitude earthquakes, large landslides, and volcanic processes. Asteroid and subaerial landslide impacts can generate tsunami waves from above the water. Earthquakes are by far the most common generator of tsunamis. Generally, earthquakes greater than magnitude (M) 6.5–7 can generate tsunamis if they occur beneath an ocean and if they result in predominantly vertical displacement. One of the greatest uncertainties in both deterministic and probabilistic hazard assessments of tsunamis is computing seafloor deformation for earthquakes of a given magnitude.

  5. Mechanical Properties and Deformation Mechanisms of Mg-Gd-Y-Zr Alloy at Cryogenic and Elevated Temperatures

    Science.gov (United States)

    Chen, Bin; Zheng, Jing-Xu; Yang, Chao-Ming; Chen, Yi-Xin; Cao, San-Chen; Zhao, Zhi-Xian; Li, Xiao-Ling; Lu, Chen

    2017-02-01

    In this study, mechanical properties and deformation mechanisms of Mg-Gd-Y-Zr alloy at temperatures ranging from 77 K to 523 K have been investigated. The effects of temperature on the mechanical properties, deformation mechanism, and fracture mechanism are discussed. The results show that the strengths of alloy decrease gradually while the elongations increase progressively with increasing temperature. The maximum ultimate tensile strength of the alloy as high as 442 MPa is obtained at 77 K. As the temperature increases from 77 K to 523 K, the ultimate tensile strength of the alloy decreases from 442 MPa to 254 MPa and the elongations increase from 6.3% to 28.9% gradually. The study verifies that the deformation at 77 K is predominated by basal slip and {10bar{1}2} {10bar{1}2} deformation twinning system. At 223 K, lots of twins emerge primarily at grain boundaries. At 373 K, all dislocations are proved to be dislocations. At 523 K, although basal slip is still the dominant deformation mechanism, non-basal slip systems also become activate.

  6. Effect of native oxide mechanical deformation on InP nanoindentation

    Science.gov (United States)

    Almeida, C. M.; Prioli, R.; Ponce, F. A.

    2008-12-01

    Native oxide has been found to have a noticeable effect on the mechanical deformation of InP during nanoindentation. The indentations were performed using spherical diamond tips and the residual impressions were studied by atomic force microscopy. It has been observed that in the early stages of mechanical deformation, plastic flow occurs in the oxide layer while the indium phosphide is still in the elastic regime. The deformed native oxide layer results in a pile-up formation that causes an increase in the contact area between the tip and the surface during the nanoindentation process. This increase in the projected contact area is shown to contribute to the apparent high pressure sustained by the crystal before the onset of plastic deformation. It is also shown that the stress necessary to generate the first dislocations from the crystal surface is ˜3 GPa higher than the stress needed for slip to occur when dislocations are already present in the crystalline structure.

  7. Microstructure evolution model based on deformation mechanism of titanium alloy in hot forming

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-li; LI Miao-quan

    2005-01-01

    The microstructure evolution in hot forming will affect the mechanical properties of the formed product.However, the microstructure is sensitive to the process variables in deformation process of metals and alloys. A microstructure evolution model of a titanium alloy in hot forming, which included dislocation density rate and primary α phase grain size, was presented according to the deformation mechanism and driving forces, in which the effect of the dislocation density rate on the grain growth was studied firstly. Applying the model to the high temperature deformation process of a TC6 alloy with deformation temperature of 1 133 - 1 223 K, strain rate of 0.01 -50 s-1 and height reduction of 30%, 40% and 50%, the material constants in the present model were calculated by the genetic algorithm(GA) based objective optimization techniques. The calculated results of a TC6 alloy are in good agreement with the experimental ones.

  8. Identification for the optimal working parameters of Ti-6Al-4V-0.1Ru alloy in a wide deformation condition range by processing maps based on DMM

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yu-feng; Long, Shuai; Zhou, Yu-ting; Zhao, Jia; Wang, Tian-yu; Zhou, Jie, E-mail: kkyttyls@vip.qq.com [School of Material Science and Engineering, Chongqing University (China)

    2016-11-15

    The hot deformation behaviours of Ti-6Al-4V-0.1Ru alloy were investigated by isothermal hot compression tests in the temperature range of 1023-1423 K and strain rate range of 0.01-10 s{sup -1}. The β transus was determined to be 1198 K by continuous heating method. The values of deformation activation energy Q at the strain of 0.3 were calculated to be 630.01 kJ/mol in dual-phase field and 331.75 kJ/mol in β-phase field. Moreover, the processing maps at the strain of 0.2, 0.4, 0.6 and 0.8 were developed based on dynamic materials model (DMM). To deeply understand the microstructure evolution mechanism during hot deformation processes and to verify the processing maps, the microstructures at different deformation conditions were observed. The stable microstructures (i.e. globularization, dynamic recovery (DRV) and β dynamic recrystallization (β-DRX)) and instable microstructures (i.e. lamellae kinking and flow localization) were obtained. To make it useful in the design of industrial hot working schedules for this material, a microstructural mechanism map was constructed on the basis of processing maps and microstructure observation. Deformation conditions in the vicinity of 1150 K & 0.01 s{sup -1} where globularization occurs and in the vicinity of 1323 K & 0.01 s{sup -1} where β-DRX occurs are recommended. (author)

  9. Uncommon deformation mechanisms during fatigue-crack propagation in nanocrystalline alloys.

    Science.gov (United States)

    Cheng, Sheng; Lee, Soo Yeol; Li, Li; Lei, Changhui; Almer, Jon; Wang, Xun-Li; Ungar, Tamas; Wang, Yinmin; Liaw, Peter K

    2013-03-29

    The irreversible damage at cracks during the fatigue of crystalline solids is well known. Here we report on in situ high-energy x-ray evidence of reversible fatigue behavior in a nanocrystalline NiFe alloy both in the plastic zone and around the crack tip. In the plastic zone, the deformation is fully recoverable as the crack propagates, and the plastic deformation invokes reversible interactions of dislocation and twinning in the nanograins. But around the crack tip lies a regime with reversible grain lattice reorientation promoted by a change of local stress state. These observations suggest unprecedented fatigue deformation mechanisms in nanostructured systems that are not addressed theoretically.

  10. Deformation characteristics of mechanical expanding of thin-walled cylindrical parts

    Institute of Scientific and Technical Information of China (English)

    郭宝锋; 聂绍珉; 金淼; 李群; 吴生富

    2003-01-01

    Mechanical expanding is one of the finishing processes in cylindrical part forming.The distribution of stress and strain shows clearly regional features.FEA simulation and experiments show that the deformation process can be divided into three phases called as rounding phase,expanding phase and unloading phase in turn,in which the main types of deformation are wall bending,circumference elongating and thickness reducing,and spring back respectively.And the longitudinal section can be divided into three portions.expanding region,transition region and rigid region.The plastic deformation occurs regionally in suspended portion.A regional convex in transitional portion is inevitable.

  11. Large Deformation Mechanisms, Plasticity, and Failure of an Individual Collagen Fibril With Different Mineral Content.

    Science.gov (United States)

    Depalle, Baptiste; Qin, Zhao; Shefelbine, Sandra J; Buehler, Markus J

    2016-02-01

    Mineralized collagen fibrils are composed of tropocollagen molecules and mineral crystals derived from hydroxyapatite to form a composite material that combines optimal properties of both constituents and exhibits incredible strength and toughness. Their complex hierarchical structure allows collagen fibrils to sustain large deformation without breaking. In this study, we report a mesoscale model of a single mineralized collagen fibril using a bottom-up approach. By conserving the three-dimensional structure and the entanglement of the molecules, we were able to construct finite-size fibril models that allowed us to explore the deformation mechanisms which govern their mechanical behavior under large deformation. We investigated the tensile behavior of a single collagen fibril with various intrafibrillar mineral content and found that a mineralized collagen fibril can present up to five different deformation mechanisms to dissipate energy. These mechanisms include molecular uncoiling, molecular stretching, mineral/collagen sliding, molecular slippage, and crystal dissociation. By multiplying its sources of energy dissipation and deformation mechanisms, a collagen fibril can reach impressive strength and toughness. Adding mineral into the collagen fibril can increase its strength up to 10 times and its toughness up to 35 times. Combining crosslinks with mineral makes the fibril stiffer but more brittle. We also found that a mineralized fibril reaches its maximum toughness to density and strength to density ratios for a mineral density of around 30%. This result, in good agreement with experimental observations, attests that bone tissue is optimized mechanically to remain lightweight but maintain strength and toughness.

  12. Work-hardening stages and deformation mechanism maps during tensile deformation of commercially pure titanium

    DEFF Research Database (Denmark)

    Becker, Hanka; Pantleon, Wolfgang

    2013-01-01

    by dislocation slip, in the following stage (for moderate stresses), an abundance of 64.6∘〈1¯010〉 twin boundaries form indicating the dominance of {112¯2}〈1¯1¯23〉 compression twinning. During the last stage before the onset of necking, additional 84.8∘〈112¯0〉 twin boundaries are detected caused by {101...

  13. Influence of Compatibilizer and Processing Conditions on Morphology, Mechanical Properties, and Deformation Mechanism of PP/Clay Nanocomposite

    Directory of Open Access Journals (Sweden)

    B. Akbari

    2012-01-01

    Full Text Available Polypropylene/montmorillonite nanocomposite was prepared by melt intercalation method using a twin-screw extruder with starve feeding system in this paper. The effects of compatibilizer, extruder rotor speed and feeding rate on properties of nanocomposite were investigated. Structure, tensile, and impact properties and deformation mechanism of the compounds were studied. For investigation of structure and deformation mechanisms, X-ray diffraction (XRD and transmission optical microscopy (TOM techniques were utilized, respectively. The results illustrate that introduction of the compatibilizer and also variation of the processing conditions affect structure and mechanical properties of nanocomposite.

  14. Uncoupled Thermo - Mechanical for the Determination of Welding Deformations

    Directory of Open Access Journals (Sweden)

    Lenuta Suciu

    2006-10-01

    Full Text Available Simulation of the welding process for butt and tee joints using finite element analyses are presented. The simulation are performed with the commercial software Ansys, which includes mathematical model, temperature dependent material properties, transfer and mechanical analyses. One way thermo – mechanical coupling is assumed.

  15. Inelastic deformation of metal matrix composites: Plasticity and damage mechanisms, part 2

    Science.gov (United States)

    Majumdar, B. S.; Newaz, G. M.

    1992-01-01

    The inelastic deformation mechanisms for the SiC (SCS-6)/Ti-15-3 system were studied at 538 C (1000 F) using a combination of mechanical measurements and detailed microstructural examinations. The objectives were to evaluate the contributions of plasticity and damage to the overall MMC response, and to compare the room temperature and elevated temperature deformation behaviors. Four different laminates were studied: (0)8, (90)8,(+ or -45)2s, and (0/90)2s, with the primary emphasis on the unidirectional (0)8, and (90)8 systems. The elevated temperature responses were similar to those at room temperature, involving a two-stage elastic-plastic type of response for the (0)8 system, and a characteristic three-stage deformation response for the (90)8 and (+ or -45)2s systems. The primary effects of elevated temperatures included: (1) reduction in the 'yield' and failure strengths; (2) plasticity through diffused slip rather than concentrated planar slip (which occurred at room temperature); and (3) time-dependent deformation. The inelastic deformation mechanism for the (0)8 MMC was dominated by plasticity at both temperatures. For the (90)8 and (+ or -45)2s MMCs, a combination of damage and plasticity contributed to the deformation at both temperatures.

  16. Mechanical Response of DNA–Nanoparticle Crystals to Controlled Deformation

    Science.gov (United States)

    2016-01-01

    The self-assembly of DNA-conjugated nanoparticles represents a promising avenue toward the design of engineered hierarchical materials. By using DNA to encode nanoscale interactions, macroscale crystals can be formed with mechanical properties that can, at least in principle, be tuned. Here we present in silico evidence that the mechanical response of these assemblies can indeed be controlled, and that subtle modifications of the linking DNA sequences can change the Young’s modulus from 97 kPa to 2.1 MPa. We rely on a detailed molecular model to quantify the energetics of DNA–nanoparticle assembly and demonstrate that the mechanical response is governed by entropic, rather than enthalpic, contributions and that the response of the entire network can be estimated from the elastic properties of an individual nanoparticle. The results here provide a first step toward the mechanical characterization of DNA–nanoparticle assemblies, and suggest the possibility of mechanical metamaterials constructed using DNA. PMID:27725959

  17. Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite.

    Science.gov (United States)

    Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

    2014-09-30

    The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties.

  18. Influence of Hot Deformation and Subsequent Austempering on the Mechanical Properties of Hot Rolled Multiphase Steel

    Institute of Scientific and Technical Information of China (English)

    Zhuang LI; Di WU

    2006-01-01

    Influence of hot deformation and subsequent austempering on the mechanical properties of hot rolled multiphase steel was investigated. Thermo-mechanical control processing (TMCP) was conducted by using a laboratory hot rolling mill, where three different kinds of finishing rolling reduction, and austemperings with various isothermal holding duration were applied. The results have shown that a multiphase microstructure consisting of polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. Mechanical properties increase with increasing the amount of deformation because of the stabilization of retained austenite. Ultimate tensile strength (σb), total elongation (δ)36% and 28476 MPa%, respectively) at optimal processes.

  19. Inelastic Deformation of Metal Matrix Composites. Part 1; Plasticity and Damage Mechanisms

    Science.gov (United States)

    Majumdar, B. S.; Newaz, G. M.

    1992-01-01

    The deformation mechanisms of a Ti 15-3/SCS6 (SiC fiber) metal matrix composite (MMC) were investigated using a combination of mechanical measurements and microstructural analysis. The objectives were to evaluate the contributions of plasticity and damage to the overall inelastic response, and to confirm the mechanisms by rigorous microstructural evaluations. The results of room temperature experiments performed on 0 degree and 90 degree systems primarily are reported in this report. Results of experiments performed on other laminate systems and at high temperatures will be provided in a forthcoming report. Inelastic deformation of the 0 degree MMC (fibers parallel to load direction) was dominated by the plasticity of the matrix. In contrast, inelastic deformations of the 90 degree composite (fibers perpendicular to loading direction) occurred by both damage and plasticity. The predictions of a continuum elastic plastic model were compared with experimental data. The model was adequate for predicting the 0 degree response; however, it was inadequate for predicting the 90 degree response largely because it neglected damage. The importance of validating constitutive models using a combination of mechanical measurements and microstructural analysis is pointed out. The deformation mechanisms, and the likely sequence of events associated with the inelastic deformation of MMCs, are indicated in this paper.

  20. Evolving Stress State and Deformation Mechanism in the Himalayan Foreland Fold-and-Thrust Belt, Northern Pakistan

    Science.gov (United States)

    Ahmad, I.; Dasti, N.

    2010-12-01

    Crustal deformation along with shortening due to northward under-thrusting of the Indian plate beneath the Eurasian plate continues to create active tectonic features on the northern fringes of the Indian craton since major collision began in the Eocene. Here the study provides insights on the evolving stress state and deformation mechanism of the Salt Range and Potwar area of Northern Pakistan. This part of Himalayan foreland fold-and-thrust-belt has severe history of deformation during 5.1 Ma and 2 Ma. This foreland area lies between Main Boundary Thrust (MBT) in the north, Himalayan Frontal Thrust (HFT) in the south and Jhelum fault of sinistral nature in the east & Kalabagh fault of dextral nature in the west. An integrated data from seismic reflection profiles and drilling logs reveal that the subsurface deformation encompasses pop-ups, imbricates, duplexes with in-sequence and out-of-sequence thrusting. It also depicts that intensity of deformation increases from the northern margin of Soan geosyncline towards north due to lacking of evaporites while in the south it decreases due to gradual increase in salt thickness. Surface geologic mapping glimpses a series of thrust sheets and anticlines trending ENE-SWS in the eastern and central part of the study area; whereas in the western part, the trend is almost E-W. This variation in the trend of structures is the result of counter clock rotational behaviour (~10°deviation from north to the west) of north-western part of the Indian lithospheric plate. Current outcrop-scale natural fracture data collected from selected anticlinal structures of the study area is presented to manifest the stress evolution and deformation styles under the established tectonic framework. Collected data is analysed for the evaluation of tectonic stress direction and deformation mechanism. The genetic arrangement and types of fractures observed in the study area indicate that the whole area is under compression. The data also testify

  1. Investigation of deformation mechanisms of staggered nanocomposites using molecular dynamics

    Science.gov (United States)

    Mathiazhagan, S.; Anup, S.

    2016-08-01

    Biological materials with nanostructure of regularly or stair-wise staggered arrangements of hard platelets reinforced in a soft protein matrix have superior mechanical properties. Applications of these nanostructures to ceramic matrix composites could enhance their toughness. Using molecular dynamics simulations, mechanical behaviour of the bio-inspired nanocomposites is studied. Regularly staggered model shows better flow behaviour compared to stair-wise staggered model due to the symmetrical crack propagation along the interface. Though higher stiffness and strength are obtained for stair-wise staggered models, rapid crack propagation reduces the toughness. Arresting this crack propagation could lead to superior mechanical properties in stair-wise staggered models.

  2. An investigation of deformed microstructure and mechanical properties of Zircaloy-4 processed through multiaxial forging

    Energy Technology Data Exchange (ETDEWEB)

    Fuloria, Devasri; Nageswararao, P. [Department of Metallurgical and Materials Engineering & Centre of Nanotechnology, IIT Roorkee, Roorkee 247667 (India); Jayaganthan, R., E-mail: rjayafmt@iitr.ernet.in [Department of Metallurgical and Materials Engineering & Centre of Nanotechnology, IIT Roorkee, Roorkee 247667 (India); Department of Engineering Design, Indian Institute of Technology Madras, Chennai 600036 (India); Jha, S. [Nuclear Fuel Complex Limited, Hyderabad 501301 (India); Srivastava, D. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 40085 (India)

    2016-04-15

    In the present work, the mechanical behavior of Zircaloy-4 subjected to various deformation strains by multiaxial forging (MAF) at cryogenic temperature (CT) was investigated. The alloy was strained up to different number of cycles, viz., 6 cycles, 9 cycles, and 12 cycles at cumulative strains of 2.96, 4.44, and 5.91, respectively. The mechanical properties of the alloy were investigated by performing the universal tensile test and the Vickers hardness test. Both the test showed improvement in the ultimate tensile strength and hardness value by 51% and 26%, respectively, at the highest cumulative strain of 5.91. The electron backscattered diffraction (EBSD) measurement and transmission electron microscopy (TEM) were used for analyzing the deformed microstructure. The microstructures of the alloy underwent deformation at various cumulative strains/cycles showed grain refinement with the evolution of shear and twin bands that were highest for the alloy deformed at the highest number of cycles. The effective grain refinement was due to twins formation and their intersection, which led to the improvement in mechanical properties of the MAFed alloy, as observed in the present work. - Highlights: • Zircaloy-4 was subjected to MAF at cryogenic temperature. • Microstructural evolution was studied through EBSD and TEM. • Deformed microstructure was marked with various types of twinning and shear banding. • Twins formations are responsible for effective grain refinement and enhanced mechanical properties.

  3. Effect of different heating methods on deformation of metal plate under upsetting mechanism in laser forming

    Science.gov (United States)

    Shi, Yongjun; Liu, Yancong; Yi, Peng; Hu, Jun

    2012-03-01

    In a laser forming process, different forming mechanisms have different deformation behaviors. The aim of laser forming is to acquire plane strain under an upsetting mechanism, while a plate undergoes a small bending deformation. In some industrial applications, the bending strain should not occur. To achieve high-precision forming, the deformation behaviors of a metal plate when an upsetting mechanism plays a dominant role are studied in the paper. Several heating methods are proposed to reduce the plane strain difference along the thickness direction and little bending deformation resulting from a small temperature difference between the top and bottom surfaces of the plate. The results show that negligible bending deformation and a uniform plastic plane strain field can be obtained by simultaneously heating the top and bottom surfaces with the same process parameters. A conventional scanning method needs a larger spot diameter and slower scanning speed under the upsetting mechanism, but a smaller spot diameter and quicker scanning speed may be selected using the simultaneous heating method, which can greatly widen the potential scope of process parameters.

  4. Thermo-mechanical modeling of dendrite deformation in continuous casting of steel

    Science.gov (United States)

    Domitner, J.; Drezet, J.-M.; Wu, M.; Ludwig, A.

    2012-07-01

    In the field of modern steelmaking, continuous casting has become the major manufacturing process to handle a wide range of steel grades. An important criterion characterizing the quality of semi-finished cast products is the macrosegregation forming at the centre of these products during solidification. The deformation induced interdendritic melt flow has been identified as the key mechanism for the formation of centreline segregation. Bulging of the solidified strand shell causes deformation of the solidifying dendrites at the casting's centre. Hence, a fundamental knowledge about the solid phase motion during casting processes is crucial to examine segregation phenomena in detail. To investigate dendritic deformation particularly at the strand centre, a thermo-mechanical Finite Element (FE) simulation model is built in the commercial software package ABAQUS. The complex dendritic shape is approximated with a conical model geometry. Varying this geometry allows considering the influence of different centreline solid fractions on the dendrite deformation. A sinusoidal load profile is used to describe bulging of the solid which deforms the dendrites. Based on the strain rates obtained in the FE simulations the dendrite deformation velocity perpendicular to the casting direction is calculated. The velocity presented for different conditions is used as input parameter for computational fluid dynamics (CFD) simulations to investigate macrosegregation formation inside of a continuous casting strand using the commercial software package FLUENT.

  5. Elucidating the Molecular Deformation Mechanism of Entangled Polymers in Fast Flow by Small Angle Neutron Scattering

    Science.gov (United States)

    Wang, Yangyang; Sanchez-Diaz, Luis; Cheng, Shiwang; Hong, Kunlun; Chen, Wei-Ren; Liu, Jianning; Lin, Panpan; Wang, Shi-Qing

    Understanding the viscoelastic properties of polymers is of fundamental and practical importance because of the vast and ever expanding demand of polymeric materials in daily life. Our current theoretical framework for describing the nonlinear flow behavior of entangled polymers is built upon the tube model pioneered by de Gennes, Doi, and Edwards. In this work, we critically examine the central hypothesis of the tube model for nonlinear rheology using small angle neutron scattering (SANS). While the tube model envisions a unique non-affine elastic deformation mechanism for entangled polymers, our SANS measurements show that the evolution of chain conformation of a well-entangled polystyrene melt closely follows the affine deformation mechanism in uniaxial extension, even when the Rouse Weissenberg number is much smaller than unity. This result provides a key clue for understanding the molecular deformation mechanism of entangled polymers in fast flow. Several implications from our analysis will be discussed in this talk.

  6. High resolution transmission electron microscope observation of zero-strain deformation twinning mechanisms in Ag.

    Science.gov (United States)

    Liu, L; Wang, J; Gong, S K; Mao, S X

    2011-04-29

    We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.

  7. The effect of mechanical deformation to the magnetic properties of stainless steel 304

    Science.gov (United States)

    Mubarok, N.; Notonegoro, H. A.; Zaini Thosin, K. A.; Manaf, A.

    2016-11-01

    A study of a non-magnetic 304 austenitic stainless steel alloy through mechanical deformation has been done. These specimens are pipe usually used to deliver gas which contains corrosive oil fields. The metallographic observation of a 20% deformation shows the increase in the value of the magnetization, as compensation for the formation of martensite phase as a result of a mechanical treatment. Martensitic phase formed due to a shift in the structure of the z-axis due to the effects of pressure and shear from the cold rolled. The existence of martensite phase and magnetic properties conducted through x-ray diffraction and permagraf investigation. An identified x-ray diffraction pattern shows the presence of a new peak between 10°-30° angle indicate the mechanical deformation in crystallite structure. Furthermore, at in 20% distortion, the value of magnetization is increased above 0.2 T in small coercivity value and caused decreased the ability of corrosion resistant.

  8. Deformation quantization of noncommutative quantum mechanics and dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Bastos, C [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Bertolami, O [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Dias, N C [Departamento de Matematica, Universidade Lusofona de Humanidades e Tecnologias, Avenida Campo Grande 376, 1749-024 Lisbon (Portugal); Prata, J N [Departamento de Matematica, Universidade Lusofona de Humanidades e Tecnologias, Avenida Campo Grande 376, 1749-024 Lisbon (Portugal)

    2007-05-15

    We review the main features of the Weyl-Wigner formulation of noncommutative quantum mechanics. In particular, we present a *-product and a Moyal bracket suitable for this theory as well as the concept of noncommutative Wigner function. The properties of these quasi-distributions are discussed as well as their relation to the sets of ordinary Wigner functions and positive Liouville probability densities. Based on these notions we propose criteria for assessing whether a commutative regime has emerged in the realm of noncommutative quantum mechanics. To induce this noncommutative-commutative transition, we couple a particle to an external bath of oscillators. The master equation for the Brownian particle is deduced.

  9. Formulation of Deformation Stress Fields and Constitutive Equations in Rational Mechanics

    CERN Document Server

    Jianhua, Xiao

    2010-01-01

    In continuum mechanics, stress concept plays an essential role. For complicated materials, different stress concepts are used with ambiguity or different understanding. Geometrically, a material element is expressed by a closed region with arbitral shape. The internal region is acted by distance dependent force (internal body force), while the surface is acted by surface force. Further more, the element as a whole is in a physical background (exterior region) which is determined by the continuum where the element is embedded (external body force). Physically, the total energy can be additively decomposed as three parts: internal region energy, surface energy, and the background energy. However, as forces, they cannot be added directly. After formulating the general forms of physical fields, the deformation tensor is introduced to formulate the force variations caused by deformation. As the force variation is expressed by the deformation tensor, the deformation stress concept is well formulated. Furthermore, a...

  10. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles

    NARCIS (Netherlands)

    Kononova, Olga; Snijder, Joost; Kholodov, Yaroslav; Marx, Kenneth A; Wuite, Gijs J L; Roos, Wouter H; Barsegov, Valeri

    The mechanical properties of virus capsids correlate with local conformational dynamics in the capsid structure. They also reflect the required stability needed to withstand high internal pressures generated upon genome loading and contribute to the success of important events in viral infectivity,

  11. Molecular mechanisms in deformation of cross-linked hydrogel nanocomposite.

    Science.gov (United States)

    Mathesan, Santhosh; Rath, Amrita; Ghosh, Pijush

    2016-02-01

    The self-folding behavior in response to external stimuli observed in hydrogels is potentially used in biomedical applications. However, the use of hydrogels is limited because of its reduced mechanical properties. These properties are enhanced when the hydrogels are cross-linked and reinforced with nanoparticles. In this work, molecular dynamics (MD) simulation is applied to perform uniaxial tension and pull out tests to understand the mechanism contributing towards the enhanced mechanical properties. Also, nanomechanical characterization is performed using quasi static nanoindentation experiments to determine the Young's modulus of hydrogels in the presence of nanoparticles. The stress-strain responses for chitosan (CS), chitosan reinforced with hydroxyapatite (HAP) and cross-linked chitosan are obtained from uniaxial tension test. It is observed that the Young's modulus and maximum stress increase as the HAP content increases and also with cross-linking process. Load displacement plot from pullout test is compared for uncross-linked and cross-linked chitosan chains on hydroxyapatite surface. MD simulation reveals that the variation in the dihedral conformation of chitosan chains and the evolution of internal structural variables are associated with mechanical properties. Additional results reveal that the formation of hydrogen bonds and electrostatic interactions is responsible for the above variations in different systems.

  12. Deformation quantization: Quantum mechanics lives and works in phase space

    Directory of Open Access Journals (Sweden)

    Zachos Cosmas K.

    2014-01-01

    A sampling of such intriguing techniques and methods has already been published in C. K. Zachos, Int Jou Mod Phys A17 297-316 (2002, and T. L. Curtright, D. B. Fairlie, and C. K. Zachos, A Concise Treatise on Quantum Mechanics in Phase Space, (Imperial Press & World Scientific, 2014.

  13. Deformation mechanisms of NiAl cyclicly deformed near the brittle-to-ductile transition temperature

    Science.gov (United States)

    Cullers, Cheryl L.; Antolovich, Stephen D.

    1993-01-01

    The intermetallic compound NiAl is one of many advanced materials which is being scrutinized for possible use in high temperature, structural applications. Stoichiometric NiAl has a high melting temperature, excellent oxidation resistance, and good thermal conductivity. Past research has concentrated on improving monotonic properties. The encouraging results obtained on binary and micro-alloyed NiAl over the past ten years have led to the broadening of NiAl experimental programs. The purpose of this research project was to determine the low cycle fatigue properties and dislocation mechanisms of stoichiometric NiAl at temperatures near the monotonic brittle-to-ductile transition. The fatigue properties were found to change only slightly in the temperature range of 600 to 700 K; a temperature range over which monotonic ductility and fracture strength increase markedly. The shape of the cyclic hardening curves coincided with the changes observed in the dislocation structures. The evolution of dislocation structures did not appear to change with temperature.

  14. Investigation of work softening mechanisms and texture in a hot deformed 6061 aluminum alloy at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ezatpour, H.R., E-mail: H.R.Ezatpour@gmail.com [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Haddad Sabzevar, M.; Sajjadi, S.A. [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Huang, Yz., E-mail: yzhuang@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2014-06-01

    Hot deformation behavior of 6061 aluminum alloy was investigated by performing compression test in the temperature range of 350–500 °C. Equivalent strain rates were selected in the range of 0.0005–0.5 s{sup −1} in order to obtain processing and stability maps of the studied material using a Dynamic Material Model. Microstructure of the samples after deformation was analyzed by light and electron microscopy and the differences were compared together. The stresses obtained from the flow curves were related to strain rate (ε) and temperature (T) by a constitutive equation in hyperbolic sine function with hot deformation activation energy of 274 kJ/mol, and were described by the Zener–Hollomon equation. Microstructure results showed that with decreasing Z value, the elongated grains coarsened and the tendency of dynamic recrystallization enhanced. Correspondingly, the subgrain size increased and the dislocation density decreased. Moreover, the main softening mechanism of the alloy transformed from dynamic recovery to dynamic recrystallization. XRD results showed that the (200) texture has an important role in development of dynamic recystallization at high temperature.

  15. Tectonic Map of the Ellesmerian and Eurekan deformation belts on Svalbard, North Greenland and the Queen Elizabeth Islands (Canadian Arctic)

    Science.gov (United States)

    Piepjohn, Karsten; von Gosen, Werner; Tessensohn, Franz; Reinhardt, Lutz; McClelland, William C.; Dallmann, Winfried; Gaedicke, Christoph; Harrison, Christopher

    2016-04-01

    The tectonic map presented here shows the distribution of the major post-Ellesmerian and pre-Eurekan sedimentary basins, parts of the Caledonian Orogen, the Ellesmerian Fold-and-Thrust Belt, structures of the Cenozoic Eurekan deformation, and areas affected by the Eurekan overprint. The present continental margin of North America towards the Arctic Ocean between the Queen Elizabeth Islands and Northeast Greenland and the present west margin of the Barents Shelf are characterized by the Paleozoic Ellesmerian Fold-and-Thrust Belt, the Cenozoic Eurekan deformation, and, in parts, the Caledonian Orogen. In many areas, the structural trends of the Ellesmerian and Eurekan deformations are more or less parallel, and often, structures of the Ellesmerian Orogeny are affected or reactivated by the Eurekan deformation. While the Ellesmerian Fold-and-Thrust Belt is dominated by orthogonal compression and the formation of wide fold-and-thrust zones on Ellesmere Island, North Greenland and Spitsbergen, the Eurekan deformation is characterized by a complex network of regional fold-and-thrust belts (Spitsbergen, central Ellesmere Island), large distinct thrust zones (Ellesmere Island, North Greenland) and a great number of strike-slip faults (Spitsbergen, Ellesmere Island). The Ellesmerian Fold-and-Thrust Belt was most probably related to the approach and docking of the Pearya Terrane (northernmost part of Ellesmere Island) and Spitsbergen against the north margin of Laurasia (Ellesmere Island/North Greenland) in the earliest Carboniferous. The Eurekan deformation was related to plate tectonic movements during the final break-up of Laurasia and the opening of Labrador Sea/Baffin Bay west, the Eurasian Basin north, and the Norwegian/Greenland seas east of Greenland. The tectonic map presented here shows the German contribution to the Tectonic Map of the Arctic 1:5,000,000 (TeMAr) as part of the international project "Atlas of geological maps of Circumpolar Arctic at 1

  16. Relationships between deformation mechanisms and initial textures in polycrystalline magnesium alloys AZ31

    Institute of Scientific and Technical Information of China (English)

    YANG Ping(杨平); CUI Fen-ge(崔凤娥); BIAN Jian-hua(边建华); G Gottstein

    2003-01-01

    Microscopy, X-ray diffractometry and EBSD analysis were applied to inspect the relationships between deformation mechanisms and initial textures in polycrystalline magnesium alloys AZ31. It is found that different deformation mechanisms proceed according to theoretic prediction. Basal slips occur when basal planes of grains are tilted toward normal direction(ND) around transverse direction(TD); prism slips dominate when basal planes are perpendicular to TD. {1012} twinning was favored when basal planes are normal to rolling direction(RD) and {1011} twinning is analyzed to be related to the basal orientation of grains.

  17. Computational implementation of the multi-mechanism deformation coupled fracture model for salt

    Energy Technology Data Exchange (ETDEWEB)

    Koteras, J.R.; Munson, D.E.

    1996-05-01

    The Multi-Mechanism Deformation (M-D) model for creep in rock salt has been used in three-dimensional computations for the Waste Isolation Pilot Plant (WIPP), a potential waste, repository. These computational studies are relied upon to make key predictions about long-term behavior of the repository. Recently, the M-D model was extended to include creep-induced damage. The extended model, the Multi-Mechanism Deformation Coupled Fracture (MDCF) model, is considerably more complicated than the M-D model and required a different technology from that of the M-D model for a computational implementation.

  18. High-Temperature Deformation Processing Map Approach for Obtaining the Desired Microstructure in a Multi-component (Ni-Ti-Cu-Fe) Alloy

    Science.gov (United States)

    Nayan, Niraj; Singh, Gaurav; Narayana Murty, S. V. S.; Jha, Abhay K.; Pant, Bhanu; George, Koshy M.

    2015-05-01

    An equiatomic NiTiCuFe multi-component alloy with simple body-centered cubic (bcc) and face-centered cubic solid-solution phases in the microstructure was processed by vacuum induction melting furnace under dynamic Ar atmosphere. High-temperature uniaxial compression experiments were conducted on it in the temperature range of 1073 K to 1303 K (800 °C to 1030 °C) and strain rate range of 10-3 to 10-1 s-1. The data generated were analyzed with the aid of the dynamic materials model through which power dissipation efficiency and instability maps were generated so as to identify the governing deformation mechanisms that are operative in different temperature-strain rate regimes with the aid of complementary microstructural analysis of the deformed specimens. Results indicate that the stable domain for the high temperature deformation of the multi-component alloy occurs in the temperature range of 1173 K to 1303 K (900 °C to 1030 °C) and range of 10-3 to 10-1.2 s-1, and the deformation is unstable at T = 1073 K to 1153 K (800 °C to 880 °C) and = 10-3 to 10-1.4 s-1 as well as T = 1223 K to 1293 K (950 °C to 1020 °C) and = 10-1.4 to 10-1 s-1, with adiabatic shear banding, localized plastic flow, or cracking being the unstable mechanisms. A constitutive equation that describes the flow stress of NiTiCuFe multi-component alloy as a function of strain rate and deformation temperature was also determined.

  19. Finite deformation mechanics in buckled thin films on compliant supports.

    Science.gov (United States)

    Jiang, Hanqing; Khang, Dahl-Young; Song, Jizhou; Sun, Yugang; Huang, Yonggang; Rogers, John A

    2007-10-02

    We present detailed experimental and theoretical studies of the mechanics of thin buckled films on compliant substrates. In particular, accurate measurements of the wavelengths and amplitudes in structures that consist of thin, single-crystal ribbons of silicon covalently bonded to elastomeric substrates of poly(dimethylsiloxane) reveal responses that include wavelengths that change in an approximately linear fashion with strain in the substrate, for all values of strain above the critical strain for buckling. Theoretical reexamination of this system yields analytical models that can explain these and other experimental observations at a quantitative level. We show that the resulting mechanics has many features in common with that of a simple accordion bellows. These results have relevance to the many emerging applications of controlled buckling structures in stretchable electronics, microelectromechanical systems, thin-film metrology, optical devices, and others.

  20. Micro-deformation mechanisms in thermoformed alumina trihydrate reinforced poly(methyl methacrylate)

    Energy Technology Data Exchange (ETDEWEB)

    Gunel, E.M., E-mail: emgunel@buffalo.edu [Civil, Structural and Environmental Engineering, State University of New York at Buffalo, Buffalo, NY 14260 (United States); Basaran, C., E-mail: cjb@buffalo.edu [Civil, Structural and Environmental Engineering, State University of New York at Buffalo, Buffalo, NY 14260 (United States)

    2009-10-15

    Micro-deformation mechanisms involved in thermoforming of alumina trihydrate (ATH) reinforced poly(methyl methacrylate) (PMMA) was investigated in a new experimental method replicating industrial heavy-gage thermoforming procedure. Uniaxial tension tests under non-steady thermal conditions were carried out at different forming rates and forming temperatures. Stress-strain curves and load-displacement histories of thermoformed samples were studied in terms of specimen temperature at different forming conditions. Neat PMMA samples were stretched to 50% strain under identical thermoforming conditions as PMMA/ATH for comparison purposes. Stress whitening in thermoformed PMMA/ATH samples was monitored with optical microscope and degree of stress whitening was characterized by an index obtained from optical image histograms. Micro-deformation features on the surface of PMMA and PMMA/ATH samples were examined by scanning electron microscopy (SEM). Micro-deformation in neat PMMA was in the form of homogenous drawing and did not include any type of void formation. SEM images of PMMA/ATH samples showed that particle cracking is the dominant deformation mechanism at low-forming temperatures, while at high-forming temperatures, combined particle disintegration and interfacial failure are dominant mechanisms. Stress whitening was not observed in neat PMMA which was attributed to absence of micro-voids or craze-like structures. On the other hand, PMMA/ATH samples displayed different levels of stress whitening depending on density, size and type of micro-deformation features.

  1. Switching deformation mode and mechanisms during subduction of continental crust: a case study from Alpine Corsica

    Science.gov (United States)

    Molli, Giancarlo; Menegon, Luca; Malasoma, Alessandro

    2017-07-01

    The switching in deformation mode (from distributed to localized) and mechanisms (viscous versus frictional) represent a relevant issue in the frame of crustal deformation, being also connected with the concept of the brittle-ductile transition and seismogenesis. In a subduction environment, switching in deformation mode and mechanisms and scale of localization may be inferred along the subduction interface, in a transition zone between the highly coupled (seismogenic zone) and decoupled deeper aseismic domain (stable slip). However, the role of brittle precursors in nucleating crystal-plastic shear zones has received more and more consideration being now recognized as fundamental in some cases for the localization of deformation and shear zone development, thus representing a case in which switching deformation mechanisms and scale and style of localization (deformation mode) interact and relate to each other. This contribution analyses an example of a millimetre-scale shear zone localized by brittle precursor formed within a host granitic protomylonite. The studied structures, developed in ambient pressure-temperature (P-T) conditions of low-grade blueschist facies (temperature T of ca. 300 °C and pressure P ≥ 0. 70 GPa) during involvement of Corsican continental crust in the Alpine subduction. We used a multidisciplinary approach by combining detailed microstructural and petrographic analyses, crystallographic preferred orientation by electron backscatter diffraction (EBSD), and palaeopiezometric studies on a selected sample to support an evolutionary model and deformation path for subducted continental crust. We infer that the studied structures, possibly formed by transient instability associated with fluctuations of pore fluid pressure and episodic strain rate variations, may be considered as a small-scale example of fault behaviour associated with a cycle of interseismic creep and coseismic rupture or a new analogue for episodic tremors and slow

  2. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy

    Directory of Open Access Journals (Sweden)

    Sean Davies

    2017-04-01

    Full Text Available The realisation of employing Additive Layer Manufacturing (ALM technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD, each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials’ mechanical properties have been assessed with the Small Punch Tensile (SPT test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength.

  3. Deforming mechanism of non-mandrel drawing process of circular aluminium tube by simulation

    Institute of Scientific and Technical Information of China (English)

    QUAN Guo-zheng; ZHOU Jie; WANG Meng-han; QUAN Guo-hui; TONG Ying

    2006-01-01

    The aluminium tubes with high strength and smooth outer-surface can be produced by non-mandrel drawing process. It is an effective method to study forming mechanism of drawing process by simulation, based on which the relevant dies with reasonable dimensions can be designed to ensure tube precision. The dynamic model and elasto-plastic finite element model of the forming process were established based on FEM software Deform-3D, then the simulation was performed. The expressions about drawing load were deduced, and the influence of friction coefficient on drawing load was computed by the expressions and software respectively. Based on simulation results the deformation mechanism of drawing process without plug was expounded. According to flowing speed vector graph the law of material flowing was summarized, by which the deformation regions were partitioned.Furthermore, some potential problems of drawing process such as diameter shrinking, thickness varying were forecast and analyzed quantificationally.

  4. Effects of deformation parameters on microstructure and mechanical properties of magnesium alloy AZ31B

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shaoming; YANG Bicheng; XU Jun; SHI Likai; CHEN Guoliang

    2006-01-01

    Plastic deformation and dynamic recrystallization (DRX) behaviors of magnesium alloy AZ31B during thermal compression and extrusion processes were studied.In addition, effects of deformation temperature and rates on the microstructure and mechanical properties were investigated.The results show that the DRX grains nucleate initially at the primary grain boundaries and the twin boundaries, and the twinning plays an important role in the grain refinement.The DRX grain size depends on the deformation temperature and strain rate The average grain size is only 1 μm when the strain rate is 5 s-1 and temperature is 250 ℃.It is also found that the DRX grain can grow up quickly at the elevated temperature.The microstructure of extruded rods was consisted of tiny equal-axis DRX grains and some elongated grains.The rods extruded slowly have tiny grains and exhibit good mechanical properties.

  5. Modelling heat and mass transfer in bread baking with mechanical deformation

    Science.gov (United States)

    Nicolas, V.; Salagnac, P.; Glouannec, P.; Ploteau, J.-P.; Jury, V.; Boillereaux, L.

    2012-11-01

    In this paper, the thermo-hydric behaviour of bread during baking is studied. A numerical model has been developed with Comsol Multiphysics© software. The model takes into account the heat and mass transfers in the bread and the phenomenon of swelling. This model predicts the evolution of temperature, moisture, gas pressure and deformation in French "baguette" during baking. Local deformation is included in equations using solid phase conservation and, global deformation is calculated using a viscous mechanic model. Boundary conditions are specified with the sole temperature model and vapour pressure estimation of the oven during baking. The model results are compared with experimental data for a classic baking. Then, the model is analysed according to physical properties of bread and solicitations for a better understanding of the interactions between different mechanisms within the porous matrix.

  6. Mapping mesoscale heterogeneity in the plastic deformation of a copper single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Magid, K. R.; Florando, J.N.; Lassila, D.H.; Leblanc, M.M.; Tamura, N.; Morris Jr, J. W.

    2008-10-01

    The work reported here is part of a 'multiscale characterization' study of heterogeneous deformation patterns in metals. A copper single crystal was oriented for single slip in the (111)[{bar 1}01] slip system and tested to {approx}10% strain in roughly uniaxial compression. The macroscopic strain field was monitored during the test by optical 'image correlation'. The strain field was measured on orthogonal surfaces, one of which (the x-face) was oriented perpendicular to [1{bar 2}1] and contained the [{bar 1}01] direction of the preferred slip system. The macroscopic strain developed in an inhomogeneous pattern of broad, crossed shear bands in the x-face. One, the primary band, lay parallel to (111). The second, the 'conjugate' band, was oriented perpendicular to (111) with an overall ({bar 1}01) habit that contains no common slip plane of the fcc crystal. The mesoscopic deformation pattern was explored with selected area diffraction, using a focused synchrotron radiation polychromatic beam with a resolution of 1-3 {micro}m. Areas within the primary, conjugate and mixed (primary + conjugate) strain regions of the x-face were identified and mapped for their orientation, excess defect density and shear stress. The mesoscopic defect structure was concentrated in broad, somewhat irregular primary bands that lay nominally parallel to (111) in an almost periodic distribution with a period of about 30 {micro}m. These primary bands were dominant even in the region of conjugate strain. There were also broad conjugate defect bands, almost precisely perpendicular to the primary bands, that tended to bridge primary bands and terminate at them. The residual shear stresses were large (ranging to well above 500 MPa) and strongly correlated with the primary shear bands; interband stresses were small. The maximum resolved shear stresses within the primary bands were oriented out of the plane of the bands, and, hence, could not recover the dislocation

  7. Relating Deformation and Thermodynamics: An Opportunity for Rethinking Basic Concepts of Continuum Mechanics

    Directory of Open Access Journals (Sweden)

    Giuseppe Guzzetta

    2013-06-01

    Full Text Available In order to treat deformation as one of the processes taking place in an irreversible thermodynamic transformation, two main conditions must be satisfied: (1 strain and stress should be defined in such a way that the modification of the symmetry of these tensorial quantities reflects that of the structure of the actual material of which the deforming ideal continuum is the counterpart; and (2 the unique decomposition of the above tensors into the algebraic sum of an isotropic and an anisotropic part with different physical meanings should be recognized. The first condition allows the distinction of the energy balance in irrotational and rotational deformations; the second allows the description of a thermodynamic transformation involving deformation as a function of both process quantities, whose values depend on the specific transition, or path, between two equilibrium states, and of state quantities, which describe equilibrium states of a system quantitatively. One of the main conclusions that can be drawn is that, dealing with deformable materials, the quantities that must appear in thermodynamic equations cannot be tensorial quantities, such as the stress tensor and the infinitesimal or finite strain tensor usually considered in continuum mechanics (or, even worse, their components. The appropriate quantities should be invariants involved by the strain and stress tensors here defined. Another important conclusion is that, from a thermodynamic point of view, the consideration of the measurable volume change occurring in an isothermal deformation does not itself give any meaningful information.

  8. Friction properties and deformation mechanisms of halite(-mica) gouges from low to high sliding velocities

    Science.gov (United States)

    Buijze, Loes; Niemeijer, André R.; Han, Raehee; Shimamoto, Toshihiko; Spiers, Christopher J.

    2017-01-01

    The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10-8-10-4 ms-1) or in the high velocity regime (0.01-1 m s-1). Here, we report on the evolution of friction and corresponding operating deformation mechanisms in analog gouges deformed from low to high slip rates, bridging the gap between these low and high velocity regimes. We used halite and halite-muscovite gouges to simulate processes, governing friction, active in upper crustal quartzitic fault rocks, at conditions accessible in the laboratory. The gouges were deformed over a 7 orders of magnitude range of slip rate (10-7-1 m s-1) using a low-to-high velocity rotary shear apparatus, using a normal stress of 5 MPa and room-dry humidity. Microstructural analysis was conducted to study the deformation mechanisms. Four frictional regimes as a function of slip rate could be recognized from the mechanical data, showing a transitional regime and stable sliding (10-7-10-6 m s-1), unstable sliding and weakening (10-6-10-3 m s-1), hardening (10-2-10-1 m s-1) and strong weakening (10-1-1 m s-1). Each of the four regimes can be associated with a distinct microstructure, reflecting a transition from mainly brittle deformation accompanied by pressure solution healing to temperature activated deformation mechanisms. Additionally, the frictional response of a sliding gouge to a sudden acceleration of slip rate to seismic velocities was investigated. These showed an initial strengthening, the amount of which depended on the friction level at which the step was made, followed by strong slip weakening.

  9. An Extension of Mapping Deformation Method and New Exact Solution for Three Coupled Nonlinear Partial Differential Equations

    Institute of Scientific and Technical Information of China (English)

    LI Hua-Mei

    2003-01-01

    In this paper, we extend the mapping deformation method proposed by Lou. It is used to find new exacttravelling wave solutions of nonlinear partial differential equation or coupled nonlinear partial differential equations(PDEs). Based on the idea of the homogeneous balance method, we construct the general mapping relation betweenthe solutions of the PDEs and those of the cubic nonlinear Klein-Gordon (NKG) equation. By using this relation andthe abundant solutions of the cubic NKG equation, many explicit and exact travelling wave solutions of three systemsof coupled PDEs, which contain solitary wave solutions, trigonometric function solutions, Jacobian elliptic functionsolutions, and rational solutions, are obtained.

  10. Effect of suction-dependent soil deformability on landslide susceptibility maps

    Science.gov (United States)

    Lizarraga, Jose J.; Buscarnera, Giuseppe; Frattini, Paolo; Crosta, Giovanni B.

    2016-04-01

    This contribution presents a physically-based, spatially-distributed model for shallow landslides promoted by rainfall infiltration. The model features a set of Factor of Safety values aimed to capture different failure mechanisms, namely frictional slips with limited mobility and flowslide events associated with the liquefaction of the considered soils. Indices of failure associated with these two modes of instability have been derived from unsaturated soil stability principles. In particular, the propensity to wetting-induced collapse of unsaturated soils is quantified through the introduction of a rigid-plastic model with suction-dependent yielding and strength properties. The model is combined with an analytical approach (TRIGRS) to track the spatio-temporal evolution of soil suction in slopes subjected to transient infiltration. The model has been tested to reply the triggering of shallow landslides in pyroclastic deposits in Sarno (1998, Campania Region, Southern Italy). It is shown that suction-dependent mechanical properties, such as soil deformability, have important effects on the predicted landslide susceptibility scenarios, resulting on computed unstable zones that may encompass a wide range of slope inclinations, saturation levels, and depths. Such preliminary results suggest that the proposed methodology offers an alternative mechanistic interpretation to the variability in behavior of rainfall-induced landslides. Differently to standard methods the explanation to this variability is based on suction-dependent soil behavior characteristics.

  11. Formation mechanism of fivefold deformation twins in a face-centered cubic alloy

    Science.gov (United States)

    Zhang, Zhenyu; Huang, Siling; Chen, Leilei; Zhu, Zhanwei; Guo, Dongming

    2017-01-01

    The formation mechanism considers fivefold deformation twins originating from the grain boundaries in a nanocrystalline material, resulting in that fivefold deformation twins derived from a single crystal have not been reported by molecular dynamics simulations. In this study, fivefold deformation twins are observed in a single crystal of face-centered cubic (fcc) alloy. A new formation mechanism is proposed for fivefold deformation twins in a single crystal. A partial dislocation is emitted from the incoherent twin boundaries (ITBs) with high energy, generating a stacking fault along {111} plane, and resulting in the nucleating and growing of a twin by the successive emission of partials. A node is fixed at the intersecting center of the four different slip {111} planes. With increasing stress under the indentation, ITBs come into being close to the node, leading to the emission of a partial from the node. This generates a stacking fault along a {111} plane, nucleating and growing a twin by the continuous emission of the partials. This process repeats until the formation of fivefold deformation twins. PMID:28349995

  12. Formation mechanism of fivefold deformation twins in a face-centered cubic alloy.

    Science.gov (United States)

    Zhang, Zhenyu; Huang, Siling; Chen, Leilei; Zhu, Zhanwei; Guo, Dongming

    2017-03-28

    The formation mechanism considers fivefold deformation twins originating from the grain boundaries in a nanocrystalline material, resulting in that fivefold deformation twins derived from a single crystal have not been reported by molecular dynamics simulations. In this study, fivefold deformation twins are observed in a single crystal of face-centered cubic (fcc) alloy. A new formation mechanism is proposed for fivefold deformation twins in a single crystal. A partial dislocation is emitted from the incoherent twin boundaries (ITBs) with high energy, generating a stacking fault along {111} plane, and resulting in the nucleating and growing of a twin by the successive emission of partials. A node is fixed at the intersecting center of the four different slip {111} planes. With increasing stress under the indentation, ITBs come into being close to the node, leading to the emission of a partial from the node. This generates a stacking fault along a {111} plane, nucleating and growing a twin by the continuous emission of the partials. This process repeats until the formation of fivefold deformation twins.

  13. Deformation mechanisms in a coal mine roadway in extremely swelling soft rock.

    Science.gov (United States)

    Li, Qinghai; Shi, Weiping; Yang, Renshu

    2016-01-01

    The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p ∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock's swelling potential.

  14. Effect of deformed microstructure on mechanical properties of Ti-22Al-25Nb alloy

    Institute of Scientific and Technical Information of China (English)

    CHENG Yun-jun; LI Shi-qiong; LIANG Xiao-bo; ZHANG Jian-wei

    2006-01-01

    Effect of the deformed microstructure on mechanical properties of an orthorhombic (Ti2AlNb) based alloy of Ti-22Al-25Nb (mole fraction, %) has been investigated. It was found that the deformed microstructures in different portions of a free forged rod with diameter of 30 mm were quite different and thus resulted in the different mechanical properties after the same subsequent heat-treatment. One deformed microstructure with less primary α2/O particles and a larger and equiaxed B2 grains resulted in poor RT ductility, but the other one with a relatively larger amount of the primary α2/O particles and non-equiaxed B2 grains had good combination of the tensile strength and ductility both at RT and 650 ℃. It was also found that two different deformed microstructures were obtained for the hot rolling plates with thickness of 3 mm even processed under an identical nominal rolling and the same post-deforming heat treatment conditions. One only has 3.5% of RT tensile elongation and the other up to 8%.

  15. Effect of chordwise deformation on unsteady aerodynamic mechanisms in hovering flapping flight

    NARCIS (Netherlands)

    Noyon, T.A.; Tay, W.B.; Van Oudheusden, B.W.; Bijl, H.

    2014-01-01

    A three-dimensional simulation of hovering flapping wings was performed using an immersed boundary method. This was done to investigate the effects of chordwise wing deformation on three important unsteady aerodynamic mechanisms found in flapping flight, namely Leading Edge Vortex (LEV) shedding, wa

  16. The influence of initial defects on mechanical stress and deformation distribution in oxidized silicon

    Directory of Open Access Journals (Sweden)

    Kulinich O. A.

    2008-10-01

    Full Text Available The near-surface silicon layers in silicon – dioxide silicon systems with modern methods of research are investigated. It is shown that these layers have compound structure and their parameters depend on oxidation and initial silicon parameters. It is shown the influence of initial defects on mechanical stress and deformation distribution in oxidized silicon.

  17. Deformation mechanisms in fine grained quartzo-feldspathic mylonites : an electron microscopy study

    NARCIS (Netherlands)

    Fliervoet, Timon F.

    1995-01-01

    Previous work on the deformation mechanisms in quartzo-feldspathic rocks from the upperand middle-crust has predominantly concentrated on single phase quartz bands within these rocks. This has served well as a first approach, but several shortcomings have become evident concerning the highest strain

  18. Acoustic Emission Determination of Deformation Mechanisms Leading to Failure of Naval Alloys. Volume 2

    Science.gov (United States)

    1983-05-01

    Emission Laser Beam Interferometer HY80 , 100, 130 Steels Mechanical Deformation Nondestructive Evaluation 2. ABSTRACT (Conetnue an rovere eli if necoo y...publication, J. Applied Phys.). 43. A. Peterlin, B.B. Djordjvic, J.C. Murphy, R.E. Green, "Acoustic Emission During Craze Forma- tion in Polymers

  19. On the deformation mechanisms and electrical behavior of highly stretchable metallic interconnects on elastomer substrates

    Science.gov (United States)

    Arafat, Yeasir; Dutta, Indranath; Panat, Rahul

    2016-09-01

    Flexible metallic interconnects are highly important in the emerging field of deformable/wearable electronics. In our previous work [Arafat et al., Appl. Phys. Lett. 107, 081906 (2015)], interconnect films of Indium metal, periodically bonded to an elastomer substrate using a thin discontinuous/cracked adhesion interlayer of Cr, were shown to sustain a linear strain of 80%-100% without failure during repeated cycling. In this paper, we investigate the mechanisms that allow such films to be stretched to a large strain without rupture along with strategies to prevent a deterioration in their electrical performance under high linear strain. Scanning Electron Microscopy and Digital Image Correlation are used to map the strain field of the Cr adhesion interlayer and the In interconnect film when the elastomer substrate is stretched. It is shown that the Cr interlayer morphology, consisting of islands separated by bi-axial cracks, accommodates the strain primarily by widening of the cracks between the islands along the tensile direction. This behavior is shown to cause the strain in the In interconnect film to be discontinuous and concentrated in bands perpendicular to the loading direction. This localization of strain at numerous periodically spaced locations preempts strain-localization at one location and makes the In film highly stretchable by delaying rupture. Finally, the elastic-plastic mismatch-driven wrinkling of the In interconnect upon release from first loading cycle is utilized to delay the onset of plasticity and allow the interconnect to be stretched repeatedly up to 25% linear strain in subsequent cycles without a deterioration of its electrical performance.

  20. Variation in deformational mechanisms in the Banda Arc: Uplift and tectonic implications of Kisar, Indonesia

    Science.gov (United States)

    Major, J. R.; Harris, R. A.; Chiang, H.; Prasetyadi, C.; Shen, C.

    2009-12-01

    Kisar island is an enigmatic feature which reveals anomalous mountain building processes in the forearc basin of the Banda arc-continent collision. The roughly circular uplift rises 3 km from the basin floor to the surface and is surrounded by uplifted coral terraces. The island is near a retrowedge thrust imaged by seismic reflection. Yet, the location, shape, and structures of the island suggest an origin more complex than simple thrusting, such as diapiric activity (i.e. an emergent gneiss dome). Kisar exposes low-grade metasediments with scattered mafic bodies and is similar to the Aileu Fm. on neighboring Timor. Detrital zircon analysis reveals an affinity to Australia’s northern continental margin. The geochemistry of mafic bodies indicates a rift environment, likely related to the breakup of Gondwana. Geothermobarometry and geochronologic data from the Aileu Complex shows the rocks were subducted to a depth of 35 km and have a long-term rock uplift rate calculated at 3-5 mm/yr. However, U-Th series age analyses of uplifted coral terraces on Kisar yield a short-term surface uplift rate of 0.15-0.8 mm/yr. In addition, several loose coral heads found at 10-20m elevation on the south, east, and west coasts yield ages of ~100 years and are likely tsunami deposits from undocumented seismic activity on the Timor trough. These are the first age data from a 400 km stretch of islands between Timor and Tanimbar where the young orogen displays varied deformational mechanisms along strike. Simplified map of southern Banda Arc with Kisar noted.

  1. Influencing Factors of Thermal Deformation on Hydrostatic Pressure Mechanical Seal and Optimization of Rotating and Stationary Rings

    Directory of Open Access Journals (Sweden)

    Lin Dong

    2013-02-01

    Full Text Available According to thermo-elastic deformation theory, take the temperature field analysis results of hydrostatic pressure mechanical seal as volume load to resolve the problem of thermal-structure coupling deformation of rotating and stationary rings in ANSYS software. The distribution laws of thermal strain, thermal stress and thermal-structure coupling deformation are obtained. The effects of working, material and structural parameters on axial, radial thermal deformation and deformation taper of the end faces are discussed in detail, and the main affecting factors are found out. Measures and structural constraint programs to control the thermal deformation are put forward. Base on the theory of thermal deformation compensation, the rotating and stationary rings are optimized, and the thermal deformation before and after their optimization are solved respectively and analyzed comparatively to verify the feasibility of the optimization program.

  2. Early stiffening and softening of collagen: interplay of deformation mechanisms in biopolymer networks.

    Science.gov (United States)

    Kurniawan, Nicholas A; Wong, Long Hui; Rajagopalan, Raj

    2012-03-12

    Collagen networks, the main structural/mechanical elements in biological tissues, increasingly serve as biomimetic scaffolds for cell behavioral studies, assays, and tissue engineering, and yet their full spectrum of nonlinear behavior remains unclear. Here, with self-assembled type-I collagen as model, we use metrics beyond those in standard single-harmonic analysis of rheological measurements to reveal strain-softening and strain-stiffening of collagen networks both in instantaneous responses and at steady state. The results show how different deformation mechanisms, such as deformation-induced increase in the elastically active fibrils, nonlinear extension of individual fibrils, and slips in the physical cross-links in the network, can lead to the observed complex nonlinearity. We demonstrate how comprehensive rheological analyses can uncover the rich mechanical properties of biopolymer networks, including the above-mentioned softening as well as an early strain-stiffening, which are important for understanding physiological response of biological materials to mechanical loading.

  3. Mechanisms of deformation and of recrystallization of imperfect uranium monocrystals; Les mecanismes de deformation et de recristallisation des monocristaux imparfaits d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Calais, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-04-15

    The various means by which plastic deformations by slip, twinning or kinking are produced by tension of imperfect {alpha} uranium single crystals prepared by a {beta} {yields} {alpha} phase change, have been studied by X-rays and micrographic examination. Depending on the crystallographic orientation with respect to the direction of the applied tension, and depending on the magnitude of the change in length, the crystals are deformed either preferentially according to a single mechanism, for example twinning, or simultaneously according to two or three mechanisms. The results of a subsequent annealing of the deformed single in the {alpha} phase are studied with respect to the deformation mechanisms. In the case of a deformation due primarily to (010) [100], (011) [100] or (110) [001] sliding, there occurs recrystallization by crystal growth selectivity. If the deformation occurs via deformation bands, there is recrystallization by 'oriented nucleation'. The crystals deformed preponderantly by twinning give on recrystallization perfect crystals having optimum dimensions and having orientational characteristics closely related to those of the original crystal. Finally are discussed some criteria relating to the geometry and the dynamics with a view to explaining the occurrence of such and such a deformation mechanism of a single crystal with a given orientation. This study, in conclusion, must help to define the best conditions (crystalline orientation and process of deformation) which will promote the growth of large, perfect, single crystals. (author) [French] Les divers modes de deformation plastique, glissement, maclage et pliage, que provoque la traction de monocristaux d'uranium {alpha} imparfaits prepares par changement de phase {beta} {yields} {alpha} ont ete etudies par rayons X et par examen micrographique. Suivant l'orientation cristallographique par rapport a la direction de l'axe de traction et suivant l'importance de l

  4. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    Science.gov (United States)

    Miner, R. V.; Castelli, M. G.

    1992-01-01

    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  5. Field-Induced Deformation as a Mechanism for Scanning Tunneling Microscopy Based Nanofabrication

    DEFF Research Database (Denmark)

    Hansen, Ole; Ravnkilde, Jan Tue; Quaade, Ulrich;

    1998-01-01

    The voltage between tip and sample in a scanning tunneling microscope (STM) results in a large electric field localized near the tip apex. The mechanical stress due to this field can cause appreciable deformation of both tip and sample on the scale of the tunnel gap. We derive an approximate...... analytical expression for this deformation and confirm the validity of the result by comparison with a finite element analysis. We derive the condition for a field-induced jump to contact of tip and sample and show that this agrees well with experimental results for material transfer between tip and sample...

  6. DTAF dye concentrations commonly used to measure microscale deformations in biological tissues alter tissue mechanics.

    Directory of Open Access Journals (Sweden)

    Spencer E Szczesny

    Full Text Available Identification of the deformation mechanisms and specific components underlying the mechanical function of biological tissues requires mechanical testing at multiple levels within the tissue hierarchical structure. Dichlorotriazinylaminofluorescein (DTAF is a fluorescent dye that is used to visualize microscale deformations of the extracellular matrix in soft collagenous tissues. However, the DTAF concentrations commonly employed in previous multiscale experiments (≥2000 µg/ml may alter tissue mechanics. The objective of this study was to determine whether DTAF affects tendon fascicle mechanics and if a concentration threshold exists below which any observed effects are negligible. This information is valuable for guiding the continued use of this fluorescent dye in future experiments and for interpreting the results of previous work. Incremental strain testing demonstrated that high DTAF concentrations (≥100 µg/ml increase the quasi-static modulus and yield strength of rat tail tendon fascicles while reducing their viscoelastic behavior. Subsequent multiscale testing and modeling suggests that these effects are due to a stiffening of the collagen fibrils and strengthening of the interfibrillar matrix. Despite these changes in tissue behavior, the fundamental deformation mechanisms underlying fascicle mechanics appear to remain intact, which suggests that conclusions from previous multiscale investigations of strain transfer are still valid. The effects of lower DTAF concentrations (≤10 µg/ml on tendon mechanics were substantially smaller and potentially negligible; nevertheless, no concentration was found that did not at least slightly alter the tissue behavior. Therefore, future studies should either reduce DTAF concentrations as much as possible or use other dyes/techniques for measuring microscale deformations.

  7. Mechanical Modeling of Near-Fault Deformation Within the Dragon's Back Pressure Ridge, San Andreas Fault, Carrizo Plain, California

    Science.gov (United States)

    Hilley, G. E.; Arrowsmith, R.

    2011-12-01

    This contribution uses field observations and numerical modeling to understand how slip along the variably oriented fault surfaces in the upper few km of the San Andreas Fault (SAF) zone produces near-fault deformation observed within a 4.5-km-long Dragon's Back Pressure Ridge (DBPR) in the Carrizo Plain, central California. Geologic and geomorphic mapping of this feature indicates that the amplitude of monoclinal warping of Quaternary sediments increases from southeast to northwest along the southwestern third of the DBPR, and remains approximately constant throughout the remaining two thirds of the landform. When viewed with other structural observations and limited near-surface magnetotelluric imaging, these geologic observations are most compatible with a scenario in which shallow offset of the SAF to the northeast creates a structural knuckle that is anchored to the North American plate. Thus, deformation accrues as right-lateral strike-slip motion along the SAF moves this obstruction along the fault plane through the DBPR block. We have used the Gale numerical model to simulate deformation expected for geometries similar to those inferred within the vicinity of the DBPR. This is accomplished by relating stresses and strains in the upper crust according to a Drucker-Prager (plastic yielding) constitutive rule. Deformation in the model is driven by applying 35 mm/yr of right-lateral strike-slip motion to the model boundary; this displacement rate is likewise applied to the base of the model. The model geometry of the SAF at the beginning of the loading was fashioned to produce the discontinuity in the geometry of the fault plane that is inferred from field observations. The friction and cohesion of crust on each side of the fault were changed between models to determine the parameter values that preserve the structural discontinuity along the SAF as finite deformation accrued. The structural discontinuity over the ~4.5 km of model displacement is maintained in

  8. Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

    Directory of Open Access Journals (Sweden)

    Fuping Yuan

    2014-12-01

    Full Text Available A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

  9. Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

    Science.gov (United States)

    Yuan, Fuping; Wu, Xiaolei

    2014-12-01

    A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

  10. Inelastic deformation mechanisms in SCS-6/Ti 15-3 MMC lamina under compression

    Science.gov (United States)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1993-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (0)(sub 8) and (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Monotonic tests were conducted at room temperature (RT), 538 C and 650 C. Results indicate that mechanical response and deformation characteristics were different in monotonic tension and compression loading whereas some of those differences could be attributed to residual stress effects. There were other differences because of changes in damage and failure modes. The inelastic deformation in the (0)(sub 8) lamina under compression was controlled primarily by matrix plasticity, although some evidence of fiber-matrix debonding was observed. Failure of the specimen in compression was due to fiber buckling in a macroscopic shear zone (the failure plane). The inelastic deformation mechanisms under compression in (90)(sub 8) lamina were controlled by radial fiber fracture, matrix plasticity, and fiber-matrix debonding. The radial fiber fracture was a new damage mode observed for MMC's. Constitutive response was predicted for both the (0)(sub 8) and (90)(sub 8) laminae, using AGLPLY, METCAN, and Battelle's Unit Cell FEA model. Results from the analyses were encouraging.

  11. Nanoscale mechanism and intrinsic structure related deformation of Ti-alloys

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, J. [IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, D-01171 Dresden (Germany)], E-mail: j.eckert@ifw-dresden.de; Das, J. [IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, D-01171 Dresden (Germany); Xu, W. [University of Melbourne, Department of Mechanical and Manufacturing Engineering, Vic 3010 (Australia); Theissmann, R. [Forschungszentrum Karlsruhe, Institut fuer Nanotechnologie, Postfach 3640, Karlsruhe D-76133 (Germany)

    2008-10-15

    A series of Ti-Nb-Ta-(In/Cr) and Ti-Fe-(Sn) alloys containing a bcc {beta}-Ti phase with a grain size ranging from the nanometer/ultrafine regime to the micrometer scale has been prepared by slow cooling from the melt. The plastic deformation behavior has been investigated under compression and the deformation-induced microstructure evolution was checked by X-ray diffraction, scanning and transmission electron microscopy. The data reveal that the underlying mechanisms related to plasticity or brittleness of the {beta}-phase depends significantly on the supersaturation, the local lattice strain, the ease of dislocation slip, as well as twinning and diffusionless transformation triggering grain refinement. The intrinsic structure, the short-range order and the stability of the {beta}-Ti phase have a strong influence on the mode of plastic deformation of the investigated Ti-alloys.

  12. Microstructural Evolution of Surface Layer of TWIP Steel Deformed by Mechanical Attrition Treatment

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    A nanocrystalline layer was synthesized on the surface of TWIP steel samples by surface mechanical attri- tion treatment (SMAT) under varying durations. Microhardness variation was examined along the depth of the de- formation layer. Microstructural characteristics of the surface at the TWIP steel SMATed for 90 min were observed and analyzed by optical microscope, x-ray diffraction, transmission and high-resolution electron microscope. The re- sults show that the orientation of austenite grains weakens, and a-martensite transformation occurs during SMAT. During the process of SMAT, the deformation twins generate and divide the austenite grains firstly~ then a-martens- ite transformation occurs beside and between the twin bundles~ after that the martensite and austenite grains rotate to accommodate deformation, and the orientations of martensite and between martensite and residual austenite increase; lastly the randomly oriented and uniform-sized nanocrystallir~e layers are formed under continuous deformation.

  13. Analysis of the Mechanism of Longitudinal Bending Deformation Due to Welding in a Steel Plate by Using a Numerical Model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Rae; Yan, Jieshen; Kim, Jae-Woong [Yeungnam Univ., Gyeongsan (Korea, Republic of); Song, Gyu Yeong [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)

    2017-01-15

    Welding deformation is a permanent deformation that is caused in structures by welding heat. Welding distortion is the primary cause of reduced productivity, due to welded structural strength degradation, low dimensional accuracy, and appearance. As a result, research and numerous experiments are being carried out to control welding deformation. The aim of this study is to analyze the mechanism of longitudinal bending deformation due to welding. Welding experiments and numerical analyses were performed for this study. The welding experiments were performed on 4 mm and 8.5 mm thickness steel plates, and the numerical analysis was conducted on the welding deformation using the FE software MSC.marc.

  14. Deformation and failure mechanisms of graphite/epoxy composites under static loading

    Science.gov (United States)

    Clements, L. L.

    1981-01-01

    The mechanisms of deformation and failure of graphite epoxy composites under static loading were clarified. The influence of moisture and temperature upon these mechanisms were also investigated. Because the longitudinal tensile properties are the most critical to the performance of the composite, these properties were investigated in detail. Both ultimate and elastic mechanical properties were investigated, but the study of mechanisms emphasized those leading to failure of the composite. The graphite epoxy composite selected for study was the system being used in several NASA sponsored flight test programs.

  15. Deformation mechanism and stability control of roadway along a fault subjected to mining

    Institute of Scientific and Technical Information of China (English)

    Yan Shuai; Bai Jianbiao; Li Wenfeng; Chen Jigang; Li Lei

    2012-01-01

    It is difficult to maintain the roadway around a fault because of the fractured surroundings,complex stress environment,and large and intense deformation in the mining process.Based on a tailgate of panel S2205 in Tunliu colliery,in Shanxi province,China,we investigated the evolution of stress and displacement of rocks surrounding the roadway during the drivage and mining period using theoretical analysis,numerical simulation and field trial methods.We analyzed the deformation and failure mechanisms of the tailgate near a fault.The deformation of surrounding rock caused by unloading in the drivage period is large and asymmetric,the roadway convergence increases with activation of the fault and secondary fracture develops in the mining period.Therefore,we proposed a specific control technique of the roadway along a fault as follows:(1) High-strength yielding bolt not only supports the shallow rock to loadbearing structures,but also releases primary deformation energy by use of a pressure release device in order to achieve high resistance to the pressure retained; (2) Grouting of near-fault ribside after initial stabilization of the rock deformation is used to reinforce the broken rock,and to improve the integral load-bearing capacity of the roadway.The research results were successfully applied to a field trial.

  16. Deformation and Failure Mechanism of Roadway Sensitive to Stress Disturbance and Its Zonal Support Technology

    Directory of Open Access Journals (Sweden)

    Qiangling Yao

    2016-01-01

    Full Text Available The 6163 haulage roadway in the Qidong coal mine passes through a fault zone, which causes severe deformation in the surrounding rock, requiring repeated roadway repairs. Based on geological features in the fault area, we analyze the factors affecting roadway deformation and failure and propose the concept of roadway sensitive to stress disturbance (RSSD. We investigate the deformation and failure mechanism of the surrounding rocks of RSSD using field monitoring, theoretical analysis, and numerical simulation. The deformation of the surrounding rocks involves dilatation of shallow rocks and separation of deep rocks. Horizontal and longitudinal fissures evolve to bed separation and fracture zones; alternatively, fissures can evolve into fracture zones with new fissures extending to deeper rock. The fault affects the stress field of the surrounding rock to ~27 m radius. Its maximum impact is on the vertical stress of the rib rock mass and its minimum impact is on the vertical stress of the floor rock mass. Based on our results, we propose a zonal support system for a roadway passing through a fault. Engineering practice shows that the deformation of the surrounding rocks of the roadway can be effectively controlled to ensure normal and safe production in the mine.

  17. Deformation Mechanism of the Northern Tibetan Plateau as Revealed by Magnetotelluric Data

    Science.gov (United States)

    Zhang, Letian; Wei, Wenbo; Jin, Sheng; Ye, Gaofeng; Xie, Chengliang

    2017-04-01

    As a unique geologic unit on the northern margin of the Tibetan Plateau, the Qaidam Basin plays a significant role in constraining the vertical uplift and horizontal expansion of the northern and northeastern Tibetan Plateau. However, due to its complex evolution history and difficult logistic condition, deformation mechanism of the lithosphere beneath the Qaidam Basin is still highly debated. To better understand the lithospheric electrical structure and deformation mechanism of the Qaidam Basin, A 250 km long, NE-SW directed Magnetotelluric (MT) profile was finished in the northern portion of the Basin, which is roughly perpendicular to the thrust fault systems on the western and eastern margins of the Basin, as well as anticlinorium systems within the Basin. The profile consists of 20 broad-band MT stations and 5 long-period MT stations. Original time series data is processed with regular robust routines. Dimensionality and regional strike direction are determined for the dataset through data analysis. Based on the analysis results, 2D inversions were performed to produce a preferred model of the lithospheric electrical structure beneath the northern Qaidam Basin. Uncertainty analysis of the 2D inversion model was also conducted based on a data resampling approach. The outcome 2D electrical model was further used to estimate the distribution of temperature and melt fraction in the upper mantle based on laboratory-determined relationships between the electrical conductivity and temperature of nominally anhydrous minerals and basaltic melt by using the mixing law of Hashin-Shtrikman's bounds. All these results suggest that: (1) the crust-mantle boundary is imaged as a conductive layer beneath the western Qaidam Basin, with its temperature estimated to be 1200-1300 °C and melt fraction 5-8%, indicating decoupling deformation of the crust and upper mantle. (2) A large-scale east-dipping conductor is imaged beneath the eastern Qaidam Basin. This conductor extends

  18. Impact of mechanical deformation on guest diffusion in zeolitic imidazolate frameworks.

    Science.gov (United States)

    Zheng, Bin; Wang, Lian Li; Hui, Jia Chen; Du, Lifei; Du, Huiling; Zhu, Ming

    2016-03-14

    The effect of the mechanical deformation of metal-organic frameworks on guest diffusion was investigated by employing molecular dynamics simulations. Two basic deformation modes, uniaxial tensile and shear deformation, were considered. The computed shear modulus of the zeolitic imidazolate framework-8 (ZIF-8) model system was much lower than the Young's modulus, which is in agreement with the experimental results. The diffusion rate in ZIF-8 was calculated for two types of guest molecules: the nonpolar H2 and the quadrupolar CO2. Under tensile strain, the diffusion of both H2 and CO2 was found to be enhanced, whereas the diffusion rates did not change significantly under shear loading. The evolution of the internal structure of ZIF-8 was studied to determine its effect on guest diffusion. The organic-inorganic connection was identified as the source of the framework's flexibility, and therefore we focused on the N-Zn bond and the N-Zn-N angle. Under stretching deformation, the N-Zn bond is elongated and the N-Zn-N angle remains constant. Thus, the length of the C2-C2 long bond, determining the size of the 6-membered ring (6MR) gate, increases and the gate is opened, allowing for faster guest diffusion. Under shear deformation, the N-Zn bond length changes very little and the N-Zn-N angle is distorted. This results in the occurrence of three peaks in the C2-C2 bond length distribution. Although the 6MR gate is distorted, the variation of its average size is small, resulting in a very small effect on the guest diffusivity. In addition, we found that the fluctuation of the ZIF-8 cell can enhance the impact of the mechanical deformation of the host on guest diffusion.

  19. Switching deformation mode and mechanisms during subduction of continental crust: a case study from Alpine Corsica

    Science.gov (United States)

    Molli, Giancarlo; Menegon, Luca; Malasoma, Alessandro

    2017-04-01

    The switching in deformation mode (from distributed to localized) and mechanism (viscous versus frictional) represent a relevant issue in the frame of processes of crustal deformation in turn connected with the concept of the brittle-"ductile" transition and seismogenesis. On the other hand the role of brittle precursors in nucleating crystal-plastic shear zones has received more and more consideration being now recognized as having a fundamental role in the localization of deformation and shear zone development, thus representing a case in which switching deformation mode and mechanisms interact and relate to each other. This contribution analyses an example of a crystal plastic shear zone localized by brittle precursor formed within a host granitic-mylonite during deformation in subduction-related environment. The studied sample come from the external Corsican continental crust units involved in alpine age subduction and characterized by a low grade blueschist facies peak assemblages. The blueschist facies host rock is cut by a thin (preserves domains with a cataclastic microstructure overprinted by mylonitic deformation. Blue amphibole is stable in the shear zone foliation, which therefore formed under HP/LT metamorphic conditions in a subduction environment. Quartz microstructure in the damage zone flanking the brittle-viscous shear zone shows evidence of both microcracking and dislocation glide, with limited recrystallization localized in intracrystalline bands. In the mylonite portion of the shear zone, quartz forms polycrystalline ribbons of dynamically recrystallized grains with a crossed-girdle c-axis CPO. Extrapolation of laboratory-derived flow laws indicates strain rate of ca. 3.5 * 10-12 s-1 during viscous flow in the shear zone. The studied structures, possibly formed by transient instability related to episodic stress/strain rate variations, may be considered as a small scale example of fault behaviour associated with a cycle of interseismic creep

  20. Influence of cross-link structure, density and mechanical properties in the mesoscale deformation mechanisms of collagen fibrils.

    Science.gov (United States)

    Depalle, Baptiste; Qin, Zhao; Shefelbine, Sandra J; Buehler, Markus J

    2015-12-01

    Collagen is a ubiquitous protein with remarkable mechanical properties. It is highly elastic, shows large fracture strength and enables substantial energy dissipation during deformation. Most of the connective tissue in humans consists of collagen fibrils composed of a staggered array of tropocollagen molecules, which are connected by intermolecular cross-links. In this study, we report a three-dimensional coarse-grained model of collagen and analyze the influence of enzymatic cross-links on the mechanics of collagen fibrils. Two representatives immature and mature cross-links are implemented in the mesoscale model using a bottom-up approach. By varying the number, type and mechanical properties of cross-links in the fibrils and performing tensile test on the models, we systematically investigate the deformation mechanisms of cross-linked collagen fibrils. We find that cross-linked fibrils exhibit a three phase behavior, which agrees closer with experimental results than what was obtained using previous models. The fibril mechanical response is characterized by: (i) an initial elastic deformation corresponding to the collagen molecule uncoiling, (ii) a linear regime dominated by molecule sliding and (iii) the second stiffer elastic regime related to the stretching of the backbone of the tropocollagen molecules until the fibril ruptures. Our results suggest that both cross-link density and type dictate the stiffness of large deformation regime by increasing the number of interconnected molecules while cross-links mechanical properties determine the failure strain and strength of the fibril. These findings reveal that cross-links play an essential role in creating an interconnected fibrillar material of tunable toughness and strength.

  1. A constitutive model of nanocrystalline metals based on competing grain boundary and grain interior deformation mechanisms

    KAUST Repository

    Gurses, Ercan

    2011-12-01

    In this work, a viscoplastic constitutive model for nanocrystalline metals is presented. The model is based on competing grain boundary and grain interior deformation mechanisms. In particular, inelastic deformations caused by grain boundary diffusion, grain boundary sliding and dislocation activities are considered. Effects of pressure on the grain boundary diffusion and sliding mechanisms are taken into account. Furthermore, the influence of grain size distribution on macroscopic response is studied. The model is shown to capture the fundamental mechanical characteristics of nanocrystalline metals. These include grain size dependence of the strength, i.e., both the traditional and the inverse Hall-Petch effects, the tension-compression asymmetry and the enhanced rate sensitivity. © 2011 Elsevier B.V. All rights reserved.

  2. Deformation mechanisms of human amnion: Quantitative studies based on second harmonic generation microscopy.

    Science.gov (United States)

    Mauri, Arabella; Ehret, Alexander E; Perrini, Michela; Maake, Caroline; Ochsenbein-Kölble, Nicole; Ehrbar, Martin; Oyen, Michelle L; Mazza, Edoardo

    2015-06-25

    Multiphoton microscopy has proven to be a versatile tool to analyze the three-dimensional microstructure of the fetal membrane and the mechanisms of deformation on the length scale of cells and the collagen network. In the present contribution, dedicated microscopic tools for in situ mechanical characterization of tissue under applied mechanical loads and the related methods for data interpretation are presented with emphasis on new stepwise monotonic uniaxial experiments. The resulting microscopic parameters are consistent with previous ones quantified for cyclic and relaxation tests, underlining the reliability of these techniques. The thickness reduction and the substantial alignment of collagen fiber bundles in the compact and fibroblast layer starting at very small loads are highlighted, which challenges the definition of a reference configuration in terms of a force threshold. The findings presented in this paper intend to inform the development of models towards a better understanding of fetal membrane deformation and failure, and thus of related problems in obstetrics and other clinical conditions.

  3. Plastic deformation mechanisms in polyimide resins and their semi-interpenetrating networks

    Science.gov (United States)

    Jang, Bor Z.

    1990-01-01

    High-performance thermoset resins and composites are critical to the future growth of space, aircraft, and defense industries in the USA. However, the processing-structure-property relationships in these materials remain poorly understood. In the present ASEE/NASA Summer Research Program, the plastic deformation modes and toughening mechanisms in single-phase and multiphase thermoset resins were investigated. Both thermoplastic and thermoset polyimide resins and their interpenetrating networks (IPNs and semi-IPNs) were included. The fundamental tendency to undergo strain localization (crazing and shear banding) as opposed to a more diffuse (or homogeneous) deformation in these polymers were evaluated. Other possible toughening mechanisms in multiphase thermoset resins were also examined. The topological features of network chain configuration/conformation and the multiplicity of phase morphology in INPs and semi-IPNs provide unprecedented opportunities for studying the toughening mechanisms in multiphase thermoset polymers and their fiber composites.

  4. The Virtual Fields Method Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements

    CERN Document Server

    Pierron, Fabrice

    2012-01-01

    The Virtual Fields Method: Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements is the first book on the Virtual Fields Method (VFM), a technique to identify materials mechanical properties from full-field measurements. Firmly rooted with extensive theoretical description of the method, the book presents numerous examples of application to a wide range of materials (composites, metals, welds, biomaterials) and situations (static, vibration, high strain rate). The authors give a detailed training section with examples of progressive difficulty to lead the reader to program the VFM and include a set of commented Matlab programs as well as GUI Matlab-based software for more general situations. The Virtual Fields Method: Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements is an ideal book for researchers, engineers, and students interested in applying the VFM to new situations motivated by their research.  

  5. A mechanical model for deformable and mesh pattern wheel of lunar roving vehicle

    Science.gov (United States)

    Liang, Zhongchao; Wang, Yongfu; Chen, Gang (Sheng); Gao, Haibo

    2015-12-01

    As an indispensable tool for astronauts on lunar surface, the lunar roving vehicle (LRV) is of great significance for manned lunar exploration. An LRV moves on loose and soft lunar soil, so the mechanical property of its wheels directly affects the mobility performance. The wheels used for LRV have deformable and mesh pattern, therefore, the existing mechanical theory of vehicle wheel cannot be used directly for analyzing the property of LRV wheels. In this paper, a new mechanical model for LRV wheel is proposed. At first, a mechanical model for a rigid normal wheel is presented, which involves in multiple conventional parameters such as vertical load, tangential traction force, lateral force, and slip ratio. Secondly, six equivalent coefficients are introduced to amend the rigid normal wheel model to fit for the wheels with deformable and mesh-pattern in LRV application. Thirdly, the values of the six equivalent coefficients are identified by using experimental data obtained in an LRV's single wheel testing. Finally, the identified mechanical model for LRV's wheel with deformable and mesh pattern are further verified and validated by using additional experimental results.

  6. Deformation mechanism of roadways in deep soft rock at Hegang Xing'an Coal Mine

    Institute of Scientific and Technical Information of China (English)

    Yang Xiaojie; Pang Jiewen; Liu Dongming; Liu Yang; Tian Yihong; Ma Jiao; Li Shaohua

    2013-01-01

    Engineering geomechanics characteristics of roadways in deep soft rock at Hegang Xing'an Coal Mine were studied and the nature of clay minerals of roadway surrounding rock was analyzed.This paper is to solve the technical problems of high stress and the difficulty in supporting the coal mine,and provide a rule for the support design.Results show that mechanical deformation mechanisms of deep soft rock roadway at Xing'an Coal Mine is of ⅠABⅡABcⅢABCD type,consisting of molecular water absorption (the ⅠAB-type),the tectonic stress type + gravity deformation type + hydraulic type (the ⅡABC-type),and the ⅢABCD-type with fault,weak intercalation and bedding formation.According to the compound mechanical deformation mechanisms,the corresponding mechanical control measures and conversion technologies were proposed,and these technologies have been successfully applied in roadway supporting practice in deep soft rock at Xing'an Coal Mine with good effect.Xing'an Coal Mine has the deepest burial depth in China,with its overburden ranging from Mesozoic Jurassic coal-forming to now.The results of the research can be used as guidance in the design of roadway support in soft rock.

  7. Perturbatively deformed defects in Pöschl-Teller-driven scenarios for quantum mechanics

    Science.gov (United States)

    Bernardini, Alex E.; da Rocha, Roldão

    2016-07-01

    Pöschl-Teller-driven solutions for quantum mechanical fluctuations are triggered off by single scalar field theories obtained through a systematic perturbative procedure for generating deformed defects. The analytical properties concerning the quantum fluctuations in one-dimension, zero-mode states, first- and second-excited states, and energy density profiles are all obtained from deformed topological and non-topological structures supported by real scalar fields. Results are firstly derived from an integrated λϕ4 theory, with corresponding generalizations applied to starting λχ4 and sine-Gordon theories. By focusing our calculations on structures supported by the λϕ4 theory, the outcome of our study suggests an exact quantitative correspondence to Pöschl-Teller-driven systems. Embedded into the perturbative quantum mechanics framework, such a correspondence turns into a helpful tool for computing excited states and continuous mode solutions, as well as their associated energy spectrum, for quantum fluctuations of perturbatively deformed structures. Perturbative deformations create distinct physical scenarios in the context of exactly solvable quantum systems and may also work as an analytical support for describing novel braneworld universes embedded into a 5-dimensional gravity bulk.

  8. Understanding deformation mechanisms during powder compaction using principal component analysis of compression data.

    Science.gov (United States)

    Roopwani, Rahul; Buckner, Ira S

    2011-10-14

    Principal component analysis (PCA) was applied to pharmaceutical powder compaction. A solid fraction parameter (SF(c/d)) and a mechanical work parameter (W(c/d)) representing irreversible compression behavior were determined as functions of applied load. Multivariate analysis of the compression data was carried out using PCA. The first principal component (PC1) showed loadings for the solid fraction and work values that agreed with changes in the relative significance of plastic deformation to consolidation at different pressures. The PC1 scores showed the same rank order as the relative plasticity ranking derived from the literature for common pharmaceutical materials. The utility of PC1 in understanding deformation was extended to binary mixtures using a subset of the original materials. Combinations of brittle and plastic materials were characterized using the PCA method. The relationships between PC1 scores and the weight fractions of the mixtures were typically linear showing ideal mixing in their deformation behaviors. The mixture consisting of two plastic materials was the only combination to show a consistent positive deviation from ideality. The application of PCA to solid fraction and mechanical work data appears to be an effective means of predicting deformation behavior during compaction of simple powder mixtures.

  9. Deformation mechanisms to ameliorate the mechanical properties of novel TRIP/TWIP Co-Cr-Mo-(Cu) ultrafine eutectic alloys.

    Science.gov (United States)

    Kim, J T; Hong, S H; Park, H J; Kim, Y S; Suh, J Y; Lee, J K; Park, J M; Maity, T; Eckert, J; Kim, K B

    2017-01-09

    In the present study, the microstructural evolution and the modulation of the mechanical properties have been investigated for a Co-Cr-Mo (CCM) ternary eutectic alloy by addition of a small amount of copper (0.5 and 1 at.%). The microstructural observations reveal a distinct dissimilarity in the eutectic structure such as a broken lamellar structure and a well-aligned lamellar structure and an increasing volume fraction of Co lamellae as increasing amount of copper addition. This microstructural evolution leads to improved plasticity from 1% to 10% without the typical tradeoff between the overall strength and compressive plasticity. Moreover, investigation of the fractured samples indicates that the CCMCu alloy exhibits higher plastic deformability and combinatorial mechanisms for improved plastic behavior. The improved plasticity of CCMCu alloys originates from several deformation mechanisms; i) slip, ii) deformation twinning, iii) strain-induced transformation and iv) shear banding. These results reveal that the mechanical properties of eutectic alloys in the Co-Cr-Mo system can be ameliorated by micro-alloying such as Cu addition.

  10. JERS-1 Synthetic Aperture Radar Interferometry Applications: Mapping of Rain Forest Environments and Crustal Deformation Studies

    Science.gov (United States)

    Rosen, P.; Hensley, S.; Peltzer, G.; Rignot, E.; Werner, C.

    1999-01-01

    This research using JERS-1 SAR data has been very fruitful, resulting in a strong collaboration with geodesists and geophysicists in Japan, and several important papers characterizing crustal deformation, and the capabilities and limitations of JERS data for these studies.

  11. Mechanisms of compressive deformation and failure of porous bulk metallic glasses

    Science.gov (United States)

    Gouripriya, S.; Tandaiya, Parag

    2017-06-01

    Bulk metallic glasses (BMGs) are a new class of engineering materials having strengths as high as 10 times that of conventional steels, but show no significant plastic strain at fracture. By introducing pores, their strain to failure has been shown to improve under uniaxial compression. In this work, three-dimensional finite element simulations of uniaxial compression are carried out on Pd-based porous BMGs having a wide range of pore volume fraction (1.9%-60%) with emphasis on understanding the underlying deformation and failure mechanisms. The resulting stress-strain curves agree reasonably well with existing experimental results. The simulations clearly bring out different failure mechanisms in low porosity BMGs and high porosity BMG foams. For low porosity BMGs (below 20%), the deformation and failure involves nucleation of shear bands around the pore diameter, linking of the shear bands with adjacent pores finally leading to initiation of ductile cracking within the shear bands. For high porosity BMG foams, the mechanism of deformation involves reduction in porosity of the material, self-contact of the pores, and their collapse on themselves causing densification of the material leading to apparent hardening in the stress strain behavior. The effect of pore geometry is also studied by considering ellipsoidal pores of volume fraction 3% and 11%. For ellipsoidal pores, the failure mechanisms are found to differ significantly when the orientation of the major axis of the pore vis-a-vis the loading axis is changed.

  12. A molecular mechanics approach for analyzing tensile nonlinear deformation behavior of single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Daining Fang; Ai Kah Soh; Bin Liu

    2007-01-01

    In this paper, by capturing the atomic informa-tion and reflecting the behaviour governed by the nonlin-ear potential function, an analytical molecular mechanics approach is proposed. A constitutive relation for single-walled carbon nanotubes (SWCNT's) is established to describe the nonlinear stress-strain curve of SWCNT's and to predict both the elastic properties and breaking strain of SWCNT's during tensile deformation. An analysis based on the virtual internal bond (VIB) model proposed by P. Zhang et al. is also presented for comparison. The results indicate that the proposed molecular mechanics approach is indeed an acceptable analytical method for analyzing the mechanical behavior of SWCNT's.

  13. Effects of Warm Deformation on Mechanical Properties of TRIP Aided Fe-C-Mn-Si Multiphase Steel

    Institute of Scientific and Technical Information of China (English)

    TIAN Yong; LI Zhuan~

    2012-01-01

    Warm deformation tests were performed using a kind of tubby heater. The microstructures and mechanical properties of an Fe-C-Mn-Si multiphase steel resulting from different warm deformation temperatures were investiga- ted by using LOM (light optical microscopy), SEM and XRD. The results indicated that the microstructure contai- ning polygonal ferrite, granular bainite and a significant amount of the stable retained austenite can be obtained through hot deformation and subsequent austempering. Warm deformation temperature affects the mechanical prop- erties of the hot rolled TRIP steels. Ultimate tensile strength balance reached maximum (881 MPa) when the speci- men was deformed at 250 ~C, and the total elongation and strength-ductility reached maximum (38% and 28 614 MPa ~ ~, respectively) at deforming temperature of 100 ~C. Martensite could nucleate when austenite was deformed above M~, because mechanical driving force compensates the decrease of chemical driving force. The TRIP effect occurs in the Fe-C-Mn-Si multiphase steel at deforming temperature ranging from 15 to 350 ~C. The results of the effects of warm deformation on the mechanical properties of the Fe-C-Mn-Si multiphase steel can provide theoretical basis for the ap- plications and the warm working of the hot rolled TRIP sheet steels in industrial manufacturing.

  14. A Case Study on the Strata Movement Mechanism and Surface Deformation Regulation in Chengchao Underground Iron Mine

    Science.gov (United States)

    Cheng, Guanwen; Chen, Congxin; Ma, Tianhui; Liu, Hongyuan; Tang, Chunan

    2017-04-01

    The regular pattern of surface deformation and the mechanism of underground strata movement, especially in iron mines constructed with the block caving method, have a great influence on infrastructure on the surface, so they are an important topic for research. Based on the engineering geology conditions and the surface deformation and fracture features in Chengchao Iron Mine, the mechanism of strata movement and the regular pattern of surface deformation in the footwall were studied by the geomechanical method, and the following conclusions can be drawn: I. The surface deformation process is divided into two stages over time, i.e., the chimney caving development stage and the post-chimney deformation stage. Currently, the surface deformation in Chengchao Iron Mine is at the post-chimney deformation stage. II. At the post-chimney deformation stage, the surface deformation and geological hazards in Chengchao Iron Mine are primarily controlled by the NWW-trending joints, with the phenomenon of toppling deformation and failure on the surface. Based on the surface deformation characteristics in Chengchao Iron Mine, the surface deformation area can be divided into the following four zones: the fracture extension zone, the fracture closure zone, the fracture formation zone and the deformation accumulation zone. The zones on the surface can be determined by the surface deformation characteristics. III. The cantilever beams near the chimney caving area, caused by the NWW-trending joints, have been subjected to toppling failure. This causes the different deformation and failure mechanisms in different locations of the deep rock mass. The deep rock can be divided into four zones, i.e., the fracture zone, fracture transition zone, deformation zone and undisturbed zone, according to the different deformation and failure mechanisms. The zones in the deep rock are the reason for the zones on the surface, so they can be determined by the zones on the surface. Through these

  15. A closure for Lagrangian velocity gradient evolution in turbulence using recent deformation mapping of initially Gaussian fields

    CERN Document Server

    Johnson, Perry L

    2016-01-01

    The statistics of the velocity gradient tensor in turbulent flows are of both theoretical and practical importance. The Lagrangian view provides a privileged perspective for studying the dynamics of turbulence in general, and of the velocity gradient tensor in particular. Stochastic models for the Lagrangian evolution of velocity gradients in isotropic turbulence, with closure models for the pressure Hesssian and viscous Laplacian, have been shown to reproduce important features such as non-Gaussian probability distributions, skewness and vorticity strain-rate alignments. The Recent Fluid Deformation (RFD) closure introduced the idea of mapping an isotropic Lagrangian pressure Hessian as upstream initial condition using the fluid deformation tensor. Recent work on a Gaussian fields closure, however, has shown that even Gaussian isotropic velocity fields contain significant anisotropy for the conditional pressure Hessian tensor due to the inherent velocity-pressure couplings, and that assuming an isotropic pre...

  16. Atomic force microscopic study of the structure of high-density polyethylene deformed in liquid medium by crazing mechanism.

    Science.gov (United States)

    Bagrov, D V; Yarysheva, A Y; Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2014-02-01

    A procedure has been developed for the direct atomic force microscopic (AFM) examination of the native structure of high-density polyethylene (HDPE) deformed in an adsorption-active liquid medium (AALM) by the crazing mechanism. The AFM investigation has been carried out in the presence of a liquid medium under conditions preventing deformed films from shrinkage. Deformation of HDPE in AALM has been shown to proceed through the delocalized crazing mechanism and result in the development of a fibrillar-porous structure. The structural parameters of the crazed polymer have been determined. The obtained AFM images demonstrate a nanosized nonuniformity of the deformation and enable one to observe the structural rearrangements that take place in the deformed polymer after removal of the liquid medium and stress relaxation. A structural similarity has been revealed between HDPE deformed in the AALM and hard elastic polymers.

  17. Perturbatively deformed defects in P\\"oschl-Teller-driven scenarios for quantum mechanics

    CERN Document Server

    Bernardini, Alex E

    2016-01-01

    P\\"oschl-Teller-driven solutions for quantum mechanical fluctuations are triggered off by single scalar field theories obtained through a systematic perturbative procedure for generating deformed defects. The analytical properties concerning the quantum fluctuations in one-dimension, zero-mode states, first- and second- excited states, and energy density profiles are all obtained from deformed topological and non-topological structures supported by real scalar fields. Results are firstly derived from an integrated $\\lambda \\phi^4$ theory, with corresponding generalizations applied to starting $\\lambda \\chi^4$ and {\\em sine}-Gordon theories. By focusing our calculations on structures supported by the $\\lambda\\phi^4$ theory, the outcome of our study suggests an exact quantitative correspondence to P\\"oschl-Teller-driven systems. Embedded into the perturbative quantum mechanics framework, such a correspondence turns into a helpful tool for computing excited states and continuous mode solutions, as well as their ...

  18. Thermo-mechanical modeling of dendrite deformation in continuous casting of steel

    OpenAIRE

    Domitner, Josef; Drezet, Jean-Marie; Wu, M.; Ludwig, Andreas

    2012-01-01

    In the field of modern steelmaking, continuous casting has become the major manufacturing process to handle a wide range of steel grades. An important criterion characterizing the quality of semi-finished cast products is the macrosegregation forming at the centre of these products during solidification. The deformation induced interdendritic melt flow has been identified as the key mechanism for the formation of centreline segregation. Bulging of the solidified strand shell causes deformatio...

  19. DEFORMATION WAVES AS A TRIGGER MECHANISM OF SEISMIC ACTIVITY IN SEISMIC ZONES OF THE CONTINENTAL LITHOSPHERE

    Directory of Open Access Journals (Sweden)

    S. I. Sherman

    2015-09-01

    Full Text Available Deformation waves as a trigger mechanism of seismic activity and migration of earthquake foci have been under discussion by researchers in seismology and geodynamics for over 50 years. Four sections of this article present available principal data on impacts of wave processes on seismicity and new data. The first section reviews analytical and experimental studies aimed at identification of relationships between wave processes in the lithosphere and seismic activity manifested as space-and-time migration of individual earthquake foci or clusters of earthquakes. It is concluded that with a systematic approach, instead of using a variety of terms to denote waves that trigger seismic process in the lithosphere, it is reasonable to apply the concise definition of ‘deformation waves’, which is most often used in fact.The second section contains a description of deformation waves considered as the trigger mechanism of seismic activity. It is concluded that a variety of methods are applied to identify deformation waves, and such methods are based on various research methods and concepts that naturally differ in sensitivity concerning detection of waves and/or impact of the waves on seismic process. Epicenters of strong earthquakes are grouped into specific linear or arc-shaped systems, which common criterion is the same time interval of the occurrence of events under analysis. On site the systems compose zones with similar time sequences, which correspond to the physical notion of moving waves (Fig. 9. Periods of manifestation of such waves are estimated as millions of years, and a direct consideration of the presence of waves and wave parameters is highly challenging. In the current state-of-the-art, geodynamics and seismology cannot provide any other solution yet.The third section presents a solution considering record of deformation waves in the lithosphere. With account of the fact that all the earthquakes with М≥3.0 are associated with

  20. High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

    Science.gov (United States)

    Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

    2017-04-01

    Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

  1. Deformation Mechanisms and Safe Drilling Fluids Density in Extremely Thick Salt Formations

    Institute of Scientific and Technical Information of China (English)

    Yang Henglin; Chen Mian; Zhang Guangqing

    2007-01-01

    Hydrocarbons are very often associated with salt structures. The oil and gas industry is often required to drill along and through long salt sections to reach and recover hydrocarbons. The unique physical properties of salt require special techniques to ensure borehole stability and adequate casing design. This paper assumed that the mechanical behavior of salt is regulated by the magnitude of mean stress and octahedral shear stress and under the influence of different stress conditions,the deformation of rock salt can be represented by three domains, i.e. compression domain, volume unchanged domain, and dilatancy domain, which are separated by a stress dependent boundary. In the compression domain, the volume of salt decreases until all microcracks are closed, with only elastic deformation and pure creep; in the volume unchanged domain the deformation is considered steady incompressible flow controlled by pure creep; and in the dilatancy domain the volume of salt increases during deformation due to micro-cracking, causing damage and accelerating "creep" until failure. This paper presents a hypothesis that the borehole is stable only when the magnitude of octahedral shear stress is below the dilatancy boundary. It gives the design method for determining drilling fluids density, and calculates the closure rate of borehole with the recommended drilling fluids density. If the closure rate of the borehole is less than 0.1%, the drilling fluids density window can be used during drilling through extremely thick salt formations.

  2. The role of dislocations in varied olivine deformation mechanisms investigated using high-angular resolution electron backscatter diffraction

    Science.gov (United States)

    Wallis, David; Hansen, Lars; Britton, Ben; Wilkinson, Angus

    2016-04-01

    Experimentally-derived flow laws can be used to predict the rheology of rocks deformed under natural conditions only if the same microphysical processes can be demonstrated to control the rate-limiting deformation mechanism in both cases. Olivine rheology may exert a principle control on the strength of the lithosphere, and therefore considerable research effort has been applied to assessing its rheology through experimental, geological, and geophysical approaches. Nonetheless, considerable uncertainty remains regarding the dominant deformation mechanisms in the upper mantle. This uncertainty arises in large part due to our limited understanding of the fundamental deformation processes associated with each mechanism. Future improvements to microphysical models of distinct deformation mechanisms require new insight into the contributions those fundamental processes to the macroscopic behaviour. The dynamics of dislocations is central to modelling viscous deformation of olivine, but characterisation techniques capable of constraining dislocation types, densities, and distributions over the critical grain to polycrystal length-scales have been lacking. High angular resolution electron backscatter diffraction (HR-EBSD), developed and increasingly applied in the material sciences, offers an approach capable of such analyses. HR-EBSD utilises diffraction pattern image cross-correlation to achieve dramatically improved angular resolution (~0.01°) of lattice orientation gradients compared to conventional Hough-based EBSD (~0.5°). This angular resolution allows very low densities (≥ 10^11 m^-2) of geometrically necessary dislocations (GND) to be resolved, facilitating analysis of a wide range of dislocation microstructures. We have developed the application of HR-EBSD to olivine and applied it to samples deformed both experimentally and naturally in grain-size sensitive and grain-size insensitive regimes. The results quantitatively highlight variations in the types and

  3. Implications of mechanical deformation and formaldehyde preservation for the identification of stage-specific characteristics of Baltic cod eggs

    DEFF Research Database (Denmark)

    Geldmacher, A.; Wieland, Kai

    1999-01-01

    The identification of developmental stages in fish eggs from plankton samples is often complicated by deformation of the embryos due to mechanical stress during the sampling procedure and by dehydration during formaldehyde fixation. The effects of formaldehyde fixation and mechanical stress on Ba...... mechanically deformed during handling were clearly distinguishable from those that died prior to catching; however, staging was generally less accurate for formaldehyde- preserved eggs when compared with living specimens....

  4. Deformation mechanisms and resealing of damage zones in experimentally deformed cemented and un-cemented clay-rich geomaterials, at low bulk strain

    Science.gov (United States)

    Desbois, Guillaume; Urai, Janos L.; Schuck, Bernhardt; Hoehne, Nadine; Oelker, Anne; Bésuelle, Pierre; Viggiani, Gioacchino; Schmatz, Joyce; Klaver, Jop

    2017-04-01

    A microphysics-based understanding of mechanical and fluid flow properties in clay-rich geomaterials is required for extrapolating better constitutive equations beyond the laboratory's time scales, so that predictions over the long term can be made less uncertain. In this contribution, we present microstructural investigations of rocks specimens sheared in triaxial compression at low bulk strain, by using the combination of broad-ion-beam (BIB) milling and scanning electron microscopy (SEM) to infer deformation mechanisms based on microstructures imaged at sub-micron resolution. Two end-member clay-rich geomaterials from European Underground Laboratories (URL) were analysed: (i) the poorly cemented Boom Clay sediment (BC from URL at Mol/Dessel, Belgium; confining pressure [CP] = 0.375 & 1.5 MPa) and (ii) the Callovo-Oxfordian claystone (COx from the URL at Bure, France; CP = 2 & 10 MPa). Although as a first approximation the inelastic bahvior of cemented and uncemented clay-rich geomaterials can be described by similar pressure-dependent hardening plasticity models, deformed samples in this contribution show very contrasting micro-scale behaviour: microstructures reveal brittle-ductile transitional behaviour in BC, whereas deformation in COx is dominantly cataclastic. In Boom Clay, at meso-scale, shear bands exhibit characteristics that are typical of uncemented small-grained clay-rich materials deformed at high shear strains, consisting of anastomosing shears interpreted as Y- and B-shears, which bound the passively deformed microlithons. At micro- down to nano-scale, the strong shape preferential orientation of clay aggregates in the anastomosing shears is interpreted to be responsible of the shear weakness. More over, the reworking of clay aggregates during deformation contributes to the collapsing of porosity in the shear band. Ductile deformation mechanisms represented by grain-rotation, grain-sliding, bending and granular flow mechanisms are strongly involved

  5. FROM CRYSTALLINE BLOCK SLIPS TO DOMINANCE OF NETWORK STRETCHING——MECHANISMS OF TENSILE DEFORMATION IN SEMI-CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    Y. Men; G. Strobl

    2002-01-01

    The mechanism of tensile deformation in semi-crystalline polymers was studied based on true stress-strain curves obtained with the aid of a video-controlled tensile set-up. The deformation is affected by both the crystalline and the amorphous phases. However, the relative weights of the two portions change with the deformation stage. At low deformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows the system to maintain a homogeneous strain distribution in the sample. As the stretching increases, at a critical strain the force generated from entangled fluid portions reaches a critical value to destroy the crystallites. The dominant deformation mechanism then changes into a disaggregation - recrystallization process.

  6. Atomistic tensile deformation mechanisms of Fe with gradient nano-grained structure

    Directory of Open Access Journals (Sweden)

    Wenbin Li

    2015-08-01

    Full Text Available Large-scale molecular dynamics (MD simulations have been performed to investigate the tensile properties and the related atomistic deformation mechanisms of the gradient nano-grained (GNG structure of bcc Fe (gradient grains with d from 25 nm to 105 nm, and comparisons were made with the uniform nano-grained (NG structure of bcc Fe (grains with d = 25 nm. The grain size gradient in the nano-scale converts the applied uniaxial stress to multi-axial stresses and promotes the dislocation behaviors in the GNG structure, which results in extra hardening and flow strength. Thus, the GNG structure shows slightly higher flow stress at the early plastic deformation stage when compared to the uniform NG structure (even with smaller grain size. In the GNG structure, the dominant deformation mechanisms are closely related to the grain sizes. For grains with d = 25 nm, the deformation mechanisms are dominated by GB migration, grain rotation and grain coalescence although a few dislocations are observed. For grains with d = 54 nm, dislocation nucleation, propagation and formation of dislocation wall near GBs are observed. Moreover, formation of dislocation wall and dislocation pile-up near GBs are observed for grains with d = 105 nm, which is the first observation by MD simulations to our best knowledge. The strain compatibility among different layers with various grain sizes in the GNG structure should promote the dislocation behaviors and the flow stress of the whole structure, and the present results should provide insights to design the microstructures for developing strong-and-ductile metals.

  7. Molecular Dynamics Simulation of Nanoindentation-induced Mechanical Deformation and Phase Transformation in Monocrystalline Silicon

    Directory of Open Access Journals (Sweden)

    Jian Sheng-Rui

    2008-01-01

    Full Text Available AbstractThis work presents the molecular dynamics approach toward mechanical deformation and phase transformation mechanisms of monocrystalline Si(100 subjected to nanoindentation. We demonstrate phase distributions during loading and unloading stages of both spherical and Berkovich nanoindentations. By searching the presence of the fifth neighboring atom within a non-bonding length, Si-III and Si-XII have been successfully distinguished from Si-I. Crystallinity of this mixed-phase was further identified by radial distribution functions.

  8. Time scales and mechanisms of relaxation in the energy landscape of polymer glass under deformation: direct atomistic modeling.

    Science.gov (United States)

    Lyulin, Alexey V; Michels, M A J

    2007-08-24

    Molecular-dynamics simulation is used to explore the influence of thermal and mechanical history of typical glassy polymers on their deformation. Polymer stress-strain and energy-strain developments have been followed for different deformation velocities, also in closed extension-recompression loops. The latter simulate for the first time the experimentally observed mechanical rejuvenation and overaging of polymers, and energy partitioning reveals essential differences between mechanical and thermal rejuvenation. All results can be qualitatively interpreted by considering the ratios of the relevant time scales: for cooling down, for deformation, and for segmental relaxation.

  9. Main Structural Styles and Deformation Mechanisms in the Northern Sichuan Basin, Southern China

    Institute of Scientific and Technical Information of China (English)

    TANG Liangjie; GUO Tonglou; JIN Wenzheng; YU Yixin; LI Rufeng

    2008-01-01

    The Triassic Jialingjiang Formation and Leikoupo Formation are characterized by thick salt layers. Three tectono-stratigraphic sequences can be identified according to detachment layers of Lower-Middle Triassic salt beds in the northern Sichuan Basin, i.e. the sub-salt sequence composed of Sinian to the Lower Triassic Feixianguan Formation, the salt sequence of the Lower Triassic Jialingjiang Formation and Mid-Triassic Leikoupou Formation, and the supra-salt sequence composed of continental clastics of the Upper-Triassic Xujiahe Formation, Jurassic and Cretaceous. A series of specific structural styles, such as intensively deformed belt of basement-involved imbricated thrust belt, basement-involved and salt-detached superimposed deformed belt, buried salt-related detached belt, duplex, piling triangle zone and pop-up, developed in the northern Sichuan Basin. The relatively thin salt beds, associated with the structural deformation of the northern Sichuan Basin, might act as a large decollement layer. The deformation mechanisms in the northern Sichuan Basin included regional compression and shortening, plastic flow and detachment, tectonic upwelling and erosion, gravitational sliding and spreading. The source rocks in the northern Sichuan Basin are strata underlying the salt layer, such as the Cambrian, Silurian and Permian. The structural deformation related to the Triassic salt controlled the styles of traps for hydrocarbon. The formation and development of hydrocarbon traps in the northern Sichuan Basin might have a bearing upon the Lower-Middle Triassic salt sequences which were favorable to the hydrocarbon accumulation and preservation. The salt layers in the Lower-Middle Triassic formed the main cap rocks and are favorable for the accumulation and preservation of hydrocarbon.

  10. Contribution of deformation mechanisms to strength and ductility in two Cr-Mn grade austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, A.S., E-mail: atef_saleh@s-petrol.suez.edu.eg [Materials Engineering Laboratory, Box 4200, University of Oulu, 90014 Oulu (Finland); Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez Canal University, Box 43721, Suez (Egypt); Karjalainen, L.P. [Materials Engineering Laboratory, Box 4200, University of Oulu, 90014 Oulu (Finland); Misra, R.D.K. [Center for Structural and Functional Materials and Chemical Engineering Department, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130, USA. (United States); Talonen, J. [Outokumpu Oyj, Box 140, FI-02201 Espoo (Finland)

    2013-01-01

    The role of different deformation mechanisms in controlling mechanical properties were studied in two low-Ni, Cr-Mn austenitic stainless steel grades (Types 201 and 201L) by tensile testing and microstructure examinations. Tensile tests were carried out at two different strain rates, 5 Multiplication-Sign 10{sup -4} and 10{sup -2} s{sup -1}, in the temperature range from -80 Degree-Sign C to 200 Degree-Sign C. It was observed that the flow properties and work hardening rate are affected significantly by temperature and strain rate for the concerned steels through variation of deformation mechanism. Deformation-induced austenite-to-martensite transformation (TRIP effect) is the dominant mechanism at temperatures below room temperature. From 50 Degree-Sign C up to 200 Degree-Sign C, plastic deformation is controlled by mechanical twinning (TWIP effect) and dislocation glide. The electron backscattered diffraction (EBSD) technique and transmission electron microscopy (TEM) were employed to study the plastic deformation accommodation and identify the primary deformation mechanisms operating in the deformed steels.

  11. Plastic deformation mechanism of polycrystalline copper foil shocked with femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Y.X., E-mail: yeyunxia@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Feng, Y.Y.; Lian, Z.C.; Hua, Y.Q. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China)

    2014-08-01

    Plastic deformation mechanism of polycrystalline copper foil shocked with femtosecond (fs) laser has been characterized through optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Experiments of ns laser shocking copper (Cu) and fs laser shocking aluminum (Al) were also conducted for comparison. Dislocations arranged in multiple forms, profuse twins and stacking faults (SFs) coexist in the fs laser shocked copper. At small strain condition, dislocation slip is the dominant deformation mode and small amount of SFs act as complementary mechanism. With strain increasing, profuse twins and SFs form to accommodate the plastic deformation. Furthermore, new formed SFs incline to locate around the old ones because the dislocation densities there are more higher. So there is a high probability for new SFs overlapping on old ones to form twins, or connecting old ones to lengthen them, which eventually produce the phenomena that twins connect with each other or twins connect with SFs. Strain greatly influences the dislocation density. Twins and SFs are more dependent on strain rate and shock pressure. Medium stacking fault energy (SFE) of copper helps to extend partial dislocations and provides sources for forming SFs and twins.

  12. Failure and deformation mechanisms at macro- and nano-scales of alkali activated clay

    Science.gov (United States)

    Sekhar Das, Pradip; Bhattacharya, Manjima; Chanda, Dipak Kr; Dalui, Srikanta; Acharya, Saikat; Ghosh, Swapankumar; Mukhopadhyay, Anoop Kumar

    2016-06-01

    Here we report two qualitative models on failure and deformation mechanisms at macro- and nano-scales of alkali activated clay (AACL), a material of extraordinary importance as a low cost building material. The models were based on experimental data of compressive failure and nanoindentation response of the AACL materials. A 420% improvement in compressive strength (σ c) of the AACL was achieved after 28 days (d) of curing at room temperature and it correlated well with the decrements in the residual alkali and pH concentrations with the increase in curing time. Based on extensive post-mortem FE-SEM examinations, a schematic model for the compressive failure mechanism of AACL was proposed. In addition, the nanoindentation results of AACL provided the first ever experimental evidence of the presence of nano-scale plasticity and a nano-scale contact deformation resistance that increased with the applied load. These results meant the development of a unique strain tolerant microstructure in the AACL of Indian origin. The implications of these new observations were discussed in terms of a qualitative model based on the deformation of layered clay structure.

  13. Quantifying and observing viscoplasticity at the nanoscale: highly localized deformation mechanisms in ultrathin nanocrystalline gold films.

    Science.gov (United States)

    Hosseinian, Ehsan; Legros, Marc; Pierron, Olivier N

    2016-04-28

    This study unveils the stress relaxation transient deformation mechanisms in 100 nm-thick, nanocrystalline Au films thanks to a robust quantitative in situ TEM MEMS nanomechanical testing approach to quantify stress relaxation and to perform in situ observations of time-dependent deformation in ultrathin nanocrystalline films. The relaxation is characterized by a decrease in plastic strain rate of more than one order of magnitude over the first ∼30 minutes (from 10(-4) to less than 10(-5) s(-1)). For longer relaxation experiments, the plastic strain rate decreases down to 10(-7) s(-1) after several hours. The power-law exponent n, relating plastic strain rate and stress, continuously decreases from initial large values (n from 6 to 14 at t = 0) down to low values (n ∼ 1-2) after several hours. In situ TEM observations reveal that the relaxation behavior is initially accommodated by highly localized, sustained, intergranular and transgranular dislocation motion. Over time, the dislocation sources become less operative or exhausted, leading to a transition to grain-boundary-diffusion based mechanisms. The results also highlight a promising technique for nanoscale characterization of time-dependent deformation.

  14. Chromium vaporization from mechanically deformed pre-coated interconnects in Solid Oxide Fuel Cells

    Science.gov (United States)

    Falk-Windisch, Hannes; Sattari, Mohammad; Svensson, Jan-Erik; Froitzheim, Jan

    2015-11-01

    Cathode poisoning, associated with Cr evaporation from interconnect material, is one of the most important degradation mechanisms in Solid Oxide Fuel Cells when Cr2O3-forming steels are used as the interconnect material. Coating these steels with a thin Co layer has proven to decrease Cr vaporization. To reduce production costs, it is suggested that thin metallic PVD coatings be applied to each steel strip before pressing the material into interconnect shape. This process would enable high volume production without the need for an extra post-coating step. However, when the pre-coated material is mechanically deformed, cracks may form and lower the quality of the coating. In the present study, Chromium volatilization is measured in an air-3% H2O environment at 850 °C for 336 h. Three materials coated with 600 nm Co are investigated and compared to an uncoated material. The effect of deformation is investigated on real interconnects. Microscopy observations reveal the presence of cracks in the order of several μm on the deformed pre-coated steel. However, upon exposure, the cracks can heal and form a continuous surface oxide rich in Co and Mn. As an effect of the rapid healing, no increase in Cr vaporization is measured for the pre-coated material.

  15. Deformation mechanism of kink-step distorted coherent twin boundaries in copper nanowire

    Directory of Open Access Journals (Sweden)

    Bobin Xing

    2017-01-01

    Full Text Available In the construction of nanotwinned (NT copper, inherent kink-like steps are formed on growth twin boundaries (TBs. Such imperfections in TBs play a crucial role in the yielding mechanism and plastic deformation of NT copper. Here, we used the molecular dynamic (MD method to examine the influence of kink-step characteristics in depth, including kink density and kink-step height, on mechanical behavior of copper nanowire (NW in uniaxial tension. The results showed that the kink-step, a stress-concentrated region, is preferential in nucleating and emitting stress-induced partial dislocations. Mixed dislocation of hard mode I and II and hard mode II dislocation were nucleated from kink-step and surface atoms, respectively. Kink-step height and kink density substantially affected the yielding mechanism and plastic behavior, with the yielding stress functional-related to kink-step height. However, intense kink density (1 kink per 4.4 nm encourages dislocation nucleation at kink-steps without any significant decline in tensile stress. Defective nanowires with low kink-step height or high kink density offered minimal resistance to kink migration, which has been identified as one of the primary mechanisms of plastic deformation. Defective NWs with refined TB spacing were also studied. A strain-hardening effect due to the refined TB spacing and dislocation pinning was observed for defective NWs. This study has implications for designing NT copper to obtain optimum mechanical performance.

  16. Stochastic mapping of the Michaelis-Menten mechanism.

    Science.gov (United States)

    Dóka, Éva; Lente, Gábor

    2012-02-07

    The Michaelis-Menten mechanism is an extremely important tool for understanding enzyme-catalyzed transformation of substrates into final products. In this work, a computationally viable, full stochastic description of the Michaelis-Menten kinetic scheme is introduced based on a stochastic equivalent of the steady-state assumption. The full solution derived is free of restrictions on amounts of substance or parameter values and is used to create stochastic maps of the Michaelis-Menten mechanism, which show the regions in the parameter space of the scheme where the use of the stochastic kinetic approach is inevitable. The stochastic aspects of recently published examples of single-enzyme kinetic studies are analyzed using these maps.

  17. Topographically induced self-deformation of the nuclei of cells: dependence on cell type and proposed mechanisms.

    Science.gov (United States)

    Davidson, Patricia M; Fromigué, Olivia; Marie, Pierre J; Hasirci, Vasif; Reiter, Günter; Anselme, Karine

    2010-03-01

    Osteosarcoma-derived cell lines (SaOs-2, MG63) have recently been shown to deform their nucleus considerably in response to surface topography. Such a deformation had not been described previously. Here we present results on additional cell lines, including cancerous (OHS4, U2OS), immortalized (F/STRO-1(+)A and FHSO6) and healthy cells (HOP). The cancerous cells were found to deform extensively, the immortalized cells showed small deformations, whereas the healthy cells showed deformation only at short incubation times. These results suggest a strong link between the malignant transformation of cells and the state of the cytoskeletal network. We propose mechanisms to explain the deformation in which the cytoskeleton either pushes down on the nucleus during spreading or pulls it down upon adhesion to the pillars.

  18. Mechanisms of plastic deformation in AZ31 magnesium alloy investigated by acoustic emission and transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Janecek, Milos [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, CZ-121 16 Prague 2 (Czech Republic)], E-mail: janecek@met.mff.cuni.cz; Kral, Robert [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, CZ-121 16 Prague 2 (Czech Republic); Dobron, Patrik [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, CZ-121 16 Prague 2 (Czech Republic); Chmelik, Frantisek [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, CZ-121 16 Prague 2 (Czech Republic); Supik, Vladimir [Department of Physical Metallurgy and Materials Technology, Technical University of Brandenburg at Cottbus, D-03010 Cottbus (Germany); Hollaender, Frank [Department of Physical Metallurgy and Materials Technology, Technical University of Brandenburg at Cottbus, D-03010 Cottbus (Germany)

    2007-07-25

    The effect of deformation conditions on plastic deformation and acoustic emission (AE) in hot-rolled magnesium alloy AZ31 has been investigated in the temperature range of 20-200 deg. C by constant strain rate tensile tests. Two sets of samples differing in the preheating temperature before individual passes of hot rolling have been studied. Both the yield stress and the tensile strength decrease with increasing temperature of deformation. The ductility was found to increase significantly with increasing temperature of deformation in both specimens. Unstable plastic deformation (Portevin-Le Chatelier effect) has been observed for all used strain rates both at room and elevated temperatures. Plastic instabilities were accompanied by a pronounced AE activity. The AE bursts were correlated with the individual regions of plastic instabilities on the deformation curve. Mechanisms controlling plastic instabilities are suggested respecting the microstructure evolution as observed by optical and transmission electron microscopy.

  19. Effect of pre-deformation on aging characteristics and mechanical properties of Mg-Gd-Nd-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of plastic deformation prior to artificial aging on the aging characteristics and mechanical properties of a Mg-11Gd-2Nd-0.5Zr (mass fraction,%) alloy was investigated. After solution treatment at 525 ℃ for 4 h, the alloy was subjected to cold stretching deformation of 0%, 5% and 10%, respectively. The as-deformed specimens possess high density of dislocations and mechanical twins, which increase with elevated deformation. As compared with non-stretched alloy, the stretched alloy shows accelerated age-hardening response and slightly enhanced peak hardness when aged at 200 ℃. Comparison of the microstructures in undeformed and deformed specimens after 200 ℃, 24 h aging reveals that pre-deformation induces the heterogeneous nucleation of precipitations at dislocations and twin boundaries in addition to the homogeneous precipitation in the matrix. Room and high temperature tensile test results show that pre-deformation enhances the strength of the alloy, especially at room temperature, though the ductility declines. The improvement in strength of deformed and aged alloy is attributed to the combined strengthening effect of precipitates, deformation structures and grain boundaries.

  20. Deformation Mechanism of Zr702 Processed by Equal Channel Angular Pressing

    Science.gov (United States)

    Cao, W. Q.; Yu, S. H.; Chun, Y. B.; Shin, D. H.; Hwang, S. K.

    2007-11-01

    Commercial purity zirconium (Zr702) was deformed by equal channel angular (ECA) pressing up to eight passes, and the resulting microstructure and texture were studied by electron backscattered diffraction, transmission electron microscopy (TEM), and X-ray diffraction. The most prominent feature of the substructure was the dislocation cell blocks (CBs), indicating that the dislocation slip rather than twinning was the main mechanism of deformation. With two passes of ECA pressing, pancake-shape grains of 0.25 μm in thickness were obtained. The grain refinement achieved by the ECA pressing was attributed to the evolution of low-angle geometrically necessary boundaries (GNBs) into high-angle grain boundaries (HAGBs) during accumulation of strain by repeated pressing. The texture characteristics were such that a shear texture was predominant in the single-pass specimen, whereas a high-strain rolling texture became apparent in the specimens repeatedly pressed.

  1. Second Hopf map and supersymmetric mechanics with Yang monopole

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, M.; Toppan, F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Kuznetsova, Z. [Universidade Federal do ABC, Santo Andre, SP (Brazil); Nersessian, F. [Artsakh State University, Stepanakert (Armenia); Yeghikyan, V. [Yerevan State University (Armenia)

    2009-07-01

    We propose to use the second Hopf map for the reduction (via SU(2) group action) of the eight-dimensional supersymmetric mechanics to five-dimensional supersymmetric systems specified by the presence of an SU(2) Yang monopole. For our purpose we develop the relevant Lagrangian reduction procedure. The reduced system is characterized by its invariance under the N = 5 or N = 4 supersymmetry generators (with or without an additional conserved BRST charge operator) which commute with the su(2) generators. (author)

  2. Computational sensitivity analysis to identify muscles that can mechanically contribute to shoulder deformity following brachial plexus birth palsy.

    Science.gov (United States)

    Crouch, Dustin L; Plate, Johannes F; Li, Zhongyu; Saul, Katherine R

    2014-02-01

    Two mechanisms, strength imbalance or impaired longitudinal muscle growth, potentially cause osseous and postural shoulder deformity in children with brachial plexus birth palsy. Our objective was to determine which muscles, via either deformity mechanism, were mechanically capable of producing forces that could promote shoulder deformity. In an upper limb computational musculoskeletal model, we simulated strength imbalance by allowing each muscle crossing the shoulder to produce 30% of its maximum force. To simulate impaired longitudinal muscle growth, the functional length of each muscle crossing the shoulder was reduced by 30%. We performed a sensitivity analysis to identify muscles that, through either simulated deformity mechanism, increased the posteriorly directed, compressive glenohumeral joint force consistent with osseous deformity or reduced the shoulder external rotation or abduction range of motion consistent with postural deformity. Most of the increase in the posterior glenohumeral joint force by the strength imbalance mechanism was caused by the subscapularis, latissimus dorsi, and infraspinatus. Posterior glenohumeral joint force increased the most owing to impaired growth of the infraspinatus, subscapularis, and long head of biceps. Through the strength imbalance mechanism, the subscapularis, anterior deltoid, and pectoralis major muscles reduced external shoulder rotation by 28°, 17°, and 10°, respectively. Shoulder motion was reduced by 40° to 56° owing to impaired growth of the anterior deltoid, subscapularis, and long head of triceps. The infraspinatus, subscapularis, latissimus dorsi, long head of biceps, anterior deltoid, pectoralis major, and long head of triceps were identified in this computational study as being the most capable of producing shoulder forces that may contribute to shoulder deformity following brachial plexus birth palsy. The muscles mechanically capable of producing deforming shoulder forces should be the focus of

  3. Research on the evolution model and deformation mechanisms of Baishuihe landslide based on analyzing geologic process of slope

    Science.gov (United States)

    Zhang, S.; Tang, H.; Cai, Y.; Tan, Q.

    2016-12-01

    The landslide is a result of both inner and exterior geologic agents, and inner ones always have significant influences on the susceptibility of geologic bodies to the exterior ones. However, current researches focus more on impacts of exterior factors, such as precipitation and reservoir water, than that of geologic process. Baishuihe landslide, located on the south bank of Yangtze River and 56km upstream from the Three Gorges Project, was taken as the study subject with the in-situ investigation and exploration carried out for the first step. After the spatial analysis using the 3D model of topography built by ArcGIS (Fig.1), geologic characteristics of the slope that lies in a certain range near the Baishuihe landslide on the same bank were investigated for further insights into geologic process of the slope, with help of the geological map and structure outline map. Baishuihe landslide developed on the north limb of Baifuping anticline, a dip slope on the southwest margin of Zigui basin. The eastern and western boundaries are both ridges and in the middle a distinct slide depression is in process of deforming. Evolutionary process of Baishuihe landslide includes three steps below. 1) Emergence of Baifuping anticline leaded to interbedded dislocation, tension cracks and joint fractures in bedrocks. 2) Weathering continuously weakened strength of soft interlayers in the Shazhenxi Formation (T3s). 3) Rock slide caused by neotectonics happened on a large scale along the weak layers and joint planes, forming initial Baishuihe landslide. Although the landslide has undergone reconstruction for a long time, it could still be divided clearly into two parts, namely a) the rock landslide at the back half (south) and b) the debris landslide at the front half (north). a) The deformation mechanism for the rock landslide is believed to be deterioration in strength of weak bedding planes due to precipitation and free face caused by human activities or river incision. b

  4. Monitoring microstructural evolution in-situ during cyclic deformation by high resolution reciprocal space mapping

    DEFF Research Database (Denmark)

    Diederichs, Annika Martina; Thiel, Felix; Fischer, Torben

    2017-01-01

    is gained by in-situ monitoring of the microstructural evolution during cyclic deformation. By HRRSM, a large number of individual subgrains can be resolved within individual grains in the bulk of polycrystalline specimens and their fate, their individual orientation and elastic stresses, tracked during...... different loading regimes as tension and compression. With this technique, the evolution of dislocation structures in selected grains was followed during an individual load cycle....

  5. Thermal activation approaches to deformation mechanisms for high Nb containing TiAl base alloys

    Institute of Scientific and Technical Information of China (English)

    刘自成; 王艳丽; 林均品; 张卫军; 陈国良

    2002-01-01

    The deformation mechanisms in a wide temperature range from room temperature to 1200K were investigated by thermal activation approach. Using observed instantaneous stress response to the strain rate jump (Δσtr), the activation volume Va, then the activation enthalpy ΔH, activation free enthalpy ΔG and activation entropy ΔS were calculated. The apparent activation energy of high temperature deformation is estimated to be 3.66eV, which is larger than the self-diffusion coefficient of binary TiAl (3.01eV). The dislocations at 1173K are generally curved or bowed, even helical-shaped dislocations. The climb of ordinary dislocations as well as twinning has greatly contributed to the plastic deformation. The CRSS at 1173K is estimated to be 180MPa. The higher resisting stress at both room temperature and elevated temperature might relate to the high Nb content of the alloy.

  6. Mechanics of leukocyte deformation and adhesion to endothelium in shear flow.

    Science.gov (United States)

    Dong, C; Cao, J; Struble, E J; Lipowsky, H H

    1999-01-01

    The mechanics of leukocyte [white blood cell (WBC)] deformation and adhesion to endothelial cells (EC) in shear flow has been investigated. Experimental data on transient WBC-EC adhesion were obtained from in vivo measurements. Microscopic images of WBC-EC contact during incipient WBC rolling revealed that for a given wall shear stress, the contact area increases with time as new bonds are formed at the leading edge, and then decreases with time as the trailing edge of the WBC membrane peels away from the EC. A two-dimensional model (2D) was developed consisting of an elastic ring adhered to a surface under fluid stresses. This ring represents an actin-rich WBC cortical layer and contains an incompressible fluid as the cell interior. All molecular bonds are modeled as elastic springs distributed in the WBC-EC contact region. Variations of the proportionality between wall shear stress (tau(w)) in the vicinity of the WBC and the resulting drag force (F(s)), i.e., F(s)/tau(w), reveal its decrease with WBC deformation and increasing vessel channel height (2D). The computations also find that the peeling zone between adherent WBC and EC may account for less than 5% of the total contact interface. Computational studies describe the WBC-EC adhesion and the extent of WBC deformation during the adhesive process.

  7. Crumpling deformation regimes of monolayer graphene on substrate: a molecular mechanics study.

    Science.gov (United States)

    Al-Mulla, Talal; Qin, Zhao; Buehler, Markus J

    2015-09-04

    Experiments and simulations demonstrating reversible and repeatable crumpling of graphene warrant a detailed understanding of the underlying mechanisms of graphene crumple formation, especially for design of tailored nanostructures. To systematically study the formation of crumples in graphene, we use a simple molecular dynamics model, and perform a series of simulations to characterize the finite number of deformation regimes of graphene on substrate after compression. We formulate a quantitative measure of predicting these deformations based on observed results of the simulations and distinguish graphene crumpling considered in this study from others. In our study, graphene is placed on a model substrate while controlling and varying the interfacial energy between graphene and substrate and the substrate roughness through a set of particles embedded in the substrate. We find that a critical value of interfacial adhesion energy marks a transition point that separates two deformation regimes of graphene on substrate under uniaxial compression. The interface between graphene and substrate plays a major role in the formation of crumples, and we show that the choice of substrate can help in designing desired topologies in graphene.

  8. Influence of the deformation mechanism on the anisotropy of the mechanical properties and workability of magnesium alloys

    Science.gov (United States)

    Betsofen, S. Ya.; Il'in, A. A.; Ashmarin, A. A.; Shaforostov, A. A.

    2008-06-01

    An experimental calculation method for the estimation of anisotropy is developed for semifinished sheet and pressed products made from magnesium alloys. The method makes it possible to calculate the anisotropy parameters from quantitative data on the texture and the relative values of the reduced critical shear stresses for the slip and twinning mechanisms operating in these alloys. The optimal alloying of magnesium alloys is shown to provide two methods for enhancing the deep drawing characteristics, namely, decreasing the intensity of the basal texture due to the formation of dispersed intermetallic compounds and increasing the compressive-strain resistance compared to tension due to a change in the deformation mechanism. Yttrium and neodymium are found to be most efficient in this respect, because they favor such a deformation mechanism that increases the Lankford coefficient by two to four times at the same texture in sheets. In addition, neodymium alloying weakens the intensity of the basal texture, which also favors an increase in the Lankford coefficient.

  9. Modification of ovalbumin with fructooligosaccharides: consequences for network morphology and mechanical deformation responses.

    Science.gov (United States)

    Munialo, Claire D; Ortega, Rodrigo G; van der Linden, Erik; de Jongh, Harmen H J

    2014-11-25

    The Maillardation of proteins has been used as a natural alternative to improve its functionality by covalent coupling of proteins with saccharides. However, the impact of Maillard reaction on the structural aspects of protein networks and, as a consequence, the mechanical breakdown properties of the gel networks has not been reported. The objective of this study was to evaluate how the attachment of linear oligo-sugar moieties onto ovalbumin affects its aggregation, network morphology, and consequently the mechanical deformation properties including the ability of the networks to elastically store energy in this material. To potentially alter the morphology of the network structure, ovalbumin was modified by conjugating some of its amino groups with fructooligosaccharide (FOS) moieties via the Maillard reaction. It was demonstrated that the attachment of FOS to ovalbumin does not affect the integrity of the secondary and tertiary structure as characterized using circular dichroism and tryptophan fluorescence. Differences in the network morphology were observed by scanning electron microscopy for FOS-modified ovalbumin variants. Upon increased modification, the microstructure of the gels had more and larger pores and had thinner strands than nonmodified variants. Evaluation of the large deformation properties of the gels demonstrated that FOS-modified gels were less strong and less brittle and showed lower stiffness than nonmodified variants. The recoverable energy (elastically stored energy) of gels reduced with an increase in the degree of modification. The results show that the attachment of FOS to ovalbumin alters the structural and mechanical (large) breakdown properties of the protein gels. The consequences of the alteration of the network structure and large deformation properties of FOS-modified ovalbumin offer opportunities to efficiently design food materials with desirable techno-functional applications.

  10. Postseismic deformation after Maule earthquake and the mechanical properties of the asthenosphere and subduction interface

    Science.gov (United States)

    Klein, Emilie; Fleitout, Luce; Vigny, Christophe

    2015-04-01

    The interseismic and postseismic deformations preceding and following the large subduction earthquake of Maule (Chile, Mw8.8, 2010) have been closely monitored with GPS from 70 km up to 2000 km away from the trench. Post-seismic deformations exhibit a behavior generally similar to that already observed after the Aceh and Tohoku-Oki earthquakes: vertical uplift is observed on the oceanward side of the volcanic arc. A moderate large scale subsidence is associated with sizeable horizontal deformation in the far-field (500-2000km from the trench). In addition, near-field data (70-200km from the trench) feature a rather complex deformation pattern. A 3D FE code (Zebulon Zset) is used to relate these deformations to the mechanical properties of the mantle and of the subduction interface. The mesh features a spherical shell-portion from the core-mantle boundary to the Earth's surface, extending over more than 60 degrees in latitude and longitude. The overridding and subducting plates are elastic, and the asthenosphere is viscoelastic. We test the presence and shape of two low viscosity areas in the mantle : a low viscosity wedge (LVW) above the subducting plate extending beneath the volcanic arc, and a narrow low viscosity channel (LVCh) along the lower part of the subduction interface, and potentially deeper. All the viscoelastic regions feature a Burgers rheology and we invert for their mechanical properties and geometrical characteristics. Our best fitting models present, (i) an asthenosphere extending down to 270km, with a 'long-term' viscosity of the order of 3.1018Pa.s; (ii) a LVCh along the plate interface extending from depths of 50 to 150 km with viscosities slightly below 1018 Pa.s; (iii) a LVW restricted to the base of the lithosphere below the volcanic arc, with viscosities of a few 1018 Pa.s. Increased horizontal velocities are due to relaxation in both the asthenosphere and the LVCh. A deep channel is necessary to produce enough uplift in the middle

  11. Mechanical Deformation Induced in Si and GaN Under Berkovich Nanoindentation

    Directory of Open Access Journals (Sweden)

    Jian Sheng-Rui

    2007-01-01

    Full Text Available AbstractDetails of Berkovich nanoindentation-induced mechanical deformation mechanisms of single-crystal Si(100 and the metal-organic chemical-vapor deposition (MOCVD derived GaN thin films have been systematic investigated by means of micro-Raman spectroscopy and cross-sectional transmission electron microscopy (XTEM techniques. The XTEM samples were prepared by using focused ion beam (FIB milling to accurately position the cross-section of the nanoindented area. The behaviors of the discontinuities displayed in the loading and unloading segments of the load-displacement curves of Si and GaN thin films performed with a Berkovich diamond indenter tip were explained by the observed microstructure features obtained from XTEM analyses. According to the observations of micro-Raman and XTEM, the nanoindentation-induced mechanical deformation is due primarily to the generation and propagation of dislocations gliding along the pyramidal and basal planes specific to the hexagonal structure of GaN thin films rather than by indentation-induced phase transformations displayed in Si.

  12. Strong Equivalence Principle in Polymer Quantum Mechanics and deformed Heisenberg Algebra

    CERN Document Server

    Kajuri, Nirmalya

    2016-01-01

    The Strong equivalence Principle (SEP) states that the description of a physical system in a gravitational field is indistinguishable from the description of the same system at rest in an accelerating frame. While this statement holds true in both General Relativity and ordinary Quantum Mechanics, one expects it to fail when quantum gravity corrections are taken into account. In this paper we investigate the possible failure of the SEP in two Quantum Gravity inspired modifications of Quantum Mechanics - Polymer Quantum Mechanics and deformed Heisenberg Algebra. We find that the SEP fails to hold in both these theories. We estimate the deviation from SEP and find in both cases that it is too small to be measured in present day experiments.

  13. Nucleation mechanisms of dynamic recrystallization in Inconel 625 superalloy deformed with different strain rates

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effects of strain rates on the hot working characteristics and nucleation mechanisms of dynamic recrystallization (DRX) were studied by optical microscopy and electron backscatter diffraction (EBSD) technique. Hot compression tests were conducted using a Gleeble-1500 simulator at a true strain of 0.7 in the temperature range of 1000 to 1150 °C and strain rate range of 0.01 to 10.00 s-1. It is found that the size and volume fraction of the DRX grains in hot-deformed Inconel 625 superalloy firstly decreas...

  14. Intraplate deformation, stress in the lithosphere and the driving mechanism for plate motions

    Science.gov (United States)

    Albee, Arden L.

    1993-01-01

    The initial research proposed was to use the predictions of geodynamical models of mantle flow, combined with geodetic observations of intraplate strain and stress, to better constrain mantle convection and the driving mechanism for plate motions and deformation. It is only now that geodetic observations of intraplate strain are becoming sufficiently well resolved to make them useful for substantial geodynamical inference to be made. A model of flow in the mantle that explains almost 90 percent of the variance in the observed longwavelength nonhydrostatic geoid was developed.

  15. Deformation mechanisms deduced from AMS data in the Jaca-Pamplona basin (southern Pyrenees)

    Science.gov (United States)

    Larrasoan˜a, J. C.; Pueyo-Morer, E. L.; Millán-Garrido, H.; Parés, J. M.; Del Valle, J.

    The first AMS data obtained in the Eocene marls and turbidites of the Jaca-Pamplona basin, and their interpretation in the local structural framework are presented. AMS data have proved to be excellent geometric indicators of microstructural features, as well as markers of the relative strain of rocks. The performed AMS analysis allowed to infer the strain of rocks, which is not possible by means of the classical structural methods, in areas where strata do not display any strain markers. Besides, the AMS data have been the sensitive enough to allow a preliminary estimation of the deformation mechanisms that ruled the structural configuration of the study area.

  16. Studies of mechanical deformations and holes of large, asymmetric GE1/1 foils

    CERN Document Server

    Pathiraja Mudiyanselage, Chamini Shammi; Singh, Rajat Pratap; Lakdee, Natthaphop; Moutinho Goes, Anna Beatriz; CERN. Geneva. EP Department

    2017-01-01

    One of the main project undergoing on the CMS department is the GE1/1 project. Under this project as summer students we had to do the study of mechanical deformations and holes diameter. Basically, this was a group project and one part of the project was to develop a structure to obtain the data from the detector. It was decided to use a digital microscope to take pictures of some particular positions and then the other part used some image processing software to analyze the data from each one.

  17. Unified Explanation of Quark-Lepton Mass Spectra in q-Deformed Quantum Mechanics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-Zu

    2000-01-01

    The quark-lepton mass spectra in q-deformed quantum mechanics are investigated. The theoretical formula of the spectrum includes two new quantum numbers: the q-exciting number n describing generations and the scaling indexes Mi describing families. This formula shows two exponential increases in the mass distribution as generation n increases, the intervals of masses in a given family exponentially increase, and the mass splittings among different members in a generation also exponentially increase. The theoretical values of masses o[ quarks and leptons reasonably agree with the experimental data except for the electron mass which is one order larger.

  18. Deformation and Damage Mechanisms in Ultrafine-Grained Austenitic Stainless Steel During Cyclic Straining

    Science.gov (United States)

    Hamada, Atef S.

    2013-04-01

    The ultrafine-grained (UFG) structure of an austenitic stainless steel (Type 301LN), processed by controlled phase-reversion annealing, was fatigued to study the deformation and damage mechanisms during cyclic straining. Fatigue cracking along the grain boundaries and the formation of extended persistent slip band-like shear bands (SBs) were observed to be the fatigue-induced microstructural features in the ultrafine-grained structure. Characterization of SBs was performed by electron backscattered diffraction and atomic force microscopy to study the fine features.

  19. Multiple deformation mechanisms operating at seismogenic depths: Tectonic pseudotachylyte and associated deformation from the central Sierra Nevada, California

    Science.gov (United States)

    Prante, M. R.; Evans, J. P.

    2012-12-01

    Description and identification of fault-related deformation products that are diagnostic of seismic slip have implications for the energy budget of earthquakes, fault strength, and fault-rock assemblages. We describe tectonic pseduotachylyte, cataclastic rocks, crystal-plastic deformation, and hydrothermal alteration form faults exhumed from seismogenic depths in the Volcanic Lakes area, in northern Sequoia and Kings Canyon National Park, CA, USA. Fault rock protoliths include Mesozoic granite and granodiorite plutonic and limited metasedimentary and metavolcanic rocks. These plutonic and metamorphic rocks are cross-cut by the E-W striking, steeply dipping, left-lateral strike-slip Granite Pass (GPF) and Glacier Lakes faults (GLF). Cross-cutting relationships and microstructural data suggest that the GPF is the oldest fault in the area and preserves evidence for coeval brittle and plastic crystal deformation, and hydrothermal fluid-flow. Tectonic pseudotachylyte from the area has been dated using the 40Ar/39Ar method at 76.6 ± 0.3 Ma; when placed into a thermochronologic framework for the plutonic host rock it can be inferred that the pseudotachylyte formed at depths between 2.4-6.0 km with ambient temperatures between 110-160°C. Exceptionally well preserved tectonic pseudotachylyte from the GLF and GPF contain evidence for a frictional melt origin including: 1) plagioclase spherulites and microlites, 2) injection vein morphology, 3) amygdules, 4) viscous flow banding and folds, and 5) embayed and corroded clasts. Pseudotachylyte from the GPF and GLF is associated with brittle and plastic deformation in the damage zone of the faults. Evidence for plastic deformation includes undulose extinction, deformation lamellae, subgrain development, and grain boundary bulging in quartz; and limited undulose extinction in feldspar. Additionally, abundant hydrothermal alteration and mineralization has been documented in the GPF and GLF fault zones, including, chlorite

  20. Mechanisms of Cenozoic deformation in the Bohai Basin, Northeast China: Physical modelling and discussions

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Jianxun; ZHOU; Jiansheng

    2006-01-01

    The Bohai Basin is a Cenozoic petroliferous extensional basin in China and has apparent geometrical and kinematic similarities with the other Meso-Cenozoic extensional basins located along the eastern margin of Eurasian Plate. However, the deformation mechanisms of the basin are still in dispute. Physcial modelling referring to the Huanghua Depression, located in the central part of the Bohai Basin was conducted employing four sets of planar sandbox experimental models with different extension directions. Only experimental results of the model with N-S extension show good structural similarity with the depression. The results also indicate that complex variations of fault strike in a rift basin are not necessarily the results of complex kinematic mechanisms or polyphase deformation. Based on comparison of experimental results with the actual structures and the good structural similarity between Huanghua Depression and the whole Bohai Basin, it is concluded that the Bohai Basin was formed by the N-S extension. The strike slip deformation along the NNE-trending border faults of the basin resulted from the N-S extension and played the role of lateral transformation for the N-S extension. In addition, according to the apparent geometrical and kinematic similarities among the Bohai Basin and other Meso-Cenozoic extensional basins located along the eastern margin of the Eurasian Plate, it is proposed that: (1) this "N-S extension" model provides a better kinematic interpretation for the formation of Bohai Basin and the other adjacent basins located along the eastern margin of the Eurasian Plate; and (2) the N-S extension was probably the effect of the "slab window" formed by the subduction of the nearly E-W trending oceanic ridge between the Kula and Pacific Plates. The "slab window" effect can also provide reasonable explanations for the phenomena that initial rifting ages of basins become progressively younger westwards along the eastern margin of the Eurasian Plate

  1. Implications of mechanical deformation and formaldehyde preservation for the identification of stage-specific characteristics of Baltic cod eggs

    DEFF Research Database (Denmark)

    Geldmacher, A.; Wieland, Kai

    1999-01-01

    The identification of developmental stages in fish eggs from plankton samples is often complicated by deformation of the embryos due to mechanical stress during the sampling procedure and by dehydration during formaldehyde fixation. The effects of formaldehyde fixation and mechanical stress...... on Baltic cod eggs (Gadus morhua callarias L.) were examined separately by visually comparing the morphological features of treated vs. live eggs of identical ontogenetic age. Microphotographs were made concurrently for documentation. In stage IA eggs, mechanical treatment resulted in scattered blastodiscs...... mechanically deformed during handling were clearly distinguishable from those that died prior to catching; however, staging was generally less accurate for formaldehyde- preserved eggs when compared with living specimens....

  2. Multi-objective optimization of flexure hinge mechanism considering thermal–mechanical coupling deformation and natural frequency

    Directory of Open Access Journals (Sweden)

    Lufan Zhang

    2017-01-01

    Full Text Available Flexure hinge mechanism plays a key part in realization of terminal nano-positioning. The performance of flexure hinge mechanism is determined by its positioning design. Based on the actual working conditions, its finite element model is built and calculated in ANSYS. Moreover, change trends of deformation and natural frequency with positioning design parameters are revealed. And sensitivity analysis is performed for exploration response to these parameters. These parameters are used to build four objective functions. To solve it conveniently, the multi-objective optimization problem is transferred to the form of single-objective function with constraints. An optimal mechanism is obtained by an optimization method combining ANSYS with MATLAB. Finite element numerical simulation has been carried out to demonstrate the superiority of the optimal flexure hinge mechanism, and the superiority can be further verified by experiment. Measurements and tests have been conducted at varying accelerations, velocities, and displacements, to quantify and characterize the amount of acceleration responses obtained from flexure hinge mechanism before and after optimization. Both time- and frequency-domain analyses of experimental data show that the optimal flexure hinge mechanism has superior effectiveness. It will provide a basic for realizing high acceleration and high precision positioning of macro–micro motion platform.

  3. Mapping the Strain Distributions in Deformed Bulk Metallic Glasses Using Hard X-Ray Diffraction

    Science.gov (United States)

    Bednarcik, J.; Chen, L. Y.; Wang, X. D.; Jiang, J. Z.; Franz, H.

    2012-05-01

    The deformation behavior of Cu45 Zr46.5 Al7Ti1.5 bulk metallic glass (BMG) under bending was investigated in-situ using high-energy X-ray synchrotron diffraction. Samples were bent using two different benders with radii of 10 and 20 mm. The components of the strain tensor were determined from the change of positions of the first maximum of the diffracted intensity in reciprocal space. The procedure of data treatment was improved by the introduction of direct beam off-center correction. Comparing results for the two different bending radii, we found that the zero stress region does not necessarily lay within the central part of the specimen. Bending with smaller radius resulted in symmetric strain distribution, whereas a larger bending radius revealed strong asymmetry. Furthermore, bending with a smaller radius (10 mm) shows steeper strain gradients as compared with the situation in which the larger bending radius (20 mm) was used. Using a smaller bending radius implies reaching higher tensile/compressive stresses and reveals the signs of the plastic deformation, which are demonstrated as a saturation of elastic strains.

  4. Analysis of Structure and Deformation Mechanisms of Mineral Wool Slabs under Compression

    Directory of Open Access Journals (Sweden)

    Laimutis STEPONAITIS

    2012-06-01

    Full Text Available The products of mineral wool are widely used for thermal insulation of buildings, both at construction of new buildings and at renovation of old ones. The mechanical resistance and stability of them, as well as their energy saving and heat saving requirements are in most cases related to the essential specifications of the building. The mechanical characteristics of these products are subject to structure of material, density, content of binder in the product and to technology of production. Subject to the latter, mineral wool products with different fibrous structure are received, therefore, for the structure of each type, the individual structural models are developed attempting to describe the properties of fibrous systems. The deformability of mineral wool products is conditioned by mobility of fibrous structure, which shows up best under compression by short term loads. This study established the impact of various thicknesses and deformations on changes in structure of rock wool products. It also established that the thickness of mineral wool products conditions and influences considerable changes in their structure.DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1926

  5. Mechanical dyssynchrony and deformation imaging in patients with functional mitral regurgitation.

    Science.gov (United States)

    Rosa, Isabella; Marini, Claudia; Stella, Stefano; Ancona, Francesco; Spartera, Marco; Margonato, Alberto; Agricola, Eustachio

    2016-02-26

    Chronic functional mitral regurgitation (FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy (DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in FMR, such as annular dilatation and dysfunction, left ventricle (LV) remodeling, dysfunction and dyssynchrony, papillary muscles displacement and dyssynchrony. The best therapeutic choice for FMR is still debated. When optimal medical treatment has already been set, a further option for cardiac resynchronization therapy (CRT) and/or surgical correction should be considered. CRT is able to contrast most of the pathophysiologic determinants of FMR by minimizing LV dyssynchrony through different mechanisms: Increasing closing forces, reducing tethering forces, reshaping annular geometry and function, correcting diastolic MR. Deformation imaging in terms of two-dimensional speckle tracking has been validated for LV dyssynchrony assessment. Radial speckle tracking and three-dimensional strain analysis appear to be the best methods to quantify intraventricular delay and to predict CRT-responders. Speckle-tracking echocardiography in patients with mitral valve regurgitation has been usually proposed for the assessment of LV and left atrial function. However it has also revealed a fundamental role of intraventricular dyssynchrony in determining FMR especially in DCM, rather than in ischemic cardiomyopathy in which MR severity seems to be more related to mitral valve deformation indexes. Furthermore speckle tracking allows the assessment of papillary muscle dyssynchrony. Therefore this technique can help to identify optimal candidates to CRT that will probably demonstrate a reduction in FMR degree and thus will experience a better outcome.

  6. Analysis of Structure and Deformation Mechanisms of Mineral Wool Slabs under Compression

    Directory of Open Access Journals (Sweden)

    Laimutis STEPONAITIS

    2012-06-01

    Full Text Available The products of mineral wool are widely used for thermal insulation of buildings, both at construction of new buildings and at renovation of old ones. The mechanical resistance and stability of them, as well as their energy saving and heat saving requirements are in most cases related to the essential specifications of the building. The mechanical characteristics of these products are subject to structure of material, density, content of binder in the product and to technology of production. Subject to the latter, mineral wool products with different fibrous structure are received, therefore, for the structure of each type, the individual structural models are developed attempting to describe the properties of fibrous systems. The deformability of mineral wool products is conditioned by mobility of fibrous structure, which shows up best under compression by short term loads. This study established the impact of various thicknesses and deformations on changes in structure of rock wool products. It also established that the thickness of mineral wool products conditions and influences considerable changes in their structure.DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1926

  7. Deformation mechanisms during nanoindentation of sodium borosilicate glasses of nuclear interest.

    Science.gov (United States)

    Kilymis, D A; Delaye, J-M

    2014-07-07

    In this paper we analyze results of Molecular Dynamics simulations of Vickers nanoindentation, performed for sodium borosilicate glasses of interest in the nuclear industry. Three glasses have been studied in their pristine form, as well as a disordered one that is analogous to the real irradiated glass. We focused in the behavior of the glass during the nanoindentation in order to reveal the mechanisms of deformation and how they are affected by microstructural characteristics. Results have shown a strong dependence on the SiO2 content of the glass, which promotes densification due to the open structure of SiO4 tetrahedra and also due to the strength of Si-O bonds. Densification for the glasses is primarily expressed by the relative decrease of the Si-O-Si and Si-O-B angles, indicating rotation of the structural units and decrease of free volume. The increase of alkali content on the other hand results to higher plasticity of the matrix and increased shear flow. The most important effect on the deformation mechanism of the disordered glasses is that of the highly depolymerized network that will also induce shear flow and, in combination with the increased free volume, will result in the decreased hardness of these glasses, as has been previously observed.

  8. Mechanisms of traumatic rupture of the aorta and associated peri-isthmic motion and deformation.

    Science.gov (United States)

    Hardy, Warren N; Shah, Chirag S; Mason, Matthew J; Kopacz, James M; Yang, King H; King, Albert I; Van Ee, Chris A; Bishop, Jennifer L; Banglmaier, Richard F; Bey, Michael J; Morgan, Richard M; Digges, Kennerly H

    2008-11-01

    This study investigated the mechanisms of traumatic rupture of the aorta (TRA). Eight unembalmed human cadavers were tested using various dynamic blunt loading modes. Impacts were conducted using a 32-kg impactor with a 152-mm face, and high-speed seatbelt pretensioners. High-speed biplane x-ray was used to visualize aortic motion within the mediastinum, and to measure deformation of the aorta. An axillary thoracotomy approach was used to access the peri-isthmic region to place radiopaque markers on the aorta. The cadavers were inverted for testing. Clinically relevant TRA was observed in seven of the tests. Peak average longitudinal Lagrange strain was 0.644, with the average peak for all tests being 0.208 +/- 0.216. Peak intraluminal pressure of 165 kPa was recorded. Longitudinal stretch of the aorta was found to be a principal component of injury causation. Stretch of the aorta was generated by thoracic deformation, which is required for injury to occur. The presence of atherosclerosis was demonstrated to promote injury. The isthmus of the aorta moved dorsocranially during frontal impact and submarining loading modes. The aortic isthmus moved medially and anteriorly during impact to the left side. The results of this study provide a better understanding of the mechanisms associated with TRA, and can be used for the validation of finite element models developed for the examination and prediction of TRA.

  9. Fault Mechanics and Post-seismic Deformation at Bam, SE Iran

    Science.gov (United States)

    Wimpenny, Sam; Copley, Alex; Ingleby, Tom

    2017-02-01

    The extent to which aseismic deformation relaxes co-seismic stress changes on a fault zone is fundamental to assessing the future seismic hazard following any earthquake, and in understanding the mechanical behaviour of faults. Here we use models of stress-driven afterslip and visco-elastic relaxation, in conjunction with post-seismic InSAR measurements, to show that there has been minimal release of co-seismic stress changes through post-seismic deformation following the 2003 Mw 6.6 Bam earthquake. Our analysis indicates the faults at Bam remain predominantly locked, suggesting that the co- plus inter-seismically accumulated elastic strain stored down-dip of the 2003 rupture patch may be released in a future Mw 6 earthquake. Our observations and models also provide an opportunity to probe the growth of topography at Bam. We find that, for our modelled afterslip distribution to be consistent with forming the sharp step in the local topography over repeated earthquake cycles, and also to be consistent with the geodetic observations, requires either (1) far-field tectonic loading equivalent to a 2-10 MPa deviatoric stress acting across the fault system, which suggests it supports stresses 60-100 times less than classical views of static fault strength, or (2) that the fault surface has some form of mechanical anisotropy, potentially related to corrugations on the fault plane, that controls the sense of slip.

  10. Influence of bone volume fraction and architecture on computed large-deformation failure mechanisms in human trabecular bone.

    Science.gov (United States)

    Bevill, Grant; Eswaran, Senthil K; Gupta, Atul; Papadopoulos, Panayiotis; Keaveny, Tony M

    2006-12-01

    Large-deformation bending and buckling have long been proposed as failure mechanisms by which the strength of trabecular bone can be affected disproportionately to changes in bone density, and thus may represent an important aspect of bone quality. We sought here to quantify the contribution of large-deformation failure mechanisms on strength, to determine the dependence of these effects on bone volume fraction and architecture, and to confirm that the inclusion of large-deformation effects in high-resolution finite element models improves predictions of strength versus experiment. Micro-CT-based finite element models having uniform hard tissue material properties were created from 54 cores of human trabecular bone taken from four anatomic sites (age = 70+/-11; 24 male, 27 female donors), which were subsequently biomechanically tested to failure. Strength predictions were made from the models first including, then excluding, large-deformation failure mechanisms, both for compressive and tensile load cases. As expected, strength predictions versus experimental data for the large-deformation finite element models were significantly improved (p deformation models in both tension and compression. Below a volume fraction of about 0.20, large-deformation failure mechanisms decreased trabecular strength from 5-80% for compressive loading, while effects were negligible above this volume fraction. Step-wise nonlinear multiple regression revealed that structure model index (SMI) and volume fraction (BV/TV) were significant predictors of these reductions in strength (R2 = 0.83, p deformation failure mechanisms on trabecular bone strength is highly heterogeneous and is not well explained by standard architectural metrics.

  11. Improving anatomical mapping of complexly deformed anatomy for external beam radiotherapy and brachytherapy dose accumulation in cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Vásquez Osorio, Eliana M., E-mail: e.vasquezosorio@erasmusmc.nl; Kolkman-Deurloo, Inger-Karine K.; Schuring-Pereira, Monica; Zolnay, András; Heijmen, Ben J. M.; Hoogeman, Mischa S. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam 3075 (Netherlands)

    2015-01-15

    Purpose: In the treatment of cervical cancer, large anatomical deformations, caused by, e.g., tumor shrinkage, bladder and rectum filling changes, organ sliding, and the presence of the brachytherapy (BT) applicator, prohibit the accumulation of external beam radiotherapy (EBRT) and BT dose distributions. This work proposes a structure-wise registration with vector field integration (SW+VF) to map the largely deformed anatomies between EBRT and BT, paving the way for 3D dose accumulation between EBRT and BT. Methods: T2w-MRIs acquired before EBRT and as a part of the MRI-guided BT procedure for 12 cervical cancer patients, along with the manual delineations of the bladder, cervix-uterus, and rectum-sigmoid, were used for this study. A rigid transformation was used to align the bony anatomy in the MRIs. The proposed SW+VF method starts by automatically segmenting features in the area surrounding the delineated organs. Then, each organ and feature pair is registered independently using a feature-based nonrigid registration algorithm developed in-house. Additionally, a background transformation is calculated to account for areas far from all organs and features. In order to obtain one transformation that can be used for dose accumulation, the organ-based, feature-based, and the background transformations are combined into one vector field using a weighted sum, where the contribution of each transformation can be directly controlled by its extent of influence (scope size). The optimal scope sizes for organ-based and feature-based transformations were found by an exhaustive analysis. The anatomical correctness of the mapping was independently validated by measuring the residual distances after transformation for delineated structures inside the cervix-uterus (inner anatomical correctness), and for anatomical landmarks outside the organs in the surrounding region (outer anatomical correctness). The results of the proposed method were compared with the results of the

  12. Macro- and microscopic mechanical behaviour of flow of coal samples experimentally deformed at high temperatures and pressures

    Institute of Scientific and Technical Information of China (English)

    LIU Junlai; YANG Guang; MA Rui

    2005-01-01

    Coal samples from Qinshui Basin, Shanxi,China are experimentally deformed at temperatures and confining pressures of 200-500 ℃ and 200-500 Mpa,strain rate of 0.5×10-5/s and total strain of 10%. The vitrinite reflectance of the coal samples varies from 3.04 to 1.79. It is shown that the strengths of the deformed samples change obviously with coeval increasing temperatures and pressures (T/P). At the experimental range of T/P, the effects of increasing temperature predominate over that of increasing pressure. Microstructural analysis indicates a brittle to ductile transition under experimental T/P conditions from 200 to 300℃, and 200 to 300Mpa. Brittle deformation microstructures include macroscopic fracture zones and penetrative fracture associations. Elongation, undulose or irregular extinction, deformation lamellae and dynamic recrystallization of grains are the main ductile deformation microstructures.The variation of deformation mechanisms of the experimentally deformed coal samples is related to both the components of coals and T/P conditions. At low T/P, fractures occur in both inertinite and vitrinite of the samples. At higher T/P,crystalline plastic deformations are observed in the inertinite only.

  13. Sintering boron carbide ceramics without grain growth by plastic deformation as the dominant densification mechanism

    Science.gov (United States)

    Ji, Wei; Rehman, Sahibzada Shakir; Wang, Weimin; Wang, Hao; Wang, Yucheng; Zhang, Jinyong; Zhang, Fan; Fu, Zhengyi

    2015-10-01

    A new ceramic sintering approach employing plastic deformation as the dominant mechanism is proposed, at low temperature close to the onset point of grain growth and under high pressure. Based on this route, fully dense boron carbide without grain growth can be prepared at 1,675-1,700 °C and under pressure of (≥) 80 MPa in 5 minutes. The dense boron carbide shows excellent mechanical properties, including Vickers hardness of 37.8 GPa, flexural strength of 445.3 MPa and fracture toughness of 4.7 MPa•m0.5. Such a process should also facilitate the cost-effective preparation of other advanced ceramics for practical applications.

  14. Strong equivalence principle in polymer quantum mechanics and deformed Heisenberg algebra

    Science.gov (United States)

    Kajuri, Nirmalya

    2016-10-01

    The strong equivalence principle (SEP) states that the description of a physical system in a gravitational field is indistinguishable from the description of the same system at rest in an accelerating frame. While this statement holds true in both general relativity and ordinary quantum mechanics, one expects it to fail when quantum gravity corrections are taken into account. In this paper we investigate the possible failure of the SEP in two quantum gravity inspired modifications of quantum mechanics—polymer quantum mechanics and deformed Heisenberg algebra. We find that the SEP fails to hold in both these theories. We estimate the deviation from SEP and find in both cases that it is too small to be measured in present day experiments.

  15. Integration of Micro-Electro-Mechanical Deformable Mirrors in Doped Fiber Amplifiers

    CERN Document Server

    Bouyge, D; Crunteanu, A; Blondy, P; Couderc, V; Lhermite, J; Grossard, L; Barthélemy, A

    2007-01-01

    We present a simple technique to produce active Q-switching in various types of fiber amplifiers by active integration of an electrostatic actuated deformable metallic micro-mirror. The optical MEMS (MOEMS) device acts as one of the laser cavity reflectors and, at the same time, as switching/ modulator element. We aim to obtain laser systems emitting short, high-power pulses and having variable repetition rate. The electro-mechanical behavior of membrane (bridge-type) was simulated by using electrostatic and modal 3D finite element analysis (FEA). The results of the simulations fit well with the experimental mechanical, electrical and thermal measurements of the components. In order to decrease the sensitiveness to fiber-mirror alignment we are developing novel optical devices based on stressed-metal cantilever-type geometry that allow deflections up to 50 $\\mu$m with increased reflectivity discrimination during actuation.

  16. Sintering boron carbide ceramics without grain growth by plastic deformation as the dominant densification mechanism.

    Science.gov (United States)

    Ji, Wei; Rehman, Sahibzada Shakir; Wang, Weimin; Wang, Hao; Wang, Yucheng; Zhang, Jinyong; Zhang, Fan; Fu, Zhengyi

    2015-10-27

    A new ceramic sintering approach employing plastic deformation as the dominant mechanism is proposed, at low temperature close to the onset point of grain growth and under high pressure. Based on this route, fully dense boron carbide without grain growth can be prepared at 1,675-1,700 °C and under pressure of (≥) 80 MPa in 5 minutes. The dense boron carbide shows excellent mechanical properties, including Vickers hardness of 37.8 GPa, flexural strength of 445.3 MPa and fracture toughness of 4.7 MPa•m(0.5). Such a process should also facilitate the cost-effective preparation of other advanced ceramics for practical applications.

  17. Mechanical properties and constitutive relations for tantalum and tantalum alloys under high-rate deformation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.R.; Gray, G.T. III; Bingert, S.R. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

    1996-05-01

    Tantalum and its alloys have received increased interest as a model bcc metal and for defense-related applications. The stress-strain behavior of several tantalums, possessing varied compositions and manufacturing histories, and tantalum alloyed with tungsten, was investigated as a function of temperature from {minus}196 C to 1,000 C, and strain rate from 10{sup {minus}3} s{sup {minus}1} to 8,000 s{sup {minus}1}. The yield stress for all the Ta-materials was found to be sensitive to the test temperature, the impurity and solute contents; however, the strain hardening remained very similar for various ``pure`` tantalums but increased with alloying. Powder-metallurgy (P/M) tantalum with various levels of oxygen content produced via different processing paths was also investigated. Similar mechanical properties compared to conventionally processed tantalums were achieved in the P/M Ta. This data suggests that the frequently observed inhomogeneities in the mechanical behavior of tantalum inherited from conventional processes can be overcome. Constitutive relations based upon the Johnson-Cook, the Zerilli-Armstrong, and the Mechanical Threshold Stress models were evaluated for all the Ta-based materials. Parameters were also fit for these models to a tantalum-bar material. Flow stresses of a Ta bar stock subjected to a large-strain deformation of {var_epsilon} = 1.85 via multiple upset forging were obtained. The capabilities and limitations of each model for large-strain applications are examined. The deformation mechanisms controlling high-rate plasticity in tantalum are revisited.

  18. Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

    Directory of Open Access Journals (Sweden)

    K. K. Song

    2013-01-01

    Full Text Available The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-“double”-to-“triple”-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.

  19. Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

    Science.gov (United States)

    Song, K. K.; Pauly, S.; Sun, B. A.; Tan, J.; Stoica, M.; Kühn, U.; Eckert, J.

    2013-01-01

    The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-"double"-to-"triple"-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.

  20. Influence of the tempurature and rate conditions of deformation on the mechanical properties of 15Kh5M steel

    Energy Technology Data Exchange (ETDEWEB)

    Muckhin, V.N.; Nikulina, O.A.; Teplova, N.I.; Vatnik, L.E.

    1986-10-01

    This paper studies the influence of temperature and rate conditions of deformation of 15Kh5M steel on its mechanical properties for the purpose of determination of the sensitivity of the steel to deform rate, features of the change in uniform and concentrated plasticity, and the deformation capacity in long operating times, since 15Kh steel is widely used for production of the tubular coils of furnances of catalytic reformers of gasolines, which operate at temperatures up to 873 K and a pressure up to 6 MPa in a dangerously explosive medium.

  1. A review of the effect of prior inelastic deformation on high temperature mechanical response of engineering alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.F. [Department of Mechanical and Aeronautical Engineering, Materials and Surface Science Institute, University of Limerick, Plassey Park, Limerick (Ireland); O' Dowd, N.P., E-mail: noel.odowd@ul.i [Department of Mechanical and Aeronautical Engineering, Materials and Surface Science Institute, University of Limerick, Plassey Park, Limerick (Ireland); Davies, C.M.; Nikbin, K.M. [Department of Mechanical Engineering, Imperial College London, United Kindom (United Kingdom)

    2010-10-15

    In this review article, we examine the influence of prior deformation (prestrain) on the subsequent high temperature mechanical behaviour of engineering alloys. We review the observed effects at a macroscopic level in terms of creep deformation, creep rupture times and crack growth rates from a number of sources and a range of materials. Microstructural explanations for the observed macroscopic effects are also reviewed and constitutive models which incorporate the effect of prior deformation are examined. The emphasis in the paper is on engineering steels though reference is also made to non-ferrous alloys.

  2. Nucleosome positioning in yeasts: methods, maps, and mechanisms.

    Science.gov (United States)

    Lieleg, Corinna; Krietenstein, Nils; Walker, Maria; Korber, Philipp

    2015-06-01

    Eukaryotic nuclear DNA is packaged into nucleosomes. During the past decade, genome-wide nucleosome mapping across species revealed the high degree of order in nucleosome positioning. There is a conserved stereotypical nucleosome organization around transcription start sites (TSSs) with a nucleosome-depleted region (NDR) upstream of the TSS and a TSS-aligned regular array of evenly spaced nucleosomes downstream over the gene body. As nucleosomes largely impede access to DNA and thereby provide an important level of genome regulation, it is of general interest to understand the mechanisms generating nucleosome positioning and especially the stereotypical NDR-array pattern. We focus here on the most advanced models, unicellular yeasts, and review the progress in mapping nucleosomes and which nucleosome positioning mechanisms are discussed. There are four mechanistic aspects: How are NDRs generated? How are individual nucleosomes positioned, especially those flanking the NDRs? How are nucleosomes evenly spaced leading to regular arrays? How are regular arrays aligned at TSSs? The main candidates for nucleosome positioning determinants are intrinsic DNA binding preferences of the histone octamer, specific DNA binding factors, nucleosome remodeling enzymes, transcription, and statistical positioning. We summarize the state of the art in an integrative model where nucleosomes are positioned by a combination of all these candidate determinants. We highlight the predominance of active mechanisms involving nucleosome remodeling enzymes which may be recruited by DNA binding factors and the transcription machinery. While this mechanistic framework emerged clearly during recent years, the involved factors and their mechanisms are still poorly understood and require future efforts combining in vivo and in vitro approaches.

  3. Mechanical analysis on deformation of surrounding rock with road-in packing of gob-side entry retaining in fully-mechanized sub-level caving face

    Institute of Scientific and Technical Information of China (English)

    ZHU Chuan-qu; MIAO Xie-xing; LIU Ze

    2008-01-01

    Based on the movement regularity of surrounding rock with road-in packing of gob-side entry retaining in fully-mechanized sub-level caving face (RPGERFCF), the me-chanical model of its surrounding rock was established and the calculating formulas of the deformation of the roof, coal wall and filling body were attained. By the mechanical analy-sis to the deformation of the surrounding rock of RPGERFCF, the major factors influencing the deformation of the surrounding rock were found out and the technologic approaches reduced the deformation and enhanced the stability of the surrounding rock were put for-ward. Consequently, the scientific bases were provided for the stability control of the sur-rounding rock of RPGERFCF.

  4. Investigation of the deformation mechanisms of core-shell rubber-modified epoxy at cryogenic temperatures

    Science.gov (United States)

    Brown, Hayley Rebecca

    The industrial demand for high strength-to-weight ratio materials is increasing due to the need for high performance components. Epoxy polymers, although often used in fiber-reinforced polymeric composites, have an inherent low toughness that further decreases with decreasing temperatures. Second-phase additives have been effective in increasing the toughness of epoxies at room temperature; however, the mechanisms at low temperatures are still not understood. In this study, the deformation mechanisms of a DGEBA epoxy modified with MX960 core-shell rubber (CSR) particles were investigated under quasi-static tensile and impact loads at room temperature (RT) and liquid nitrogen (LN 2) temperature. Overall, the CSR had little effect on the tensile properties at RT and LN2 temperature. The impact strength decreased from neat to 3 wt% but increased from neat to 5 wt% at RT and LN2 temperature, with a higher impact strength at RT at all CSR loadings. The CSR particles debonded in front of the crack tip, inducing voids into the matrix. It was found that an increase in shear deformation and void growth likely accounted for the higher impact strength at 5 wt% CSR loading at RT while the thermal stress fields due to the coefficient of thermal expansion mismatch between rubber and epoxy and an increase in secondary cracking is likely responsible for the higher impact strength at 5 wt% tested at LN2 temperature. While a large toughening effect was not seen in this study, the mechanisms analyzed herein will likely be of use for further material investigations at cryogenic temperatures.

  5. Homogeneous Field and WKB Approximation in Deformed Quantum Mechanics with Minimal Length

    Directory of Open Access Journals (Sweden)

    Jun Tao

    2015-01-01

    Full Text Available In the framework of the deformed quantum mechanics with a minimal length, we consider the motion of a nonrelativistic particle in a homogeneous external field. We find the integral representation for the physically acceptable wave function in the position representation. Using the method of steepest descent, we obtain the asymptotic expansions of the wave function at large positive and negative arguments. We then employ the leading asymptotic expressions to derive the WKB connection formula, which proceeds from classically forbidden region to classically allowed one through a turning point. By the WKB connection formula, we prove the Bohr-Sommerfeld quantization rule up to Oβ2. We also show that if the slope of the potential at a turning point is too steep, the WKB connection formula is no longer valid around the turning point. The effects of the minimal length on the classical motions are investigated using the Hamilton-Jacobi method. We also use the Bohr-Sommerfeld quantization to study statistical physics in deformed spaces with the minimal length.

  6. Modeling the Mechanical Response of In Vivo Human Skin Under a Rich Set of Deformations

    KAUST Repository

    Flynn, Cormac

    2011-03-11

    Determining the mechanical properties of an individual\\'s skin is important in the fields of pathology, biomedical device design, and plastic surgery. To address this need, we present a finite element model that simulates the skin of the anterior forearm and posterior upper arm under a rich set of three-dimensional deformations. We investigated the suitability of the Ogden and Tong and Fung strain energy functions along with a quasi-linear viscoelastic law. Using non-linear optimization techniques, we found material parameters and in vivo pre-stresses for different volunteers. The model simulated the experiments with errors-of-fit ranging from 13.7 to 21.5%. Pre-stresses ranging from 28 to 92 kPa were estimated. We show that using only in-plane experimental data in the parameter optimization results in a poor prediction of the out-of-plane response. The identifiability of the model parameters, which are evaluated using different determinability criteria, improves by increasing the number of deformation orientations in the experiments. © 2011 Biomedical Engineering Society.

  7. Effect of the mechanical deformation on the electrical properties of the polymer/CNT fiber

    Science.gov (United States)

    Cho, Hyun Woo; Sung, Bong June; Nano-Bio Computational Chemistry Laboratory Team

    2014-03-01

    We elucidate the effect of the mechanical deformation on the electrical properties of the polymer/CNT fiber. The conductive polymer fiber has drawn a great attention for its potential application to a stretchable electronics such as wearable devices and artificial muscles, etc. However, the electrical conductivity of the polymer-based stretchable electronics decreases significantly during the deformation, which may limit the applicability of the polymer/CNT fiber for the stretchable electronics. Moreover, its physical origin for the decrease in electrical conductivity has not been explained clearly. In this work, we employ a coarse-grained model for the polymer/CNT fiber, and we calculate the electric conductivity using global tunneling network (GTN) model. We show that the electric conductivity decreases during the elongation of the polymer/CNT fiber. We also find using critical path approximation (CPA) that the structure of the electrical network of the CNTs changes collectively during the elongation of the fiber, which is strongly responsible for the reduction of the electrical conductivity of the polymer/CNT fiber.

  8. High purity ultrafine-grained nickel processed by dynamic plastic deformation: microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Farbaniec, Lukasz; Dirras, Guy [Universite Paris 13, Sorbonne Paris Cite LSPM-CNRS, 99, Avenue J. B. Clement, 93430 Villetaneuse (France); Abdul-Latif, Akrum [Laboratoire d' Ingenierie des Systemes Mecaniques et des Materiaux 3, Rue Fernand Hainaut, 93407 St. Ouen Cedex (France); Gubicza, Jeno [Department of Materials Physics, Eoetvoes Lorand University Budapest, P.O. Box 32, H-1518 (Hungary)

    2012-11-15

    Bulk ultrafine-grained samples are processed by dynamic plastic deformation at an average strain rate of 3.3 x 10{sup 2} s{sup -1} from bulk coarse-grained nickel with purity higher than 98.4 wt.%. The obtained microstructure is investigated by electron backscattering diffraction, transmission electron microscopy and X-ray line profile analysis. After dynamic deformation the microstructure evolves into submicron-size lamellar and subgrain structures. Evaluation of average grain size shows a heterogeneous microstructure along both the diameter and the thickness of the sample. X-ray line profile analysis reveals high dislocation density of about 13 {+-} 2 x 10{sup 14} m{sup -2} in the impacted material. The mechanical properties are investigated by means of uniaxial quasi-static compression tests conducted at room temperature. The stress-strain behavior of the impacted Ni depends on the location in the impacted disk and on the orientation of the compression axis relative to the impact direction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Microstructure and mechanical properties of halite/coarse muscovite synthetic aggregates deformed in torsion

    Science.gov (United States)

    Marques, F. O.; Burlini, L.; Burg, J.-P.

    2011-04-01

    We investigated the behavior of a synthetic two-phase aggregate composed of 80% halite + 20% coarse muscovite under torsion deformation, at 100, 200 and 300 °C, a confining pressure of 250 MPa, and a constant strain rate of 3E-4 s -1. At all temperatures, the two-phase aggregate deformed homogeneously at the sample scale. The strength of the aggregate and muscovite deformation depended on temperature, strain rate and initial orientation of muscovite greatest dimension relative to the shear plane. With muscovite initially parallel to the shear plane, halite flowed plastically and long muscovite grains were not strong enough to behave as a rigid inclusion rotating in a ductile matrix. Instead, high aspect ratio grains deformed by folding, which was visibly accomplished by slip along mica {001} cleavage and by great flattening of halite in the core of the folds. When initially normal to the shear plane, high aspect ratio muscovite grains passively rotated towards the shear plane. In both cases, small and low aspect ratio muscovite grains behaved mostly as mica-fish, with mica grains tilted opposite to shear sense. Similarly to natural mylonites, σ-porphyroclast systems and rolling structures were also common in the microstructure. A strong foliation made of halite ribbons and aligned muscovite flakes rapidly developed but did not make the composite aggregate weaker when compared with single-phase halite. Comparison with synthetic aggregates of single-phase halite shows that the two-phase aggregate was much stronger than single-phase halite in all cases. Comparison with a synthetic aggregate with calcite porphyroclasts shows that the strength of the aggregate with muscovite at 100 °C was lower below a strain of ca. 2.6 and higher beyond this value, and that the aggregate with calcite was stronger at 200 °C. Strain rate stepping tests (1E-5 s -1-2E-3 s -1) indicate that the two-phase aggregate behaved as power-law viscous, with stress exponents of ca. 12 and 10 at

  10. The mechanical properties and the deformation microstructures of the C15 Laves phase Cr2Nb at high temperatures

    NARCIS (Netherlands)

    Kazantzis, A. V.; Aindow, M.; Jones, I. P.; Triantafyllidis, G. K.; De Hosson, J. Th. M.

    Compression tests between 1250 and 1550 degrees C and 10(-5) and 5 x 10(-3) s(-1) and transmission electron microscopy have been employed to investigate the high temperature mechanical properties and the deformation mechanisms of the C15 Cr2Nb Laves phase. The stress-peaks in the compression curves

  11. 4-D crustal structure of the conterminous U.S.: Continental assembly, crustal growth, and deformation history from receiver functions, xenoliths, and structural mapping

    Science.gov (United States)

    Schulte-Pelkum, V.; Mahan, K. H.

    2015-12-01

    We investigate seismic and geological features related to the tectonic evolution of the crust on a continent-wide scale. We present continent-wide features using Transportable Array data receiver function analysis, followed by regional comparisons to tie to ground truth from xenolith studies and structural mapping. We stress that the Transportable Array, at ~75 km station spacing, only offers a collection of point measurements of the crust due to the lack of crossing raypaths. 7.x layers (lower crust with high seismic velocities) can be created during crustal growth processes such as magmatic or mechanical underplating and during crustal modification such as large-scale melting. We present receiver function results and a compilation of previous regional studies using refraction data or receiver functions from regional dense networks. 7.x layers appear predominantly in parts of the northern U.S. Cordillera and across the southeastern U.S. We compare the seismic results with a xenolith study in Montana that details incremental growth of the 7.x layer from the Archean on. Hydration of a granulitic lower crust can destroy the 7.x layer and has the potential to cause epirogenic uplift. We interpret the pattern seen across the Transportable Array in the light of this hypothesis. Ductile deformation of the deep crust generates shear fabrics that can be detected seismically. Receiver functions detect shear zones via contrasts in foliation to the surrounding material. We map foliation strikes and depths in the crust across the Transportable Array using azimuthal analysis of receiver functions. Strikes from receiver functions typically align with surface fault traces in tectonically active regions, with depths of the converters exceeding the brittle zone. We discuss continent-wide strikes mapped with receiver functions. Contrasting orientations of Proterozoic shear zones and pervasive surrounding foliations in basement exposures in Colorado are reflected in seismic results

  12. Coupled Simulations of Mechanical Deformation and Microstructural Evolution Using Polycrystal Plasticity and Monte Carlo Potts Models

    Energy Technology Data Exchange (ETDEWEB)

    Battaile, C.C.; Buchheit, T.E.; Holm, E.A.; Neilsen, M.K.; Wellman, G.W.

    1999-01-12

    The microstructural evolution of heavily deformed polycrystalline Cu is simulated by coupling a constitutive model for polycrystal plasticity with the Monte Carlo Potts model for grain growth. The effects of deformation on boundary topology and grain growth kinetics are presented. Heavy deformation leads to dramatic strain-induced boundary migration and subsequent grain fragmentation. Grain growth is accelerated in heavily deformed microstructures. The implications of these results for the thermomechanical fatigue failure of eutectic solder joints are discussed.

  13. A 3D Analysis of Rock Block Deformation and Failure Mechanics Using Terrestrial Laser Scanning

    Science.gov (United States)

    Rowe, Emily; Hutchinson, D. Jean; Kromer, Ryan A.; Edwards, Tom

    2017-04-01

    planes on the slope that were confining the block. It is concluded that rock blocks in White Canyon may be classified as one of five main failure mechanisms based on their pre-failure deformation and structure: planar slide, topple, rotation, wedge, and overhang, with overhang failures representing a large portion of rockfalls in this area. Overhang rockfalls in the White Canyon are characterized by blocks that (a) are not supported by an underlying discontinuity plane, and (b) generally do not exhibit pre-failure deformation. Though overhanging rock blocks are a structural subset of toppling failure, their behavior suggests a different mechanism of detachment. Future work will further populate the present database of rockfalls in White Canyon and will expand the study to include other sites along this corridor. The ultimate goal of this research is to establish warning thresholds based on deformation magnitudes for rockfalls in White Canyon to assist Canadian railways in better understanding and managing these slopes.

  14. Numerical simulation of mechanisms of deformation,failure and energy dissipation in porous rock media subjected to wave stresses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The pore characteristics,mineral compositions,physical and mechanical properties of the subarkose sandstones were acquired by means of CT scan,X-ray diffraction and physical tests.A few physical models possessing the same pore characteristics and matrix properties but different porosities compared to the natural sandstones were developed.The 3D finite element models of the rock media with varied porosities were established based on the CT image processing of the physical models and the MIMICS software platform.The failure processes of the porous rock media loaded by the split Hopkinson pressure bar(SHPB) were simulated by satisfying the elastic wave propagation theory.The dynamic responses,stress transition,deformation and failure mechanisms of the porous rock media subjected to the wave stresses were analyzed.It is shown that an explicit and quantitative analysis of the stress,strain and deformation and failure mechanisms of porous rocks under the wave stresses can be achieved by using the developed 3D finite element models.With applied wave stresses of certain amplitude and velocity,no evident pore deformation was observed for the rock media with a porosity less than 15%.The deformation is dominantly the combination of microplasticity(shear strain),cracking(tensile strain) of matrix and coalescence of the cracked regions around pores.Shear stresses lead to microplasticity,while tensile stresses result in cracking of the matrix.Cracking and coalescence of the matrix elements in the neighborhood of pores resulted from the high transverse tensile stress or tensile strain which exceeded the threshold values.The simulation results of stress wave propagation,deformation and failure mechanisms and energy dissipation in porous rock media were in good agreement with the physical tests.The present study provides a reference for analyzing the intrinsic mechanisms of the complex dynamic response,stress transit mode,deformation and failure mechanisms and the disaster

  15. Mechanical stability model of progradational carbonate platform margins under tectonic loads: Deformation of Cretaceous carbonate platforms in the Sierra Madre Oriental fold-thrust belt (east central Mexico)

    Science.gov (United States)

    Contreras, Juan; Suter, Max

    2015-02-01

    Shortening in the Sierra Madre Oriental fold-thrust belt (east central Mexico) is localized along the margins of Cretaceous carbonate platforms and controlled by mechanical stratigraphy. The platform margins are deformed by imbricate series of thrust ramps, whereas the coeval basins and platform interiors are deformed by map-scale detachment folds. Here we present a finite element model to evaluate the influence of the boundary geometry and boundary conditions on the style of deformation observed at these basinward progradational platform margins. We calculate the stress distribution in a linearly elastic platform-basin transition zone under the action of horizontal tectonic stress, taking into account changes of rock mechanical properties across the platform margin, as well as their dependence on direction, and infer the resulting fracture patterns based on the Mohr-Coulomb failure criterion. Stress concentrations are predicted at the contacts between the massive rocks of the platform margin and the well-layered rocks of both, the platform interior and the adjacent basin. Brittle failure of the platform border can be mostly attributed to three effects: mechanical coupling between the carbonate platform and a substratum of moderate to low viscosity, variations in layering and texture that governed the mechanical properties of the involved carbonates as well as their dependence on direction, and the development of sharp domain boundary corners associated with progradational facies changes. In contrast, the dip of the basement and a possible taper of the overlying Upper Cretaceous shale toward the basin appear to have little influence on the mechanical failure of the platform margin.

  16. Mechanism of cube grain nucleation during recrystallization of deformed commercial purity aluminium

    Indian Academy of Sciences (India)

    K T Kashyap; R George

    2006-04-01

    Cube texture is a sharp recrystallization texture component in fcc metals like aluminium, copper, etc. It is described by an ideal orientation i.e. (100) $\\langle 100 \\rangle$. The subject of cube texture nucleation i.e. cube grain nucleation, from the deformed state of aluminium and copper is of scientific curiosity with concurrent technological implications. There are essentially two models currently in dispute over the mechanism of cube grain nucleation i.e. the differential stored energy model founded on the hypothesis proposed by Ridha and Hutchinson and the micro-growth selection model of Duggan et al. In this paper, calculations are made on the proposal of Ridha and Hutchinson model and the results are obtained in favour of the differential stored energy model. It is also shown that there is no need for the micro-growth model.

  17. Deformation mechanisms, defects, heat treatment, and thermal conductivity in large grain niobium

    Energy Technology Data Exchange (ETDEWEB)

    Bieler, Thomas R., E-mail: bieler@egr.msu.edu; Kang, Di, E-mail: kangdi@msu.edu; Baars, Derek C., E-mail: baarsder@gmail.com [Chemical Engineering and Materials Science, Michigan State University, East Lansing MI 48824-1226, US (United States); Chandrasekaran, Saravan, E-mail: saravan@fnal.gov [Mechanical Engineering, Michigan State University, East Lansing MI 48824-1226, US (United States); Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606, US (United States); Mapar, Aboozar, E-mail: maparabo@egr.msu.edu; Wright, Neil T., E-mail: ntwright@egr.msu.edu [Mechanical Engineering, Michigan State University, East Lansing MI 48824-1226, US (United States); Ciovati, Gianluigi, E-mail: gciovati@jlab.org; Myneni, Ganapati Rao, E-mail: rao@jlab.org [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606, US (United States); Pourboghrat, Farhang, E-mail: pourboghrat.2@osu.edu [Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210, US (United States); Murphy, James E., E-mail: jim@unr.edu [Chemical and Materials Engineering, University of Nevada at Reno, Reno NV, 89557, US (United States); Compton, Chris C., E-mail: compton@frib.msu.edu [Facility for Rare Isotope Beams, Michigan State University, East Lansing MI 48824-1226, US (United States)

    2015-12-04

    The physical and mechanical metallurgy underlying fabrication of large grain cavities for superconducting radio frequency accelerators is summarized, based on research of 1) grain orientations in ingots, 2) a metallurgical assessment of processing a large grain single cell cavity and a tube, 3) assessment of slip behavior of single crystal tensile samples extracted from a high purity ingot slice before and after annealing at 800 °C / 2 h, 4) development of crystal plasticity models based upon the single crystal experiments, and 5) assessment of how thermal conductivity is affected by strain, heat treatment, and exposure to hydrogen. Because of the large grains, the plastic anisotropy of deformation is exaggerated, and heterogeneous strains and localized defects are present to a much greater degree than expected in polycrystalline material, making it highly desirable to computationally anticipate potential forming problems before manufacturing cavities.

  18. Directionally tunable and mechanically deformable ferroelectric crystals from rotating polar globular ionic molecules

    Science.gov (United States)

    Harada, Jun; Shimojo, Takafumi; Oyamaguchi, Hideaki; Hasegawa, Hiroyuki; Takahashi, Yukihiro; Satomi, Koichiro; Suzuki, Yasutaka; Kawamata, Jun; Inabe, Tamotsu

    2016-10-01

    Ferroelectrics are used in a wide range of applications, including memory elements, capacitors and sensors. Recently, molecular ferroelectric crystals have attracted interest as viable alternatives to conventional ceramic ferroelectrics because of their solution processability and lack of toxicity. Here we show that a class of molecular compounds—known as plastic crystals—can exhibit ferroelectricity if the constituents are judiciously chosen from polar ionic molecules. The intrinsic features of plastic crystals, for example, the rotational motion of molecules and phase transitions with lattice-symmetry changes, provide the crystals with unique ferroelectric properties relative to those of conventional molecular crystals. This allows a flexible alteration of the polarization axis direction in a grown crystal by applying an electric field. Owing to the tunable nature of the crystal orientation, together with mechanical deformability, this type of molecular crystal represents an attractive functional material that could find use in a diverse range of applications.

  19. Quantitative formulation of mechanism of sintering process during creep deformation of refractory concretes

    Directory of Open Access Journals (Sweden)

    Terzić Anja

    2009-01-01

    Full Text Available This paper is concerned with quantitative formulation of the mechanism of the sintering process during secondary state creep deformation of refractory concretes. Investigated concretes varied in, both, chemical and mineralogical compositions. The sintering process during secondary state creep within refractory concrete has an isothermal character. Thus, an attempt was made to describe the mentioned process quantitatively. Creep was investigated at three different temperatures: 1200, 1300 and 1400ºC. Variations of the microstructure of concrete samples, exposed to constant static pressure and constant temperature during certain time-intervals, were investigated using a scanning electron microscope. Obtained results of the investigation proved that creep resistance is an irreplaceable method when the decision about the best possible type of refractory concrete for application in metallurgical furnaces is required.

  20. Homogeneous Field and WKB Approximation In Deformed Quantum Mechanics with Minimal Length

    CERN Document Server

    Tao, Jun; Yang, Haitang

    2012-01-01

    In the framework of the deformed quantum mechanics with minimal length, we consider the motion of a non-relativistic particle in a homogeneous external field. We find the integral representation for the physically acceptable wave function in the position representation. Using the method of steepest descent, we obtain the asymptotic expansions of the wave function at large positive and negative arguments. We then employ the leading asymptotic expressions to derive the WKB connection formula, which proceeds from classically forbidden region to classically allowed one through a turning point. By the WKB connection formula, we prove the Bohr-Sommerfeld quantization rule up to $\\mathcal{O}(\\beta)$. We also show that, if the slope of the potential at a turning point is too steep, the WKB connection formula fall apart around the turning point.

  1. Hazard development mechanism and deformation estimation of water solution mining area

    Institute of Scientific and Technical Information of China (English)

    HE Yue-guang; LI Zhi-wei; YANG Xiao-li

    2006-01-01

    Based on the hazard development mechanism, a water solution area is closely related to the supporting effect of pressure-bearing water, the relaxing and collapsing effect of orebody interlayer, the collapsing effect of thawless material in orebody,filling effect caused by cubical expansibility of hydrate crystallization and uplifting effect of hard rock layer over cranny belt. The movement and deformation of ground surface caused by underground water solution mining is believed to be much weaker than that caused by well lane mining, which can be predicted by the stochastic medium theory method. On the basis of analysis on the engineering practice of water solution mining, its corresponding parameters can be obtained from the in-site data of the belt water and sand filling mining in engineering analog approach.

  2. A Continuum Damage Mechanics Model to Predict Kink-Band Propagation Using Deformation Gradient Tensor Decomposition

    Science.gov (United States)

    Bergan, Andrew C.; Leone, Frank A., Jr.

    2016-01-01

    A new model is proposed that represents the kinematics of kink-band formation and propagation within the framework of a mesoscale continuum damage mechanics (CDM) model. The model uses the recently proposed deformation gradient decomposition approach to represent a kink band as a displacement jump via a cohesive interface that is embedded in an elastic bulk material. The model is capable of representing the combination of matrix failure in the frame of a misaligned fiber and instability due to shear nonlinearity. In contrast to conventional linear or bilinear strain softening laws used in most mesoscale CDM models for longitudinal compression, the constitutive response of the proposed model includes features predicted by detailed micromechanical models. These features include: 1) the rotational kinematics of the kink band, 2) an instability when the peak load is reached, and 3) a nonzero plateau stress under large strains.

  3. How stress and temperature conditions affect rock-fluid chemistry and mechanical deformation

    Directory of Open Access Journals (Sweden)

    Anders eNermoen

    2016-02-01

    Full Text Available We report the results from a series of chalk flow-through-compaction experiments performed at three effective stresses (0.5 MPa, 3.5 MPa and 12.3 MPa and two temperatures (92℃ and and 130℃. The results show that both stress and temperature are important to both chemical alteration and mechanical deformation. The experiments were conducted on cores drilled from the same block of outcrop chalks from the Obourg quarry within the Saint Vast formation (Mons, Belgium. The pore pressure was kept at 0.7 MPa for all experiments with a continuous flow of 0.219 M MgCl2 brine at a constant flow rate; 1 original pore volume (PV per day. The experiments have been performed in tri-axial cells with independent control of the external stress (hydraulic pressure in the confining oil, pore pressure, temperature, and the injected flow rate. Each experiment consists of two phases; a loading phase where stress-strain dependencies are investigated (approx. 2 days, and a creep phase that lasts for more than 150-160 days. During creep, the axial deformation was logged, and the effluent samples were collected for ion chromatography analyses. Any difference between the injected and produced water chemistry gives insight into the rock-fluid interactions that occur during flow through of the core. The observed effluent concentration shows a reduction in Mg2+, while the Ca2+ concentration is increased. This, together with SEM-EDS analysis, indicates that magnesium-bearing mineral phases are precipitated leading to dissolution of calcite, an observation . This is in-line with other flow-through experiments reported earlier. The observed dissolution and precipitation are sensitive to the effective stress and test temperature. Typically. H, higher stress and temperature lead to increased concentration differences of Mg2+ and Ca2+ concentration changes.. The observed strain can be partitioned additively into a mechanical and chemical driven component.

  4. How stress and temperature conditions affect rock-fluid chemistry and mechanical deformation

    Science.gov (United States)

    Nermoen, Anders; Korsnes, Reidar; Aursjø, Olav; Madland, Merete; Kjørslevik, Trygve Alexander; Østensen, Geir

    2016-02-01

    We report the results from a series of chalk flow-through-compaction experiments performed at three effective stresses (0.5 MPa, 3.5 MPa and 12.3 MPa) and two temperatures (92° and and 130°). The results show that both stress and temperature are important to both chemical alteration and mechanical deformation. The experiments were conducted on cores drilled from the same block of outcrop chalks from the Obourg quarry within the Saint Vast formation (Mons, Belgium). The pore pressure was kept at 0.7 MPa for all experiments with a continuous flow of 0.219 M MgCl2 brine at a constant flow rate; 1 original pore volume (PV) per day. The experiments have been performed in tri-axial cells with independent control of the external stress (hydraulic pressure in the confining oil), pore pressure, temperature, and the injected flow rate. Each experiment consists of two phases; a loading phase where stress-strain dependencies are investigated (approx. 2 days), and a creep phase that lasts for more than 150-160 days. During creep, the axial deformation was logged, and the effluent samples were collected for ion chromatography analyses. Any difference between the injected and produced water chemistry gives insight into the rock-fluid interactions that occur during flow through of the core. The observed effluent concentration shows a reduction in Mg2+, while the Ca2+ concentration is increased. This, together with SEM-EDS analysis, indicates that magnesium-bearing mineral phases are precipitated leading to dissolution of calcite, an observation . This is in-line with other flow-through experiments reported earlier. The observed dissolution and precipitation are sensitive to the effective stress and test temperature. Typically. H, higher stress and temperature lead to increased concentration differences of Mg2+ and Ca2+ concentration changes.. The observed strain can be partitioned additively into a mechanical and chemical driven component.

  5. Dependence of deformation mechanisms on grain orientations and their changes calculated based on Sachs model in magnesium alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    Qing-ge XIE; Ping YANG; Li MENG

    2008-01-01

    During deformation, the orientation of a grain influences not only the deformation mechanisms (slip or twinning) and the specific selection of activated slip or twinning systems for that grain, but also the kinetics of different types of transformation. Schmid factor analysis was applied to determine the orientation dependency of deformation mechanisms in magnesium alloys AZ31 in this work. The orientation changes after the operation of the specific deformation mechanisms were also calcu-lated based on Sachs model. It was found that different deformation mechanisms proceeded differently according to theoretical predictions. Basal slip occurred when basal planes of grains were tilted toward ND around TD. Prismatic slip dominated when basal planes were approxi-mately perpendicular to TD. Calculation results also indi-cated that the operating of pyramidal slip can not be neglected. {10 12} twinning was favorable when basal planes were approximately normal to RD and { 10 11 } twinning was analyzed to be related to the grains with basal orientations. The operating of slip could greatly suppress the activating of twinning by our Schmid factor analysis. Basal orientations with TD and RD scattering can favor basal slip and tension twinning, respectively, after the operation of compression twinning based on the Schmid factor calculations.

  6. Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

    Directory of Open Access Journals (Sweden)

    Karl Ulrich Kainer

    2012-08-01

    Full Text Available The hot deformation characteristics of AZ31 magnesium alloy rod extruded at temperatures of 300 °C, 350 °C and 450 °C have been studied in compression. The extruded material had a fiber texture with  parallel to the extrusion axis. When extruded at 450 °C, the texture was less intense and the  direction moved away from the extrusion axis. The processing maps for the material extruded at 300 °C and 350 °C are qualitatively similar to the material with near-random texture (cast-homogenized and exhibited three dynamic recrystallization (DRX domains. In domains #1 and #2, prismatic slip is the dominant process and DRX is controlled by lattice self-diffusion and grain boundary self-diffusion, respectively. In domain #3, pyramidal slip occurs extensively and DRX is controlled by cross-slip on pyramidal slip systems. The material extruded at 450 °C exhibited two domains similar to #1 and #2 above, which moved to higher temperatures, but domain #3 is absent. The results are interpreted in terms of the changes in  fiber texture with extrusion temperature. Highly intense  texture, as in the rod extruded at 350 °C, will enhance the occurrence of prismatic slip in domains #1 and #2 and promotes pyramidal slip at temperatures >450 °C (domain #3.

  7. Quantitative Mapping of Mechanisms for Photoinitiated Coating Degradation

    DEFF Research Database (Denmark)

    Kiil, Søren

    2015-01-01

    This work concerns the mathematical modeling of photoinitiated coating degradation. Using experimental evidence available, some of the most importantassumptions underlying existing models for the rmoset coatings are analyzed and suggestions for further work provided. A modeling approach that can...... be used toimplement the various effects of water on the degradation mechanisms of cross-linked coatings is also presented and experiments to test the approach are suggested. Additionally, simulations with an existing degradation model for an epoxy–amine coating are used to map the influence of model...... parameters on the lag time (i.e., the time passing prior to the onset of erosion) and the stable erosion rate. The simulation results can be used in the optimization of UV radiation-induced intercoat adhesion losses, which are often observed in multilayer coating systems based on top coated epoxy coatings...

  8. THE INFLUENCE OF GRAIN SIZE AND TEMPERATURE ON THE MECHANICAL DEFORMATION OF NANOCRYSTALLINE MATERIALS:MOLECULAR DYNAMICS SIMULATION

    Institute of Scientific and Technical Information of China (English)

    WEN YU-HUA; ZHOU FU-XIN; LIU YUE-WU

    2001-01-01

    Nanocrystalline (nc) materials are characterized by a typical grain size of 1-100nm. The uniaxial tensile deformation of computer-generated nc samples, with several average grain sizes ranging from 5.38 to 1.79nm, is simulated by using molecular dynamics with the Finnis-Sinclair potential. The influence of grain size and temperature on the mechanical deformation is studied in this paper. The simulated nc samples show a reverse Hall-Petch effect. Grain boundary sliding and motion, as well as grain rotation are mainly responsible for the plastic deformation. At low temperatures, partial dislocation activities play a minor role during the deformation. This role begins to occur at the strain of 5%, and is progressively remarkable with increasing average grain size. However, at elevated temperatures no dislocation activity is detected, and the diffusion of grain boundaries may come into play.

  9. Emerging spectra of singular correlation matrices under small power-map deformations

    Science.gov (United States)

    Vinayak; Schäfer, Rudi; Seligman, Thomas H.

    2013-09-01

    Correlation matrices are a standard tool in the analysis of the time evolution of complex systems in general and financial markets in particular. Yet most analysis assume stationarity of the underlying time series. This tends to be an assumption of varying and often dubious validity. The validity of the assumption improves as shorter time series are used. If many time series are used, this implies an analysis of highly singular correlation matrices. We attack this problem by using the so-called power map, which was introduced to reduce noise. Its nonlinearity breaks the degeneracy of the zero eigenvalues and we analyze the sensitivity of the so-emerging spectra to correlations. This sensitivity will be demonstrated for uncorrelated and correlated Wishart ensembles.

  10. Research of prediction for mine earthquake basing on underground rock's movement and deformation mechanism

    Institute of Scientific and Technical Information of China (English)

    LI Yong-jing

    2008-01-01

    Movement and deformation of underground rock include vertical dislocation and horizontal deformation, and the energy released by mine earthquake can be calculated basing on deformation energy. So put forwards the prediction for degree and spread of mine earthquake according to the underground rock's movement and deformation. The actual number of times and spread of mine earthquake on site were greatly identical to the prediction. The practice proves the possibility of prediction for mine earthquake basing on the analysis of underground rock's movement and deformation, and sets up new approach of mine earthquake prediction.

  11. Research of prediction for mine earthquake basing on underground rock's movement and deformation mechanism

    Institute of Scientific and Technical Information of China (English)

    LI Yong-jing

    2008-01-01

    Movement and deformation of underground rock include vertical dislocation and horizontal deformation,and the energy released by mine earthquake can be calculated basing on deformation energy.So put forwards the prediction for degree and spread of mine earthquake according to the underground rock's movement and deformation.The actual number of times and spread of mine earthquake on site were greatly identical to the prediction.The practice proves the possibility of prediction for mine earthquake basing on the analysis of underground rock's movement and deformation,and sets up new approach of mine earthquake prediction.

  12. STRUCTURAL AND MECHANICAL CHARACTERIZATION OF DEFORMED POLYMER USING CONFOCAL RAMAN MICROSCOPY AND DSC

    Directory of Open Access Journals (Sweden)

    Birgit Neitzel

    2016-02-01

    Full Text Available Polymers have various interesting properties, which depend largely on their inner structure. One way to influence the macroscopic behaviour is the deformation of the polymer chains, which effects the change in microstructure. For analyzing the microstructure of non-deformed and deformed polymer materials, Raman spectroscopy as well as differential scanning calorimetry (DSC were used. In the present study we compare the results for crystallinity measurements of deformed polymers using both methods in order to characterize the differences in micro-structure due to deformation. The study is ongoing, and we present the results of the first tests.

  13. The mechanisms of driving lithospheric deformation in India-Asia collision zone: a perspective from 3-D numerical modeling

    Science.gov (United States)

    Yang, Jianfeng; Kaus, Boris

    2016-04-01

    The mechanism of intraplate deformation remains incompletely understood by plate tectonics theory. The India-Asia collision zone is the largest present-day example of continental collision, which makes it an ideal location to study the processes of continental deformation. Existing models of lithospheric deformation are typically quasi two-dimensional and often assume that the lithosphere is a thin viscous sheet, which deforms homogeneously as a result of the collision, or flows above a partially molten lower crust, which explains the exhumation of Himalayan units and lateral spreading of Tibetan plateau. An opposing view is that most deformation localize in shear zones separating less deformed blocks, requiring the lithosphere to have an elasto-plastic rather than a viscous rheology. In order to distinguish which model best fits the observations we develop a 3-D visco-elasto-plastic model, which can model both distributed and highly localized deformation. In our preliminary result, most of the large-scale strike-slips faults including Altyn-Tagh fault, Xianshuihe fault, Red-River fault, Sagaing fault and Jiali fault can be simulated. The topography is consistent with observations that flat plateau in central Tibet and steep, abrupt margins adjacent to Sichuan basin, and gradual topography in southeast Tibet. These models suggest that the localized large-scale strike-slip faults accommodate the continental deformation. These results show the importance of a weak lower crust and topographic effects, as well as the effect of rheology and temperature structure of the lithosphere on the deformation patterns.

  14. Deformation Mechanisms of Carrara Marble Under Increasing Temperatures from 300℃ to 550℃

    Institute of Scientific and Technical Information of China (English)

    Ma Lijie; Liu Junlai; Li Haifeng; Wang Xiaoyong; Zhong Xinyong

    2000-01-01

    Deformation experiments of Carrara marble were conducted under increasing temperatures (temperatures 300℃~550℃ , confining pressure 0.5Mpa, strain - rate 5 × 10- 6 s-1). The experiments reveal that calcite rocks show different deformation behaviors and corresponding microstructural characteristics under different temperatures. By analyzing microstructural characteristics, preferred grain shape orientation variation of the primary rocks and deformed specimen, the deformation features of Carrara marble are summarized: twinning, fracturing dominates deformation of the rocks at temperatures between300℃ and 450℃; dynamic recrystallization occurs in the temperature range of 450~550℃; the brittle to crystalline plasticity transition deformation is observed at around 450℃, twinning and crystal - plastic deformation become dominant with further increasing temperature.

  15. Time-dependent deformation behavior of polyvinylidene fluoride binder: Implications on the mechanics of composite electrodes

    Science.gov (United States)

    Santimetaneedol, Arnuparp; Tripuraneni, Rajasekhar; Chester, Shawn A.; Nadimpalli, Siva P. V.

    2016-11-01

    The majority of existing battery models that simulate composite electrode behavior assume the binder as a linear elastic material due to lack of a thorough understanding of time-dependent mechanical behavior of binders. Here, thin films of polyvinylidene fluoride binder, prepared according to commercial battery manufacturing method, are subjected to standard monotonic, load-unload, and relaxation tests to characterize the time-dependent mechanical behavior. The strain in the binder samples is measured with the digital image correlation technique to eliminate experimental errors. The experimental data showed that for (charging/discharging) time scales of practical importance, polyvinylidene fluoride behaves more like an elastic-viscoplastic material as opposed to a visco-elastic material; based on this observation, a simple elastic-viscoplastic model, calibrated against the data is adopted to represent the deformation behavior of binder in a Si-based composite electrode; the lithiation/delithiation process of this composite was simulated at different C rates and the stress/strain behavior was monitored. It is observed that the linear elastic assumption of the binder leads to inaccurate results and the time-dependent constitutive behavior of the binder not only leads to accurate prediction of the mechanics but is an essential step towards developing advanced multi-physics models for simulating the degradation behavior of batteries.

  16. Texture evolution and deformation mechanism in friction stir welding of 2219Al

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S., E-mail: sjchen@bjut.edu.cn; Jiang, X.

    2014-08-26

    Texture evolution and deformation mechanism in the weld zones of friction stir welded 2219Al alloy have been investigated by the electron backscatter diffraction method. The weld zones are characterized by elongated structure in the base material, the heat affected zone and the thermo-mechanically affected zone and rotated elongated structure in the nugget zone. Four main texture components, Cube {001}〈100〉, Goss {011}〈100〉, Brass {011}〈211〉 and Cube ND {001}〈110〉 close to Cube component, were developed in the TMAZ, the HAZ and the nugget zone; S {123}〈634〉 was developed in the nugget zone only with Cube component orientated as their next neighbour and the nugget zone is dominated by Cube, Goss and S texture components. Cube grains in the nugget zone were formed by strain induced boundary migration mechanism (SIBM). Both variants of the texture components have two slip systems with the highest Schmid factors 0.42. Both Cube and Goss components slip on two planes (111) and (1{sup ¯}11). Relatively larger fractions of Σ3, Σ9 twin boundaries and Σ11, Σ29a boundaries have been found in the centre of the weld zone. Materials in the TMAZ have undergone dynamic recovery; geometric dynamic recrystallization (GDRX) occurred in the nugget zone.

  17. Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing

    Science.gov (United States)

    Mansoor, Bilal

    The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

  18. A study on role of nanosized SiO2 on deformation mechanism of vinyl ester

    Indian Academy of Sciences (India)

    D Dehghan Baniani; S A J Jahromi; S Mojtaba Zebarjad

    2014-12-01

    Vinyl ester (VE) resins have good resistance against corrosive and hostile environments, and formation of micro cracks. They also have good thermal resistivity as well as mechanical properties which result in their usage in many applications such as sewer pipes, solvent storage tanks, and mining and other industrial equipments. In the present work, nanosized silica was employed as reinforcement to improve VE mechanical properties. Hence, to study the influence of nanosilica particles on the tensile strength, Young’s modulus and toughness of mentioned nanocomposites, nanosilica-vinyl ester nanocomposites with different silica weight percentages (0.3, 0.75, 1) were fabricated. Moreover, the effects of nanosilica particles on the tensile fracture surfaces and VE deformation mechanisms were studied by scanning electron microscopy (SEM). It was observed that increasing the nanosilica fillers results in tensile strength deterioration as well as Young’s Modulus increasing. Adding nanosilica reinforcements up to 0.3 (%wt) improves the fracture toughness while decreasing the fracture energy.

  19. Ore body shapes versus regional deformation patterns as a base for 3D prospectivity mapping in the Skellefte Mining District, Sweden

    Science.gov (United States)

    Bauer, T.; Skyttä, P.; Hermansson, T.; Weihed, P.

    2012-04-01

    The current work in progress is based on detailed structural analysis carried out during the last years, which unravels the crustal evolution of the ore bearing Palaeoproterozoic Skellefte District in northern Sweden. The shape and orientation of the volcanic-hosted massive sulfide (VMS) ore bodies through the district is modeled in three dimensions and reflected against the regional deformation patterns. By doing this we aim to understand the coupling between the transposition of the ore bodies and the deformation structures in the host rocks, honoring both local deformation features and regional structural transitions. The VMS ore bodies are modeled in gOcad (Paradigm) visualizing both the strike and dip of the ore lenses as well as their dimensions. 25 deposits are currently available in 3D and modelling of the remaining 55 deposits is planned or partly in progress. The ore deposits and mineralizations are classified according to their shape and size. The complexly deformed ore bodies are described each independently. Subsequently, the VMS deposits are plotted on the structural map of the Skellefte district displaying their size and strike, dip and plunge values in order to show their spatial distribution and their relationship with shear zones. The preliminary results show a good correlation between the shape and orientation of the ore bodies and the related structures. Plotting the VMS deposits on a structural map clearly demonstrates the close spatial relation of the ore deposits and regional scale shear zones. Furthermore, the deformation style within the ore deposits generally mimics the deformation style of the shear zones, e.g. the plunge of elongate ore bodies parallels the mineral lineation of the related shear zone. Based on these results, the location and shape of ore deposits may be estimated, which is an important tool for prospectivity mapping and near mine exploration of ore districts.

  20. Statistical model for the mechanical behavior of the tissue engineering non-woven fibrous matrices under large deformation.

    Science.gov (United States)

    Rizvi, Mohd Suhail; Pal, Anupam

    2014-09-01

    The fibrous matrices are widely used as scaffolds for the regeneration of load-bearing tissues due to their structural and mechanical similarities with the fibrous components of the extracellular matrix. These scaffolds not only provide the appropriate microenvironment for the residing cells but also act as medium for the transmission of the mechanical stimuli, essential for the tissue regeneration, from macroscopic scale of the scaffolds to the microscopic scale of cells. The requirement of the mechanical loading for the tissue regeneration requires the fibrous scaffolds to be able to sustain the complex three-dimensional mechanical loading conditions. In order to gain insight into the mechanical behavior of the fibrous matrices under large amount of elongation as well as shear, a statistical model has been formulated to study the macroscopic mechanical behavior of the electrospun fibrous matrix and the transmission of the mechanical stimuli from scaffolds to the cells via the constituting fibers. The study establishes the load-deformation relationships for the fibrous matrices for different structural parameters. It also quantifies the changes in the fiber arrangement and tension generated in the fibers with the deformation of the matrix. The model reveals that the tension generated in the fibers on matrix deformation is not homogeneous and hence the cells located in different regions of the fibrous scaffold might experience different mechanical stimuli. The mechanical response of fibrous matrices was also found to be dependent on the aspect ratio of the matrix. Therefore, the model establishes a structure-mechanics interdependence of the fibrous matrices under large deformation, which can be utilized in identifying the appropriate structure and external mechanical loading conditions for the regeneration of load-bearing tissues.

  1. Molecular and nanostructural mechanisms of deformation, strength and toughness of spider silk fibrils.

    Science.gov (United States)

    Nova, Andrea; Keten, Sinan; Pugno, Nicola M; Redaelli, Alberto; Buehler, Markus J

    2010-07-14

    Spider dragline silk is one of the strongest, most extensible and toughest biological materials known, exceeding the properties of many engineered materials including steel. Silk features a hierarchical architecture where highly organized, densely H-bonded beta-sheet nanocrystals are arranged within a semiamorphous protein matrix consisting of 3(1)-helices and beta-turn protein structures. By using a bottom-up molecular-based approach, here we develop the first spider silk mesoscale model, bridging the scales from Angstroms to tens to potentially hundreds of nanometers. We demonstrate that the specific nanoscale combination of a crystalline phase and a semiamorphous matrix is crucial to achieve the unique properties of silks. Our results reveal that the superior mechanical properties of spider silk can be explained solely by structural effects, where the geometric confinement of beta-sheet nanocrystals, combined with highly extensible semiamorphous domains, is the key to reach great strength and great toughness, despite the dominance of mechanically inferior chemical interactions such as H-bonding. Our model directly shows that semiamorphous regions govern the silk behavior at small deformation, unraveling first when silk is being stretched and leading to the large extensibility of the material. Conversely, beta-sheet nanocrystals play a significant role in defining the mechanical behavior of silk at large-deformation. In particular, the ultimate tensile strength of silk is controlled by the strength of beta-sheet nanocrystals, which is directly related to their size, where small beta-sheet nanocrystals are crucial to reach outstanding levels of strength and toughness. Our results and mechanistic insight directly explain recent experimental results, where it was shown that a significant change in the strength and toughness of silk can be achieved solely by tuning the size of beta-sheet nanocrystals. Our findings help to unveil the material design strategy that

  2. Effect of Cold Deformation on Phase Evolution and Mechanical Properties in an Austenitic Stainless Steel for Structural and Safety Applications

    Institute of Scientific and Technical Information of China (English)

    S K Ghosh; P Mallick; P P Chattopadhyay

    2012-01-01

    The effects of cold deformation on the formation of strain induced α’ martensite and mechanical properties of an austenitic stainless steel have been examined.X-ray diffraction analysis has revealed that 30% and 40% cold rolling have resulted in the formation of 24% and 31.5% martensite respectively.Microstructural investigation has demonstrated that the formation of martensite is enhanced with increase in the percent deformation at 0 ℃.Investigation of mechanical properties reveals that hardness,yield strength and tensile strength values increase where as percent elongation drops with increasing deformation.The fractographic observation corroborates the tensile results.Examination of sub-surface at the fractured end of the tensile sample manifests that void/microcrack nucleation occurs in the interfacial regions of the martensite phase as well as at the austenite-martensite interface

  3. Influence of Heat Treatment Conditions on Microstructure and Mechanical Properties of Austempered Ductile Iron After Dynamic Deformation Test

    Directory of Open Access Journals (Sweden)

    Myszka D.

    2014-10-01

    Full Text Available In this article, an attempt was made to determine the effect of dynamic load on the austempered ductile iron resistance obtained under different conditions of heat treatment. Tests were carried out on six types of cylindrical ductile iron samples austempered at 320, 370 and 400oC for 30 and 180 minutes. For each type of material, two samples were collected. As a next step in the investigations, the samples were subjected to a Taylor impact test. The samples after striking a non-deformable, rigid target were deformed on their front face. After Taylor test, a series of material tests was performed on these samples, noting a significant increase of hardness in the deformed part. This was particularly well visible in the ductile iron isothermally quenched at higher temperatures of 370 and 400oC. Inthezone of sample deformation, an increase in the content of ferromagnetic phase was also reported, thus indicating the occurrence of martensitic transformation in the microstructure containing mechanically unstable austenite. A significant amount of deformed graphite was also observed, which was a symptom of the deformation process taking place in samples. The ductile iron was characterized by high toughness and high resistance to the effect of dynamic loads, especially as regards the grade treated at a temperature of 370oC.

  4. Mechanical Properties and Microstructures of Ni20Cr Micro-wires with Abnormal Plastic Deformation

    Science.gov (United States)

    Zhou, Xiuwen; Liu, Xudong; Qi, Yidong; Wu, Weidong

    2017-05-01

    Ni80Cr20 (Ni20Cr, wt%) micro-wires were fabricated by the cold-drawing method with single die. Abnormal engineering strains were approximately 17.3-46.6 % for each pass. The relationship between mechanical properties and microstructures of Ni20Cr micro-wires were investigated under different engineering strains and annealing conditions. Experiment results indicate that the as-drawn NiCr micro-wires present obviously brittle fractures. The ultimate tensile strength (UTS) significantly increases from 781 to 1,147 MPa and the elongation decreases from 17.2 % to 1 % with engineering strains increasing. The deformed microstructures of Ni20Cr micro-wire were analyzed in detail including two-phase (solid solution/amorphous phase), edge dislocations and twins. With the annealing temperature increasing, specimens had experienced three stages and their mechanical properties were improved. After annealing at 890 °C (with 6.5 g stress) for 7.3 s in N2, the Ni20Cr micro-wires benefited for the second drawing pass. The results are very importance in fabricating Ni20Cr micro-wire with the diameter from 25 to 10 μm.

  5. Resurgence structure to all orders of multi-bions in deformed SUSY quantum mechanics

    Science.gov (United States)

    Fujimori, Toshiaki; Kamata, Syo; Misumi, Tatsuhiro; Nitta, Muneto; Sakai, Norisuke

    2017-08-01

    We investigate the resurgence structure in quantum mechanical models originating in 2d nonlinear sigma models with emphasis on nearly supersymmetric and quasi-exactly solvable parameter regimes. By expanding the ground state energy in powers of a supersymmetry-breaking deformation parameter δ ɛ, we derive exact results for the expansion coefficients. In the class of models described by real multiplets, the O(δɛ) ground state energy has a non-Borel summable asymptotic series, which gives rise to imaginary ambiguities leading to rich resurgence structure. We discuss sine-Gordon quantum mechanics (QM) as an example and show that the semiclassical contributions from complex multi-bion solutions correctly reproduce the corresponding part in the exact result including the imaginary ambiguities. As a typical model described by chiral multiplets, we discuss CP^{N-1} QM and show that the exact O(δɛ) ground state energy can be completely reconstructed from the semiclassical multi-bion contributions. Although the O(δɛ) ground state energy has trivial resurgence structure, a simple but rich resurgence structure appears at O(δɛ2). We show the complete cancelation between the O(δɛ2) imaginary ambiguities arising from the non-Borel summable perturbation series and those in the semiclassical contributions of N-1 complex bion solutions. We also discuss the resurgence structure of a squashed {C}P^1 QM.

  6. Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica

    Science.gov (United States)

    Lamarque, Gaëlle; Bascou, Jérôme; Maurice, Claire; Cottin, Jean-Yves; Riel, Nicolas; Ménot, René-Pierre

    2016-06-01

    The Mertz shear zone (MSZ) is a lithospheric scale structure that recorded mid-crustal deformation during the 1.7 Ga orogeny. We performed a microstructural and crystallographic preferred orientation (CPO) study of samples from both mylonites and tectonic boudins that constitute relics of the Terre Adélie Craton (TAC). The deformation is highly accommodated in the MSZ by anastomosed shear bands, which become more scattered elsewhere in the TAC. Most of the MSZ amphibolite-facies mylonites display similar CPO, thermal conditions, intensity of deformation and dominant shear strain. Preserved granulite-facies boudins show both coaxial and non-coaxial strains related to the previous 2.45 Ga event. This former deformation is more penetrative and less localized and shows a deformation gradient, later affected by a major phase of recrystallization during retrogression at 2.42 Ga. Both MSZ samples and granulite-facies tectonic boudins present microstructures that reflect a variety of deformation mechanisms associated with the rock creep that induce contrasted CPO of minerals (quartz, feldspar, biotite, amphibole and orthopyroxene). In particular, we highlight the development of an "uncommon" CPO in orthopyroxene from weakly deformed samples characterized by (010)-planes oriented parallel to the foliation plane, [001]-axes parallel to the stretching lineation and clustering of [100]-axes near the Y structural direction. Lastly, we computed the seismic properties of the amphibolite and granulite facies rocks in the MSZ area in order to evaluate the contribution of the deformed intermediate and lower continental crust to the seismic anisotropy recorded above the MSZ. Our results reveal that (i) the low content of amphibole and biotite in the rock formations of the TAC, and (ii) the interactions between the CPO of the different mineralogical phases, generate a seismically isotropic crust. Thus, the seismic anisotropy recorded by the seismic stations of the TAC, including the

  7. Deformation mechanism of leukocyte adhering to vascular surface under steady shear flow

    Institute of Scientific and Technical Information of China (English)

    LIU; Xiaoheng; WANG; Xiong; YIN; Hongmei; CHEN; Huaiqing

    2004-01-01

    The adhesion of leukocytes to vascular surface is an important biomedical problem and has drawn extensive attention. In this study, we propose a compound drop model to simulate a leukocyte with a nucleus adhering to the surface of blood vessel under steady shear flow. A two-dimensional computational fluid dynamics (CFD) is conducted to determine the local distribution of pressure on the surface of the adherent model cell. By introducing the parameter of deformation index (DI), we investigate the deformation of the leukocyte and its nucleus under controlled conditions. Our numerical results show that: (i) the leukocyte is capable of deformation under external exposed flow field. The deformation index increases with initial contact angle and Reynolds number of external exposed flow. (ii) The nucleus deforms with the cell, and the deformation index of the leukocyte is greater than that of the nucleus. The leukocyte is more deformable while the nucleus is more capable of resisting external shear flow. (iii) The leukocyte and the nucleus are not able to deform infinitely with the increase of Reynolds number because the deformation index reaches a maximum. (iv) Pressure distribution confirms that there exists a region downstream of the cell, which produces high pressure to retard continuous deformation and provide a positive lift force on the cell. Meanwhile, we have measured the deformation of human leukocytes exposed to shear flow by using a flow chamber system. We found that the numerical results are well consistent with those of experiment. We conclude that the nucleus with high viscosity plays a particular role in leukocyte deformation.

  8. PSI Deformation Map Retrieval by Means of Temporal Sublook Coherence on Reduced Sets of SAR Images

    Directory of Open Access Journals (Sweden)

    Rubén Iglesias

    2015-01-01

    Full Text Available Prior to the application of any persistent scatterer interferometry (PSI technique for the monitoring of terrain displacement phenomena, an adequate pixel selection must be carried out in order to prevent the inclusion of noisy pixels in the processing. The rationale is to detect the so-called persistent scatterers, which are characterized by preserving their phase quality along the multi-temporal set of synthetic aperture radar (SAR images available. Two criteria are mainly available for the estimation of pixels’ phase quality, i.e., the coherence stability and the amplitude dispersion or permanent scatterers (PS approach. The coherence stability method allows an accurate estimation of the phase statistics, even when a reduced number of SAR acquisitions is available. Unfortunately, it requires the multi-looking of data during the coherence estimation, leading to a spatial resolution loss in the final results. In contrast, the PS approach works at full-resolution, but it demands a larger number of SAR images to be reliable, typically more than 20. There is hence a clear limitation when a full-resolution PSI processing is to be carried out and the number of acquisitions available is small. In this context, a novel pixel selection method based on exploiting the spectral properties of point-like scatterers, referred to as temporal sublook coherence (TSC, has been recently proposed. This paper seeks to demonstrate the advantages of employing PSI techniques by means of TSC on both orbital and ground-based SAR (GB-SAR data when the number of images available is small (10 images in the work presented. The displacement maps retrieved through the proposed technique are compared, in terms of pixel density and phase quality, with traditional criteria. Two X-band datasets composed of 10 sliding spotlight TerraSAR-X images and 10 GB-SAR images, respectively, over the landslide of El Forn de Canillo (Andorran Pyrenees, are employed for this study. For both

  9. Mapping and Measuring the Microrelief of Slope Deformations Using Modern Contactless Technologies and Practical Application in Territorial Planning

    Science.gov (United States)

    Chudý, František; Slámová, Martina; Tomaštík, Julián; Kardoš, Miroslav; Tunák, Daniel; Saloň, Šimon

    2017-04-01

    Slope deformations are risks limiting economic land use potential. A national database system keeps records of slope disturbances and deformations, however, it is important to update the information mainly from the point of view of practical territorial planning, especially in the high-risk areas presented in the study. The paper explains the possibilities of applying modern methods of mapping the microrelief of slope deformations of a lower extent (up to several hundreds of m2) and using not very well known contactless technologies, which could be applied in practice due to their low-cost and low-time consuming nature. In order to create a digital model of the microrelief used to carry out the measurements we applied the method of terrestrial photogrammetry, terrestrial scanning using Lenovo Phab 2Pro. It is the first device available for users that uses the Google Tango technology. So far there have been only prototypes of devices available for the developers only. The Tango technology consists of 3 partial technologies - "depth perception" (measuring the distance to objects, nowadays it uses mainly infrared radiation), "motion tracking" (tracking the position and motion of the device using embedded sensors) and "area learning" (simply learning the area, where the device looks for same objects within already existing 3D models and real space). Even though the technology utilisation is nowadays presented mainly in the field of augmented reality and navigation in the interior, there are already some applications for collecting the point clouds in real time, which can be used in a wide spectrum of applications in exterior, which was also applied in our research. Data acquired this way can be processed in readily available software products, what enabled a high degree of automation also in our case. After comparing with the reference point field that was measured using GNSS and electronic tachymeter, we reached accuracy of point position determination from a digital

  10. Three-dimensional (3D) coseismic deformation map produced by the 2014 South Napa Earthquake estimated and modeled by SAR and GPS data integration

    Science.gov (United States)

    Polcari, Marco; Albano, Matteo; Fernández, José; Palano, Mimmo; Samsonov, Sergey; Stramondo, Salvatore; Zerbini, Susanna

    2016-04-01

    In this work we present a 3D map of coseismic displacements due to the 2014 Mw 6.0 South Napa earthquake, California, obtained by integrating displacement information data from SAR Interferometry (InSAR), Multiple Aperture Interferometry (MAI), Pixel Offset Tracking (POT) and GPS data acquired by both permanent stations and campaigns sites. This seismic event produced significant surface deformation along the 3D components causing several damages to vineyards, roads and houses. The remote sensing results, i.e. InSAR, MAI and POT, were obtained from the pair of SAR images provided by the Sentinel-1 satellite, launched on April 3rd, 2014. They were acquired on August 7th and 31st along descending orbits with an incidence angle of about 23°. The GPS dataset includes measurements from 32 stations belonging to the Bay Area Regional Deformation Network (BARDN), 301 continuous stations available from the UNAVCO and the CDDIS archives, and 13 additional campaign sites from Barnhart et al, 2014 [1]. These data constrain the horizontal and vertical displacement components proving to be helpful for the adopted integration method. We exploit the Bayes theory to search for the 3D coseismic displacement components. In particular, for each point, we construct an energy function and solve the problem to find a global minimum. Experimental results are consistent with a strike-slip fault mechanism with an approximately NW-SE fault plane. Indeed, the 3D displacement map shows a strong North-South (NS) component, peaking at about 15 cm, a few kilometers far from the epicenter. The East-West (EW) displacement component reaches its maximum (~10 cm) south of the city of Napa, whereas the vertical one (UP) is smaller, although a subsidence in the order of 8 cm on the east side of the fault can be observed. A source modelling was performed by inverting the estimated displacement components. The best fitting model is given by a ~N330° E-oriented and ~70° dipping fault with a prevailing

  11. Absorption spectroscopy of single red blood cells in the presence of mechanical deformations induced by optical traps

    Science.gov (United States)

    Wojdyla, Michal; Raj, Saurabh; Petrov, Dmitri

    2012-09-01

    The electronic properties of single human red blood cells under mechanical deformations were investigated using a combination of dual beam optical tweezers and UV-vis absorption spectroscopy. The mechanical deformations were induced by two near-infrared optical traps with different trapping powers and trap configurations. The deformations were applied in two ways: locally, due to the mechanical forces around the traps, and by stretching the cell by moving the traps in opposite directions. In the presence of local deformations, the single cell undergoes a transition from an oxygenated state to a partially deoxygenated state. This process was found to be reversible and strongly power-dependent. Stretching the cell caused an opposite effect, indicating that the electronic response of the whole cell is dominated by the local interaction with the trapping beams. Results are discussed considering light-induced local heating, the Stark effect, and biochemical alterations due to mechanical forces, and are compared with reports of previous Raman spectroscopy studies. The information gained by the analysis of a single red blood cell's electronic response facilitates the understanding of fundamental physiological processes and sheds further light on the cell's mechanochemistry. This information may offer new opportunities for the diagnosis and treatment of blood diseases.

  12. Analysis of the thermo-mechanical deformations in a hot forging tool by numerical simulation

    Science.gov (United States)

    L-Cancelos, R.; Varas, F.; Martín, E.; Viéitez, I.

    2016-03-01

    Although programs have been developed for the design of tools for hot forging, its design is still largely based on the experience of the tool maker. This obliges to build some test matrices and correct their errors to minimize distortions in the forged piece. This phase prior to mass production consumes time and material resources, which makes the final product more expensive. The forging tools are usually constituted by various parts made of different grades of steel, which in turn have different mechanical properties and therefore suffer different degrees of strain. Furthermore, the tools used in the hot forging are exposed to a thermal field that also induces strain or stress based on the degree of confinement of the piece. Therefore, the mechanical behaviour of the assembly is determined by the contact between the different pieces. The numerical simulation allows to analyse different configurations and anticipate possible defects before tool making, thus, reducing the costs of this preliminary phase. In order to improve the dimensional quality of the manufactured parts, the work presented here focuses on the application of a numerical model to a hot forging manufacturing process in order to predict the areas of the forging die subjected to large deformations. The thermo-mechanical model developed and implemented with free software (Code-Aster) includes the strains of thermal origin, strains during forge impact and contact effects. The numerical results are validated with experimental measurements in a tooling set that produces forged crankshafts for the automotive industry. The numerical results show good agreement with the experimental tests. Thereby, a very useful tool for the design of tooling sets for hot forging is achieved.

  13. Personalized Map Symbol Design Mechanism Based on Linguistics

    Directory of Open Access Journals (Sweden)

    LI Wei

    2015-03-01

    Full Text Available The personalization and intelligence of map service ultimately reflects in their symbol design. By establishing conceptual models of personalized map symbols, a theoretical discussion of the symbols is launched from a perspective which both human perceptions and logistic comprehension are considered in this paper, thus to help analyzing the relationship among geographic objects, map symbols and the interpretation of users and exploring the design basis of personalized map symbol. According to some key points such as relevant linguistic theories, the interpretation of the symbol contexts and symbolic statement syntax, design strategies of personalized map symbols is parsed. Thus, methods and processes of personalized map symbol design are proposed accordingly, following by experiments which could verify the hypothesis.

  14. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, Bachu Narain

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly...

  15. Deformation and reconstruction mechanisms in coarse-grained superplastic Al-Mg alloys

    NARCIS (Netherlands)

    Soer, W. A.; Chezan, A. R.; De Hosson, J. Th. M.

    2006-01-01

    This paper concentrates on the superplastic response of fine-grained and coarse-grained Al-Mg alloys under uniaxial tension. To identify the main characteristics of superplastic deformation and to determine the optimum deformation parameters, the microstructure and dislocation substructure of the al

  16. Effect of Cooling Start Temperature on Microstructure and Mechanical Properties of X80 High Deformability Pipeline Steel

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiao-fei; KANG Yong-lin; MENG De-liang; AN Shou-yong; XIA Dian-xiu

    2011-01-01

    The effect of cooling (laminar cooling) start temperature on the phase constitution was analyzed by quanti- tative metallography. The martensite/austenite (M/A) island distribution was fixed by colour metallography. The strength and uniform elongation of the steels were tested with quasi-static tensile testing machine. The in-coordinate deformation of the soft and hard phases was analyzed using FEM. The results indicate that when the cooling start temperature is 690 ℃, the mechanical properties are the best, meeting the requirements of X80 high deformability pipeline steel.

  17. Slip as the basic mechanism for formation of deformation relief structural elements

    Science.gov (United States)

    Lychagin, D. V.; Alfyorova, E. A.

    2017-07-01

    The experimental results of investigation of the nickel single crystal surface morphology after compression deformation are presented. The quasi-periodic character of the deformation profile, common for shear deformation of different types of relief structural elements, is found. It is demonstrated that the morphological manifestation of these structural elements is determined by local shear systems along octahedral planes. The regularities of the deformation structure in these regions defining the material extrusion and intrusion regions and the specific features of disorientation accumulation are established. If reorientation of local regions takes part in the relief element formation, along with octahedral slip, much stronger growth of the surface area is observed. The possibility of application of two-dimensional and three-dimensional surface roughness parameters for description of deformation relief is considered.

  18. Spatial features of dose-surface maps from deformably-registered plans correlate with late gastrointestinal complications

    Science.gov (United States)

    Moulton, Calyn R.; House, Michael J.; Lye, Victoria; Tang, Colin I.; Krawiec, Michele; Joseph, David J.; Denham, James W.; Ebert, Martin A.

    2017-05-01

    This study investigates the associations between spatial distribution of dose to the rectal surface and observed gastrointestinal toxicities after deformably registering each phase of a combined external beam radiotherapy (EBRT)/high-dose-rate brachytherapy (HDRBT) prostate cancer treatment. The study contains data for 118 patients where the HDRBT CT was deformably-registered to the EBRT CT. The EBRT and registered HDRBT TG43 dose distributions in a reference 2 Gy/fraction were 3D-summed. Rectum dose-surface maps (DSMs) were obtained by virtually unfolding the rectum surface slice-by-slice. Associations with late peak gastrointestinal toxicities were investigated using voxel-wise DSM analysis as well as parameterised spatial patterns. The latter were obtained by thresholding DSMs from 1-80 Gy (increment  =  1) and extracting inferior-superior extent, left-right extent, area, perimeter, compactness, circularity and ellipse fit parameters. Logistic regressions and Mann-Whitney U-tests were used to correlate features with toxicities. Rectal bleeding, stool frequency, diarrhoea and urgency/tenesmus were associated with greater lateral and/or longitudinal spread of the high doses near the anterior rectal surface. Rectal bleeding and stool frequency were also influenced by greater low-intermediate doses to the most inferior 20% of the rectum and greater low-intermediate-high doses to 40-80% of the rectum length respectively. Greater low-intermediate doses to the superior 20% and inferior 20% of the rectum length were associated with anorectal pain and urgency/tenesmus respectively. Diarrhoea, completeness of evacuation and proctitis were also related to greater low doses to the posterior side of the rectum. Spatial features for the intermediate-high dose regions such as area, perimeter, compactness, circularity, ellipse eccentricity and confinement to ellipse fits were strongly associated with toxicities other than anorectal pain. Consequently, toxicity is

  19. Effect of the compaction platform on the densification parameters of tableting excipients with different deformation mechanisms.

    Science.gov (United States)

    Rojas, John; Hernandez, Santiago

    2014-01-01

    Several compaction models have been attempted to explain the compression and compaction phenomena of excipients. However, the resulting parameters could be influenced by the compaction platform such as dwell time, compact mass, geometry and type of material. The goal of this study is to assess the effect of these variables on the densification parameters obtained from key models such as Heckel, non-linear Heckel, Kawakita, Carstensen, and Leuenberger. The relationship among the parameters derived was determined by employing a Principal Component Analysis. Results indicated that factors such as compact geometry, consolidation time and compact mass had a negligible impact on parameters such as tensile strength, yield pressure and compressibility. On the contrary, the excipient type had the largest influence on these parameters. Further, the Leuenberger (γ) and Carstensen (f) parameters were highly correlated and related to the excipient deformation mechanism. Sorbitol and PVP-k30 were the most highly compactable excipients and were characterized for having a low yield pressure (P(y)), compressibility (a), and critical porosity (ε(c)). The magnitude of these parameters was highly dependent on the consolidation behavior of each material.

  20. The influence of deformation on barbell mechanics during the clean pull.

    Science.gov (United States)

    Chiu, Loren Z F; Schilling, Brian K; Fry, Andrew C; Salem, George J

    2008-05-01

    For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, nondeformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90-155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5-30% (P 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre.

  1. Microstructural mechanisms of cyclic deformation, fatigue crack initiation and early crack growth.

    Science.gov (United States)

    Mughrabi, Haël

    2015-03-28

    In this survey, the origin of fatigue crack initiation and damage evolution in different metallic materials is discussed with emphasis on the responsible microstructural mechanisms. After a historical introduction, the stages of cyclic deformation which precede the onset of fatigue damage are reviewed. Different types of cyclic slip irreversibilities in the bulk that eventually lead to the initiation of fatigue cracks are discussed. Examples of trans- and intercrystalline fatigue damage evolution in the low cycle, high cycle and ultrahigh cycle fatigue regimes in mono- and polycrystalline face-centred cubic and body-centred cubic metals and alloys and in different engineering materials are presented, and some microstructural models of fatigue crack initiation and early crack growth are discussed. The basic difficulties in defining the transition from the initiation to the growth of fatigue cracks are emphasized. In ultrahigh cycle fatigue at very low loading amplitudes, the initiation of fatigue cracks generally occupies a major fraction of fatigue life and is hence life controlling.

  2. Cyclic Deformation of Advanced High-Strength Steels: Mechanical Behavior and Microstructural Analysis

    Science.gov (United States)

    Hilditch, Timothy B.; Timokhina, Ilana B.; Robertson, Leigh T.; Pereloma, Elena V.; Hodgson, Peter D.

    2009-02-01

    The fatigue properties of multiphase steels are an important consideration in the automotive industry. The different microstructural phases present in these steels can influence the strain life and cyclic stabilized strength of the material due to the way in which these phases accommodate the applied cyclic strain. Fully reversed strain-controlled low-cycle fatigue tests have been used to determine the mechanical fatigue performance of a dual-phase (DP) 590 and transformation-induced plasticity (TRIP) 780 steel, with transmission electron microscopy (TEM) used to examine the deformed microstructures. It is shown that the higher strain life and cyclic stabilized strength of the TRIP steel can be attributed to an increased yield strength. Despite the presence of significant levels of retained austenite in the TRIP steel, both steels exhibited similar cyclic softening behavior at a range of strain amplitudes due to comparable ferrite volume fractions and yielding characteristics. Both steels formed low-energy dislocation structures in the ferrite during cyclic straining.

  3. Mechanical Properties and Atomic Explanation of Plastic Deformation for Diamond-Like BC2

    Directory of Open Access Journals (Sweden)

    Baobing Zheng

    2016-06-01

    Full Text Available Motivated by a recently predicted structure of diamond-like BC2 with a high claimed hardness of 56 GPa (J. Phys. Chem. C 2010, 114, 22688–22690, we focus on whether this tetragonal BC2 (t-BC2 is superhard or not in spite of such an ultrahigh theoretical hardness. The mechanical properties of t-BC2 were thus further extended by using the first principles in the framework of density functional theory. Our results suggest that the Young’s and shear moduli of t-BC2 exhibit a high degree of anisotropy. For the weakest shear direction, t-BC2 undergoes an electronic instability and structural collapse upon a shear strain of about 0.11, with its theoretically ideal strength of only 36.2 GPa. Specifically, the plastic deformation under shear strain along the (110[001] direction can be attributed to the breaking of d1 B–C bonds.

  4. Evaluation of the Mechanical Properties of AA 6063 Processed by Severe Plastic Deformation

    Science.gov (United States)

    Jafarlou, Davoud Mashhadi; Zalnezhad, Erfan; Hamouda, Abdelmagid Salem; Faraji, Ghader; Mardi, Noor Azizi Bin; Hassan Mohamed, Mohsen Abdelnaeim

    2015-05-01

    In this study, the mechanical properties, including surface hardness, tensile strength, fatigue, and fretting fatigue behavior of AA 6063 processed by equal channel angular pressing as the most efficient severe shear plastic deformation (SPD) technique, were investigated. Following the SPD process, samples were subjected to heat treatment (HT), hard anodizing (HA), and a combination of HT and HA. Rotating-bending fretting fatigue tests were performed to explore the samples' response to the fretting condition. From the experimental fatigue and fretting fatigue tests, it was apparent that the SPD treatment had a positive effect on enhancing the fatigue and fretting fatigue lives of the samples at low and high-cyclic loads compared with the HT technique by 78 and 67 pct, and 131 and 154 pct respectively. The results also indicate that the SPD + HT technique significantly increased the fatigue and fretting fatigue lives of the samples at high and low cycles by 15.56 and 8.33 pct, and 14.4 and 5.1 pct respectively, compared with the SPD method. HA of AA6063 increased the fatigue and fretting fatigue lives of SPD + HT-processed samples at low cycle by 15.5 and 18.4 pct respectively; however, at high cycle, HA had reverse effects, whereby the fatigue and fretting fatigue lives of SPD + HT-processed samples decreased by 16.7 and 30 pct, respectively.

  5. q-deformed statistical-mechanical property in the dynamics of trajectories en route to the Feigenbaum attractor.

    Science.gov (United States)

    Robledo, A; Moyano, L G

    2008-03-01

    We demonstrate that the dynamics toward and within the Feigenbaum attractor combine to form a q -deformed statistical-mechanical construction. The rate at which ensemble trajectories converge to the attractor (and to the repellor) is described by a q entropy obtained from a partition function generated by summing distances between neighboring positions of the attractor. The values of the q indices involved are given by the unimodal map universal constants, while the thermodynamic structure is closely related to that formerly developed for multifractals. As an essential component in our demonstration we expose, in great detail, the features of the dynamics of trajectories that either evolve toward the Feigenbaum attractor or are captured by its matching repellor. The dynamical properties of the family of periodic superstable cycles in unimodal maps are seen to be key ingredients for the comprehension of the discrete scale invariance features present at the period-doubling transition to chaos. Elements in our analysis are the following. (i) The preimages of the attractor and repellor of each of the supercycles appear entrenched into a fractal hierarchical structure of increasing complexity as period doubling develops. (ii) The limiting form of this rank structure results in an infinite number of families of well-defined phase-space gaps in the positions of the Feigenbaum attractor or of its repellor. (iii) The gaps in each of these families can be ordered with decreasing width in accordance with power laws and are seen to appear sequentially in the dynamics generated by uniform distributions of initial conditions. (iv) The power law with log-periodic modulation associated with the rate of approach of trajectories toward the attractor (and to the repellor) is explained in terms of the progression of gap formation. (v) The relationship between the law of rate of convergence to the attractor and the inexhaustible hierarchy feature of the preimage structure is elucidated

  6. Dolomite microstructures between 390° and 700 °C: Indications for deformation mechanisms and grain size evolution

    Science.gov (United States)

    Berger, Alfons; Ebert, Andreas; Ramseyer, Karl; Gnos, Edwin; Decrouez, Danielle

    2016-08-01

    Dolomitic marble on the island of Naxos was deformed at variable temperatures ranging from 390 °C to >700 °C. Microstructural investigations indicate two end-member of deformation mechanisms: (1) Diffusion creep processes associated with small grain sizes and weak or no CPO (crystallographic preferred orientation), whereas (2) dislocation creep processes are related with larger grain sizes and strong CPO. The change between these mechanisms depends on grain size and temperature. Therefore, sample with dislocation and diffusion creep microstructures and CPO occur at intermediate temperatures in relative pure dolomite samples. The measured dolomite grain size ranges from 3 to 940 μm. Grain sizes at Tmax >450 °C show an Arrhenius type evolution reflecting the stabilized grain size in deformed and relative pure dolomite. The stabilized grain size is five times smaller than that of calcite at the same temperature and shows the same Arrhenius-type evolution. In addition, the effect of second phase particle influences the grain size evolution, comparable with calcite. Calcite/dolomite mixtures are also characterized by the same difference in grain size, but recrystallization mechanism including chemical recrystallization induced by deformation may contribute to apparent non-temperature equilibrated Mg-content in calcite.

  7. Dislocation-accommodated grain boundary sliding as the major deformation mechanism of olivine in the Earth's upper mantle.

    Science.gov (United States)

    Ohuchi, Tomohiro; Kawazoe, Takaaki; Higo, Yuji; Funakoshi, Ken-Ichi; Suzuki, Akio; Kikegawa, Takumi; Irifune, Tetsuo

    2015-10-01

    Understanding the deformation mechanisms of olivine is important for addressing the dynamic processes in Earth's upper mantle. It has been thought that dislocation creep is the dominant mechanism because of extrapolated laboratory data on the plasticity of olivine at pressures below 0.5 GPa. However, we found that dislocation-accommodated grain boundary sliding (DisGBS), rather than dislocation creep, dominates the deformation of olivine under middle and deep upper mantle conditions. We used a deformation-DIA apparatus combined with synchrotron in situ x-ray observations to study the plasticity of olivine aggregates at pressures up to 6.7 GPa (that is, ~200-km depth) and at temperatures between 1273 and 1473 K, which is equivalent to the conditions in the middle region of the upper mantle. The creep strength of olivine deforming by DisGBS is apparently less sensitive to pressure because of the competing pressure-hardening effect of the activation volume and pressure-softening effect of water fugacity. The estimated viscosity of olivine controlled by DisGBS is independent of depth and ranges from 10(19.6) to 10(20.7) Pa·s throughout the asthenospheric upper mantle with a representative water content (50 to 1000 parts per million H/Si), which is consistent with geophysical viscosity profiles. Because DisGBS is a grain size-sensitive creep mechanism, the evolution of the grain size of olivine is an important process controlling the dynamics of the upper mantle.

  8. Mechanism of rock deformation and failure and monitoring analysis in water-rich soft rock roadway of western China

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-bin; HAN Li-jun; QIAO Wei-guo; LIN Deng-ge; YANG Ling

    2012-01-01

    Aiming to get the strata behavior and stability rules of surrounding rock of the main return airway of Yushujing Coal Mine,convergence deformation of two sides and force of U-shaped steel yieldable support and bolt were monitored,and deformation of surrounding rock and mechanical characteristics of support structure were timely obtained to guide the information construction and optimize supporting parameters in water-rich soft rock roadway.The field monitoring results indicate the following.(1) Convergence displacement of rock surface increases with time continuity and shows surrounding rock's intense rheological behavior.The original support scheme cannot control the large deformation and strongly rheological behavior;(2) Without backfilling,the U-shaped steel support begins to bear load after erecting for 4-7 days and increases rapidly in the first 30 days.The U-shaped steel support at the right shoulder and top of roadway bears a larger force and the left side and shoulder bears a smaller force; (3) The stress of bolt increasing over time and at the right shoulder of roadway has larger growth and value.The mechanism of rock deformation and the failure and strata behavior in water-rich soft rock roadway are revealed based on the results of the measured relaxation zone of surrounding rock,measured stresses,and the rock mechanics tests.

  9. A multiscale approach for the deformation mechanism in pearlite microstructure: Experimental measurements of strain distribution using a novel technique of precision markers

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Masaki, E-mail: masaki@zaiko.kyushu-u.ac.jp [Department of Materials Science and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Yoshimi, Yusuke; Higashida, Kenji [Department of Materials Science and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Shimokawa, Tomotsugu [School of Mechanical Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Ohashi, Tetsuya [Kitami Institute of Technology, 165 Koencho, Kitami 090-8507 (Japan)

    2014-01-10

    Plastic deformation of fully pearlitic steels was investigated using a multiscale approach: experimentally, the finite element method and molecular dynamics. This paper is the first in a series of three papers demonstrating the strain distribution in uniaxial tensile deformation with high-precision markers drawn by electron beam lithography. Strain was measured at loads of 1.98 kN, 2.21 kN and 2.28 kN in tensile deformation. Scanning electron microscopy (SEM) images and strain maps show the plastic deformation of cementite lamellae and homogenous plastic deformation under uniaxial tensile deformation in the area where the cementite lamellae are aligned in the tensile direction. The areas where strain was enhanced were both block/colony boundaries and the areas where the cementite lamellae are inclined approximately 45° to the tensile direction.

  10. Effects of Fault Segmentation, Mechanical Interaction, and Structural Complexity on Earthquake-Generated Deformation

    Science.gov (United States)

    Haddad, David Elias

    Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that nearly half of Earth's human population lives along active fault zones, a quantitative understanding of the mechanics of earthquakes and faulting is necessary to build accurate earthquake forecasts. My research relies on the quantitative documentation of the geomorphic expression of large earthquakes and the physical processes that control their spatiotemporal distributions. The first part of my research uses high-resolution topographic lidar data to quantitatively document the geomorphic expression of historic and prehistoric large earthquakes. Lidar data allow for enhanced visualization and reconstruction of structures and stratigraphy exposed by paleoseismic trenches. Lidar surveys of fault scarps formed by the 1992 Landers earthquake document the centimeter-scale erosional landforms developed by repeated winter storm-driven erosion. The second part of my research employs a quasi-static numerical earthquake simulator to explore the effects of fault roughness, friction, and structural complexities on earthquake-generated deformation. My experiments show that fault roughness plays a critical role in determining fault-to-fault rupture jumping probabilities. These results corroborate the accepted 3-5 km rupture jumping distance for smooth faults. However, my simulations show that the rupture jumping threshold distance is highly variable for rough faults due to heterogeneous elastic strain energies. Furthermore, fault roughness controls spatiotemporal variations in slip rates such that rough faults exhibit lower slip rates relative to their smooth counterparts. The central implication of these results lies in guiding the

  11. Surface analysis and mechanical behaviour mapping of vertically aligned CNT forest array through nanoindentation

    Science.gov (United States)

    Koumoulos, Elias P.; Charitidis, C. A.

    2017-02-01

    Carbon nanotube (CNT) based architectures have increased the scientific interest owning to their exceptional performance rendering them promising candidates for advanced industrial applications in the nanotechnology field. Despite individual CNTs being considered as one of the most known strong materials, much less is known about other CNT forms, such as CNT arrays, in terms of their mechanical performance (integrity). In this work, thermal chemical vapor deposition (CVD) method is employed to produce vertically aligned multiwall (VA-MW) CNT carpets. Their structural properties were studied by means of scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Raman spectroscopy, while their hydrophobic behavior was investigated via contact angle measurements. The resistance to indentation deformation of VA-MWCNT carpets was investigated through nanoindentation technique. The synthesized VA-MWCNTs carpets consisted of well-aligned MWCNTs. Static contact angle measurements were performed with water and glycerol, revealing a rather super-hydrophobic behavior. The structural analysis, hydrophobic behavior and indentation response of VA-MWCNTs carpets synthesized via CVD method are clearly demonstrated. Additionally, cycle indentation load-depth curve was applied and hysteresis loops were observed in the indenter loading-unloading cycle due to the local stress distribution. Hardness (as resistance to applied load) and modulus mapping, at 200 nm of displacement for a grid of 70 μm2 is presented. Through trajection, the resistance is clearly divided in 2 regions, namely the MWCNT probing and the in-between area MWCNT - MWCNT interface.

  12. Mechanism of crustal deformation in the Sichuan-Yunnan region, southeastern Tibetan Plateau: Insights from numerical modeling

    Science.gov (United States)

    Li, Yujiang; Liu, Shaofeng; Chen, Lianwang; Du, Yi; Li, Hong; Liu, Dongying

    2017-09-01

    The characteristics of crustal deformation and its dynamical mechanisms in the Sichuan-Yunnan region are of interest to many researchers because they can help explain the deformation pattern of the eastern Tibetan Plateau. In this paper, we employ a precise three-dimensional viscoelastic finite element model to simulate the crustal deformation in the Sichuan-Yunnan region, southeastern Tibetan Plateau. We investigate the influence of lower crustal flow and rheological variations by comparing the modeled results with GPS observations. The results demonstrate that lower crustal flow plays an important role in crustal deformation in the Sichuan-Yunnan region. The best fitting is achieved when the flow velocity of the lower crust is approximately 10-11 mm/a faster than that of the upper crust. Additionally, crustal rheological properties affect regional crustal deformation. When the viscosity of the middle and lower crust in the South China block reaches 1022 and 1023 Pa·s, respectively, the modeled results match observations well, especially for the magnitude of crustal motion within the South China block. Finally, our dynamic model shows that the maximum principal stress field of the Sichuan-Yunnan region exhibits clear zoning, gradually shifting from an approximately east-west orientation in the northern Bayan Har block to southeast in the South China block, southwest in the western Yunnan block, and a radially divergent distribution in the Middle Yunnan and Southern Yunnan blocks.

  13. Control technology and coordination deformation mechanism of rise entry group with high ground stress

    Institute of Scientific and Technical Information of China (English)

    Li Qingfeng; Zhu Quanqu

    2012-01-01

    Based on engineering practices of Wuyang Coal Mine,we carried out X-ray diffract researches on No.3 coal; and the rocks of its roof and floor by XRD meter,and simulated the interactive effect of the surrounding rock deformation by FLAC2D5.0 numerical simulation software under the condition of different tunneling method of multimine roadway in parallel.The internal structures of the surrounding rocks of 76 belt roadway were monitored by borehole observation instruments; and then,we analyzed the reason of failure and deformation of surrounding rocks of several rise entry,and proposed the technical measures for controlling interactive effect of several rise entry surrounding rock deformation at last.For the thickness seam rise roadway,two conclusions were drawn:one is that the co-deformation among roadway groups mainly reflecton that both shear failure and deformation in coal pillar among roadways have decreased the width of pillar core region and clamping action of coal pillar to roof strata,increased the actual span of roof strata,intensified the flexural failure of roof strata and prized the bed separation of roof deep rock strata.The other conclusion is that the factors controlling the interactive deformation among roadways is obvious when appropriate re-adjustment in construction sequence of the tunneling of multimine parallel roadways because the construction sequence among roadways also has great effects on deformation of the surrounding rock in roadway.

  14. The role of mechanical heterogeneities in evaporite sequence during deformation initiated by basement fault activity

    Science.gov (United States)

    Adamuszek, Marta; Dabrowski, Marcin; Burliga, Stanisław

    2016-04-01

    Kłodawa Salt Structure (KSS) situated in the centre of the Polish Zechstein Basin started to rise above a basement fault in the Early Triassic. Geological studies of the KSS revealed significant differences in the deformation patterns between the PZ1-PZ2 (intensely deformed) and PZ3-PZ4 (less deformed) cycle evaporites. These two older and two younger cycle evaporite complexes are separated by the thick Main Anhydrite (A3) bed. We use numerical simulations to assess the impact of a thick anhydrite bed on intrasalt deformation. In our models, the overburden consists of clastic sediments. A normal fault located in the rigid basement beneath the salt is activated due to model extension. At the same time, the sedimentation process takes place. The evaporites consist of a salt bed intercalated with a thick anhydrite layer of varying position and geometry. To understand the role of anhydrite layer, we run comparative simulations, in which no anhydrite layer is present. In the study, we use our own numerical codes implemented in MATLAB combined with the MILAMIN and MUTILS numerical packages. Our investigations revealed a significant influence of the anhydrite on deformation style in the evaporate series. The supra-anhydrite domain is characterized by weaker deformation and lower rates of salt flow in comparison to the sub-anhydrite domain. The highest contrast in the rate of salt flow between the two domains is observed in the case of the anhydrite layer situated close to the bottom of the salt complex. The thick anhydrite layer additionally diminishes the deformation rate in the supra-anhydrite domain and can lead to detachment of the basement deformation from its overlay. Our numerical simulations showed that the presence of the A3 Main Anhydrite bed could be the dominant factor responsible for the decoupling of deformation in the KSS salt complex.

  15. Molecular dynamics simulation on mechanical property of carbon nanotube torsional deformation

    Institute of Scientific and Technical Information of China (English)

    Chen Ming-Jun; Liang Ying-Chun; Li Hong-Zhu; Li Dan

    2006-01-01

    In this paper torsional deformation of the carbon nanotubes is simulated by molecular dynamics method. The Brenner potential is used to set up the simulation system. Simulation results show that the carbon nanotubes can bear larger torsional deformation, for the armchair type (10,10) single wall carbon nanotubes, with a yielding phenomenon taking place when the torsional angle is up to 63°(1.1rad). The influence of carbon nanotube helicity in torsional deformation is very small. The shear modulus of single wall carbon nanotubes should be several hundred GPa, not 1 GPa as others reports.

  16. Competition between inverse piezoelectric effect and deformation potential mechanism in undoped GaAs revealed by ultrafast acoustics

    Directory of Open Access Journals (Sweden)

    Pezeril T.

    2013-03-01

    Full Text Available By using the picosecond ultrasonics technique, piezoelectric effect in GaAs undoped sample at both faces (A[111] and B[-1-1-1] is experimentally studied. We demonstrate that piezoelectric generation of sound can dominate in GaAs material over the deformation potential mechanism even in the absence of static externally applied or built-in electric field in the semiconductor material. In that case, the Dember field, caused by the separation of photo-generated electrons and holes in the process of supersonic diffusion, is sufficient for the dominance of the piezoelectric mechanism during the optoacoustic excitation. The experimental results on the sample at both faces reveal that in one case (A face, the two mechanisms, piezoelectric effect and deformation potential, can compensate each other leading to a large decrease of the measured Brillouin oscillation magnitude.

  17. Large deformation diffeomorphic metric mapping registration of reconstructed 3D histological section images and in vivo MR images

    Directory of Open Access Journals (Sweden)

    Can Ceritoglu

    2010-05-01

    Full Text Available Our current understanding of neuroanatomical abnormalities in neuropsychiatric diseases is based largely on magnetic resonance imaging (MRI and post mortem histological analyses of the brain. Further advances in elucidating altered brain structure in these human conditions might emerge from combining MRI and histological methods. We propose a multistage method for registering 3D volumes reconstructed from histological sections to corresponding in vivo MRI volumes from the same subjects: (1 manual segmentation of white matter (WM, gray matter (GM and cerebrospinal fluid (CSF compartments in histological sections, (2 alignment of consecutive histological sections using 2D rigid transformation to construct a 3D histological image volume from the aligned sections, (3 registration of reconstructed 3D histological volumes to the corresponding 3D MRI volumes using 3D affine transformation, (4 intensity normalization of images via histogram matching and (5 registration of the volumes via intensity based Large Deformation Diffeomorphic Metric (LDDMM image matching algorithm. Here we demonstrate the utility of our method in the transfer of cytoarchitectonic information from histological sections to identify regions of interest in MRI scans of nine adult macaque brains for morphometric analyses. LDDMM improved the accuracy of the registration via decreased distances between GM/CSF surfaces after LDDMM (0.39±0.13 mm compared to distances after affine registration (0.76±0.41 mm. Similarly, WM/GM distances decreased to 0.28±0.16 mm after LDDMM compared to 0.54±0.39 mm after affine registration. The multistage registration method may find broad application for mapping histologically based information, e.g., receptor distributions, gene expression, onto MRI volumes.

  18. Static and Metadynamic Recrystallization of Low Carbon Steels During Mechanical Deformation

    Institute of Scientific and Technical Information of China (English)

    沈丙振; 方能炜; 沈厚发; 柳百成

    2004-01-01

    Static and metadynamic recrystallization models were developed with the coefficients determined by multiple nonlinear regression analyses to describe microstructure evolution in low carbon steels. The effects of initial grain size, deformation temperature, strain, and strain rate on the austenitic recrystallized volume fraction and grain size were studied using a Gleeble machine. The results show that deformation reduces the grain size when the recrystallized volume fraction is large. The static recrystallized volume fraction increases with increasing deformation temperature, strain, and strain rate, and decreasing initial grain size. The grain size during metadynamic recrystallization is independent of the deformation strain and the initial grain size. The recrystallized volume fraction, the grain size, and the grown grain size calculated by the correlations are consistent with the measured values.

  19. Investigation of microstructure and mechanical properties of hot worked NiAl bronze alloy with different deformation degree

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yuting; Wang, Liqiang, E-mail: wang_liqiang@sjtu.edu.cn; Han, Yuanfei; Xu, Xiaoyan; Lu, Weijie, E-mail: luweijie@sjtu.edu.cn

    2015-09-03

    In this study, the forged NiAl bronze (NAB) were hot rolled with the deformation degree of 40%, 60%, 80%, 90% and 95% at 850 °C, respectively. Effects of rolling deformation degree on the microstructure and mechanical properties of the NAB alloy were investigated. Scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) methods were used to characterize the microstructure. The results show that α grains are refined by the dynamic recovery and recrystallization, penetration of β phase into α phase and particle-stimulated nucleation (PSN) of recrystallization during rolling. The refined grains make a main contribution to the increase of mechanical properties of rolled NAB. When the deformation degree is increased to 80%, the optimum tensile properties with ultimate strength of 861.3±8.5 MPa, yield strength of 634.5±7 MPa and elongation of 19.3±0.05% is obtained. With further increasing the deformation degree, the strength of rolled NAB alloy increase and the elongation decrease due to the increase of work hardening effect and the formation of martensitic nano-twins.

  20. Confocal microscopy-based three-dimensional cell-specific modeling for large deformation analyses in cellular mechanics.

    Science.gov (United States)

    Slomka, Noa; Gefen, Amit

    2010-06-18

    This study introduces a new confocal microscopy-based three-dimensional cell-specific finite element (FE) modeling methodology for simulating cellular mechanics experiments involving large cell deformations. Three-dimensional FE models of undifferentiated skeletal muscle cells were developed by scanning C2C12 myoblasts using a confocal microscope, and then building FE model geometries from the z-stack images. Strain magnitudes and distributions in two cells were studied when the cells were subjected to compression and stretching, which are used in pressure ulcer and deep tissue injury research to induce large cell deformations. Localized plasma membrane and nuclear surface area (NSA) stretches were observed for both the cell compression and stretching simulation configurations. It was found that in order to induce large tensile strains (>5%) in the plasma membrane and NSA, one needs to apply more than approximately 15% of global cell deformation in cell compression tests, or more than approximately 3% of tensile strains in the elastic plate substrate in cell stretching experiments. Utilization of our modeling can substantially enrich experimental cellular mechanics studies in classic cell loading designs that typically involve large cell deformations, such as static and cyclic stretching, cell compression, micropipette aspiration, shear flow and hydrostatic pressure, by providing magnitudes and distributions of the localized cellular strains specific to each setup and cell type, which could then be associated with the applied stimuli.

  1. The influence of metallic shell deformation on the contact mechanics of a ceramic-on-ceramic total hip arthroplasty.

    Science.gov (United States)

    Qiu, Changdong; Wang, Ling; Li, Dichen; Jin, Zhongmin

    2016-01-01

    Total hip arthroplasty of ceramic-on-ceramic bearing combinations is increasingly used clinically. The majority of these implants are used with cementless fixation that a metal-backing shell is press-fitted into the pelvic bone. This usually results in the deformation of the metallic shell, which may also influence the ceramic liner deformation and consequently the contact mechanics between the liner and the femoral head under loading. The explicit dynamic finite element method was applied to model the implantation of a cementless ceramic-on-ceramic with a titanium shell and subsequently to investigate the effect of the metallic shell deformation on the contact mechanics. A total of three impacts were found to be necessary to seat the titanium alloy shell into the pelvic bone cavity with a 1 mm diameter interference and a 1.3 kg impactor at 4500 mm s(-1) velocity. The maximum deformation of the metallic shell was found to be 160 µm in the antero-superior and postero-inferior direction and 97 µm in the antero-inferior and postero-superior direction after the press-fit. The corresponding values were slightly reduced to 67 and 45 µm after the ceramic liner was inserted and then modified to 74 and 43 µm under loading, respectively. The maximum deformation and the maximum principal stress of the ceramic liner were 31 µm and 144 MPa (tensile stress), respectively, after it was inserted into the shell and further increased to 52 µm and 245 MPa under loading. This research highlights the importance of the press-fit of the metallic shell on the contact mechanics of the ceramic liner for ceramic-on-ceramic total hip arthroplasties and potential clinical performances.

  2. Structural ensembles of the north belt of Venus deformations and possible mechanisms of their formation

    Science.gov (United States)

    Markov, M. S.

    1986-01-01

    The author discusses structural formations in the northern deformation belt of Venus, studied according to the data of the radar pictures obtained with the Venera 15 and 16 probes. He shows that it consists of regions of compression with submeridional orientation, regions of displacement, extending in the sublatitudinal direction and individual slightly deformed blocks. He puts forward the hypothesis that the formation of these structures is related with horizontal movements in the mantle in the sublatitudinal direction.

  3. EXPERIMENTAL ANALYSIS TO IDENTIFY THE DEFORMATION MECHANISMS DURING SINTERING OF COLD COMPACTED POLYTETRAFLUOROETHYLENE (PTFE) POWDERS

    OpenAIRE

    Canto, Rodrigo,; Schmitt, Nicolas; Carvalho, Jonas; Billardon, René R.

    2009-01-01

    Soumis; International audience; Thermal dilatometry analyses were performed on specimens made of pure or filled PTFE powders. The specimens were obtained by isostatic pressing or by uniaxial compaction up to different values of the residual void ratio. The large deformations that were recorded during different heating-cooling treatments strongly depend on the mode and level of compaction, as well as on the presence or the absence of fillers. Besides, these deformations are strongly anisotropi...

  4. The mechanical properties of austenite stainless steel 304 after structural deformation through cold work

    Energy Technology Data Exchange (ETDEWEB)

    Mubarok, Naila; Manaf, Azwar, E-mail: azwar@ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Notonegoro, Hamdan Akbar [Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa,Cilegon 42435 (Indonesia); Thosin, Kemas Ahmad Zaini [Pusat Penelitian Fisika,LIPI, Serpong (Indonesia)

    2016-06-17

    The 304 stainless steel (SS) type is widely used in oil and gas operations due to its excellent corrosion resistance. However, the presence of the fine sand particles and H{sub 2}S gas contained in crude oil could lead the erosion and abrasion in steel. In this study, cold rolled treatments were conducted to the 304 SS in order to increase the wear resistance of the steel. The cold work has resulted in thickness reduction to 20%, 40% and 60% of the original. Various microstructural characterizations were used to analyze the effect of deformation. The hardness characterization showed that the initial hardness value increased from 145 HVC to 395 HVC as the level of deformation increase. Further, the wear resistance increased with the deformation rate from 0% to 40% and subsequently decreased from 40% to 60% deformation rate. Microstructural characterization shows that the boundary change to coincide by 56 µm, 49 µm, 45 µm, and 43 µm width and the grain go to flatten and being folded like needles. The effect of deformation on the grain morphology and structure was also studied by optical metallography and X-Ray Diffraction. It is shown that the deformation by means of a cold rolled process has transformed the austenite structure into martensitic structure.

  5. Mechanical analysis of temperature impact on stability during superplastic tensile deformation

    Institute of Scientific and Technical Information of China (English)

    SONG; Yuquan; GUAN; Zhiping; WANG; Minghui; SONG; Jiawang

    2006-01-01

    Based on state equation that stress is the function of strain, strain-rate and temperature, the paper establishes the differential constitutive equation used for analyzing load-stability and the variational constitutive equation used for analyzing geometry-stability during superplastic tensile deformation, which contain strain hardening index, strain-rate sensitivity index, temperature sensitivity index introducted for the first time and temperature undulation index introducted for the first time in the paper. And then, based on the universal condition of plastic elementary theory, the paper analyzes load-stability and geometry-stability under continuously rising temperature and under the non-uniform temperature along the axes of specimen respectively. The results prove the impact of continuously rising speed and non-uniform value of temperature on deformation stability is that the faster temperature rises and the more non-uniform temperature is, the smaller the corresponding uniform strain of load-stability and geometry-stability are; strain hardening index is the necessary condition of stability during superplastic tensile deformation, and geometry-instability will not happen when load-instability occurs, but happen when uniform deformation has lasted after load-instability; in the superplastic temperature field, constant temperature is not necessary condition of superplasticitiy, but during the deformation, the slower temperature rises and the more uniform temperature is, the more stable deformation is.

  6. High-strain-induced deformation mechanisms in block-graft and multigraft copolymers

    KAUST Repository

    Schlegel, Ralf

    2011-12-13

    The molecular orientation behavior and structural changes of morphology at high strains for multigraft and block-graft copolymers based on polystyrene (PS) and polyisoprene (PI) were investigated during uniaxial monotonic loading via FT-IR and synchrotron SAXS. Results from FT-IR revealed specific orientations of PS and PI segments depending on molecular architecture and on the morphology, while structural investigations revealed a typical decrease in long-range order with increasing strain. This decrease was interpreted as strain-induced dissolution of the glassy blocks in the soft matrix, which is assumed to affect an additional enthalpic contribution (strain-induced mixing of polymer chains) and stronger retracting forces of the network chains during elongation. Our interpretation is supported by FT-IR measurements showing similar orientation of rubbery and glassy segments up to high strains. It also points to highly deformable PS domains. By synchrotron SAXS, we observed in the neo-Hookean region an approach of glassy domains, while at higher elongations the intensity of the primary reflection peak was significantly decreasing. The latter clearly verifies the assumption that the glassy chains are pulled out from the domains and are partly mixed in the PI matrix. Results obtained by applying models of rubber elasticity to stress-strain and hysteresis data revealed similar correlations between the softening behavior and molecular and morphological parameters. Further, an influence of the network modality was observed (random grafted branches). For sphere forming multigraft copolymers the domain functionality was found to be less important to achieve improved mechanical properties but rather size and distribution of the domains. © 2011 American Chemical Society.

  7. Mechanical and structural aspects of high temperature deformation in Ni alloy

    Directory of Open Access Journals (Sweden)

    A. Nowotnik

    2008-02-01

    Full Text Available Purpose: Experimental results on hot deformation and dynamic structural processes of nickel based alloy were reviewed. The attention was given to the analysis of dynamic structural processes which operate during hot deformation of the material.Design/methodology/approach: Hot compression tests were performed on solution treated precipitations hardenable nickel based superalloy of Inconel 718 within a temperature range of 720-1150°C at constant true strain rates of 10-4, 4x10-4s-1. The flow stress curves and microstructure of deformed nickel based superalloy were presented.Findings: During hot compression of solution treated material, highly localized flow was observed at relatively low deformation temperatures 720 - 850°C. The particle distribution and their morphology were not found to be affected by localized flow within the investigated strain range. At low strain rate the shear banding and intergranular cracks and cavities growth were found to be responsible for the observed flow stress decrease at 720, 800 and 850°C and might result in a sample fracture at larger strains.Research limitations/implications: In spite of intense strain hardening due to deformation and phase transformation overlapping, light optical microstructure observation of deformed samples did not reveal significant effects of heterogeneous distribution of the phase components. Therefore, in order to complete and confirm obtained results it is recommended to perform further analysis of the alloy by using transmission electron microscopy technique (TEM.Practical implications: An interaction between dynamic precipitation and flow localization may become an important feature of high temperature performance and may also allow producing specific structures of materials.Originality/value: The contribution of flow localization to the strain hardening or flow softening and the flow stress-strain behavior during hot deformation of precipitation hardenable alloys is still a

  8. Microstructures and deformation mechanisms in Opalinus Clay: insights from scaly clay from the Main Fault in the Mont Terri Rock Laboratory (CH)

    Science.gov (United States)

    Laurich, Ben; Urai, Janos L.; Nussbaum, Christophe

    2017-01-01

    The Main Fault in the shaly facies of Opalinus Clay is a small reverse fault formed in slightly overconsolidated claystone at around 1 km depth. The fault zone is up to 6 m wide, with micron-thick shear zones, calcite and celestite veins, scaly clay and clay gouge. Scaly clay occurs in up to 1.5 m wide lenses, providing hand specimens for this study. We mapped the scaly clay fabric at 1 m-10 nm scale, examining scaly clay for the first time using broad-ion beam polishing combined with scanning electron microscopy (BIB-SEM). Results show a network of thin shear zones and microveins, separating angular to lensoid microlithons between 10 cm and 10 µm in diameter, with slickensided surfaces. Our results show that microlithons are only weakly deformed and that strain is accumulated by fragmentation of microlithons by newly formed shear zones, by shearing in the micron-thick zones and by rearrangement of the microlithons.The scaly clay aggregates can be easily disintegrated into individual microlithons because of the very low tensile strength of the thin shear zones. Analyses of the microlithon size by sieving indicate a power-law distribution model with exponents just above 2. From this, we estimate that only 1 vol % of the scaly clay aggregate is in the shear zones.After a literature review of the hypotheses for scaly clay generation, we present a new model to explain the progressive formation of a self-similar network of anastomosing thin shear zones in a fault relay. The relay provides the necessary boundary conditions for macroscopically continuous deformation. Localization of strain in thin shear zones which are locally dilatant, and precipitation of calcite veins in dilatant shear fractures, evolve into complex microscale re-partitioning of shear, forming new shear zones while the microlithons remain much less deformed internally and the volume proportion of the µm-thick shear zones slowly increases. Grain-scale deformation mechanisms are microfracturing

  9. Effect of various mechanical deformation processes on critical current density and microstructure in MgB2 tapes and wires

    Science.gov (United States)

    Zhou, Sihai; Pan, Alexey V.; Liu, Huakun; Horvat, Joseph; Dou, Shixue

    2002-11-01

    MgB2 tapes and wires have been prepared by the in situ reaction method. Two cycle drawing and groove-rolling were used for the mechanic deformation of the samples. The critical current density, Jc, as a function of applied magnetic field, Ba, was measured and compared for all the prepared samples. The influence of the different processing at its different stages on the MgB2 microstructure was studied by scanning electron microscopy. Weak links introduced in the superconducting core after the second cycle mechanical deformation could not be re-joined with a consecutive heat treatment. Accordingly, for these samples Jc(Ba) turned out to decrease significantly faster in an increasing field than for samples prepared with one-cycle processing.

  10. Effects of Austempering after Hot Deformation on the Mechanical Properties of Hot Rolled Si-Mn TRIP Steel Sheets

    Institute of Scientific and Technical Information of China (English)

    LI Zhuang; ZHANG Ping-li; WU Di

    2004-01-01

    Excellent mechanical properties are obtained by austempering after hot deformation without subsequent heat treatment in the present Si-Mn TRIP steel sheets. Isothermal holding time after finishing rolling has affected the mechanical properties of this steel. The results show that the sample exhibits a good combination of ultimate tensile strength and total elongation when it is held at the bainite transformation temperature after hot deformation. The stability of retained austenite increases with an increase of isothermal holding time, and a further increase in the holding duration results in a decrease of it. The tensile strength, total elongation and strength ductility reach the maximum values(774MPa, 33% and 25542MPa% respectively) for this sort of hot rolled Si-Mn TRIP steel using the optimal technology.

  11. Effect of bimodal harmonic structure design on the deformation behaviour and mechanical properties of Co-Cr-Mo alloy.

    Science.gov (United States)

    Vajpai, Sanjay Kumar; Sawangrat, Choncharoen; Yamaguchi, Osamu; Ciuca, Octav Paul; Ameyama, Kei

    2016-01-01

    In the present work, Co-Cr-Mo alloy compacts with a unique bimodal microstructural design, harmonic structure design, were successfully prepared via a powder metallurgy route consisting of controlled mechanical milling of pre-alloyed powders followed by spark plasma sintering. The harmonic structured Co-Cr-Mo alloy with bimodal grain size distribution exhibited relatively higher strength together with higher ductility as compared to the coarse-grained specimens. The harmonic Co-Cr-Mo alloy exhibited a very complex deformation behavior wherein it was found that the higher strength and the high retained ductility are derived from fine-grained shell and coarse-grained core regions, respectively. Finally, it was observed that the peculiar spatial/topological arrangement of stronger fine-grained and ductile coarse-grained regions in the harmonic structure promotes uniformity of strain distribution, leading to improved mechanical properties by suppressing the localized plastic deformation during straining.

  12. Actuation Mechanism of Two-step Reverse Transformation Behavior in TiNi Alloys Deformed at Parent Phase

    Institute of Scientific and Technical Information of China (English)

    HUAILi-min; CUILi-shan; ZHANGLai-bin; ZHENGYan-jun

    2004-01-01

    The actuation mechanism of TiNi shape memory alloy wires, which were deformed at parentphase followed by a cooling process under constant strain constraint, was investigated. The experimental resuhsshow that the two-step reverse martensitic transformation behavior occurs during the heating process, and the tem-perature range of reverse transformation was olwiously widened with the increasing of prestrain,The recovery strainvs temperature curves exhibits an actuation eharaeteristic of linear output recovery strain in a wide temperaturerange.

  13. Influence of the Repetitive Corrugation on the Mechanism Occuring During Plastic Deformation of CuSn6 Alloy

    OpenAIRE

    Nuckowski P. M.; Kwaśny W.; Rdzawski Z.; Głuchowski W.; Pawlyta M.

    2016-01-01

    This paper presents the research results of CuSn6 alloy strip at semi-hard state, plastically deformed in the process of repetitive corrugation. The influence of process parameters on the mechanical properties and structure of examined alloy were investigated. Examination in high-resolution transmission electron microscopy (HRTEM) confirmed the impact of the repetitive corrugation to obtain the nano-scale structures. It has been found, that the application of repetitive corrugation increases ...

  14. The Features of Microstructure and Mechanical Properties of Metastable Austenitic Steel Subjected to Low-Temperature and Subsequent Warm Deformation

    Science.gov (United States)

    Litovchenko, I. Yu.; Akkuzin, S. A.; Polekhina, N. A.; Tyumentsev, A. N.; Naiden, E. P.

    2016-10-01

    The features of microstructure and phase composition of metastable austenitic steel subjected to thermomechanical treatment, including low-temperature processing accompanied by warm rolling deformation, are investigated. Direct (γ → α΄) and reverse strain-induced martensitic transformations are shown to take place, followed by the formation of submicrocrystalline states and 3-4-fold increase in the yield point values. The mechanisms of formation of submicrocrystalline states and the reasons for increased strength are discussed.

  15. MAPPING FLOW LOCALIZATION PROCESSES IN DEFORMATION OF IRRADIATED REACTOR STRUCTURAL ALLOYS - FINAL REPORT. Nuclear Energy Research Initiative Program No. MSF99-0072. Period: August 1999 through September 2002. (ORNL/TM-2003/63)

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K.

    2003-09-26

    Metals that can sustain plastic deformation homogeneously throughout their bulk tend to be tough and malleable. Often, however, if a metal has been hardened it will no longer deform uniformly. Instead, the deformation occurs in narrow bands on a microscopic scale wherein stresses and strains become concentrated in localized zones. This strain localization degrades the mechanical properties of the metal by causing premature plastic instability failure or by inducing the formation of cracks. Irradiation with neutrons hardens a metal and makes it more prone to deformation by strain localization. Although this has been known since the earliest days of radiation damage studies, a full measure of the connection between neutron irradiation hardening and strain localization is wanting, particularly in commercial alloys used in the construction of nuclear reactors. Therefore, the goal of this project is to systematically map the extent of involvement of strain localization processes in plastic deformation of three reactor alloys that have been neutron irradiated. The deformation processes are to be identified and related to changes in the tensile properties of the alloys as functions of neutron fluence (dose) and degree of plastic strain. The intent is to define the role of strain localization in radiation embrittlement phenomena. The three test materials are a tempered bainitic A533B steel, representing reactor pressure vessel steel, an annealed 316 stainless steel and annealed Zircaloy-4 representing reactor internal components. These three alloys cover the range of crystal structures usually encountered in structural alloys, i.e. body-centered cubic (bcc), face-centered cubic (fcc), and close-packed hexagonal (cph), respectively. The experiments were conducted in three Phases, corresponding to the three years duration of the project. Phases 1 and 2 addressed irradiations and tensile tests made at near-ambient temperatures, and covered a wide range of neutron fluences

  16. Indentation-Induced Mechanical Deformation Behaviors of AlN Thin Films Deposited on c-Plane Sapphire

    Directory of Open Access Journals (Sweden)

    Sheng-Rui Jian

    2012-01-01

    Full Text Available The mechanical properties and deformation behaviors of AlN thin films deposited on c-plane sapphire substrates by helicon sputtering method were determined using the Berkovich nanoindentation and cross-sectional transmission electron microscopy (XTEM. The load-displacement curves show the “pop-ins” phenomena during nanoindentation loading, indicative of the formation of slip bands caused by the propagation of dislocations. No evidence of nanoindentation-induced phase transformation or cracking patterns was observed up to the maximum load of 80 mN, from either XTEM or atomic force microscopy (AFM of the mechanically deformed regions. Instead, XTEM revealed that the primary deformation mechanism in AlN thin films is via propagation of dislocations on both basal and pyramidal planes. Furthermore, the hardness and Young’s modulus of AlN thin films estimated using the continuous contact stiffness measurements (CSMs mode provided with the nanoindenter are 16.2 GPa and 243.5 GPa, respectively.

  17. Efficiency of five chemical protective clothing materials against nano and submicron aerosols when submitted to mechanical deformations.

    Science.gov (United States)

    Ben Salah, Mehdi; Hallé, Stéphane; Tuduri, Ludovic

    2016-01-01

    Due to their potential toxicity, the use of nanoparticles in the workplace is a growing concern. Some studies indicate that nanoparticles can penetrate the skin and lead to adverse health effects. Since chemical protective clothing is the last barrier to protect the skin, this study aims to better understand nanoparticle penetration behaviour in dermal protective clothing under mechanical deformation. For this purpose, five of the most common types of fabrics used in protective clothing, one woven and four nonwoven, were chosen and submitted to different simulated exposure conditions. They were tested against polydispersed NaCl aerosols having an electrical-mobility diameter between 14 and 400 nm. A bench-scale exposure setup and a sampling protocol was developed to measure the level of penetration of the aerosols through the material samples of disposable coveralls and lab coat, while subjecting them to mechanical deformations to simulate the conditions of usage in the workplace. Particle size distribution of the aerosol was determined upstream and downstream using a scanning mobility particle sizer (SMPS). The measured efficiencies demonstrated that the performances of nonwoven materials were similar. Three nonwovens had efficiencies above 99%, while the woven fabric was by far, the least effective. Moreover, the results established that mechanical deformations, as simulated for this study, did not have a significant effect on the fabrics' efficiencies.

  18. Modeling the mechanical deformation of nickel foils for nanoimprint lithography on double-curved surfaces

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Cech, Jiri; Hattel, Jesper Henri;

    2013-01-01

    . Experimentally, it is possible to address this stretch by counting the periods of the cross-gratings via SEM characterization. A model for the deformation of the nickel foil during nanoimprint is developed, utilizing non-linear material and geometrical behaviour. Good agreement between measured and numerically...... calculated stretch ratios on the surface of the deformed nickel foil is found, and it is shown, that from the model it is also possible to predict the geometrical extend of the nano-structured area on the curved surfaces....

  19. Deformation microstructures and mechanisms in the high-pressure granulites of the Bacariza Formation (Cabo Ortegal, NW Spain): going up to the surface

    Science.gov (United States)

    Puelles, P.; Abalos, B.

    2009-04-01

    between the mafic (G1) and intermediate (G2) granulites of the high-pressure Bacariza Formation and the structurally underlying eclogite massif. A petrographic, microstructural and crystallographic analysis has been carried out in these rocks in order to characterize ductile deformations at deep crustal levels and to shed some light on the structural imprints recorded at various scales. On these lines, overprinting relationships of the metamorphic assemblages enable us to interpret that partitioning and deformation localization took place at different scales under similar high-grade conditions, including the localization effect involved in the development of subduction channels at the lithospheric plate boundary scale. First, ductile deformation concentrated, at the map and outcrop scales, along the contact with peridotites and eclogites, rheologically stronger, leading to accommodation of large tectonic displacements under faster strain rates due to its relative weakness. Second, within the shear zones, bands of contrasted lithology exhibit contrasting deformation intensities, getting it concentrated in the leucocratic layers. Thus, every lithological layer behaved as a separate rheological unit. Last, deformation partition occurred within each layer. Layers are often polymineralic and both the microstructures and the lattice-preferred orientation patterns observed denote that crystal-plastic mechanisms dominated mineral deformation, in such a way that deformation of the same mineral assemblage under the same thermobaric conditions also resulted in petrographically different tectonites, depending on the proportions and rheology of the minerals involved. In order to determine the deformation mechanisms operative in each phase during the initial exhumation of the Bacariza Formation, the lattice-preferred orientation (LPO) of the constituent minerals of these rocks (garnet, augite, plagioclase, quartz and amphibole) has been studied with the Electron Back

  20. Effect of deformation on microstructure and mechanical properties of dual phase steel produced via strip casting simulation

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Z.P., E-mail: zuileniwota@126.com [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Kostryzhev, A.G. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Stanford, N.E. [Institute of Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Pereloma, E.V. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Electron Microscopy Centre, University of Wollongong, Wollongong, NSW 2519 (Australia)

    2016-01-10

    The strip casting is a recently appeared technology with a potential to significantly reduce energy consumption in steel production, compared to hot rolling and cold rolling. However, the quantitative dependences of the steel microstructure and mechanical properties on strip casting parameters are unknown and require investigation. In the present work we studied the effects of strain and interrupted cooling temperature on microstructure and mechanical properties in conventional dual phase steel (0.08C–0.81Si–1.47Mn–0.03Al wt%). The strip casting process was simulated using a Gleeble 3500 thermo-mechanical simulator. The steel microstructures were studied using optical, scanning and transmission electron microscopy. Mechanical properties were measured using microhardness and tensile testing. Microstructures consisting of 40–80% polygonal ferrite with remaining martensite, bainite and very small amount of Widmanstätten ferrite were produced. Deformation to 0.17–0.46 strain at 1050 °C refined the prior austenite grain size via static recrystallisation, which led to the acceleration of ferrite formation and the ferrite grain refinement. The yield stress and ultimate tensile strength increased with a decrease in ferrite fraction, while the total elongation decreased. The improvement of mechanical properties via deformation was ascribed to dislocation strengthening and grain boundary strengthening. - Highlights: • A processing route of strip casting was developed to produce dual phase steel. • The mechanical properties were comparable to cold rolled and hot rolled DP steels.

  1. Severe plastic deformation using friction stir processing, and the characterization of microstructure and mechanical behavior using neutron diffraction

    Science.gov (United States)

    Woo, Wanchuck

    Friction-stir welding (FSW) is a solid-state joining process, which utilizes a cylindrical rotating tool consisting of a concentric threaded tool pin and tool shoulder. The strong metallurgical bonding during the FSW is accomplished through: (1) the severe plastic deformation caused by the rotation of the tool pin that plunges into the material and travels along the joining line; and (2) the frictional heat generated mainly from the pressing tool shoulder. Recently, a number of variations of the FSW have been applied to modify the microstructure, for example, grain refinements and homogenization of precipitate particles, namely friction-stir processing (FSP). Applications of the FSP/FSW are widespread for the transportation industries. The microstructure and mechanical behavior of light-weight materials subjected to the FSW/FSP are being studied extensively. However, separating the effect of the frictional heat and severe plastic deformation on the residual stress and texture has been a standing problem for the fundamental understanding of FSW/FSP. The fundamental issues are: (i) the heat- and plastic-deformation-induced internal stresses that may be detrimental to the integrity and performance of components; (ii) the frictional heating that causes a microstructural softening due to the dissolution or growth of the precipitates in precipitation-hardenable Al alloys during the process; and (iii) the crystallographic texture can be significantly altered from the original texture, which could affect the physical and mechanical properties. The understanding of the influences of the de-convoluted sources (e.g. frictional heat, severe plastic deformation, or their combination) on the residual stress, microstructural softening, and texture variations during FSW can be used for a physicsvi based optimization of the processing parameters and new tool designs. Furthermore, the analyses and characterization of the natural aging behavior and the aging kinetics can be

  2. Salt deformation mechanism and gas accumulation in the Transylvanian Basin, Romania

    Science.gov (United States)

    Pene, Constantin; Floroiu, Alina

    2017-04-01

    The Transylvanian Basin is the main producer of hydrocarbon gases in Romania. The first gas field (Sarmasel) has been discovered in 1909, untill now more than 129 gas structures being identified and exploited. The aim of this paper is to investigate the causes that created zones with different intensity of the diapirism in relation with the methane generation and accumulation. The Badenian salt movement had different intensities in the Transylvanian Basin. In the central part there are salt pillows, salt layers and piercement of salt. In this zone the salt is not outcropping and its flow produced only the doming of the overlying deposits. In the eastern and western parts of the basin salt flow determined an intensively deformation of the overlying rocks and the formation of the salt diapirs and salt wall growth. In these areas the salt even outcrops within a few sectors. The following mechanisms could be implied in the Badenian salt flow: salt buoyancy, differential sediment loading, flexural buckling of the overburden and drag by overburden. To evaluate which mechanism dominates in the Badenian salt flow in the Transylvanian Basin a simple model has been used considering an elastic plate overlying a viscous fluid. In this model the viscous fluid is the layer of Badenian salt and the elastic plate is represented by the overburden composed of Upper Miocene and Pliocene deposits. The vertical pressure gradient was calculated considering a constant density of overburden (2500 kg/m3) in correlation with the different sedimentary rates of the Upper Badenian (450 m/Ma), Sarmatian (150 m/Ma) and Pliocene (80 m/Ma). The initial salt thickness was variable, less than 300 m south of Mureş River and more than 500 m in the other zones of the basin. The amplitude and the wavelength of folding as well as the others parameters, like the thickness of the overburden and of the salt encountered in the apex of the structures as well as in the adjacent synclines have been measured on

  3. Mechanical Design of Odin, an Extendable Heterogeneous Deformable Modular Robot

    DEFF Research Database (Denmark)

    Lyder, Andreas; Garcia, Ricardo Franco Mendoza; Støy, Kasper

    2008-01-01

    Highly sophisticated animals consist of a set of heterogenous modules decided by nature so that they can survive in a complex environment. In this paper we present a new modular robot inspired by biology called Odin. The Odin robot is based on a deformable lattice and consists of an extendable se...

  4. Effects of Fault Segmentation, Mechanical Interaction, and Structural Complexity on Earthquake-Generated Deformation

    Science.gov (United States)

    Haddad, David Elias

    2014-01-01

    Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that…

  5. Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films

    NARCIS (Netherlands)

    Chen, C.Q.; Pei, Y.T.; Shaha, K.P.; Hosson, J.Th.M. De

    2009-01-01

    This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures depos

  6. Effects of Fault Segmentation, Mechanical Interaction, and Structural Complexity on Earthquake-Generated Deformation

    Science.gov (United States)

    Haddad, David Elias

    2014-01-01

    Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that…

  7. Deformation mechanisms of IN713C nickel based superalloy during Small Punch Testing

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, M., E-mail: m.p.coleman@swansea.ac.uk; Alshehri, H.; Banik, R.; Harrison, W.; Birosca, S.

    2016-01-05

    The role of local microstructure is critical in materials performance and integrity in a cast alloy. The grain size and grain boundary distributions as well as local texture can create various microstructure/microtexture clusters that cause deformation localisation in the alloy. Inconel 713C nickel base superalloys are used as turbocharger turbine wheels for modern diesel engines, produced via investment casting. In such an alloy localised deformation is highly expected during service, as the strain distribution is not uniform in the component due to casting geometrical factors in addition to non-homogenous microstructure and microtexture in the cast alloy. In the current investigation Small Punch (SP) tensile tests were carried out on IN713C at room temperature and 650 °C in an air environment under stroke control at a rate of 0.02 mm/s. The fracture surface examination and microstructure characterisation as well as detailed texture analyses were performed using Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD). Finite Element (FE) analysis of the SP test was also implemented to investigate the role of stress state on the local deformation. It was evident that microstructure parameters such as grain morphology and original texture existed in the disc were the most influential factors in governing the deformation texture in mixed columnar/equiaxed (transition) disc microstructure. Whereas, the temperature was the determining parameter in grain rotations and texture changes for wholly columnar disc microstructures.

  8. Tailoring dislocation structures and mechanical properties of nanostructured metals produced by plastic deformation

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2009-01-01

    The presence of a dislocation structure associated with low-angle dislocation boundaries and interior dislocations is a common and characteristic feature in nanostructured metals produced by plastic deformation, and plays an important role in determining both the strength and ductility of the nan...

  9. Mechanisms of submicron inclusion re-equilibration during host mineral deformation

    Science.gov (United States)

    Griffiths, Thomas; Habler, Gerlinde; Abart, Rainer; Rhede, Dieter; Wirth, Richard

    2014-05-01

    Both brittle and ductile deformation can facilitate re-equilibration of mineral inclusions. The presence of inclusions also influences stress and strain distribution in the host. The processes governing feedbacks between brittle deformation, ductile deformation, and inclusion re-equilibration have been studied using unique microstructures in Permian meta-pegmatite garnets from the Koralpe, Eastern Alps, Austria. Sampled almandine-spessartine garnets contain highly abundant submicron-sized inclusions, which originated during or subsequent to magmatic garnet growth. The Permian magmatic assemblages were affected by eclogite facies metamorphism during the Cretaceous tectono-metamorphic event. The meta-pegmatite garnet deformed crystal-plastically at this metamorphic stage (Bestmann et al. 2008) and the host-inclusion system was affected by partial recrystallization. Trails of coarser inclusions (1-10µm diameter) crosscut the magmatic submicron inclusion density zoning in the garnet, defining curviplanar geometrical surfaces in 3D. In 10-40µm broad 'bleaching zones' flanking inclusion trails, the original ≤1µm sized inclusions are not seen in the optical microscope or SEM, however inclusions crystal axes is observed in connection with some already coarsened inclusions. Strain concentrations are widespread in some trails, but rare in others. A TEM foil transecting a garnet domain with concentrated lattice rotation in association with inclusions reveals well developed polygonal subgrain walls with few free dislocations. Where dislocation density is greatest, almost no Journal of Structural Geology 30: 777-790

  10. Helical Nanomachines for Fast Mechanical Mapping of Heterogeneous Environments

    CERN Document Server

    Ghosh, Arijit

    2016-01-01

    Artificial micro and nano machines have been envisioned and demonstrated as potential candidates for variety of applications, ranging from targeted drug or gene delivery, cell manipulation, environmental sensing and many more. Here, we demonstrate the application of helical nanomachines that can measure and map the local rheological properties of a complex heterogeneous environment. The position of the helical nanomachine was controlled precisely using magnetic fields, while the instantaneous orientation provided an estimation of the viscosity of the surrounding medium with high spatial and temporal accuracy. Apart from providing viscosity estimates in purely viscous and viscoelastic media with shear rate independent viscosity (Boger fluids), their motion was also found to be extremely sensitive to fluid elasticity. Taken together we report a promising new technique of mapping the rheological properties of a complex fluidic environment by helical nanomachines with high spatial and temporal resolutions, a func...

  11. Deformation mechanism of surrounding rocks and key control technology for a roadway driven along goaf in fully mechanized top-coal caving face

    Institute of Scientific and Technical Information of China (English)

    李学华

    2003-01-01

    The variation of the stress in the bolted surrounding rocks structure of the roadway driven along goaf in a fully mechanized top-coal caving face with moderate stable conditions are studied by using numerical calculation. The essential deformation characteristics of the surrounding rocks in this kind of roadway are obtained and the key technology of bolting support used under these conditions is put forward.

  12. Deformation mechanism of surrounding rocks and key control technology for a roadway driven along goaf in fully mechanized top-coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Li, X. [China University of Mining and Technology, Xuzhou (China). School of Energy Science and Engineering

    2003-06-01

    The variation of the stress in the bolted surrounding rocks structure of the roadway driven along the goaf in a fully mechanized top-coal caving face with moderate stable conditions are studied by using numerical calculation. The essential deformation characteristics of the surrounding rocks in this kind of roadway are obtained and the key technology of bolting support used under these conditions is put forward. 3 refs., 2 figs., 1 tab.

  13. Deformation mechanism at impact test of Al-11% Si alloy processed by equal-channel angular pressing with rotary die

    Institute of Scientific and Technical Information of China (English)

    MA Ai-bin; Y. NISHIDA; JIANG Jing-hua; N. SAITO; I. SHIGEMATSU; A. WATAZU

    2007-01-01

    Al-11%Si (mass fraction) alloy was transformed into a ductile material by equal-channel angular pressing (ECAP) with a rotary die. Two mechanisms at impact test, slip deformation by dislocation motion and grain boundary sliding, were discussed. The ultrafine grains with modified grain boundaries and the high content of fine particles (<1 μm) were necessary for attaining high absorbed energy. The results contradict the condition of slip deformation by dislocation motion and coincide with that of grain boundary sliding. Many fine zigzag lines like a mosaic were observed on the side surface of the tested specimens. These observed lines may show grain boundaries appeared by the sliding of grains.

  14. Use of Concept Maps as an Assessment Tool in Mechanical Engineering Education

    Science.gov (United States)

    Tembe, B. L.; Kamble, S. K.

    2013-01-01

    The purpose of this study to investigate, how third year mechanical engineering students are able to use their knowledge of concept maps in their study of the topic of "Introduction to the Internal Combustion Engines (IICE)". 41 students participated in this study. Firstly, the students were taught about concept maps and then asked to…

  15. Structural mapping: how to study the genetic architecture of a phenotypic trait through its formation mechanism.

    Science.gov (United States)

    Tong, Chunfa; Shen, Lianying; Lv, Yafei; Wang, Zhong; Wang, Xiaoling; Feng, Sisi; Li, Xin; Sui, Yihan; Pang, Xiaoming; Wu, Rongling

    2014-01-01

    Traditional approaches for genetic mapping are to simply associate the genotypes of a quantitative trait locus (QTL) with the phenotypic variation of a complex trait. A more mechanistic strategy has emerged to dissect the trait phenotype into its structural components and map specific QTLs that control the mechanistic and structural formation of a complex trait. We describe and assess such a strategy, called structural mapping, by integrating the internal structural basis of trait formation into a QTL mapping framework. Electrical impedance spectroscopy (EIS) has been instrumental for describing the structural components of a phenotypic trait and their interactions. By building robust mathematical models on circuit EIS data and embedding these models within a mixture model-based likelihood for QTL mapping, structural mapping implements the EM algorithm to obtain maximum likelihood estimates of QTL genotype-specific EIS parameters. The uniqueness of structural mapping is to make it possible to test a number of hypotheses about the pattern of the genetic control of structural components. We validated structural mapping by analyzing an EIS data collected for QTL mapping of frost hardiness in a controlled cross of jujube trees. The statistical properties of parameter estimates were examined by simulation studies. Structural mapping can be a powerful alternative for genetic mapping of complex traits by taking account into the biological and physical mechanisms underlying their formation.

  16. Simulation of coupled flow and mechanical deformation using IMplicit Pressure-Displacement Explicit Saturation (IMPDES) scheme

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    The problem of coupled structural deformation with two-phase flow in porous media is solved numerically using cellcentered finite difference (CCFD) method. In order to solve the system of governed partial differential equations, the implicit pressure explicit saturation (IMPES) scheme that governs flow equations is combined with the the implicit displacement scheme. The combined scheme may be called IMplicit Pressure-Displacement Explicit Saturation (IMPDES). The pressure distribution for each cell along the entire domain is given by the implicit difference equation. Also, the deformation equations are discretized implicitly. Using the obtained pressure, velocity is evaluated explicitly, while, using the upwind scheme, the saturation is obtained explicitly. Moreover, the stability analysis of the present scheme has been introduced and the stability condition is determined.

  17. Extensional Elastica in large deformation as $Gamma $ Γ -limit of a discrete 1D mechanical system

    Science.gov (United States)

    Alibert, Jean-Jacques; Della Corte, Alessandro; Giorgio, Ivan; Battista, Antonio

    2017-04-01

    The present paper deals with the rigorous homogenization of a discrete system consisting of extensible rods linked by rotational springs. Specifically, a Γ -convergence result is proven for a sequence of discrete measure functionals En, describing the energy of the discrete system, toward the continuous energy functional for the extensible Euler beam model ( Elastica) in large deformation regime. A relative compactness result for the sequence En is also proven. Moreover, numerical results are shown on the deformed shape and on the total energy of the system when the number of elements of the discrete system increases. The numerical convergence of the energy to a definite value is shown in two cases. The results provide rigorous justification of a very commonly used algorithm for the discretization of the extensible Euler beam, namely Hencky-type beam model.

  18. Transformation mechanism of lamellar microstructure of AZ80 wrought Mg alloy during warm deformation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The microstructure especially the lamellar second phase evolution by a combination of deformation and heat treatment for AZ80 alloy was investigated. The results show that there are finer lamellar Mg17Al12 phases after hot compression with the increasing strain, while there are coarse lamellar discontinuous precipitation cells of β-Mg17Al12 phase spreading from the grain boundaries into the grains after T6 treatment of the compressed samples. The lamellar morphologies especially the lamellar distance of β-Mg17Al12phase precipitation of the T6 treated deformation specimen at different strains differ from each other as there are different grain boundaries in the corresponding compressed specimens.

  19. Microstructural Development and Deformation Mechanisms during Cold Rolling of a Medium Stacking Fault Energy TWIP Steel

    Institute of Scientific and Technical Information of China (English)

    K.A. Ofei; L. Zhao; J. Sietsma

    2013-01-01

    The magnetic response,microstructural and texture changes occurring during cold rolling of a Fe-14Mn-0.64C-2.4Al-0.25Si medium stacking fault energy TWlP (twinning induced plasticity) steel have been studied by X-ray diffraction and magnetic techniques.The changes in the sub-grain size (Ds),probability of stacking fault formation (Psf) and microstrain in the material as cold rolling progressed were determined by using a modified version of the Williamson and Hall equation.A strong development of the crystallographic texture with increasing deformation was observed.Deformation-induced formation of a small fraction α'-martensite was observed,indicating that the steel also exhibits y → α'-martensite transformation during cold rolling,which is discussed via the changes of the stacking-fault probability and the texture development during cold rolling.

  20. Atomistic simulation study of the shear-band deformation mechanism in Mg-Cu metallic glasses

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2006-01-01

    We have simulated plastic deformation of a model Mg-Cu metallic glass in order to study shear banding. In uniaxial tension, we find a necking instability occurs rather than shear banding. We can force the latter to occur by deforming in plane strain, forbidding the change of length in one...... of the transverse directions. Furthermore, in most of the simulations a notch is used to initiate shear bands, which lie at a 45 degrees angle to the tensile loading direction. The shear bands are characterized by the Falk and Langer local measure of plastic deformation D-min(2), averaged here over volumes...... containing many atoms. The D-min(2) profile has a peak whose width is around 10 nm; this width is largely independent of the strain rate. Most of the simulations were, at least nominally, at 100 K, about T-g/3 for this system. The development of the shear bands takes a few tens of ps, once plastic flow has...

  1. The role of deformation twinning in the fracture behavior and mechanism of basal textured magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ando, D., E-mail: dando@material.tohoku.ac.jp; Koike, J.; Sutou, Y.

    2014-04-01

    AZ31 magnesium alloys were deformed to 10% and to failure strain by tensile loading at room temperature. Scribed grids were drawn by a focused ion beam system (FIB) to visualize the local deformation in each grain. This showed that the magnitude of the strain was distributed non-uniformly in each grain. It was found that the low-strain grains accompanied {10–12} twins, while the severely strained grains accompanied {10–11}–{10–12} double twins. Cracks nucleated at the double twins and tended to propagate along {10–12} twin interfaces as well as within grains. Furthermore, fractography revealed three types of microstructural features: dimples, elliptic facets and sheared dimples. Most abundant were the dimples formed by ductile failure. The elliptic facets appeared to be due to crack propagation along the {10–12} twin interfaces. The sheared dimples were frequently observed in connection with localized shear deformation within the double twins. These results led us to conclude that premature and catastrophic failure of Mg alloys is mainly associated with double twins. Prevention of double twinning is essential to improve the ductility of Mg alloys.

  2. Criminal Investigation EIDSS Based on Cooperative Mapping Mechanism

    Directory of Open Access Journals (Sweden)

    Ping He

    2014-10-01

    Full Text Available On purpose of improving the research in extension intelligence systems when the knowledge in hand is not sufficient, an intuition evidence model (IEM based on human-computer cooperative is presented. From the initial intuition process space defined by the primitive experience, a series of interactive mapping learning systems (IMLS with various reductive levels are created. For, each IELS, the rule sets with respective belief degree are induced and saved. The paper introduces cooperative mapping of intuition evidence and object hypothesesmethod to the criminal investigation, and poses a skeleton of cooperative reasoning. The paper views that the reliability of the cooperative reasoning depends on the human-computer interaction results. Simultaneously, choosing the case-cracking clue should be determined by comprehensive evaluations and self-learning of intuition-formal judgments are essentially needed. When applying the model to reasoning and decision making, one can match the intuition judge of the given object to the rule sets of relative nodes, and then draw the conclusion by using some kind of evaluation algorithm. A simple example on how to create and apply the model is give.

  3. Deformation mechanisms during compressive loading of tantalum and tantalum-2.5 weight percent tungsten

    Science.gov (United States)

    Kapoor, Rajeev

    In this study it was attempted to understand the deformation behavior of tantalum and tantalum alloyed with 2.5 weight % tungsten. Uniaxial compressive deformation was carried out on polycrystalline Ta, Ta-2.5%W, and single crystal Ta. Experiments were carried out for a range of strain rates (10sp{-4}/s to 3000/s), and for a range of temperatures (77K, 296K-1000K). During high strain rate adiabatic plastic deformation of Ta-2.5%W, the energy converted to heat was directly measured using an infra-red method, and indirectly, using the recovery Hopkinson bar technique. It was concluded that within experimental error close to 100% of the work is converted to heat. During high strain rate deformation, the internal dislocation structure of both Ta and Ta-2.5%W was found to be independent of testing temperature. Thus the flow stress could be separated into two types of components, one type which are strain rate - temperature dependent and the other type which are only strain dependent. However, at lower strain rates prominent dynamic strain aging is observed and the effect of strain is coupled with the strain rate - temperature effect. At these lower strain rates, the evolution of structure does depend on the applied strain rate and temperature. When deformed at liquid nitrogen temperature, tantalum twins even at strain rates as low as 0.001/s. In the high strain rate - room temperature regime no twinning is observed. With the addition of tungsten to tantalum, the temperature and strain rate sensitivity of flow stress reduces. In addition to this, twinning is inhibited and occurs only at high strain rates - liquid nitrogen temperatures. Experiments on single crystal tantalum carried out revealed that the temperature sensitivity of flow stress on the (211) (111) slip system is similar to that on the (101) (111) slip system. Further experiments carried out on single crystal tantalum to study latent hardening did show 10% latent hardening on the \\{211\\} intersecting slip

  4. Numerical investigation of the deformation mechanism of a bubble or a drop rising or falling in another fluid

    Institute of Scientific and Technical Information of China (English)

    Wang Han; Zhang Zhen-Yu; Yang Yong-Ming; Hu Yue; Zhang Hui-Sheng

    2008-01-01

    A numerical method for simulating the motion and deformation of an axisymmetric bubble or drop rising or falling in another infinite and initially stationary fluid is developed based on the volume of fluid(VOF)method in the frame of two incompressible and immiscible viscous fluids under the action of gravity,taking into consideration of surface tension effects.A comparison of the numerical results by this method with those by other works indicates the validity of the method.In the frame of inviscid and incompressible fluids without taking into consideration of surface tension effects,the mechanisms of the generation of the liquid jet and the transition from spherical shape to toroidal shape during the bubble or drop deformation,the increase of the ring diameter of the toroidal bubble or drop and the decrease of its cross-section area during its motion,and the effects of the density ratio of the two fluids on the deformation of the bubble or drop are analysed both theoretically and numerically.

  5. Effect of rolling deformation and solution treatment on microstructure and mechanical properties of a cast duplex stainless steel

    Indian Academy of Sciences (India)

    S K Ghosh; D Mahata; R Roychaudhuri; R Mondal

    2012-10-01

    The present study deals with the effect of rolling deformation and solution treatment on the microstructure and mechanical properties of a cast duplex stainless steel. Cast steel reveals acicular/Widmanstätten morphology as well as island of austenite within the -ferrite matrix. Hot rolled samples exhibit the presence of lower volume percent of elongated band of -ferrite (∼40%) and austenite phase which convert into finer and fragmented microstructural constituents after 30% cold deformation. By the solution treatment, the elongated and broken crystalline grains recrystallize which leads to the formation of finer grains (<10 m) of austenite. X-ray diffraction analysis has corroborated well with the above-mentioned microstructural investigation. Enhancement in hardness, yield strength and tensile strength values as well as drop in percent elongation with cold deformation increases its suitability for use in thinner sections. 30% cold rolled and solution treated sample reveals attractive combination of strength and ductility (25.22 GPa%). The examination of fracture surface also substantiates the tensile results. The sub-surface micrographs provide the potential sites for initiation of microvoids.

  6. A molecular mechanism for the topographic alignment of convergent neural maps

    Science.gov (United States)

    Savier, Elise; Eglen, Stephen J; Bathélémy, Amélie; Perraut, Martine; Pfrieger, Frank W; Lemke, Greg; Reber, Michael

    2017-01-01

    Sensory processing requires proper alignment of neural maps throughout the brain. In the superficial layers of the superior colliculus of the midbrain, converging projections from retinal ganglion cells and neurons in visual cortex must be aligned to form a visuotopic map, but the basic mechanisms mediating this alignment remain elusive. In a new mouse model, ectopic expression of ephrin-A3 (Efna3) in a subset of retinal ganglion cells, quantitatively altering the retinal EFNAs gradient, disrupts cortico-collicular map alignment onto the retino-collicular map, creating a visuotopic mismatch. Genetic inactivation of ectopic EFNA3 restores a wild-type cortico-collicular map. Theoretical analyses using a new mapping algorithm model both map formation and alignment, and recapitulate our experimental observations. The algorithm is based on an initial sensory map, the retino-collicular map, which carries intrinsic topographic information, the retinal EFNAs, to the superior colliculus. These EFNAs subsequently topographically align ingrowing visual cortical axons to the retino-collicular map. DOI: http://dx.doi.org/10.7554/eLife.20470.001 PMID:28322188

  7. Mapping the deformation in the "island of inversion": Inelastic scattering of 30Ne and 36Mg at intermediate energies

    Science.gov (United States)

    Doornenbal, P.; Scheit, H.; Takeuchi, S.; Aoi, N.; Li, K.; Matsushita, M.; Steppenbeck, D.; Wang, H.; Baba, H.; Ideguchi, E.; Kobayashi, N.; Kondo, Y.; Lee, J.; Michimasa, S.; Motobayashi, T.; Poves, A.; Sakurai, H.; Takechi, M.; Togano, Y.; Yoneda, K.

    2016-04-01

    The transition strengths of the first-excited 2+ states and deformation lengths of the nuclei 30Ne and 36Mg were determined via Coulomb- and nuclear-force-dominated inelastic scattering at intermediate energies. Beams of these exotic nuclei were produced at the RIKEN Radioactive Isotope Beam Factory and were incident on lead and carbon targets at energies above 200 MeV/u . Absolute excitation cross sections on the lead target yielded reduced transition probabilities of 0.0277(79) and 0.0528(121) e2b2 , while the measurements with the carbon target revealed nuclear deformation lengths of δN=1.98 (11) and 1.93(11) fm for 30Ne and 36Mg, respectively. Corresponding quadrupole deformation parameters of β2˜0.5 from the two probes were found comparable in magnitude, showing no indication for a reduction in deformation along isotopic and isotonic chains from 32Mg towards the neutron drip-line. Comparisons to shell-model calculations illustrate the importance of neutron excitations across the N =20 shell for 30Ne and suggest that shallow maximums of collectivity may occur around N =22 and 24 along the neon and magnesium isotopic chains, respectively.

  8. Mechanical Properties and Fracture Behavior of Cu-Co-Be Alloy after Plastic Deformation and Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Yan-jun ZHOU; Ke-xing SONG; Jian-dong XING; Zhou LI; Xiu-hua GUO

    2016-01-01

    Mechanical properties and fracture behavior of Cu-0.84Co-0.23Be alloy after plastic deformation and heat treatment were comparatively investigated.Severe plastic deformation by hot extrusion and cold drawing was adopted to induce large plastic strain of Cu-0.84Co-0.23Be alloy.The tensile strength and elongation are up to 476.6 MPa and 1 8%,respectively.The fractured surface consists of deep dimples and micro-voids.Due to the formation of su-persaturated solid solution on the Cu matrix by solution treatment at 950 ℃ for 1 h,the tensile strength decreased to 271.9 MPa,while the elongation increased to 42%.The fracture morphology is parabolic dimple.Furthermore,the tensile strength increased significantly to 580.2 MPa after aging at 480 ℃ for 4 h.During the aging process,a large number of precipitates formed and distributed on the Cu matrix.The fracture feature of aged specimens with low elongation (4.6%)exhibits an obvious brittle intergranular fracture.It is confirmed that the mechanical properties and fracture behavior are dominated by the microstructure characteristics of Cu-0.84Co-0.23Be alloy after plastic de-formation and heat treatment.In addition,the fracture behavior at 450 ℃ of aged Cu-0.84Co-0.23Be alloy was also studied.The tensile strength and elongation are 383.6 MPa and 11.2%,respectively.The fractured morphologies are mainly candy-shaped with partial parabolic dimples and equiaxed dimples.The fracture mode is multi-mixed mechanism that brittle intergranular fracture plays a dominant role and ductile fracture is secondary.

  9. Mechanism and technology study of collaborative support with long and short bolts in large-deformation roadways

    Institute of Scientific and Technical Information of China (English)

    Yu Hui⇑; Niu Zhiyong; Kong Linggen; Hao Caicheng; Cao Peng

    2015-01-01

    Common short bolts of equal length are widely used to support the roofs of roadways in coal mines. However, they are insufficient to keep the roof stable against large deformations, so docking long bolts with high levels of elongation that can adapt to large deformations of the surrounding rock have been adopted. This paper proposes a collaborative support method that uses long and short bolts. In this study, the mechanism of docking long bolts and collaborative support was studied. Numerical simulation, sim-ilarity simulation, and field testing were used to analyze the distribution law of the displacement, stress, and plastic failure in the surrounding rock under different support schemes. Compared with the equal-length short bolt support, the collaborative support changed the maximum principal stress of the shallow roof from tensile stress to compressive stress, and the minimum principal stress of the roof significantly increased. The stress concentration degree of the anchorage zone clearly increased. The deformation of the roof and the two sides was greatly reduced, and the subsidence shape of the shallow roof changed from serrated to a smooth curve. The roof integrity was enhanced, and the roof moved down as a whole. Plastic failure significantly decreased, and the plastic zone of the roof was within the anchorage range. The similarity simulation results showed that, under the maximum mining stress, the roof collapsed with the equal-length short bolt support but remained stable with the collaborative support. The collaborative support method was successfully applied in the field and clearly improved the stability of the surrounding rock for a large deformation roadway.

  10. Mechanisms of plastic deformation in highly cross-linked UHMWPE for total hip components--the molecular physics viewpoint.

    Science.gov (United States)

    Takahashi, Yasuhito; Shishido, Takaaki; Yamamoto, Kengo; Masaoka, Toshinori; Kubo, Kosuke; Tateiwa, Toshiyuki; Pezzotti, Giuseppe

    2015-02-01

    Plastic deformation is an unavoidable event in biomedical polymeric implants for load-bearing application during long-term in-vivo service life, which involves a mass transfer process, irreversible chain motion, and molecular reorganization. Deformation-induced microstructural alterations greatly affect mechanical properties and durability of implant devices. The present research focused on evaluating, from a molecular physics viewpoint, the impact of externally applied strain (or stress) in ultra-high molecular weight polyethylene (UHMWPE) prostheses, subjected to radiation cross-linking and subsequent remelting for application in total hip arthroplasty (THA). Two different types of commercial acetabular liners, which belong to the first-generation highly cross-linked UHMWPE (HXLPE), were investigated by means of confocal/polarized Raman microprobe spectroscopy. The amount of crystalline region and the spatial distribution of molecular chain orientation were quantitatively analyzed according to a combined theory including Raman selection rules for the polyethylene orthorhombic structure and the orientation distribution function (ODF) statistical approach. The structurally important finding was that pronounced recrystallization and molecular reorientation increasingly appeared in the near-surface regions of HXLPE liners with increasing the amount of plastic (compressive) deformation stored in the microstructure. Such molecular rearrangements, occurred in response to external strains, locally increase surface cross-shear (CS) stresses, which in turn trigger microscopic wear processes in HXLPE acetabular liners. Thus, on the basis of the results obtained at the molecular scale, we emphasize here the importance of minimizing the development of irrecoverable deformation strain in order to retain the pristine and intrinsically high wear performance of HXLPE components.

  11. Development of TRIP-Aided Lean Duplex Stainless Steel by Twin-Roll Strip Casting and Its Deformation Mechanism

    Science.gov (United States)

    Zhao, Yan; Zhang, Weina; Liu, Xin; Liu, Zhenyu; Wang, Guodong

    2016-12-01

    In the present work, twin-roll strip casting was carried out to fabricate thin strip of a Mn-N alloyed lean duplex stainless steel with the composition of Fe-19Cr-6Mn-0.4N, in which internal pore defects had been effectively avoided as compared to conventional cast ingots. The solidification structure observed by optical microscope indicated that fine Widmannstatten structure and coarse-equiaxed crystals had been formed in the surface and center, respectively, with no columnar crystal structures through the surface to center of the cast strip. By applying hot rolling and cold rolling, thin sheets with the thickness of 0.5 mm were fabricated from the cast strips, and no edge cracks were formed during the rolling processes. With an annealing treatment at 1323 K (1050 °C) for 5 minutes after cold rolling, the volume fractions of ferrite and austenite were measured to be approximately equal, and the distribution of alloying elements in the strip was further homogenized. The cold-rolled and annealed sheet exhibited an excellent combination of strength and ductility, with the ultimate tensile strength and elongation having been measured to be 1000 MPa and 65 pct, respectively. The microstructural evolution during deformation was investigated by XRD, EBSD, and TEM, indicating that ferrite and austenite had different deformation mechanisms. The deformation of ferrite phase was dominated by dislocation slipping, and the deformation of austenite phase was mainly controlled by martensitic transformation in the sequence of γ→ ɛ-martensite→ α'-martensite, leading to the improvement of strength and plasticity by the so-called transformation-induced plasticity (TRIP) effect. By contrast, lean duplex stainless steels of Fe-21Cr-6Mn-0.5N and Fe-23Cr-7Mn-0.6N fabricated by twin-roll strip casting did not show TRIP effects and exhibited lower strength and elongation as compared to Fe-19Cr-6Mn-0.4N.

  12. A versatile lab-on-chip test platform to characterize elementary deformation mechanisms and electromechanical couplings in nanoscopic objects

    Science.gov (United States)

    Pardoen, Thomas; Colla, Marie-Sthéphane; Idrissi, Hosni; Amin-Ahmadi, Behnam; Wang, Binjie; Schryvers, Dominique; Bhaskar, Umesh K.; Raskin, Jean-Pierre

    2016-03-01

    A nanomechanical on-chip test platform has recently been developed to deform under a variety of loading conditions freestanding thin films, ribbons and nanowires involving submicron dimensions. The lab-on-chip involves thousands of elementary test structures from which the elastic modulus, strength, strain hardening, fracture, creep properties can be extracted. The technique is amenable to in situ transmission electron microscopy (TEM) investigations to unravel the fundamental underlying deformation and fracture mechanisms that often lead to size-dependent effects in small-scale samples. The method allows addressing electrical and magnetic couplings as well in order to evaluate the impact of large mechanical stress levels on different solid-state physics phenomena. We had the chance to present this technique in details to Jacques Friedel in 2012 who, unsurprisingly, made a series of critical and very relevant suggestions. In the spirit of his legacy, the paper will address both mechanics of materials related phenomena and couplings with solids state physics issues.

  13. Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zelada, Griselda I. [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Lambri, Osvaldo Agustin [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Instituto de Fisica Rosario - CONICET, Member of the CONICET& #x27; s Research Staff, Avda. Pellegrini 250, 2000 Rosario (Argentina); Bozzano, Patricia B. [Laboratorio de Microscopia Electronica, Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, 1650 San Martin (Argentina); Garcia, Jose Angel [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2012-10-15

    Mechanical spectroscopy (MS) and transmission electron microscopy (TEM) studies have been performed in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum, oriented for single slip, in order to study the dislocation dynamics in the temperature range within one third of the melting temperature. A damping peak related to the interaction of dislocation lines with both prismatic loops and tangles of dislocations was found. The peak temperature ranges between 900 and 1050 K, for an oscillating frequency of about 1 Hz. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Approximation solution of Schrodinger equation for Q-deformed Rosen-Morse using supersymmetry quantum mechanics (SUSY QM)

    Energy Technology Data Exchange (ETDEWEB)

    Alemgadmi, Khaled I. K., E-mail: azozkied@yahoo.com; Suparmi; Cari [Department of Physics, the State University of Surabaya (Unesa), Jl. Ketintang, Surabaya 60231 (Indonesia); Deta, U. A., E-mail: utamaalan@yahoo.co.id [Departmet of Physics, Sebelas Maret University, Jl. Ir. Sutami 36A Kentingan, Surakarta 57126 (Indonesia)

    2015-09-30

    The approximate analytical solution of Schrodinger equation for Q-Deformed Rosen-Morse potential was investigated using Supersymmetry Quantum Mechanics (SUSY QM) method. The approximate bound state energy is given in the closed form and the corresponding approximate wave function for arbitrary l-state given for ground state wave function. The first excited state obtained using upper operator and ground state wave function. The special case is given for the ground state in various number of q. The existence of Rosen-Morse potential reduce energy spectra of system. The larger value of q, the smaller energy spectra of system.

  15. Study of mechanical deformations and holes of large, asymmetric GE1/1 foils

    CERN Document Server

    Moutinho Goes, Anna Beatriz

    2017-01-01

    A CMS upgrade requires the installation of GEM detectors, namely the GE1/1. Its installation will take place in 2018 during the LS2. However, such a project demands a collaboration of different teams. The part assigned to me was done in collaboration with Chamini SHAMMI and consisted of studying how much deformation there was after stretching the GE1/1 foils. For that, an analysis code was written to calculation the diameter evolution and its deviation, according to the forces applied.

  16. Deformation and failure mechanism of excavation in clay subjected to hydraulic uplift

    CERN Document Server

    Hong, Yi

    2016-01-01

    This book presents the latest experimental and numerical analysis work in the field of ground deformation and base instability of deep excavations in soft clay subjected to hydraulic uplift. The authors’ latest research findings, based on dimensional analyses, well-instrumented full-scale field tests, systematic coupled-consolidation finite element analyses and centrifuge tests are reported. This book shows how to systematically approach a complex geotechnical problem, from identifying existing problems, reviewing literature, to dimensional and numerical analyses, validation through full-scale testing and centrifuge model testing. The methodologies are also introduced as major tools adopted in geotechnical research.

  17. Tharsis Province of Mars - Geologic sequence, geometry, and a deformation mechanism

    Science.gov (United States)

    Wise, D. U.; Golombek, M. P.; Mcgill, G. E.

    1979-01-01

    Tharsis development apparently involved two stages: (1) an initial rapid topographic rise accompanied by the development of a vast radial fault system and (2) an extremely long-lived volcanic stage apparently continuing to the geological present. A deformation model is proposed in which a first-order mantle convection cell caused early subcrustal erosion and foundering of the low third of the planet. Underplating and deep intrusion by the eroded materials beneath Tharsis caused isostatic doming. Minor radial gravity motions of surficial layers off the dome produced the radial fault system. The hot underplate eventually affected the surface to cause the very long-lived volcanic second stage.

  18. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Trinkaus, H. [Institut fuer Festkoerperforschung, Forschungszentrum Juelich (Germany); Singh, B.N. [Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Materials Research Dept., Roskilde (Denmark)

    2008-04-15

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly observed in PITs. An increase in the pre-yield dose results in an increase in the level of hardening over the whole test periods and a decrease in the uniform elongation suggesting that the materials 'remember' the impact of the pre-yield damage level. These features are modelled in terms of the decoration of dislocations with glissile dislocation loops. During pre-yield irradiation, dislocation decoration is due to the one-dimensional (1D) diffusion of cascade induced self-interstitial (SIA) clusters and their trapping in the stress field of the static grown-in dislocations. During post-yield irradiation and deformation, moving dislocations are decorated by the sweeping of matrix loops. The interaction of dislocations with loops and between loops is discussed as a function of the relevant parameters. On this basis, the kinetics of decoration is treated in terms of fluxes of loops to and reactions with each other in a conceived 2D space of decoration. In this space, loop coalescence, alignment and mutual blocking reactions are characterised by appropriate reaction cross sections. In the kinetic equations for 'dynamic decoration' under deformation, the evolution of the dislocation density is taken into account. Simple solutions of the kinetic equations are discussed. The apparent memory of the system for the pre-yield dose is identified as the result of simultaneous and closely parallel transient evolutions of the cascade damage and the dislocations up to the end of the IRTs. The contributions of dislocation decoration to yield and flow stresses are attributed to the interaction of dislocations with aligned loops temporarily or permanently immobilized

  19. Mapping Nondominant Voices into Understanding Stress-Coping Mechanisms

    Science.gov (United States)

    Iwasaki, Yoshitaka; Bartlett, Judith; MacKay, Kelly; Mactavish, Jennifer; Ristock, Janice

    2008-01-01

    This study reports key findings from a research project, which examined the stress and coping mechanisms of several nondominant groups of individuals. The groups were based in Winnipeg, Manitoba, Canada and included (a) Aboriginal individuals with diabetes, (b) individuals with disabilities, and (c) gays and lesbians. Our analyses of personal…

  20. Wide-Area Landslide Deformation Mapping with Multi-Path ALOS PALSAR Data Stacks: A Case Study of Three Gorges Area, China

    Directory of Open Access Journals (Sweden)

    Xuguo Shi

    2016-02-01

    Full Text Available In recent years, satellite synthetic aperture radar interferometry (InSAR has been adopted as a spaceborne geodetic tool to successfully measure surface deformation of a few well-known landslides in the Three Gorges area. In consideration of the fact that most events of slope failure happened at places other than those famous landslides since the reservoir impoundment in 2003, focusing on a limited number of slopes is insufficient to meet the requirements of regional-scale landslide disaster prevention and early warning. As a result, it has become a vital task to evaluate the overall stability of slopes across the vast area of Three Gorges using wide-coverage InSAR datasets. In this study, we explored the approach of carrying out joint analysis of multi-path InSAR data stacks for wide-area landslide deformation mapping. As an example, three ALOS (Advanced Land Observing Satellite PALSAR (Phased Array type L-band Synthetic Aperture Radar data stacks of neighboring ascending paths covering the area along the Yangtze River from Fengjie to Zigui were analyzed. A key problem to be solved is the separation of the tropospheric signal from the interferometric phase, for which we employed a hybrid description model of the atmospheric phase screen (APS to improve APS estimation from time series interferograms. The estimated atmospheric phase was largely correlated with the seasonal rainfall in the temporal dimension. The experimental results show that about 30 slopes covering total areas of 48 km2 were identified to be landslides in active deformation and should be kept under routine surveillance. Analyses of time series displacement measurements revealed that most landslides in the mountainous area far away from Yangtze River suffered from linear deformation, whereas landslides located on the river bank were destabilized predominantly by the influences of reservoir water level fluctuation and rainfall.

  1. Coseismic and post-seismic deformation fields mapped using satellite radar interferometry and fault slip inversion of the 2015 Mw8.3 Illapel earthquake, Chile

    Science.gov (United States)

    Chunyan, Qu; Ronghu, Zuo; XinJian, Shan; Guohong, Zhang; Yingfeng, Zhang; Xiaogang, Song; Yunhua, Liu; Guifang, Zhang

    2017-02-01

    We analyzed Sentinel-1A (S1A)/IW satellite descending data from multiple acquisitions to map coseismic and post-seismic deformation fields and invert the fault slip and afterslip models associated with the seismic moment magnitude (Mw)8.3 earthquake that occurred at Illapel, Chile, on September 16th, 2015. We generated one coseismic and four post-seismic interferograms to analyze temporal and spatial variations in the deformation field after the mainshock; we found that the coseismic deformation field has a semicircular shape and covers a 300-km long and 190-km wide area. The maximum displacement reaches ca. 1.33 m in the LOS subsidence direction, while post-seismic deformation derived from four interferograms with different time intervals is mainly distributed within a long narrow area approximately 65 km wide. Maximum displacement is ca. 8 cm, including two regions of line of sight (LOS) uplift and sinking. Major regions of deformation exhibit opposite directions to the mainshock just after the event, before reverting to consistency. We inverted the coseismic fault slip and afterslip models based on a shallow-dip single fault plane in a homogeneous elastic half space. Our inversion suggests that coseismic slip is mainly concentrated in a shallow region to the northwest of the source, and that rupture length along strike is close to 340 km, with a maximum slip of about 8.16 m to the trench. The estimated moment is 3.126 × 1021 N m (Mw8.27), and the maximum rupture depth is 50 km. Inverted residual slip also shows just one region of slip in the shallow subsurface, which is shifted slightly to the south. In the early stage of deformation, the residual is along the down-dip direction, with a maximum value of ca. 32 cm, before turning into the up-dip direction, with a maximum value of ca. 23 cm. Finally, we present a preliminary analysis of these complex changes in space and time.

  2. Deformation Mechanism of Hot Spinning of NiTi Shape Memory Alloy Tube Based on FEM

    Institute of Scientific and Technical Information of China (English)

    JIANG Shuyong; ZHANG Yanqiu; ZHENG Yufeng; LI Chunfeng

    2012-01-01

    As a successively and locally plastic deformation process,ball spinning is applied to manufacturing thin-walled Nickel-Titanium shape memory alloy (NiTi SMA) tube at high temperature.NiTi SMA tube blank belongs to the as-cast state which consists of a lot of dendritic grains and a few equiaxed grains.The compression tests of NiTi SMA were carried out at various strain rates at high temperature in order to obtain the constitutive model of NiTi SMA.Because NiTi SMA is sensitive to the strain rates at high temperature,rigid-viscoplastic finite element method (FEM) is used to simulate ball spinning of thin-walled NiTi SMA tube in order to analyze the deformation behavior of ball spinning of NiTi SMA tube.Stress fields,strain fields as well as velocity fields is obtained by means of rigid-viscoplastic FEM,which lays the profound foundations for studying the metal flow rule in ball spinning and forming perfect spun NiTi SMA tube.

  3. A simple higher order shear deformation theory for mechanical behavior of laminated composite plates

    Science.gov (United States)

    Adim, Belkacem; Daouadji, Tahar Hassaine; Rabahi, Aberezak

    2016-06-01

    In the present study, the static, buckling, and free vibration of laminated composite plates is examined using a refined shear deformation theory and developed for a bending analysis of orthotropic laminated composite plates. These models take into account the parabolic distribution of transverse shear stresses and satisfy the condition of zero shear stresses on the top and bottom surfaces of the plates. The most interesting feature of this theory is that it allows for parabolic distributions of transverse shear stresses across the plate thickness and satisfies the conditions of zero shear stresses at the top and bottom surfaces of the plate without using shear correction factors. The number of independent unknowns in the present theory is four, as against five in other shear deformation theories. In the analysis, the equation of motion for simply supported thick laminated rectangular plates is obtained through the use of Hamilton's principle. The accuracy of the analysis presented is demonstrated by comparing the results with solutions derived from other higher order models and with data found in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static, the buckling, and free vibration behaviors of laminated composite plates.

  4. SU-E-J-113: Effects of Deformable Registration On First-Order Texture Maps Calculated From Thoracic Lung CT Scans

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C; Cunliffe, A; Al-Hallaq, H; Armato, S [The University of Chicago, Chicago, IL (United States)

    2015-06-15

    Purpose: To determine the stability of eight first-order texture features following the deformable registration of serial computed tomography (CT) scans. Methods: CT scans at two different time points from 10 patients deemed to have no lung abnormalities by a radiologist were collected. Following lung segmentation using an in-house program, texture maps were calculated from 32×32-pixel regions of interest centered at every pixel in the lungs. The texture feature value of the ROI was assigned to the center pixel of the ROI in the corresponding location of the texture map. Pixels in the square ROI not contained within the segmented lung were not included in the calculation. To quantify the agreement between ROI texture features in corresponding pixels of the baseline and follow-up texture maps, the Fraunhofer MEVIS EMPIRE10 deformable registration algorithm was used to register the baseline and follow-up scans. Bland-Altman analysis was used to compare registered scan pairs by computing normalized bias (nBias), defined as the feature value change normalized to the mean feature value, and normalized range of agreement (nRoA), defined as the range spanned by the 95% limits of agreement normalized to the mean feature value. Results: Each patient’s scans contained between 6.8–15.4 million ROIs. All of the first-order features investigated were found to have an nBias value less than 0.04% and an nRoA less than 19%, indicating that the variability introduced by deformable registration was low. Conclusion: The eight first-order features investigated were found to be registration stable. Changes in CT texture maps could allow for temporal-spatial evaluation of the evolution of lung abnormalities relating to a variety of diseases on a patient-by-patient basis. SGA and HA receives royalties and licensing fees through the University of Chicago for computer-aided diagnosis technology. Research reported in this publication was supported by the National Institute Of General

  5. Stretch fast dynamo mechanism via conformal mapping in Riemannian manifolds

    Science.gov (United States)

    Garcia de Andrade, L. C.

    2007-10-01

    Two new analytical solutions of the self-induction equation in Riemannian manifolds are presented. The first represents a twisted magnetic flux tube or flux rope in plasma astrophysics, where the rotation of the flow implies that the poloidal field is amplified from toroidal field, in the spirit of dynamo theory. The value of the amplification depends on the Frenet torsion of the magnetic axis of the tube. Actually this result illustrates the Zeldovich stretch, twist, and fold method to generate dynamos from straight and untwisted ropes. Based on the fact that this problem was previously handled, using a Riemannian geometry of twisted magnetic flux ropes [Phys Plasmas 13, 022309 (2006)], investigation of a second dynamo solution, conformally related to the Arnold kinematic fast dynamo, is obtained. In this solution, it is shown that the conformal effect on the fast dynamo metric enhances the Zeldovich stretch, and therefore a new dynamo solution is obtained. When a conformal mapping is performed in an Arnold fast dynamo line element, a uniform stretch is obtained in the original line element.

  6. Site investigation SFR. Rock type coding, overview geological mapping and identification of rock units and possible deformation zones in drill cores from the construction of SFR

    Energy Technology Data Exchange (ETDEWEB)

    Petersson, Jesper (Vattenfall Power Consultant AB, Stockholm (Sweden)); Curtis, Philip; Bockgaard, Niclas (Golder Associates AB (Sweden)); Mattsson, Haakan (GeoVista AB, Luleaa (Sweden))

    2011-01-15

    This report presents the rock type coding, overview lithological mapping and identification of rock units and possible deformation zones in drill cores from 32 boreholes associated with the construction of SFR. This work can be seen as complementary to single-hole interpretations of other older SFR boreholes earlier reported in /Petersson and Andersson 2010/: KFR04, KFR08, KFR09, KFR13, KFR35, KFR36, KFR54, KFR55, KFR7A, KFR7B and KFR7C. Due to deficiencies in the available material, the necessary activities have deviated somewhat from the established methodologies used during the recent Forsmark site investigations for the final repository for spent nuclear fuel. The aim of the current work has been, wherever possible, to allow the incorporation of all relevant material from older boreholes in the ongoing SFR geological modelling work in spite of the deficiencies. The activities include: - Rock type coding of the original geological mapping according to the nomenclature used during the preceding Forsmark site investigation. As part of the Forsmark site investigation such rock type coding has already been performed on most of the old SFR boreholes if the original geological mapping results were available. This earlier work has been complemented by rock type coding on two further boreholes: KFR01 and KFR02. - Lithological overview mapping, including documentation of (1) rock types, (2) ductile and brittle-ductile deformation and (3) alteration for drill cores from eleven of the boreholes for which no original geological borehole mapping was available (KFR31, KFR32, KFR34, KFR37,KFR38, KFR51, KFR69, KFR70, KFR71, KFR72 and KFR89). - Identification of possible deformation zones and merging of similar rock types into rock units. This follows SKB's established criteria and methodology of the geological Single-hole interpretation (SHI) process wherever possible. Deviations from the standard SHI process are associated with the lack of data, for example BIPS images

  7. Neurons respond directly to mechanical deformation with pannexin-mediated ATP release and autostimulation of P2X7 receptors.

    Science.gov (United States)

    Xia, Jingsheng; Lim, Jason C; Lu, Wennan; Beckel, Jonathan M; Macarak, Edward J; Laties, Alan M; Mitchell, Claire H

    2012-05-15

    Mechanical deformation produces complex effects on neuronal systems, some of which can lead to dysfunction and neuronal death. While astrocytes are known to respond to mechanical forces, it is not clear whether neurons can also respond directly. We examined mechanosensitive ATP release and the physiological response to this release in isolated retinal ganglion cells. Purified ganglion cells released ATP upon swelling. Release was blocked by carbenoxolone, probenecid or peptide (10)panx, implicating pannexin channels as conduits. Mechanical stretch of retinal ganglion cells also triggered a pannexin-dependent ATP release. Whole cell patch clamp recording demonstrated that mild swelling induced the activation of an Ohmic cation current with linear kinetics. The current was inhibited by removal of extracellular ATP with apyrase, by inhibition of the P2X(7) receptor with A438079, zinc, or AZ 10606120, and by pannexin blockers carbenoxolone and probenecid. Probenecid also inhibited the regulatory volume decrease observed after swelling isolated neurons. Together, these observations indicate mechanical strain triggers ATP release directly from retinal ganglion cells and that this released ATP autostimulates P2X(7) receptors. Since extracellular ATP levels in the retina increase with elevated intraocular pressure, and stimulation of P2X(7) receptors on retinal ganglion cells can be lethal, this autocrine response may impact ganglion cells in glaucoma. It remains to be determined whether the autocrine stimulation of purinergic receptors is a general response to a mechanical deformation in neurons, or whether preventing ATP release through pannexin channels and blocking activation of the P2X(7) receptor, is neuroprotective for stretched neurons.

  8. Digital moiré interferometric analysis on the effect of nanoparticle conditioning on the mechanical deformation in dentin

    Science.gov (United States)

    Li, Fang Chi; Kishen, Anil

    2016-02-01

    Dentin is a biological composite that forms the major bulk of tooth structure. Understanding the biomechanical response of dentin structure to forces is essential to restore the loss of mechanical integrity associated with dentin loss during disease or treatment procedures. Moiré interferometry is an optical interferometry based method, which allows wholefield, real-time analysis of dental structures with high-sensitivity. The aim of this study was to investigate the deformation gradients in dentin during function and subsequent to surface conditioning with bioactive biopolymeric nanoparticle. Slab shaped dentin specimens were prepared and a customized loading jig was used to compressively load the specimens from 10 N to 50 N. Specific regions of interest was chosen on the dentin specimens for strain analysis. The digital moiré interferometry experiments showed a distinct deformation pattern in dentin in the direction perpendicular to the dentinal tubules, which increased with increase in dentin loss. The dentin conditioned with nanoparticles did not display marked increase in strain gradients with loads. The current photomechanical experiment highlighted the impact of nanoparticle treatment to improve the mechanical integrity of dentin.

  9. Contributions of microbiome and mechanical deformation to intestinal bacterial overgrowth and inflammation in a human gut-on-a-chip.

    Science.gov (United States)

    Kim, Hyun Jung; Li, Hu; Collins, James J; Ingber, Donald E

    2016-01-05

    A human gut-on-a-chip microdevice was used to coculture multiple commensal microbes in contact with living human intestinal epithelial cells for more than a week in vitro and to analyze how gut microbiome, inflammatory cells, and peristalsis-associated mechanical deformations independently contribute to intestinal bacterial overgrowth and inflammation. This in vitro model replicated results from past animal and human studies, including demonstration that probiotic and antibiotic therapies can suppress villus injury induced by pathogenic bacteria. By ceasing peristalsis-like motions while maintaining luminal flow, lack of epithelial deformation was shown to trigger bacterial overgrowth similar to that observed in patients with ileus and inflammatory bowel disease. Analysis of intestinal inflammation on-chip revealed that immune cells and lipopolysaccharide endotoxin together stimulate epithelial cells to produce four proinflammatory cytokines (IL-8, IL-6, IL-1β, and TNF-α) that are necessary and sufficient to induce villus injury and compromise intestinal barrier function. Thus, this human gut-on-a-chip can be used to analyze contributions of microbiome to intestinal pathophysiology and dissect disease mechanisms in a controlled manner that is not possible using existing in vitro systems or animal models.

  10. A multiscale approach for the deformation mechanism in pearlite microstructure: Atomistic study of the role of the heterointerface on ductility

    Energy Technology Data Exchange (ETDEWEB)

    Shimokawa, Tomotsugu, E-mail: simokawa@se.kanazawa-u.ac.jp [School of Mechanical Engineering, Kanazawa University, Ishikawa 920-1192 (Japan); Oguro, Takuma [Division of Mechanical Science and Engineering, Kanazawa University, Ishikawa 920-1192 (Japan); Tanaka, Masaki; Higashida, Kenji [Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Ohashi, Tetsuya [Department of Mechanical Engineering, Kitami Institute of Technology, Hokkaido 090-8507 Japan (Japan)

    2014-03-01

    The role of the ferrite/cementite heterointerface on the mechanical properties of heavily-drawn-pearlitic steel is investigated via tensile deformation tests of multilayered composite models with brittle and ductile virtual materials in a two-dimensional triangle-lattice system by using molecular dynamics simulations. The interface strength is controlled by introducing a heterointerface potential. The dominant role of heterointerface on the mechanical properties of multilayered composite models is influenced by the interface strength. In case of weak interface strength, the heterointerface acts as a strong barrier to dislocation motion in the ductile phase; hence, the multilayered composite model shows high strength but extremely low ductility. This tendency corresponds well to that of as-drawn pearlitic steel with cementite decomposition. In case of strong interface strength, the heterointerface acts as a dislocation source of the brittle phase by dislocation transmission through the heterointerface from the ductile to brittle phase; hence, the multilayered composite model shows good ductility with a small decrease in strength. This tendency corresponds well to annealed pearlitic steel recovered from cementite decomposition. These results suggest that cementite decomposition decreases the plastic deformation potential of the heterointerface. The conditions necessary for the heterointerface to simultaneously exhibit high strength and ductility are discussed on the basis of the results of atomic simulations.

  11. Mechanical behavior of materials engineering methods for deformation, fracture, and fatigue

    CERN Document Server

    Dowling, Norman E

    2012-01-01

    For upper-level undergraduate engineering courses in Mechanical Behavior of Materials. Mechanical Behavior of Materials, 4/e introduces the spectrum of mechanical behavior of materials, emphasizing practical engineering methods for testing structural materials to obtain their properties, and predicting their strength and life when used for machines, vehicles, and structures. With its logical treatment and ready-to-use format, it is ideal for upper-level undergraduate students who have completed elementary mechanics of materials courses.

  12. Effect of Heat Assisted Bath Sonication on the Mechanical and Thermal Deformation Behaviours of Graphene Nanoplatelets Filled Epoxy Polymer Composites

    Directory of Open Access Journals (Sweden)

    Jin-Luen Phua

    2016-01-01

    Full Text Available Graphene nanoplatelets (GNP filled epoxy composites ranged from 0.2 to 5 vol.% were prepared in this study using simple heat assisted bath sonication for better GNP dispersion and exfoliation. The effects of GNP filler loading via heat assisted bath sonication on the mechanical properties and thermal deformation behaviour were investigated. Improvements on flexural strength and fracture toughness up to 0.4 vol.% filler loading were recorded. Further addition of GNP filler loading shows a deteriorating behaviour on the mechanical properties on the composites. The bulk electrical conductivity of the epoxy composites is greatly improved with the addition of GNP filler loading up to 1 vol.%. The thermal expansion of epoxy composites is reduced with the addition of GNP; however poor thermal stability of the composites is observed.

  13. Numerical simulation of mechanical deformation of semi-solid material using a level-set based finite element method

    Science.gov (United States)

    Sun, Zhidan; Bernacki, Marc; Logé, Roland; Gu, Guochao

    2017-09-01

    In this work, a level-set based finite element method was used to numerically evaluate the mechanical behavior in a small deformation range of semi-solid materials with different microstructure configurations. For this purpose, a finite element model of the semi-solid phase was built based on Voronoï diagram. Interfaces between the solid and the liquid phases were implicitly described by level-set functions coupled to an anisotropic meshing technique. The liquid phase was considered as a Newtonian fluid, whereas the behavior of the solid phase was described by a viscoplastic law. Simulations were performed to study the effect of different parameters such as solid phase fraction and solid bridging. Results show that the macroscopic mechanical behavior of semi-solid material strongly depends on the solid fraction and the local microstructure which play important roles in the formation of hot tearing. These results could provide valuable information for the processing of semi-solid materials.

  14. Influence of the Repetitive Corrugation on the Mechanism Occuring During Plastic Deformation of CuSn6 Alloy

    Directory of Open Access Journals (Sweden)

    Nuckowski P.M.

    2016-09-01

    Full Text Available This paper presents the research results of CuSn6 alloy strip at semi-hard state, plastically deformed in the process of repetitive corrugation. The influence of process parameters on the mechanical properties and structure of examined alloy were investigated. Examination in high-resolution transmission electron microscopy (HRTEM confirmed the impact of the repetitive corrugation to obtain the nano-scale structures. It has been found, that the application of repetitive corrugation increases the tensile strength (Rm, yield strength (Rp0.2 and elastic limit (Rp0,05 of CuSn6 alloy strips. In the present work it has been confirmed that the repetitive corrugation process is a more efficient method for structure and mechanical properties modification of commercial CuSn6 alloy strip (semi-hard as compared with the classic rolling process.

  15. DEFORMATION CHARACTERISTICS OF CRUSHED-STONE LAYER UNDER CYCLIC IMPACT LOADING FROM MICRO-MECHANICAL VIEW

    Science.gov (United States)

    Kono, Akiko; Matsushima, Takashi

    'Hanging sleepers', which have gaps between sleepers and ballast layer are often found in the neighborhood of rail joints or rugged surface rails. This suggests that differential settlement of the ballast layer is due to impact loading generated by the contact between running wheel and rugged surface rail. Then cyclic loading tests were performed on crushed-stone layer with two loading patterns, the one is a cyclic impact loading and the other one is cyclic 'standard' loading controlled at 1/10 loading velocity of the impact loading. It was shown that the crashed-stone layer deforms with volumetric expansion during every off-loading processes under the cyclic impact loading. This phenomena prevents crushed stone layer from forming stable grain columns, then the residual settlement under the cyclic impact loading is larger than that under the cyclic 'standard' loading. A simple mass-spring model simulates that two masses move in the opposite direction with increased frequency of harmonic excitation.

  16. Mechanical Deformation Behavior of Sn-Ag-Cu Solders with Minor Addition of 0.05 wt.% Ni

    Science.gov (United States)

    Hammad, A. E.; El-Taher, A. M.

    2014-11-01

    The aim of the present work is to develop a comparative evaluation of the microstructural and mechanical deformation behavior of Sn-Ag-Cu (SAC) solders with the minor addition of 0.05 wt.% Ni. Test results showed that, by adding 0.05Ni element into SAC solders, generated mainly small rod-shaped (Cu,Ni)6Sn5 intermetallic compounds (IMCs) inside the β-Sn phase. Moreover, increasing the Ag content and adding Ni could result in the change of the shape and size of the IMC precipitate. Hence, a significant improvement is observed in the mechanical properties of SAC solders with increasing Ag content and Ni addition. On the other hand, the tensile results of Ni-doped SAC solders showed that both the yield stress and ultimate tensile strengths decrease with increasing temperature and with decreasing strain rate. This behavior was attributed to the competing effects of work hardening and dynamic recovery processes. The Sn-2.0Ag-0.5Cu-0.05Ni solder displayed the highest mechanical properties due to the formation of hard (Cu,Ni)6Sn5 IMCs. Based on the obtained stress exponents and activation energies, it is suggested that the dominant deformation mechanism in SAC (205)-, SAC (0505)- and SAC (0505)-0.05Ni solders is pipe diffusion, and lattice self-diffusion in SAC (205)-0.05Ni solder. In view of these results, the Sn-2.0Ag-0.5Cu-0.05Ni alloy is a more reliable solder alloy with improved properties compared with other solder alloys tested in the present work.

  17. Comments on “Deformation of clinopyroxenite: Evidence for a transition in flow mechanisms and semibrittle behavior” By S.H. Kirby and A.K. Kronenberg

    Science.gov (United States)

    Boland, J. N.

    1986-04-01

    Attempts to improve the accuracy of experimentation in the Griggs-type piston-cylinder deformation apparatus are most welcome and the recent study by Kirby and Kronenberg [1984] on the deformation of clinopyroxenite has the potential for useful quantitative manipulation of rheological data. However, there are many apparent inconsistencies and data-handling inaccuracies in this work that require clarification before further use can be made of the data. The following comments relate specifically to (1) the presentation and/or selection of data, (2) rheological relationships, (3) semibrittle behavior, reproducibility and instability, and (4) single versus multiple mechanisms of deformation.

  18. On The Creep Behavior and Deformation Mechanisms Found in an Advanced Polycrystalline Nickel-Base Superalloy at High Temperatures

    Science.gov (United States)

    Deutchman, Hallee Zox

    Polycrystalline Ni-base superalloys are used as turbine disks in the hot section in jet engines, placing them in a high temperature and stress environment. As operating temperatures increase in search of better fuel efficiency, it becomes important to understand how these higher temperatures are affecting mechanical behavior and active deformation mechanisms in the substructure. Not only are operating temperatures increasing, but there is a drive to design next generation alloys in shorter time periods using predictive modeling capabilities. This dissertation focuses on mechanical behavior and active deformation mechanisms found in two different advanced polycrystalline alloy systems, information which will then be used to build advanced predictive models to design the next generation of alloys. The first part of this dissertation discusses the creep behavior and identifying active deformation mechanisms in an advanced polycrystalline Ni-based superalloy (ME3) that is currently in operation, but at higher temperatures and stresses than are experienced in current engines. Monotonic creep tests were run at 700°C and between 655-793MPa at 34MPa increments, on two microstructures (called M1 and M2) produced by different heat treatments. All tests were crept to 0.5% plastic strain. Transient temperature and transient stress tests were used determine activation energy and stress exponents of the M1 microstructure. Constant strain rate tests (at 10-4s-1) were performed on both microstructures as well. Following creep testing, both M1 and M2 microstructures were fully characterized using Scanning Electron Microscopy (SEM) for basic microstructure information, and Scanning Transmission Electron Microscopy (STEM) to determine active deformation mechanism. It was found that in the M1 microstructure, reorder mediated activity (such as discontinuous faulting and microtwinning) is dominant at low stresses (655-724 MPa). Dislocations in the gamma matrix, and overall planar

  19. Building keypoint mappings on multispectral images by a cascade of classifiers with a resurrection mechanism.

    Science.gov (United States)

    Li, Yong; Jing, Jing; Jin, Hongbin; Qiao, Wei

    2015-05-21

    Inspired by the boosting technique for detecting objects, this paper proposes a cascade structure with a resurrection mechanism to establish keypoint mappings on multispectral images. The cascade structure is composed of four steps by utilizing best bin first (BBF), color and intensity distribution of segment (CIDS), global information and the RANSAC process to remove outlier keypoint matchings. Initial keypoint mappings are built with the descriptors associated with keypoints; then, at each step, only a small number of keypoint mappings of a high confidence are classified to be incorrect. The unclassified keypoint mappings will be passed on to subsequent steps for determining whether they are correct. Due to the drawback of a classification rule, some correct keypoint mappings may be misclassified as incorrect at a step. Observing this, we design a resurrection mechanism, so that they will be reconsidered and evaluated by the rules utilized in subsequent steps. Experimental results show that the proposed cascade structure combined with the resurrection mechanism can effectively build more reliable keypoint mappings on multispectral images than existing methods.

  20. Building Keypoint Mappings on Multispectral Images by a Cascade of Classifiers with a Resurrection Mechanism

    Directory of Open Access Journals (Sweden)

    Yong Li

    2015-05-01

    Full Text Available Inspired by the boosting technique for detecting objects, this paper proposes a cascade structure with a resurrection mechanism to establish keypoint mappings on multispectral images. The cascade structure is composed of four steps by utilizing best bin first (BBF, color and intensity distribution of segment (CIDS, global information and the RANSAC process to remove outlier keypoint matchings. Initial keypoint mappings are built with the descriptors associated with keypoints; then, at each step, only a small number of keypoint mappings of a high confidence are classified to be incorrect. The unclassified keypoint mappings will be passed on to subsequent steps for determining whether they are correct. Due to the drawback of a classification rule, some correct keypoint mappings may be misclassified as incorrect at a step. Observing this, we design a resurrection mechanism, so that they will be reconsidered and evaluated by the rules utilized in subsequent steps. Experimental results show that the proposed cascade structure combined with the resurrection mechanism can effectively build more reliable keypoint mappings on multispectral images than existing methods.

  1. Interpolation of GPS and Geological Data Using InSAR Deformation Maps: Method and Application to Land Subsidence in the Alto Guadalentín Aquifer (SE Spain

    Directory of Open Access Journals (Sweden)

    Marta Béjar-Pizarro

    2016-11-01

    Full Text Available Land subsidence resulting from groundwater extractions is a global phenomenon adversely affecting many regions worldwide. Understanding the governing processes and mitigating associated hazards require knowing the spatial distribution of the implicated factors (piezometric levels, lithology, ground deformation, usually only known at discrete locations. Here, we propose a methodology based on the Kriging with External Drift (KED approach to interpolate sparse point measurements of variables influencing land subsidence using high density InSAR measurements. In our study, located in the Alto Guadalentín basin, SE Spain, these variables are GPS vertical velocities and the thickness of compressible soils. First, we estimate InSAR and GPS rates of subsidence covering the periods 2003–2010 and 2004–2013, respectively. Then, we apply the KED method to the discrete variables. The resulting continuous GPS velocity map shows maximum subsidence rates of 13 cm/year in the center of the basin, in agreement with previous studies. The compressible deposits thickness map is significantly improved. We also test the coherence of Sentinel-1 data in the study region and evaluate the applicability of this methodology with the new satellite, which will improve the monitoring of aquifer-related subsidence and the mapping of variables governing this phenomenon.

  2. Pre-lithification structures, deformation mechanisms, and fabric ellipsoids in slumped turbidites from the Pigeon Point Formation, California

    Science.gov (United States)

    Paterson, Scott R.; Tobisch, Othmar T.

    1993-06-01

    Paterson, S.R. and Tobisch, O.T. 1993. Pre-lithification structures, deformation mechanisms, and fabric ellipsoids in slumped turbidites from the Pigeon Point Formation, California. Tectonophysics, 222: 135-149. Quantitative fabric, structural, and microstructural analyses of pre-lithification folds, foliations, and lineations formed by slumping of turbidite sequences in the Cretaceous Pigeon Point Formation, California, provide a useful comparison with strain and microstructures developed in lithified and tectonically deformed turbidites. Our results indicate the following: (1) multiple generations of folds, cleavages, and lineations can develop prior to any post-lithification tectonic deformation (2) individual grains in sandstones have variable axial ratios, but the ratios and orientations of large populations of grains define fabric ellipsoids with small axial ratios ( ave. = 1.25:1.13:1) (3) phyllosilicate grains define moderate flattening fabrics (reflecting 20-40% shortening or volume loss), with the intensity of alignment partly controlled by the percent of quartz and feldspar grains (4) the fabric ellipsoids in sand-rich layers largely reflect deposition and slumping: pre- and post-slump compactions did not occur, in sand-rich units but did align clay particles in mud-siltstone units, and (5) intra-grain microstructures in quartz and feldspar (e.g., undulose extinction, subgrains) are inherited or recycled features rather than representing effects of post-lithification strains. Our data also suggest that prelithification slumping occurred by pervasive grain rotation and grain boundary sliding in saturated sands with some local movement of material along bedding horizons. A likely model for the folding and associated fabrics is that buckling and fold-hinge flattening drove fluid expulsion, which in turn caused local grain-scale realignment, transposition of bedding, and the development of an axial planar cleavage in the hinge zones. Continued fluid flow was

  3. Microstructure, elastic deformation behavior and mechanical properties of biomedical β-type titanium alloy thin-tube used for stents.

    Science.gov (United States)

    Tian, Yuxing; Yu, Zhentao; Ong, Chun Yee Aaron; Kent, Damon; Wang, Gui

    2015-05-01

    Cold-deformability and mechanical compatibility of the biomedical β-type titanium alloy are the foremost considerations for their application in stents, because the lower ductility restricts the cold-forming of thin-tube and unsatisfactory mechanical performance causes a failed tissue repair. In this paper, β-type titanium alloy (Ti-25Nb-3Zr-3Mo-2Sn, wt%) thin-tube fabricated by routine cold rolling is reported for the first time, and its elastic behavior and mechanical properties are discussed for the various microstructures. The as cold-rolled tube exhibits nonlinear elastic behavior with large recoverable strain of 2.3%. After annealing and aging, a nonlinear elasticity, considered as the intermediate stage between "double yielding" and normal linear elasticity, is attributable to a moderate precipitation of α phase. Quantitive relationships are established between volume fraction of α phase (Vα) and elastic modulus, strength as well as maximal recoverable strain (εmax-R), where the εmax-R of above 2.0% corresponds to the Vα range of 3-10%. It is considered that the "mechanical" stabilization of the (α+β) microstructure is a possible elastic mechanism for explaining the nonlinear elastic behavior.

  4. Triple junction motion - A new recovery mechanism in metals deformed to large strains

    DEFF Research Database (Denmark)

    Yu, Tianbo; Hansen, Niels; Huang, Xiaoxu

    2013-01-01

    A phenomenologically new recovery mechanism - triple junction motion is presented. This recovery mechanism is found to be the dominant one at low and medium temperatures in highly strained aluminum, which has a very fine microstructure, composed of lamellae with the thickness of a few hundred nan...

  5. Modelling time-dependent mechanical behaviour of softwood using deformation kinetics

    DEFF Research Database (Denmark)

    Engelund, Emil Tang; Svensson, Staffan

    2010-01-01

    The time-dependent mechanical behaviour (TDMB) of softwood is relevant, e.g., when wood is used as building material where the mechanical properties must be predicted for decades ahead. The established mathematical models should be able to predict the time-dependent behaviour. However, these models...

  6. In-situ SEM indentation studies of the deformation mechanisms in TiN, CrN and TiN/CrN.

    Science.gov (United States)

    Rzepiejewska-Malyska, K; Parlinska-Wojtan, M; Wasmer, K; Hejduk, K; Michler, J

    2009-01-01

    In this study, the microstructure and the deformation mechanisms of TiN, CrN and multilayer TiN/CrN thin films on silicon substrates were investigated. Cross-sectional lamellas of nanoindents were prepared by focused ion beam milling to observe by transmission electron microscopy the microstructure of the as-deposited and deformed materials. TiN film exhibits nanocrystalline columns, whereas CrN shows large grains. The TiN/CrN multilayer presents microstructural features typical for both materials. A film hardness of 16.9GPa for CrN, 15.8GPa for TiN and 16.6GPa for TiN/CrN was found by the nanoindentation. Reduced modulus recorded for TiN and CrN reference coatings were 221.54 and 171.1GPa, respectively, and 218.6GPa for the multilayer coating. The deformation mechanisms were observed via in-situ scanning electron microscope nanoindentation. The TiN thin film showed short radial cracks, whereas CrN deformed through pile-up and densification of the material. For TiN/CrN multilayer pile-up and cracks were found. Transmission electron microscopy observations indicated that TiN deforms through grain boundary sliding and CrN via densification and material flow. The deformation mechanism observed in TiN/CrN multilayer was found to be a mixture of both modes.

  7. Study of microstructural evolution, microstructure-mechanical properties correlation and collaborative deformation-transformation behavior of quenching and partitioning (Q and P) steel

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jing; Yu, Hao, E-mail: yhzhmr@126.com; Wang, Shaoyang; Fan, Yongfei

    2014-02-24

    This paper presents a detailed characterization of the microstructural evolution of quenching and partitioning (Q and P) steel by dilatometer, X-ray diffraction and scanning electron microscopy. Influence of partitioning time on mechanical properties was investigated and the relationship between microstructures and mechanical properties was established. The results indicate that bainite transformation occurs at the preliminary stage of partitioning and the amount is proportional to quenching temperature. Martensite softening, bainite transformation kinetics, amount and stability of retained austenite collaboratively have effects on mechanical properties. The purpose of the EBSD investigation is to study the changes in the microstructure of the Q and P steel during deformation and obtain a better understanding of collaborative deformation-transformation behavior. During deformation, plastic deformation preferentially occurred in the vicinity of ferrite–martensite interfaces and spread to the interior of ferrite grain with strain increasing. Plastic deformation started to occur in martensite after large strain. Furthermore, grain rotation occurred in some austenite grains or divided into subgrains during deformation.

  8. Hot deformation mechanisms and microstructural control in high-temperature extruded AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Y.V.R.K.; Rao, K.P. [Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon (China)

    2007-07-15

    A Processing map has been developed for Magnesium alloy AZ31 extruded at 450 C which revealed that the extruded rods may be further processed into components industrially at 400 C and at a strain rate of 10 s{sup -1}. If processed at lower strain rates in the vicinity of 0.1 s{sup -1}, unusual grain size variations with temperature and strain rate are observed, suggesting that grain size control will be difficult. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  9. Mapping the Broad Structural and Mechanical Properties of Amyloid Fibrils.

    Science.gov (United States)

    Lamour, Guillaume; Nassar, Roy; Chan, Patrick H W; Bozkurt, Gunes; Li, Jixi; Bui, Jennifer M; Yip, Calvin K; Mayor, Thibault; Li, Hongbin; Wu, Hao; Gsponer, Jörg A

    2017-02-28

    Amyloids are fibrillar nanostructures of proteins that are assembled in several physiological processes in human cells (e.g., hormone storage) but also during the course of infectious (prion) and noninfectious (nonprion) diseases such as Creutzfeldt-Jakob and Alzheimer's diseases, respectively. How the amyloid state, a state accessible to all proteins and peptides, can be exploited for functional purposes but also have detrimental effects remains to be determined. Here, we measure the nanomechanical properties of different amyloids and link them to features found in their structure models. Specifically, we use shape fluctuation analysis and sonication-induced scission in combination with full-atom molecular dynamics simulations to reveal that the amyloid fibrils of the mammalian prion protein