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Sample records for structural deformation mechanisms

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

    International Nuclear Information System (INIS)

    Kim, Sang Woo

    2016-01-01

    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

  2. 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.

  3. 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......, but vacancies can be permanently present. The transition states and energies for slip mechanisms have been determined using the nudged elastic band method, and we find a size-dependent crossover from a dislocation-mediated slip to a homogeneous slip when the contact diameter becomes less than a few nm. We show...

  4. Mechanical design of deformation compensated flexural pivots structured for linear nanopositioning stages

    Science.gov (United States)

    Shu, Deming; Kearney, Steven P.; Preissner, Curt A.

    2015-02-17

    A method and deformation compensated flexural pivots structured for precision linear nanopositioning stages are provided. A deformation-compensated flexural linear guiding mechanism includes a basic parallel mechanism including a U-shaped member and a pair of parallel bars linked to respective pairs of I-link bars and each of the I-bars coupled by a respective pair of flexural pivots. The basic parallel mechanism includes substantially evenly distributed flexural pivots minimizing center shift dynamic errors.

  5. Detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural components

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C. [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Laboratoire de Mecanique des Contacts et des Structures (LaMCoS), INSA Lyon, 20 Avenue des Sciences, F-69621 Villeurbanne Cedex (France); Li, H. [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Li, M.Q., E-mail: zc9997242256@126.com [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China)

    2016-05-15

    Graphical abstract: This study focused on the detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural component. A special surface with regular patterns was processed to be joined so as to observe the extent of surface asperity deformation under different applied bonding pressures. Fracture surface characteristic combined with surface roughness profiles distinctly revealed the enhanced surface asperity deformation as the applied pressure increases. The influence of surface asperity deformation mechanism on joint formation was analyzed: (a) surface asperity deformation not only directly expanded the interfacial contact areas, but also released deformation heat and caused defects, indirectly accelerating atomic diffusion, then benefits to void shrinkage; (b) surface asperity deformation readily introduced stored energy difference between two opposite sides of interface grain boundary, resulting in strain induced interface grain boundary migration. In addition, the influence of void on interface grain boundary migration was analyzed in detail. - Highlights: • A high quality hollow structural component has been fabricated by diffusion bonding. • Surface asperity deformation not only expands the interfacial contact areas, but also causes deformation heat and defects to improve the atomic diffusion. • Surface asperity deformation introduces the stored energy difference between the two opposite sides of interface grain boundary, leading to strain induced interface grain boundary migration. • The void exerts a dragging force on the interface grain boundary to retard or stop interface grain boundary migration. - Abstract: This study focused on the detailed analysis of surface asperity deformation mechanism in similar diffusion bonding as well as on the fabrication of high quality martensitic stainless steel hollow structural components. A special surface with regular patterns was processed to be joined so as to

  6. Deformation mechanisms of a porous structure of the poly(ethylene terephthalate) nuclear track membrane

    International Nuclear Information System (INIS)

    Ovchinnikov, V.V.

    1989-01-01

    The deformation mechanisms of a porous structure of the nuclear track membrane made of poly(ethylene terephthalate) are investigated in the temperature range from 333 to 473 K. It is shown that the pore size of the membrane can both decrease and increase. The analytical equation based on the Alfrey mechanical approach to the relaxation deformation of polymers describes the experimental data satisfactorily over the whole range of temperatures and pore radii of the membranes. 21 refs.; 5 figs.; 3 tabs

  7. Extremely deformable structures

    CERN Document Server

    2015-01-01

    Recently, a new research stimulus has derived from the observation that soft structures, such as biological systems, but also rubber and gel, may work in a post critical regime, where elastic elements are subject to extreme deformations, though still exhibiting excellent mechanical performances. This is the realm of ‘extreme mechanics’, to which this book is addressed. The possibility of exploiting highly deformable structures opens new and unexpected technological possibilities. In particular, the challenge is the design of deformable and bi-stable mechanisms which can reach superior mechanical performances and can have a strong impact on several high-tech applications, including stretchable electronics, nanotube serpentines, deployable structures for aerospace engineering, cable deployment in the ocean, but also sensors and flexible actuators and vibration absorbers. Readers are introduced to a variety of interrelated topics involving the mechanics of extremely deformable structures, with emphasis on ...

  8. Real-time deformations of organ based on structural mechanics for surgical simulators

    Science.gov (United States)

    Nakaguchi, Toshiya; Tagaya, Masashi; Tamura, Nobuhiko; Tsumura, Norimichi; Miyake, Yoichi

    2006-03-01

    This research proposes the deformation model of organs for the development of the medical training system using Virtual Reality (VR) technology. First, the proposed model calculates the strains of coordinate axis. Secondly, the deformation is obtained by mapping the coordinate of the object to the strained coordinate. We assume the beams in the coordinate space to calculate the strain of the coordinate axis. The forces acting on the object are converted to the forces applied to the beams. The bend and the twist of the beams are calculated based on the theory of structural mechanics. The bend is derived by the finite element method. We propose two deformation methods which differ in the position of the beams in the coordinate space. One method locates the beams along the three orthogonal axes (x, y, z). Another method locates the beam in the area where the deformation is large. In addition, the strain of the coordinate axis is attenuated in proportion to the distance from the point of action to consider the attenuation of the stress which is a viscoelastic feature of the organs. The proposed model needs less computational cost compared to the conventional deformation method since our model does not need to divide the object into the elasticity element. The proposed model was implemented in the laparoscopic surgery training system, and a real-time deformation can be realized.

  9. Mechanics of deformable bodies

    CERN Document Server

    Sommerfeld, Arnold Johannes Wilhelm

    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.

  10. Forecasting of mechanical - and structural behavior of 316 austenitic stainless steels by deformation charts

    International Nuclear Information System (INIS)

    Monteiro, S.N.

    1980-01-01

    The utilization of deformation charts applied to AISI 316 austenitic stainless steel with the purpose of foreseeing its behavior associated with structural and mechanical phenomena, is evaluated. The ocurrence of phenomena such as dynamic aging, martensite transformation, static aging, failure at creep curve, cells, subgrains and boundary slips is discussed in the different regions of the chart. A practical example of the charts' utilization for components of fast reactors is finally presented. (Author) [pt

  11. Severe plastic deformation effect on structure and mechanical properties of Al-Mg-Li system alloys

    International Nuclear Information System (INIS)

    Kolobov, Yu.R.; Najdenkin, E.V.; Dudarev, E.F.; Bakach, G.P.; Pochivalov, Yu.I.; Girsova, N.V.; Ivanov, M.B.

    2002-01-01

    The study on the structural-phase states and mechanical properties of the industrial aluminium alloys Al - 5.5% Mg - 2.2% Li - 0.12% Zr, percent by weight and Al - 5% Mg - 2.2% Li -0.12% Zr - 0.2% Sc percent by weight, obtained by the impact of the intensive plastic deformation, is carried out in comparison with the initial polycrystalline state. It is established that the homogeneous ultrafine-grained structure with the second phase particles, located primarily by the grain boundaries, is formed in the studied samples by the above-mentioned treatment. Such a character of the structure leads to the shift of the temperature-velocity interval of the superplastic properties to the area of lower temperatures and higher deformation velocities [ru

  12. Optimisation by plastic deformation of structural and mechanical uranium alloys properties

    International Nuclear Information System (INIS)

    Prunier, Claude.

    1981-08-01

    Structural and mechanical properties evolution of rich and poor uranium alloys are investigated. Good usual properties are obtained with few metallic additions with a limited effect giving a fine and isotrope grain structure. Amelioration is observed with heat treatment from β and γ phases high temperature range. However, dynamic recrystallisation, related to hot working, is the better phenomena to maximize the usual mechanical and structural properties. So high temperature behaviour of rich and poor uranium alloys in α, β and γ crystalline structure is studied: - dynamic recrystallisation phenomena begins only in α, and β phases high temperature range; - high strength and brittle β phase shows a very large ductility above 700 deg C. Recrystallisation is a thermal actived phenomena localised at grain boundary, dependant with alloys concentration and crystalline structure. β phase activation energy and deformation rate for dynamic recrystallisation beginning are most important, than α and γ phases in relation with quadratic structure complexity. Both temperature and deformation rate are the main dynamic recrystallisation factors. Optimal usual mechanical and structural properties obtained by hot working (forging, milling) are sensible to hydrogen embrittlement [fr

  13. 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.

  14. Structural and magnetic study of mechanically deformed Fe rich FeAlSi ternary alloys

    International Nuclear Information System (INIS)

    Legarra, E.; Apiñaniz, E.; Plazaola, F.

    2012-01-01

    Highlights: ► Addition of Si to binary Fe–Al alloys makes the disordering more difficult. ► Si addition opposes the large volume increase found in FeAl alloys with deformation. ► Disordering induces a redistribution of non-ferrous atoms around Fe atoms in Fe 75 Al 25−x Si x and Fe 70 Al 30−x Si x . ► Addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe. ► Si inhibits the para-ferro transition found in Fe 60 Al 40 alloy with disordering. - Abstract: In this work we study systematically the influence of different Al/Si ratios on the magnetic and structural properties of mechanically disordered powder Fe 75 Al 25−x Si x , Fe 70 Al 30−x Si x and Fe 60 Al 40−x Si x alloys by means of Mössbauer spectroscopy, X-ray diffraction and magnetic measurements. In order to obtain different stages of disorder the alloys were deformed by different methods: crushing induction melted alloys and ball milling annealed (ordered) alloys using different number of balls and speed. X-ray and Mössbauer data show that mechanical deformation induces the disordered A2 structure in these alloys. The results indicate that addition of Si to binary Fe–Al alloys makes the disordering more difficult. In addition, X-ray diffraction patterns show that the normalized lattice parameter variation of the disordered alloys of each composition decreases monotonically with Si content, indicating clearly that Si addition opposes the large volume increase found in FeAl alloys with deformation. The study of the hyperfine fields indicates that there is a redistribution of non-ferrous atoms around Fe atoms with the disordering; indeed, there is an inversion of the behavior of the hyperfine field of the Fe atoms. On the other hand, the magnetic measurements indicate that addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe.

  15. 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.

  16. Mechanical and structural behaviour of uranium α, β, γ phases during plastic deformation

    International Nuclear Information System (INIS)

    Prunier, C.; Collot, C.

    1981-06-01

    High temperature behaviour of rich and poor uranium alloys in α, β and γ crystalline structures is studied: dynamic recrystallization phenomena begins only in α and β phases high temperature range, high strength and brittle β phase shows a very large ductility above 700 0 C. Dynamic recrystallization in γ phase rich alloys is observed only if large energy is available. Recrystallization is a thermal actived phenomena localised at grain boundary, dependant with alloy concentration and crystalline structure. β phase activation energy and deformation rate for dynamic recrystallization beginning are the most important in relation with structure complexity; both temperature and rate deformation are dynamic recrystallization factors [fr

  17. 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...

  18. Tuning transport properties of graphene three-terminal structures by mechanical deformation

    Science.gov (United States)

    Torres, V.; Faria, D.; Latgé, A.

    2018-04-01

    Straintronic devices made of carbon-based materials have been pushed up due to the graphene high mechanical flexibility and the possibility of interesting changes in transport properties. Properly designed strained systems have been proposed to allow optimized transport responses that can be explored in experimental realizations. In multiterminal systems, comparisons between schemes with different geometries are important to characterize the modifications introduced by mechanical deformations, especially if the deformations are localized at a central part of the system or extended in a large region. Then, in the present analysis, we study the strain effects on the transport properties of triangular and hexagonal graphene flakes, with zigzag and armchair edges, connected to three electronic terminals, formed by semi-infinite graphene nanoribbons. Using the Green's function formalism with circular renormalization schemes, and a single band tight-binding approximation, we find that resonant tunneling transport becomes relevant and is more affected by localized deformations in the hexagonal graphene flakes. Moreover, triangular systems with deformation extended to the leads, like longitudinal three-folded type, are shown as an interesting scenario for building nanoscale waveguides for electronic current.

  19. Influence of Severe Plastic Deformation on Mechanical Properties and Structure of Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Ondřej Hilšer

    2016-09-01

    Full Text Available Article is devoted to analysis of ECAP (Equal Channel Angular Pressing method, which uses a high degree of deformation to achieve a very fine-grained structure of formed material. Utilization of The ECAP technology enables attainment of required properties of selected materials by using of severe plastic deformation (SPD methods. In the experimental part the influence of the number of passes through forming tool with classical geometry (angle of 90° between channels was studied to achieve maximum hardening (expressed by deformation resistance and achieved value of hardness HV10. Also the metallographic analysis (detection of achieved grain refinement was carried out. From comparison of results achieved at both alloys it can be stated that for given forming by ECAP method the EN AW-8006 alloy is preferable, because higher strength degree was obtained by achieving of very fine grained structure. When using the same method of forming by ECAP method the EN AW-2024 alloy has lower hardening and structure refinement.

  20. Effects of Structural Deformations of the Crank-Slider Mechanism on the Estimation of the Instantaneous Engine Friction Torque

    Science.gov (United States)

    CHALHOUB, N. G.; NEHME, H.; HENEIN, N. A.; BRYZIK, W.

    1999-07-01

    The focus on the current study is to assess the effects of structural deformations of the crankshaft/connecting-rod/piston mechanism on the computation of the instantaneous engine friction torque. This study is performed in a fully controlled environment in order to isolate the effects of structural deformations from those of measurement errors or noise interference. Therefore, a detailed model, accounting for the rigid and flexible motions of the crank-slider mechanism and including engine component friction formulations, is considered in this study. The model is used as a test bed to generate the engine friction torque,Tfa, and to predict the rigid and flexible motions of the system in response to the cylinder gas pressure. The torsional vibrations and the rigid body angular velocity of the crankshaft, as predicted by the detailed model of the crank-slider mechanism, are used along with the engine load torque and the cylinder gas pressure in the (P-ω) method to estimate the engine friction torque,Tfe. This method is well suited for the purpose of this study because its formulation is based on the rigid body model of the crank-slider mechanism. The digital simulation results demonstrate that the exclusion of the structural deformations of the crank-slider mechanism from the formulation of the (P-ω) method leads to an overestimation of the engine friction torque near the top-dead-center (TDC) position of the piston under firing conditions. Moreover, for the remainder of the engine cycle, the estimated friction torque exhibits large oscillations and takes on positive numerical values as if it is inducing energy into the system. Thus, the adverse effects of structural deformations of the crank-slider mechanism on the estimation of the engine friction torque greatly differ in their nature from one phase of the engine cycle to another.

  1. Stochastic deformation of a thermodynamic symplectic structure

    OpenAIRE

    Kazinski, P. O.

    2008-01-01

    A stochastic deformation of a thermodynamic symplectic structure is studied. The stochastic deformation procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). Gauge symmetries of thermodynamics and corresponding stochastic mechanics, which describes fluctuations of a thermodynamic system, are revealed and gauge fields are introduced. A physical interpretation to the gauge transform...

  2. Deformed supersymmetric mechanics

    International Nuclear Information System (INIS)

    Ivanov, E.; Sidorov, S.

    2013-01-01

    Motivated by a recent interest in curved rigid supersymmetries, we construct a new type of N = 4, d = 1 supersymmetric systems by employing superfields defined on the cosets of the supergroup SU(2|1). The relevant worldline supersymmetry is a deformation of the standard N = 4, d = 1 supersymmetry by a mass parameter m. As instructive examples we consider at the classical and quantum levels the models associated with the supermultiplets (1,4,3) and (2,4,2) and find out interesting interrelations with some previous works on nonstandard d = 1 supersymmetry. In particular, the d = 1 systems with 'weak supersymmetry' are naturally reproduced within our SU(2|1) superfield approach as a subclass of the (1,4,3) models. A generalization to the N = 8, d = 1 case implies the supergroup SU(2|2) as a candidate deformed worldline supersymmetry

  3. A novel deformation mechanism for superplastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Muto, H.; Sakai, M. (Toyohashi Univ. of Technology (Japan). Dept. of Materials Science)

    1999-01-01

    Uniaxial compressive creep tests with strain value up to -0.1 for a [beta]-spodumene glass ceramic are conducted at 1060 C. From the observation of microstructural changes between before and after the creep deformations, it is shown that the grain-boundary sliding takes place via cooperative movement of groups of grains rather than individual grains under the large-scale-deformation. The deformation process and the surface technique used in this work are not only applicable to explain the deformation and flow of two-phase ceramics but also the superplastic deformation. (orig.) 12 refs.

  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. Twist deformations of the supersymmetric quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Castro, P.G.; Chakraborty, B.; Toppan, F., E-mail: pgcastro@cbpf.b, E-mail: biswajit@bose.res.i, E-mail: toppan@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Kuznetsova, Z., E-mail: zhanna.kuznetsova@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2009-07-01

    The N-extended supersymmetric quantum mechanics is deformed via an abelian twist which preserves the super-Hopf algebra structure of its universal enveloping superalgebra. Two constructions are possible. For even N one can identify the 1D N-extended superalgebra with the fermionic Heisenberg algebra. Alternatively, supersymmetry generators can be realized as operators belonging to the Universal Enveloping Superalgebra of one bosonic and several fermionic oscillators. The deformed system is described in terms of twisted operators satisfying twist deformed (anti)commutators. The main differences between an abelian twist defined in terms of fermionic operators and an abelian twist defined in terms of bosonic operators are discussed. (author)

  6. Deformation twinning in a creep-deformed nanolaminate structure

    International Nuclear Information System (INIS)

    Hsiung, Luke L

    2010-01-01

    The underlying mechanism of deformation twinning occurring in a TiAl-(γ)/Ti 3 Al-(α 2 ) nanolaminate creep deformed at elevated temperatures has been studied. Since the multiplication and propagation of lattice dislocations in both γ and α 2 thin lamellae are very limited, the total flow of lattice dislocations becomes insufficient to accommodate the accumulated creep strains. Consequently, the movement of interfacial dislocations along the laminate interfaces, i.e., interface sliding, becomes an alternative deformation mode of the nanolaminate structure. Pile-ups of interfacial dislocations occur when interfacial ledges and impinged lattice dislocations act as obstacles to impede the movement of interfacial dislocations. Deformation twinning can accordingly take place to relieve a stress concentration resulting from the pile-up of interfacial dislocations. An interface-controlled twinning mechanism driven by the pile-up and dissociation of interfacial dislocations is accordingly proposed.

  7. Deformation twinning in a creep-deformed nanolaminate structure

    Science.gov (United States)

    Hsiung, Luke L.

    2010-10-01

    The underlying mechanism of deformation twinning occurring in a TiAl-(γ)/Ti3Al-(α2) nanolaminate creep deformed at elevated temperatures has been studied. Since the multiplication and propagation of lattice dislocations in both γ and α2 thin lamellae are very limited, the total flow of lattice dislocations becomes insufficient to accommodate the accumulated creep strains. Consequently, the movement of interfacial dislocations along the laminate interfaces, i.e., interface sliding, becomes an alternative deformation mode of the nanolaminate structure. Pile-ups of interfacial dislocations occur when interfacial ledges and impinged lattice dislocations act as obstacles to impede the movement of interfacial dislocations. Deformation twinning can accordingly take place to relieve a stress concentration resulting from the pile-up of interfacial dislocations. An interface-controlled twinning mechanism driven by the pile-up and dissociation of interfacial dislocations is accordingly proposed.

  8. Microstructure, plastic deformation and strengthening mechanisms of an Al–Mg–Si alloy with a bimodal grain structure

    International Nuclear Information System (INIS)

    Shakoori Oskooie, M.; Asgharzadeh, H.; Kim, H.S.

    2015-01-01

    Highlights: • Al6063 with bimodal grain structures was fabricated by a powder metallurgy route. • The bimodal alloys showed a reasonable ductility together with a high strength. • Grain boundary strengthening was reduced at higher fraction of coarse grains. • The enhanced tensile ductility was attributed to crack blunting and delamination. - Abstract: Al6063 alloys with bimodal grain size distributions comprised of ultrafine-grained (UFG) and coarse-grained (CG) regions were produced via mechanical milling followed by hot extrusion. High-energy planetary ball milling for 22.5 h with a rotational speed of 350 rpm was employed for the synthesis of nanocrystalline Al6063 powders. The as-milled Al6063 powders were mixed with 15, 30, and 45 vol.% of the unmilled powders and then the powder mixtures were consolidated via extrusion at 450 °C with an extrusion ratio of 9:1. The microstructure of the bimodal extrudates was investigated using optical microscope, transmission electron microscope (TEM) and field emission scanning electron microscope equipped with an electron backscattered diffraction (EBSD) detector. The deformation behavior was investigated by means of uniaxial tensile tests. The bimodal Al6063 exhibited balanced mechanical properties, including high yield stress and ultimate tensile strength resulting from the UFG regions together with reasonable ductility attained from the CG areas. The fracture surfaces demonstrated a ductile fracture mode, in which the dimple size was correlated with the grain structure. The strengthening mechanisms are discussed based on the dislocation models and the functions of the CGs in the deformation behavior and ductility enhancement of bimodal Al6063 are explored

  9. 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. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Deformation mechanisms of nanotwinned Al

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinghang [Texas A & M Univ., College Station, TX (United States)

    2016-11-10

    The objective of this project is to investigate the role of different types of layer interfaces on the formation of high density stacking fault (SF) in Al in Al/fcc multilayers, and understand the corresponding deformation mechanisms of the films. Stacking faults or twins can be intentionally introduced (via growth) into certain fcc metals with low stacking fault energy (such as Cu, Ag and 330 stainless steels) to achieve high strength, high ductility, superior thermal stability and good electrical conductivity. However it is still a major challenge to synthesize these types of defects into metals with high stacking fault energy, such as Al. Although deformation twins have been observed in some nanocrystalline Al powders by low temperature, high strain rate cryomilling or in Al at the edge of crack tip or indentation (with the assistance of high stress intensity factor), these deformation techniques typically introduce twins sporadically and the control of deformation twin density in Al is still not feasible. This project is designed to test the following hypotheses: (1) Certain type of layer interfaces may assist the formation of SF in Al, (2) Al with high density SF may have deformation mechanisms drastically different from those of coarse-grained Al and nanotwinned Cu. To test these hypotheses, we have performed the following tasks: (i) Investigate the influence of layer interfaces, stresses and deposition parameters on the formation and density of SF in Al. (ii) Understand the role of SF on the deformation behavior of Al. In situ nanoindentation experiments will be performed to probe deformation mechanisms in Al. The major findings related to the formation mechanism of twins and mechanical behavior of nanotwinned metals include the followings: 1) Our studies show that nanotwins can be introduced into metals with high stacking fault energy, in drastic contrast to the general anticipation. 2) We show two strategies that can effectively introduce growth twins in

  11. Deformation mechanisms of nanotwinned Al

    International Nuclear Information System (INIS)

    Zhang, Xinghang

    2016-01-01

    The objective of this project is to investigate the role of different types of layer interfaces on the formation of high density stacking fault (SF) in Al in Al/fcc multilayers, and understand the corresponding deformation mechanisms of the films. Stacking faults or twins can be intentionally introduced (via growth) into certain fcc metals with low stacking fault energy (such as Cu, Ag and 330 stainless steels) to achieve high strength, high ductility, superior thermal stability and good electrical conductivity. However it is still a major challenge to synthesize these types of defects into metals with high stacking fault energy, such as Al. Although deformation twins have been observed in some nanocrystalline Al powders by low temperature, high strain rate cryomilling or in Al at the edge of crack tip or indentation (with the assistance of high stress intensity factor), these deformation techniques typically introduce twins sporadically and the control of deformation twin density in Al is still not feasible. This project is designed to test the following hypotheses: (1) Certain type of layer interfaces may assist the formation of SF in Al, (2) Al with high density SF may have deformation mechanisms drastically different from those of coarse-grained Al and nanotwinned Cu. To test these hypotheses, we have performed the following tasks: (i) Investigate the influence of layer interfaces, stresses and deposition parameters on the formation and density of SF in Al. (ii) Understand the role of SF on the deformation behavior of Al. In situ nanoindentation experiments will be performed to probe deformation mechanisms in Al. The major findings related to the formation mechanism of twins and mechanical behavior of nanotwinned metals include the followings: 1) Our studies show that nanotwins can be introduced into metals with high stacking fault energy, in drastic contrast to the general anticipation. 2) We show two strategies that can effectively introduce growth twins in

  12. Dislocation structures and mechanical behaviour of Ge single crystals deformed by compression

    International Nuclear Information System (INIS)

    Nyilas, K.; Dupas, C.; Kruml, T.; Zsoldos, L.; Ungar, T.; Martin, J.L.

    2004-01-01

    Stress-strain curves of germanium interrupted by dip tests reveal that the internal stresses ascend parallel to the applied stress in a strain-rate dependent way. To understand this peculiar behaviour, the dislocation microstructure has been characterized. Transmission electron microscopy images show that regions of high dislocation activity along the primary slip system are separated by dislocation-free zones. X-ray microdiffraction reveals that the dislocation density is fluctuating on a 100 μm scale. X-ray reciprocal-space mapping, together with scanning microdiffraction, shows that misoriented mosaic blocks are forming owing to the boundary conditions in the compression test. These preliminary results reveal deformation heterogeneity both at macroscopic and mesoscopic scales

  13. Structure of deformed metals. Struktura deformirovannykh metallov

    Energy Technology Data Exchange (ETDEWEB)

    Bernshtein, M L

    1977-01-01

    A teaching aid for students at metallurgical and machine-building institutions of higher learning. It can also be used by engineering-technical personnel and scientists. A presentation is made of physical concepts on the mechanism of plastic deformation and its effect on fine structure, structure and properties of metals and alloys. An examination is made of the processes of recovery, polygonization and recrystallization during the heating of cold-deformed metals. The influence of thermal deformation is described to account for the interaction between admixture atoms and dislocations, phase and structural transformations. An examination is made of the phenomenon of superplasticity. Special attention is given to the process of hot deformation. An analysis is made of phenomena at the basis of hardening steel as a result of thermo-mechanical processing, including controlled rolling.

  14. Deformation Characteristics of Composite Structures

    Directory of Open Access Journals (Sweden)

    Theddeus T. AKANO

    2016-08-01

    Full Text Available The composites provide design flexibility because many of them can be moulded into complex shapes. The carbon fibre-reinforced epoxy composites exhibit excellent fatigue tolerance and high specific strength and stiffness which have led to numerous advanced applications ranging from the military and civil aircraft structures to the consumer products. However, the modelling of the beams undergoing the arbitrarily large displacements and rotations, but small strains, is a common problem in the application of these engineering composite systems. This paper presents a nonlinear finite element model which is able to estimate the deformations of the fibre-reinforced epoxy composite beams. The governing equations are based on the Euler-Bernoulli beam theory (EBBT with a von Kármán type of kinematic nonlinearity. The anisotropic elasticity is employed for the material model of the composite material. Moreover, the characterization of the mechanical properties of the composite material is achieved through a tensile test, while a simple laboratory experiment is used to validate the model. The results reveal that the composite fibre orientation, the type of applied load and boundary condition, affect the deformation characteristics of the composite structures. The nonlinearity is an important factor that should be taken into consideration in the analysis of the fibre-reinforced epoxy composites.

  15. Study of fine structure of deformed hafnium

    International Nuclear Information System (INIS)

    Voskresenskaya, L.A.; Petukhova, A.S.; Kovalev, K.S.

    1978-01-01

    Variations in the hafnium fine structure following the cold plastic deformation have been studied. The fine structure condition has been studied through the harmonic analysis of the profile of the X-ray diffraction line, obtained at the DRON-I installation. Received has been the dependence of the crystal lattice microdistortions value on the deformation extent for hafnium. This dependence is compared with the corresponding one for zirconium. It is found out that at all the deformations the microdistortion distribution is uniform. The microdistortion value grows with the increase in the compression. During the mechanical impact higher microdistortions of the crystal lattice occur in the hafnium rather than in zirconium

  16. Correlation of substructure with mechanical properties of plastically deformed reactor structural materials. Progress report, January 1, 1974--December 31, 1975

    International Nuclear Information System (INIS)

    Moteff, J.

    1976-01-01

    Ratio of the subgrain boundary dislocations to those contributing to creep deformation was found to be independent of applied stress and creep strain after the steady-state creep stage is reached. The observed cell or subgrain sizes are correlated with flow stress in Type 304 ss, and the deformation rate-stress relation obeys the equation epsilon =β lambda 3 (sigma/sub T//E)/sub n/ exp (-Q/sub c//RT), where lambda = subgrain size, sigma/sub T/ = effective true stress, E = Young modulus, and Q/sub c/ = 85 kcal/mole. Well-developed subgrains were observed in TEM on 304 ss tested in creep at 704 0 C. Role of twin boundary-grain boundary intersections in microcracking behavior of 304 ss deformed in slow tension and creep at 650 0 C was investigated. Grain shape analysis show that intragranular deformation becomes more predominant in the grains with the larger intercept distances, and that grain boundary sliding becomes important as the strain rate decreases. RT mechanical properties of austenitic ss are enhanced by subgrains formed during high-temperature deformation. The substructural development during high-temperature low-cycle fatigue of 304 ss was studied using TEM. Fatigue properties of Incoloy 800 tested in bend and push-pull modes are being compared. Effects of hold time on fatigue substructure and fracture of 304 ss are being studied. 31 figures, 53 references

  17. The Effect of Mechanical Characteristics of Basal Decollement and Basement Structures on Deformation of the Zagros Basin

    OpenAIRE

    Bahroudi, Abbas

    2003-01-01

    Two fundamental structural elements, basement architecture and basal decollement, play a significant role in the evolution of a tectonically active region. Using different approaches (field data, literature review and analogue models) this thesis demonstrates that these two elements affected the deformation style in the Zagros fold-thrust belt during Mesozoic extensional and Cenozoic contractional episodes. Reassessment of available data suggests a new configuration for the basement to Zagro...

  18. Deformation and fracture mechanics of engineering materials

    National Research Council Canada - National Science Library

    Hertzberg, Richard W; Vinci, Richard Paul; Hertzberg, Jason L

    2012-01-01

    "Hertzberg's 5th edition of Deformation & Fracture Mechanics of Engineering Materials offers several new features including a greater number and variety of homework problems using more computational software...

  19. The thermal and mechanical deformation study of up-stream pumping mechanical seal

    International Nuclear Information System (INIS)

    Chen, H L; Xu, C; Zuo, M Z; Wu, Q B

    2015-01-01

    Taking the viscosity-temperature relationship of the fluid film into consideration, a 3-D numerical model was established by ANSYS software which can simulate the heat transfer between the upstream pumping mechanical seal stationary and rotational rings and the fluid film between them as well as simulate the thermal deformation, structure deformation and the coupling deformation of them. According to the calculation result, thermal deformation causes the seal face expansion and the maximum thermal deformation appears at the inside of the seal ring. Pressure results in a mechanical deformation, the maximum deformation occurs at the top of the spiral groove and the overall trend is inward the mating face, opposite to the thermal deformation. The coupling deformation indicate that the thermal deformation can be partly counteracted by pressure deformation. Using this model, the relationship between deformation and shaft speed and the sealing liquid pressure was studied. It's found that the shaft speed will both enhance the thermal and structure deformation and the fluid pressure will enhance the structure deformation but has little to do with the thermal deformation. By changing the sealing material, it's found that material with low thermal expansion coefficient and low elastic modulus will suffer less thermal-pressure deformation

  20. The thermal and mechanical deformation study of up-stream pumping mechanical seal

    Science.gov (United States)

    Chen, H. L.; Xu, C.; Zuo, M. Z.; Wu, Q. B.

    2015-01-01

    Taking the viscosity-temperature relationship of the fluid film into consideration, a 3-D numerical model was established by ANSYS software which can simulate the heat transfer between the upstream pumping mechanical seal stationary and rotational rings and the fluid film between them as well as simulate the thermal deformation, structure deformation and the coupling deformation of them. According to the calculation result, thermal deformation causes the seal face expansion and the maximum thermal deformation appears at the inside of the seal ring. Pressure results in a mechanical deformation, the maximum deformation occurs at the top of the spiral groove and the overall trend is inward the mating face, opposite to the thermal deformation. The coupling deformation indicate that the thermal deformation can be partly counteracted by pressure deformation. Using this model, the relationship between deformation and shaft speed and the sealing liquid pressure was studied. It's found that the shaft speed will both enhance the thermal and structure deformation and the fluid pressure will enhance the structure deformation but has little to do with the thermal deformation. By changing the sealing material, it's found that material with low thermal expansion coefficient and low elastic modulus will suffer less thermal-pressure deformation.

  1. 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

  2. Nonlinear continuum mechanics and large inelastic deformations

    CERN Document Server

    Dimitrienko, Yuriy I

    2010-01-01

    This book provides a rigorous axiomatic approach to continuum mechanics under large deformation. In addition to the classical nonlinear continuum mechanics - kinematics, fundamental laws, the theory of functions having jump discontinuities across singular surfaces, etc. - the book presents the theory of co-rotational derivatives, dynamic deformation compatibility equations, and the principles of material indifference and symmetry, all in systematized form. The focus of the book is a new approach to the formulation of the constitutive equations for elastic and inelastic continua under large deformation. This new approach is based on using energetic and quasi-energetic couples of stress and deformation tensors. This approach leads to a unified treatment of large, anisotropic elastic, viscoelastic, and plastic deformations. The author analyses classical problems, including some involving nonlinear wave propagation, using different models for continua under large deformation, and shows how different models lead t...

  3. Structural and mechanical behaviour of severe plastically deformed high purity aluminium sheets processed by constrained groove pressing technique

    International Nuclear Information System (INIS)

    Satheesh Kumar, S.S.; Raghu, T.

    2014-01-01

    Highlights: • High purity aluminium sheets constrained groove pressed up to plastic strain of 5.8. • Microstructural evolution studied by TEM and X-ray diffraction profile analysis. • Ultrafine grained structure with grain size ∼900 nm achieved in sheets. • Yield strength increased by 5.3 times and tensile strength doubled after first pass. • Enhanced deformation homogeneity seen with increased accumulated plastic strain. - Abstract: High purity aluminium sheets (∼99.9%) are subjected to intense plastic straining by constrained groove pressing method successfully up to 5 passes thereby imparting an effective plastic strain of 5.8. Transmission electron microscopy studies of constrained groove pressed sheets divulged significant grain refinement and the average grain sizes obtained after five pass is estimated to be ∼0.9 μm. In addition to that, microstructural evolution of constrained groove pressed sheets is characterized by X-ray diffraction peak profile analysis employing Williamson–Hall method and the results obtained fairly concur with electron microscopy findings. The tensile behaviour evolution with increased straining indicates substantial improvement of yield strength by ∼5.3 times from 17 MPa to 90 MPa during first pass corroborated to grain refinement observed. Marginal increase in strengths is noticed during second pass followed by minor drop in strengths attributed to predominance of dislocation recovery is noticed in subsequent passes. Quantitative assessment of degree of deformation homogeneity using microhardness profiles reveal relatively better strain homogeneity at higher number of passes

  4. Deformed configurations, band structures and spectroscopic ...

    Indian Academy of Sciences (India)

    2014-03-20

    Mar 20, 2014 ... The deformed configurations and rotational band structures in =50 Ge and Se nuclei are studied by deformed Hartree–Fock with quadrupole constraint and angular momentum projection. Apart from the `almost' spherical HF solution, a well-deformed configuration occurs at low excitation. A deformed ...

  5. Influence of grain structure on the deformation mechanism in martensitic shear reversion-induced Fe-16Cr-10Ni model austenitic alloy with low interstitial content: Coarse-grained versus nano-grained/ultrafine-grained structure

    Energy Technology Data Exchange (ETDEWEB)

    Challa, V.S.A. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials Engineering, and Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Misra, R.D.K., E-mail: dmisra2@utep.edu [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials Engineering, and Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Somani, M.C. [Center for Advanced Steels Research, The University of Oulu, P.O. Box 4200, 90014 Oulu (Finland); Wang, Z.D. [State Key Laboratory for Rolling and Automation, Northeastern University, 3-11 Wenhua Road, Shenyang 110819 (China)

    2016-04-20

    Nanograined/ultrafine-grained (NG/UFG) materials characterized by high strength-high ductility combination are excellent vehicles to obtain an unambiguous understanding of deformation mechanisms vis-à-vis their coarse-grained counterparts. In this context, the innovative concept of phase reversion-induced NG/UFG structure enabled achieving high strength besides comparable ductility, for instance, in metastable austenitic stainless steels. In the phase reversion process, severe deformation of austenite at room temperature (typically ~60–80%) transforms face-centered cubic austenite (γ) to body centered cubic martensite (α′). Upon annealing, martensite reverts to austenite leading to extensive grain refinement. The objective of the present study to fundamentally understand the deformation mechanisms in NG/UFG structure in relation to that of the coarse-grained (CG) structure was accomplished by combining depth-sensing nanoscale experiments on an Fe-16Cr-10Ni model austenitic alloy conducted at different strain rates, followed by the study of structural evolution in the deformed zone using transmission electron microscopy (TEM). In the high strength NG/UFG steel (YS~585 MPa), stacking faults and nanotwins contributed to the enhanced ductility (El~35%), while in the case of low strength (YS~260 MPa) coarse-grained (CG) counterpart, ductility was also high (El~40%), but chiefly due to strain-induced martensite, which points to a clear case of grain size effect (and the corresponding level of strength). The distinct change in the deformation mechanism from stacking faults and twinning-induced plasticity (TWIP) in the NG structure to transformation-induced plasticity (TRIP) in the CG structure is elucidated in terms of austenite stability-strain energy relationship. The insights on the relationship between grain structure (and strength) and deformation mechanisms are envisaged to be important in providing a new direction for the futuristic design of high strength

  6. Deformed configurations, band structures and spectroscopic ...

    Indian Academy of Sciences (India)

    2014-03-20

    Mar 20, 2014 ... Our study gives insight into possible deformed structures at spherical shell closure. ... Considerable experimental and theoretical efforts ... True deformation effects can be seen only by considering configuration mixing.

  7. Deformation mechanisms in cyclic creep and fatigue

    International Nuclear Information System (INIS)

    Laird, C.

    1979-01-01

    Service conditions in which static and cyclic loading occur in conjunction are numerous. It is argued that an understanding of cyclic creep and cyclic deformation are necessary both for design and for understanding creep-fatigue fracture. Accordingly a brief, and selective, review of cyclic creep and cyclic deformation at both low and high strain amplitudes is provided. Cyclic loading in conjunction with static loading can lead to creep retardation if cyclic hardening occurs, or creep acceleration if softening occurs. Low strain amplitude cyclic deformation is understood in terms of dislocation loop patch and persistent slip band behavior, high strain deformation in terms of dislocation cell-shuttling models. While interesting advances in these fields have been made in the last few years, the deformation mechanisms are generally poorly understood

  8. Intermetallic alloys: Deformation, mechanical and fracture behaviour

    International Nuclear Information System (INIS)

    Dogan, B.

    1988-01-01

    The state of the art in intermetallic alloys development with particular emphasis on deformation, mechanical and fracture behaviour is documented. This review paper is prepared to lay the ground stones for a future work on mechanical property characterization and fracture behaviour of intermetallic alloys at GKSS. (orig.)

  9. Deformation compatibility control for engineering structures methods and applications

    CERN Document Server

    Zhu, Hanhua; Chen, Mengchong; Deng, Jianliang

    2017-01-01

    This book presents essential methods of deformation compatibility control, and explicitly addresses the implied conditions on the methods’ deformation compatibility. Consequently, these conditions can be considered in engineering structure design, while the conditions on stable equilibrium can be taken into account in the design method. Thus, the designed deformation and the actual deformation of the respective structure are approximately identical, guaranteeing both the flexibility of the construction material in force transmission and the equilibrium of force in the structure. Though equilibrium theory in engineering structures has been extensively studied, there has been comparatively little research on compatibility. In the limited researches available, the topics are primarily the theories and assumptions on the deformation compatibility, while few systematic works focus on the mechanical theoretical principles and methods of deformation compatibility control. As such, the flexibility of the constructi...

  10. Formation of disorientations in dislocation structures during plastic deformation

    DEFF Research Database (Denmark)

    Pantleon, W.

    2002-01-01

    Disorientations developing during plastic deformation in dislocation structures are investigated. Based on expected mechanisms for the formation of different types of dislocation boundaries (statistical trapping of dislocations or differently activated slip systems) the formation of the disorient...

  11. Thermomechanical Modeling of Laser-Induced Structural Relaxation and Deformation of Glass: Volume Changes in Fused Silica at High Temperatures [Thermo-mechanical modeling of laser-induced structural relaxation and deformation of SiO2 glass

    Energy Technology Data Exchange (ETDEWEB)

    Vignes, Ryan M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Soules, Thomas F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Stolken, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Settgast, Randolph R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Elhadj, Selim [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Matthews, Manyalibo J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Mauro, J.

    2012-12-17

    In a fully coupled thermomechanical model of the nanoscale deformation in amorphous SiO2 due to laser heating is presented. Direct measurement of the transient, nonuniform temperature profiles was used to first validate a nonlinear thermal transport model. Densification due to structural relaxation above the glass transition point was modeled using the Tool-Narayanaswamy (TN) formulation for the evolution of structural relaxation times and fictive temperature. TN relaxation parameters were derived from spatially resolved confocal Raman scattering measurements of Si–O–Si stretching mode frequencies. These thermal and microstructural data were used to simulate fictive temperatures which are shown to scale nearly linearly with density, consistent with previous measurements from Shelby et al. Volumetric relaxation coupled with thermal expansion occurring in the liquid-like and solid-like glassy states lead to residual stresses and permanent deformation which could be quantified. But, experimental surface deformation profiles between 1700 and 2000 K could only be reconciled with our simulation by assuming a roughly 2 × larger liquid thermal expansion for a-SiO2 with a temperature of maximum density ~150 K higher than previously estimated by Bruckner et al. Calculated stress fields agreed well with recent laser-induced critical fracture measurements, demonstrating accurate material response prediction under processing conditions of practical interest.

  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. Structural refinement and coarsening in deformed metals

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Xing, Q.

    2005-01-01

    The microstructural refinement by plastic deformation is analysed in terms of key parameters, the spacing between and the misorientation angle across the boundaries subdividing the structure. Coarsening of such structures by annealing is also characterised. For both deformed and annealed structur...

  14. Texture and deformation mechanism of yttrium

    International Nuclear Information System (INIS)

    Adamesku, R.A.; Grebenkin, S.V.; Stepanenko, A.V.

    1992-01-01

    X-ray pole figure analysis was applied to study texture and deformation mechanism in pure and commercial polycrystalline yttrium on cold working. It was found that in cast yttrium the texture manifected itself weakly enough both for pure and commercial metal. Analysis of the data obtained made it possible to assert that cold deformation of pure yttrium in the initial stage occurred mainly by slip the role of which decreased at strains higher than 36%. The texture of heavily deformed commercial yttrium contained two components, these were an 'ideal' basic orientation and an axial one with the angle of inclination about 20 deg. Twinning mechanism was revealed to be also possible in commercial yttrium

  15. Study of deformation behavior, structure and mechanical properties of the AlSiMnFe alloy during ECAP-PBP.

    Science.gov (United States)

    Naizabekov, A B; Andreyachshenko, V A; Kocich, Radim

    2013-01-01

    The presented article deals with the effects of equal channel angular pressing (ECAP) with a newly adjusted die geometry on the microstructure and mechanical properties of the Al-Si-Mn-Fe alloy. This alloy was subjected to two modes of heat treatment followed by the ECAP process, which led to partial back pressure (ECAP-PBP). Ultra-fine grained (UFG) structure formed through ECAP-PBP process has been studied by methods of optical as well as electron microscopy. The obtained results indicate that quenched alloys, in comparison to slowly cooled alloys, do not contain large brittle particles which subsequently initiate a premature creation of cracks. It was shown that the mechanical properties of these alloys after such processing depend first and foremost on the selected type of heat treatment and on the number of performed passes. The maximum of ultimate tensile strength (417 MPa) was obtained for quenched alloy after 3 passes. On the other hand, maximum ductility was found in slowly cooled alloy after second pass. Further passes reduced strength due to the brittle behavior of excluded particles. One of the partial findings is that there is only a small dependency of the resulting size of grains on previously applied thermal processing. The minimum grain sizes were obtained after 3 passages, where their size ranged between 0.4 and 0.8 μm. The application of quick cooling after heat processing due to the occurrence of finer precipitates in the matrix seems to produce better results. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Deformation mechanisms in ferritic/martensitic steels and the impact on mechanical design

    International Nuclear Information System (INIS)

    Ghoniem, Nasr M.; Po, Giacomo; Sharafat, Shahram

    2013-01-01

    Structural steels for nuclear applications have undergone rapid development during the past few decades, thanks to a combination of trial-and-error, mechanism-based optimization, and multiscale modeling approaches. Deformation mechanisms are shown to be intimately related to mechanical design via dominant plastic deformation modes. Because mechanical design rules are mostly based on failure modes associated with plastic strain damage accumulation, we present here the fundamental deformation mechanisms for Ferritic/Martensitic (F/M) steels, and delineate their operational range of temperature and stress. The connection between deformation mechanisms, failure modes, and mechanical design is shown through application of design rules. A specific example is given for the alloy F82H utilized in the design of a Test Blanket Module (TBM) in the International Thermonuclear Experimental Reactor (ITER), where several constitutive equations are developed for design-related mechanical properties

  17. Deformation mechanisms in ferritic/martensitic steels and the impact on mechanical design

    Energy Technology Data Exchange (ETDEWEB)

    Ghoniem, Nasr M., E-mail: ghoniem@seas.ucla.edu; Po, Giacomo; Sharafat, Shahram

    2013-10-15

    Structural steels for nuclear applications have undergone rapid development during the past few decades, thanks to a combination of trial-and-error, mechanism-based optimization, and multiscale modeling approaches. Deformation mechanisms are shown to be intimately related to mechanical design via dominant plastic deformation modes. Because mechanical design rules are mostly based on failure modes associated with plastic strain damage accumulation, we present here the fundamental deformation mechanisms for Ferritic/Martensitic (F/M) steels, and delineate their operational range of temperature and stress. The connection between deformation mechanisms, failure modes, and mechanical design is shown through application of design rules. A specific example is given for the alloy F82H utilized in the design of a Test Blanket Module (TBM) in the International Thermonuclear Experimental Reactor (ITER), where several constitutive equations are developed for design-related mechanical properties.

  18. Structural Characteristics and Physical Properties of Tectonically Deformed Coals

    OpenAIRE

    Yiwen Ju; Zhifeng Yan; Xiaoshi Li; Quanlin Hou; Wenjing Zhang; Lizhi Fang; Liye Yu; Mingming Wei

    2012-01-01

    Different mechanisms of deformation could make different influence on inner structure and physical properties of tectonically deformed coal (TDC) reservoirs. This paper discusses the relationship between macromolecular structure and physical properties of the Huaibei-Huainan coal mine areas in southern North China. The macromolecular structure and pore characteristics are systematically investigated by using techniques such as X-ray diffraction (XRD), high-resolution transmission electron mic...

  19. Deformed metals - structure, recrystallisation and strength

    DEFF Research Database (Denmark)

    Hansen, Niels; Juul Jensen, Dorte

    2011-01-01

    It is shown how new discoveries and advanced experimental techniques in the last 25 years have led to paradigm shifts in the analysis of deformation and annealing structures of metals and in the way the strength of deformed samples is related to structural parameters. This is described in three...

  20. Correlation of substructure with mechanical properties of plastically deformed reactor structural materials. Progress report, January 1, 1976--June 30, 1977

    International Nuclear Information System (INIS)

    Moteff, J.

    1977-01-01

    Transmission electron microscopy used to evaluate the deformation (creep, fatigue and tensile) induced microstructure of 304 SS, Incoloy 800, 330 SS and three of the experimental alloys (E19, E23 and E36) obtained from the National Alloy Program clearly shows that the relationship between the subgrain size (lambda) and the applied stress (sigma) obeys the equation lambda = Ab (sigma/E) -1 where A is a constant of the order of 4, b the Burgers rector and E is Young's modulus. Hot-hardness studies on 304 SS, 316 SS, Incoloy 800, 2 1 / 4 Cr-1 Mo steels, 330 SS, Inconel 718, PE-16, Inconel 706, M-813 and the above three experimental alloys suggests that reasonable effective activation energies for creep may be obtained through the use of the hardness test as a strength microprobe tool. The ordering of the strength levels obtained through hot-hardness follows quite closely that obtained in tensile tests when those data are available

  1. Effect of deformation on the structural state of piracetam

    Science.gov (United States)

    Kanunnikova, O. M.; Mikhailova, S. S.; Karban', O. V.; Mukhgalin, V. V.; Aksenova, V. V.; Sen'kovskii, B. V.; Pechina, E. A.; Lad'yanov, V. I.

    2016-04-01

    The effect of various deformation actions on the structure-phase transformations in piracetam of modifications I and II with a sodium acetate addition is studied. Mechanical activation and pressing are shown to cause the polymorphic transformation of modification I into modification II, and modification III forms predominantly during severe plastic deformation by torsion. The structural difference between the piracetam molecules of modifications I and II is found to be retained in aqueous solutions.

  2. Effect of heat treatment and plastic deformation on the structure and the mechanical properties of nitrogen-bearing 04N9Kh2A steel

    Science.gov (United States)

    Blinov, V. M.; Bannykh, O. A.; Lukin, E. I.; Kostina, M. V.; Blinov, E. V.

    2014-11-01

    The effect of the conditions of heat treatment and plastic deformation on the structure and the mechanical properties of low-carbon martensitic nickel steel (9 wt % Ni) with an overequilibrium nitrogen content is studied. The limiting strain to failure of 04N9Kh2A steel is found to be 40% at a rolling temperature of 20°C and 80% at a rolling temperature of 900°C. Significant strengthening of the steel (σ0.2 = 1089 MPa) is obtained after rolling at a reduction of 40% at 20°C. The start and final temperatures of the α → γ transformation on heating and those of the γ → α transformation on cooling are determined by dilatometry. The specific features of the formation of the steel structure have been revealed as functions of the annealing and tempering temperatures. Electron-microscopic studies show that, after quenching from 850°C and tempering at 600°C for 1 h, the structure contains packet martensite with thin interlayers of retained austenite between martensite crystals. The strength of the nitrogen-bearing 04N9Kh2A steel after quenching from 850 and 900°C, cooling in water, and subsequent tempering at 500°C for 1 h is significantly higher than that of carboncontaining 0H9 steel used in cryogenic engineering.

  3. Structural and failure mechanics of sandwich composites

    CERN Document Server

    Carlsson, LA; Carlsson, Leif A

    2011-01-01

    Focusing on important deformation and failure modes of sandwich structures, this volume describes the mechanics behind fracture processes. The text also reviews test methods developed for the cr, structural integrity, and failure mechanisms of sandwich structures.

  4. Different Rols of Modified Organoclay in Deformation Mechanism Control of Polymeric Matrices

    Directory of Open Access Journals (Sweden)

    Babak Akbari

    2014-04-01

    Full Text Available The effect of organically modified clay on the structure and deformation mechanism of polymeric matrices was investigated. For this purpose, the role of organoclay in deformation control of polymeric matrices, with different deformation mechanisms, has been studied methodically in order to determine a relationship between the structure and deformation mechanisms. In this respect polypropylene and polystyrene composites systems were designed using montmorillonite through melt intercalation technique using a twin, co-rotating extruder with starve feeding system. Also an epoxy was employed to design a nanocomposite system prepared by in-situ polymerization technique. The structure and deformation mechanism of nanocomposites were investigated using appropriate techniques. X-Ray diffraction and transmission electron microscopy were used to explore the structure of various systems while, the reflection and transmission optical microscopy were used in order to study their corresponding deformation mechanisms. The bulk polymer was also studied for its deformation mechanism by reflection optical microscopy and the notch tip of the samples were examined by transmission optical microscopy. The results of experiments showed that organoclays acted as initiator sites for shear yielding mechanism as the dominant deformation mechanism in epoxies. It may be noted that, these particles may act as initiator sites for crazing, the dominant deformation mechanism of polystyrene, and alter the mechanism from local to massive. In polypropylene systems, which may exhibit both shear yielding and crazing organoclays can facilitate or postpone both mechanisms in different conditions, related to PP morphology and other conditions.

  5. Types of soft-sediment deformation structures in a lacustrine Ploužnice member (Stephanian, Gzhelian, Pennsylvanian, Bohemian Massif), their timing, and possible trigger mechanism

    Czech Academy of Sciences Publication Activity Database

    Stárková, M.; Martínek, K.; Mikuláš, Radek; Rosenau, N.

    2015-01-01

    Roč. 104, č. 5 (2015), s. 1277-1298 ISSN 1437-3254 Institutional support: RVO:67985831 Keywords : soft-sediment deformation structures * bioturbation * early diagenetic carbonate * lacustrine facies * Bohemian Massif * Stephanian C * Krkonoše Piedmont Basin Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.133, year: 2015

  6. Characteristics of aluminum alloy microplastic deformation in different structural states

    Energy Technology Data Exchange (ETDEWEB)

    Seregin, G.V.; Efimenko, L.L.; Leonov, M.V. [Novosibirsk Pedagogical Inst. (Russian Federation)

    1995-07-01

    The solution to the problem of improving the mechanical properties (including cyclic strength) of structural materials is largely dependent on our knowledge of the laws governing the development of microplastic deformations in them. The effect of heat and mechanical treatment on the elastoplastic properties and fatigue resistance of the commercial aluminum alloys AK4-1 and D16 is analyzed.

  7. Deformation mechanisms of silicon during nanoscratching

    Energy Technology Data Exchange (ETDEWEB)

    Gassilloud, R.; Gasser, P.; Buerki, G.; Michler, J. [EMPA, Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland); Ballif, C. [University of Neuchatel, A.-L. Breguet 2, 2000 Neuchatel (Switzerland)

    2005-12-01

    The deformation mechanisms of silicon {l_brace}001{r_brace} surfaces during nanoscratching were found to depend strongly on the loading conditions. Nanoscratches with increasing load were performed at 2 {mu}m/s (low velocity) and 100 {mu}m/s (high velocity). The load-penetration-distance curves acquired during the scratching process at low velocity suggests that two deformation regimes can be defined, an elasto-plastic regime at low loads and a fully plastic regime at high loads. High resolution scanning electron microscopy of the damaged location shows that the residual scratch morphologies are strongly influenced by the scratch velocity and the applied load. Micro-Raman spectroscopy shows that after pressure release, the deformed volume inside the nanoscratch is mainly composed of amorphous silicon and Si-XII at low scratch speeds and of amorphous silicon at high speeds. Transmission electron microscopy shows that Si nanocrystals are embedded in an amorphous matrix at low speeds, whereas at high speeds the transformed zone is completely amorphous. Furthermore, the extend of the transformed zone is almost independent of the scratching speed and is delimited by a dislocation rich area that extends about as deep as the contact radius into the surface. To explain the observed phase and defect distribution a contact mechanics based decompression model that takes into account the load, the velocity, the materials properties and the contact radius in scratching is proposed. It shows that the decompression rate is higher at low penetration depth, which is consistent with the observation of amorphous silicon in this case. The stress field under the tip is computed using an elastic contact mechanics model based on Hertz's theory. The model explains the observed shape of the transformed zone and suggests that during load increase, phase transformation takes place prior to dislocation nucleation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Surface Spectroscopic Signatures of Mechanical Deformation in HDPE.

    Science.gov (United States)

    Averett, Shawn C; Stanley, Steven K; Hanson, Joshua J; Smith, Stacey J; Patterson, James E

    2018-01-01

    High-density polyethylene (HDPE) has been extensively studied, both as a model for semi-crystalline polymers and because of its own industrial utility. During cold drawing, crystalline regions of HDPE are known to break up and align with the direction of tensile load. Structural changes due to deformation should also manifest at the surface of the polymer, but until now, a detailed molecular understanding of how the surface responds to mechanical deformation has been lacking. This work establishes a precedent for using vibrational sum-frequency generation (VSFG) spectroscopy to investigate changes in the molecular-level structure of the surface of HDPE after cold drawing. X-ray diffraction (XRD) was used to confirm that the observed surface behavior corresponds to the expected bulk response. Before tensile loading, the VSFG spectra indicate that there is significant variability in the surface structure and tilt of the methylene groups away from the surface normal. After deformation, the VSFG spectroscopic signatures are notably different. These changes suggest that hydrocarbon chains at the surface of visibly necked HDPE are aligned with the direction of loading, while the associated methylene groups are oriented with the local C 2 v symmetry axis roughly parallel to the surface normal. Small amounts of unaltered material are also found at the surface of necked HDPE, with the relative amount of unaltered material decreasing as the amount of deformation increases. Aspects of the nonresonant SFG response in the transition zone between necked and undeformed polymer provide additional insight into the deformation process and may provide the first indication of mechanical deformation. Nonlinear surface spectroscopy can thus be used as a noninvasive and nondestructive tool to probe the stress history of a HPDE sample in situations where X-ray techniques are not available or not applicable. Vibrational sum-frequency generation thus has great potential as a platform for

  9. Control and large deformations of marginal disordered structures

    Science.gov (United States)

    Murugan, Arvind; Pinson, Matthew; Chen, Elizabeth

    Designed deformations, such as origami patterns, provide a way to make easily controlled mechanical metamaterials with tailored responses to external forces. We focus on an often overlooked regime of origami - non-linear deformations of large disordered origami patterns with no symmetries. We find that practical questions of control in origami have counterintuitive answers, because of intimate connections to spin glasses and neural networks. For example, 1 degree of freedom origami structures are actually difficult to control about the flat state with a single actuator; the actuator is thrown off by an exponential number of `red herring' zero modes for small deformations, all but one of which disappear at larger deformations. Conversely, structures with multiple programmed motions are much easier to control than expected - in fact, they are as easy to control as a dedicated single-motion structure if the number of programmed motions is below a threshold (`memory capacity').

  10. Energy balance and deformation mechanisms of duplexes

    Science.gov (United States)

    Mitra, Gautam; Boyer, Steven E.

    A duplex consists of a series of imbricate faults that are asymptotic to a roof thrust and a floor thrust. Depending on the final orientations of the imbricate faults and the final position of the branch lines, a duplex may be hinterland-dipping, foreland-dipping, or an antiformal stack. The exact geometry depends on various factors such as the initial dimensions of the individual slices (horses), their lithology, the amount of displacement (normalized to size of horse) on each fault, and the mechanics of movement along each fault. The energy required in duplex formation can be determined by calculating the total work involved in emplacing each horse: this is given by where W t=W p+W b+W g+W iWp is the work involved in initiating and propagating a fracture. Wb is the work involved in basal sliding, which may be frictional or some form of ductile flow, Wg is the work done against gravity during the emplacement of the horse, and Wi is the work involved in the internal deformation of the horse. By calculating and comparing these work terms it is possible to predict the conditions under which the different types of duplexes will form. Normally, the development of a hinterland-dipping duplex is most likely. However, if deformation conditions are favorable, displacements on individual imbricate faults may be very large compared to the size of the horses, leading to the formation of either antiformal stacks or foreland-dipping duplexes.

  11. Late-Paleozoic-Mesozoic deformational and deformation related metamorphic structures of Kuznetsk-Altai region

    Science.gov (United States)

    Zinoviev, Sergei

    2014-05-01

    Kuznetsk-Altai region is a part of the Central Asian Orogenic Belt. The nature and formation mechanisms of the observed structure of Kuznetsk-Altai region are interpreted by the author as the consequence of convergence of Tuva-Mongolian and Junggar lithospheric block structures and energy of collision interaction between the blocks of crust in Late-Paleozoic-Mesozoic period. Tectonic zoning of Kuznetsk-Altai region is based on the principle of adequate description of geological medium (without methods of 'primary' state recovery). The initial indication of this convergence is the crust thickening in the zone of collision. On the surface the mechanisms of lateral compression form a regional elevation; with this elevation growth the 'mountain roots' start growing. With an approach of blocks an interblock elevation is divided into various fragments, and these fragments interact in the manner of collision. The physical expression of collision mechanisms are periodic pulses of seismic activity. The main tectonic consequence of the block convergence and collision of interblock units is formation of an ensemble of regional structures of the deformation type on the basis of previous 'pre-collision' geological substratum [Chikov et al., 2012]. This ensemble includes: 1) allochthonous and autochthonous blocks of weakly deformed substratum; 2) folded (folded-thrust) systems; 3) dynamic metamorphism zones of regional shears and main faults. Characteristic of the main structures includes: the position of sedimentary, magmatic and PT-metamorphic rocks, the degree of rock dynamometamorphism and variety rock body deformation, as well as the styles and concentrations of mechanic deformations. 1) block terranes have weakly elongated or isometric shape in plane, and they are the systems of block structures of pre-collision substratum separated by the younger zones of interblock deformations. They stand out among the main deformation systems, and the smallest are included into the

  12. Deformed supersymmetric quantum mechanics with spin variables

    Science.gov (United States)

    Fedoruk, Sergey; Ivanov, Evgeny; Sidorov, Stepan

    2018-01-01

    We quantize the one-particle model of the SU(2|1) supersymmetric multiparticle mechanics with the additional semi-dynamical spin degrees of freedom. We find the relevant energy spectrum and the full set of physical states as functions of the mass-dimension deformation parameter m and SU(2) spin q\\in (Z_{>0,}1/2+Z_{≥0}) . It is found that the states at the fixed energy level form irreducible multiplets of the supergroup SU(2|1). Also, the hidden superconformal symmetry OSp(4|2) of the model is revealed in the classical and quantum cases. We calculate the OSp(4|2) Casimir operators and demonstrate that the full set of the physical states belonging to different energy levels at fixed q are unified into an irreducible OSp(4|2) multiplet.

  13. Mechanical Deformation Behavior of Lean Duplex 329LA Steel

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Byung-Jun [Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of); Choi, Jeom-Yong [POSCO Technical Research Lab., Pohang (Korea, Republic of); Park, Kyung-Tae [Hanvat National University, Daejeon (Korea, Republic of); Lee, Ho Seong [Kyungpook National University, Daegu (Korea, Republic of)

    2015-09-15

    The tensile response of Lean Duplex 329LA stainless steel was investigated over various strain rates. It was observed that the mechanical response, including in particular the total elongation of the tested alloy, was strongly affected by the strain rate. As the strain rate decreased from 10-1 s-1 to 10-4 s-1, the elongation increased. As the strain rate increased, the deformation mode in an austenite phase was dominated by dislocation glide, resulting in deterioration of the elongation. The substructure of the ferritic phase showed a dislocation cell structure, independent of the applied strain rate. The optimum mechanical properties of lean duplex stainless steel thus can be obtained by controlling the deformation mode in the austenitic phase.

  14. Mechanical Deformation Behavior of Lean Duplex 329LA Steel

    International Nuclear Information System (INIS)

    Yoon, Byung-Jun; Choi, Jeom-Yong; Park, Kyung-Tae; Lee, Ho Seong

    2015-01-01

    The tensile response of Lean Duplex 329LA stainless steel was investigated over various strain rates. It was observed that the mechanical response, including in particular the total elongation of the tested alloy, was strongly affected by the strain rate. As the strain rate decreased from 10-1 s-1 to 10-4 s-1, the elongation increased. As the strain rate increased, the deformation mode in an austenite phase was dominated by dislocation glide, resulting in deterioration of the elongation. The substructure of the ferritic phase showed a dislocation cell structure, independent of the applied strain rate. The optimum mechanical properties of lean duplex stainless steel thus can be obtained by controlling the deformation mode in the austenitic phase.

  15. Effect of structural factors on mechanical properties of the magnesium alloy Ma2-1 under quasi-static and high strain rate deformation conditions

    Science.gov (United States)

    Garkushin, G. V.; Razorenov, S. V.; Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.

    2015-02-01

    The elastic limit and tensile strength of deformed magnesium alloys Ma2-1 with different structures and textures were measured with the aim of finding a correlation between the spectrum of defects in the material and the resistance to deformation and fracture under quasi-static and dynamic loading conditions. The studies were performed using specimens in the as-received state after high-temperature annealing and specimens subjected to equal-channel angular pressing at a temperature of 250°C. The anisotropy of strength characteristics of the material after shock compression with respect to the direction of rolling of the original alloy was investigated. It was shown that, in contrast to the quasi-static loading conditions, under the shock wave loading conditions, the elastic limit and tensile strength of the magnesium alloy Ma2-1 after equal-channel angular pressing decrease as compared to the specimens in the as-received state.

  16. Plastic deformation mechanisms of the uranium-alpha. Review

    International Nuclear Information System (INIS)

    Loureiro, A.P.

    1975-01-01

    A survey of the bibliography on the behaviour of the alpha-Uranium during its plastic deformation is made, with the aim of knowing the mechanisms which control that deformation. An analysis is made of some of the mechanisms suggested in the literature as controlling, with particular emphasis on the Peierls-Nabarro mechanism

  17. Fine structure in deformed proton emitting nuclei

    International Nuclear Information System (INIS)

    Sonzogni, A. A.; Davids, C. N.; Woods, P. J.; Seweryniak, D.; Carpenter, M. P.; Ressler, J. J.; Schwartz, J.; Uusitalo, J.; Walters, W. B.

    1999-01-01

    In a recent experiment to study the proton radioactivity of the highly deformed 131 Eu nucleus, two proton lines were detected. The higher energy one was assigned to the ground-state to ground-state decay, while the lower energy, to the ground-state to the 2 + state decay. This constitutes the first observation of fine structure in proton radioactivity. With these four measured quantities, proton energies, half-life and branching ratio, it is possible to determine the Nilsson configuration of the ground state of the proton emitting nucleus as well as the 2 + energy and nuclear deformation of the daughter nucleus. These results will be presented and discussed

  18. Cyclic deformation mechanisms in a cast gamma titanium aluminide alloy

    International Nuclear Information System (INIS)

    Jouiad, Mustapha; Gloanec, Anne-Lise; Grange, Marjolaine; Henaff, Gilbert

    2005-01-01

    The present study tackles the issue of the identification of the deformation mechanisms governing the cyclic stress-strain behaviour of a cast Ti-48Al-2Cr-2Nb (numbers indicate at.%) with a nearly fully lamellar microstructure. At room temperature, this behaviour and the corresponding deformation mechanisms are shown to be strongly dependent on the applied strain range. Indeed, at low strain range, where almost no hardening is noticed, deformation occurs by motion of long and straight ordinary dislocations. The moderate hardening observed at intermediate values of the strain range is associated with the formation of a vein-like structure due to the progressive tangling of ordinary dislocations. Finally, at higher strain-range values, twinning, by delaying the formation of this vein-like structure, induces a more pronounced cyclic strain hardening. At high temperature (750 deg. C), the material exhibits a rapid saturation of the stress amplitude, regardless of the applied strain range. Transmission electron microscopy indicates that twinning is no longer operative at this temperature, but that dislocation climb is activated

  19. Mechanisms of deformation and of recrystallization of imperfect uranium monocrystals

    International Nuclear Information System (INIS)

    Calais, D.

    1960-04-01

    The various means by which plastic deformations by slip, twinning or kinking are produced by tension of imperfect α uranium single crystals prepared by a β → α 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 α 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) [fr

  20. Mechanical stability of heat-treated nanoporous anodic alumina subjected to repetitive mechanical deformation

    Science.gov (United States)

    Bankova, A.; Videkov, V.; Tzaneva, B.; Mitov, M.

    2018-03-01

    We report studies on the mechanical response and deformation behavior of heat-treated nanoporous anodic alumina using a micro-balance test and experimental test equipment especially designed for this purpose. AAO samples were characterized mechanically by a three-point bending test using a micro-analytical balance. The deformation behavior was studied by repetitive mechanical bending of the AAO membranes using an electronically controlled system. The nanoporous AAO structures were prepared electrochemically from Al sheet substrates using a two-step anodizing technique in oxalic acid followed by heat treatment at 700 °C in air. The morphological study of the aluminum oxide layer after the mechanical tests and mechanical deformation was conducted using scanning electron and optical microscopy, respectively. The experimental results showed that the techniques proposed are simple and accurate; they could, therefore, be combined to constitute a method for mechanical stability assessment of nanostructured AAO films, which are important structural components in the design of MEMS devices and sensors.

  1. Deformation mechanisms of nanograined metallic polycrystals

    Czech Academy of Sciences Publication Activity Database

    Saada, G.; Kruml, Tomáš

    2011-01-01

    Roč. 59, - (2011), s. 2565-2574 ISSN 1359-6454 Institutional research plan: CEZ:AV0Z20410507 Keywords : nanocrystalline materials * grain boundary defects * plastic deformation Subject RIV: JJ - Other Materials Impact factor: 3.755, year: 2011

  2. Fracture behavior and deformation mechanisms under fast neutron irradiation

    International Nuclear Information System (INIS)

    Boutard, J.L.; Dupouy, J.M.

    1980-09-01

    We have established the out-of-pile and in-pile deformation mechanism maps of a 316 stainless steel irradiated in a fast reactor. The knowledge of the dominating deformation mechanism either in post irradiation creep experiments or during the in-pile steady state operating conditions allows to rationalize the apparent discrepancy between the very low out-of-pile ductility and the rather high plastic diametral strains which are obtained in the fast reactor environment without fracture

  3. The mechanism of strength and deformation in Gum Metal

    International Nuclear Information System (INIS)

    Furuta, T.; Kuramoto, S.; Morris, J.W.; Nagasako, N.; Withey, E.; Chrzan, D.C.

    2013-01-01

    “Gum Metal” refers to β-Ti alloys that achieve exceptional elastic elongation and, with a specific alloy composition, appear to deform via a dislocation-free mechanism involving elastic instability at the limit of strength. This paper describes the current status of research on its strength, deformation mechanism and the possible role of stress-induced martensite. The theoretical basis for deformation at ideal strength is presented. The relevant experimental data is then discussed, including ex situ nanoindentation behavior and in situ pillar compression observed by transmission electron microscopy

  4. Influence of Compatibilizer and Processing Conditions on Morphology, Mechanical Properties, and Deformation Mechanism of PP/Clay Nano composite

    International Nuclear Information System (INIS)

    Akbari, B.; Bagheri, R.

    2012-01-01

    Polypropylene/montmorillonite nano composite 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 nano composite 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 nano composite.

  5. Deformation mechanisms in the San Andreas Fault zone - a comparison between natural and experimentally deformed microstructures

    Science.gov (United States)

    van Diggelen, Esther; Holdsworth, Robert; de Bresser, Hans; Spiers, Chris

    2010-05-01

    The San Andreas Fault (SAF) in California marks the boundary between the Pacific plate and the North American plate. The San Andreas Fault Observatory at Depth (SAFOD) is located 9 km northwest of the town of Parkfield, CA and provide an extensive set of samples through the SAF. The SAFOD drill hole encountered different lithologies, including arkosic sediments from the Salinian block (Pacific plate) and claystones and siltstones from the Great Valley block (North American plate). Fault deformation in the area is mainly by a combination of micro-earthquakes and fault creep. Deformation of the borehole casing indicated that the SAFOD drill hole cross cuts two actively deforming strands of the SAF. In order to determine the deformation mechanisms in the actively creeping fault segments, we have studied thin sections obtained from SAFOD phase 3 core material using optical and electron microscopy, and we have compared these natural SAFOD microstructures with microstructures developed in simulated fault gouges deformed in laboratory shear experiments. The phase 3 core material is divided in three different core intervals consisting of different lithologies. Core interval 1 consists of mildly deformed Salinian rocks that show evidence of cataclasis, pressure solution and reaction of feldspar to form phyllosilicates, all common processes in upper crustal rocks. Most of Core interval 3 (Great Valley) is also only mildly deformed and very similar to Core interval 1. Bedding and some sedimentary features are still visible, together with limited evidence for cataclasis and pressure solution, and reaction of feldspar to form phyllosilicates. However, in between the relatively undeformed rocks, Core interval 3 encountered a zone of foliated fault gouge, consisting mostly of phyllosilicates. This zone is correlated with one of the zones of localized deformation of the borehole casing, i.e. with an actively deforming strand of the SAF. The fault gouge zone shows a strong, chaotic

  6. Mechanisms of dynamic deformation and dynamic failure in aluminum nitride

    International Nuclear Information System (INIS)

    Hu Guangli; Chen, C.Q.; Ramesh, K.T.; McCauley, J.W.

    2012-01-01

    Uniaxial quasi-static, uniaxial dynamic and confined dynamic compression experiments have been performed to characterize the failure and deformation mechanisms of a sintered polycrystalline aluminum nitride using a servohydraulic machine and a modified Kolsky bar. Scanning electron microscopy and transmission electron microscopy (TEM) are used to identify the fracture and deformation mechanisms under high rate and high pressure loading conditions. These results show that the fracture mechanisms are strong functions of confining stress and strain rate, with transgranular fracture becoming more common at high strain rates. Dynamic fracture mechanics and micromechanical models are used to analyze the observed fracture mechanisms. TEM characterization of fragments from the confined dynamic experiments shows that at higher pressures dislocation motion becomes a common dominant deformation mechanism in AlN. Prismatic slip is dominant, and pronounced microcrack–dislocation interactions are observed, suggesting that the dislocation plasticity affects the macroscopic fracture behavior in this material under high confining stresses.

  7. Deformation mechanisms in nanotwinned copper by molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xing [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083 (China); Lu, Cheng, E-mail: chenglu@uow.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Tieu, Anh Kiet; Pei, Linqing; Zhang, Liang; Su, Lihong [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Zhan, Lihua [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083 (China)

    2017-02-27

    Nanotwinned materials exhibit simultaneous ultrahigh strength and high ductility which is attributed to the interactions between dislocations and twin boundaries but the specific deformation mechanisms are rarely seen in experiments at the atomic level. Here we use large scale molecular dynamics simulations to explore this intricate interplay during the plastic deformation of nanotwinned Cu. We demonstrate that the dominant deformation mechanism transits dynamically from slip transfer to twin boundary migration to slip-twin interactions as the twin boundary orientation changes from horizontal to slant, and then to a vertical direction. Building on the fundamental physics of dislocation processes from computer simulations and combining the available experimental investigations, we unravel the underlying deformation mechanisms for nanotwinned Cu, incorporating all three distinct dislocation processes. Our results give insights into systematically engineering the nanoscale twins to fabricate nanotwinned metals or alloys that have high strength and considerable ductility.

  8. Deformation mechanisms in the frontal Lesser Himalayan Duplex in ...

    Indian Academy of Sciences (India)

    kinematics of the LHD is in the process of being worked out .... also played a major role in the deformation process as evident from .... mation occurred at shallow crustal levels within ..... deep structure of the outer and Lesser Himalaya, Jumoan.

  9. EBSD characterization of low temperature deformation mechanisms in modern alloys

    Science.gov (United States)

    Kozmel, Thomas S., II

    For structural applications, grain refinement has been shown to enhance mechanical properties such as strength, fatigue resistance, and fracture toughness. Through control of the thermos-mechanical processing parameters, dynamic recrystallization mechanisms were used to produce microstructures consisting of sub-micron grains in 9310 steel, 4140 steel, and Ti-6Al-4V. In both 9310 and 4140 steel, the distribution of carbides throughout the microstructure affected the ability of the material to dynamically recrystallize and determined the size of the dynamically recrystallized grains. Processing the materials at lower temperatures and higher strain rates resulted in finer dynamically recrystallized grains. Microstructural process models that can be used to estimate the resulting microstructure based on the processing parameters were developed for both 9310 and 4140 steel. Heat treatment studies performed on 9310 steel showed that the sub-micron grain size obtained during deformation could not be retained due to the low equilibrium volume fraction of carbides. Commercially available aluminum alloys were investigated to explain their high strain rate deformation behavior. Alloys such as 2139, 2519, 5083, and 7039 exhibit strain softening after an ultimate strength is reached, followed by a rapid degradation of mechanical properties after a critical strain level has been reached. Microstructural analysis showed that the formation of shear bands typically preceded this rapid degradation in properties. Shear band boundary misorientations increased as a function of equivalent strain in all cases. Precipitation behavior was found to greatly influence the microstructural response of the alloys. Additionally, precipitation strengthened alloys were found to exhibit similar flow stress behavior, whereas solid solution strengthened alloys exhibited lower flow stresses but higher ductility during dynamic loading. Schmid factor maps demonstrated that shear band formation behavior

  10. Deformations of Geometric Structures in Topological Sigma Models

    International Nuclear Information System (INIS)

    Bytsenko, A. A.

    2010-01-01

    We study a Lie algebra of formal vector fields W n with it application to the perturbative deformed holomorphic symplectic structure in the A-model, and a Calabi-Yau manifold with boundaries in the B-model. We show that equivalent classes of deformations are described by a Hochschild cohomology of the DG-algebra A = (A,Q), Q = ∂-bar+∂ deform, which is defined to be the cohomology of (-1) n Q+d Hoch . Here ∂-bar is the initial non-deformed BRST operator while ∂ deform is the deformed part whose algebra is a Lie algebra of linear vector fields gl n .

  11. Hopf structure and Green ansatz of deformed parastatistics algebras

    Energy Technology Data Exchange (ETDEWEB)

    Aneva, Boyka [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, bld. Tsarigradsko chaussee 72, BG-1784 Sofia (Bulgaria); Popov, Todor [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, bld. Tsarigradsko chaussee 72, BG-1784 Sofia (Bulgaria)

    2005-07-22

    Deformed parabose and parafermi algebras are revised and endowed with Hopf structure in a natural way. The noncocommutative coproduct allows for construction of parastatistics Fock-like representations, built out of the simplest deformed Bose and Fermi representations. The construction gives rise to quadratic algebras of deformed anomalous commutation relations which define the generalized Green ansatz.

  12. In-situ studies of bulk deformation structures: Static properties under load and dynamics during deformation

    DEFF Research Database (Denmark)

    Jakobsen, Bo

    2006-01-01

    The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (model system for cell forming pure fcc metals. Anovel synchrotron...... grains in polycrystalline samples during tensile deformation. We have shown that the resulting 3D reciprocal space maps from tensile deformed copper comprise a pronounced structure, consisting of bright sharp peaks superimposed on a cloud of enhanced intensity. Based on the integrated intensity......, the width of the peaks, and spatial scanning experiments it is concluded that the individual peaks arise from individual dislocation-free regions (the subgrains) in the dislocation structure. The cloud is attributed to the dislocation rich walls. Samples deformed to 2% tensile strain were investigated under...

  13. Deformations of symplectic Lie algebroids, deformations of holomorphic symplectic structures, and index theorems

    DEFF Research Database (Denmark)

    Nest, Ryszard; Tsygan, Boris

    2001-01-01

    Recently Kontsevich solved the classification problem for deformation quantizations of all Poisson structures on a manifold. In this paper we study those Poisson structures for which the explicit methods of Fedosov can be applied, namely the Poisson structures coming from symplectic Lie algebroids......, as well as holomorphic symplectic structures. For deformations of these structures we prove the classification theorems and a general a general index theorem....

  14. Granular deformation mechanisms in semi-solid alloys

    International Nuclear Information System (INIS)

    Gourlay, C.M.; Dahle, A.K.; Nagira, T.; Nakatsuka, N.; Nogita, K.; Uesugi, K.; Yasuda, H.

    2011-01-01

    Deformation mechanisms in equiaxed, partially solid Al-15 wt.% Cu are studied in situ by coupling shear-cell experiments with synchrotron X-ray radiography. Direct evidence is presented for granular deformation mechanisms in both globular and equiaxed-dendritic samples at solid fractions shortly after crystal impingement. It is demonstrated that dilatancy, arching and jamming occur at the crystal scale, and that these can cause stick-slip flow due to periodic dilation and compaction at low displacement rate. Granular deformation is found to be similar in globular and equiaxed-dendritic samples if length is scaled by the crystal size and packing is considered to occur among crystal envelopes. Rheological differences between the morphologies are discussed in terms of the competition between crystal rearrangement and crystal deformation.

  15. Low temperature deformation mechanisms in LiF single crystals

    International Nuclear Information System (INIS)

    Fotedar, H.L.; Stroebe, T.G.

    1976-01-01

    An analysis of the deformation behavior of high purity LiF single crystals is given using yielding and work hardening data and thermally activated deformation parameters obtained in the temperature range 77-423 0 K. It is found that while the Fleischer mechanism is apparently valid experimentally over the thermally activated temperature range, vacancies produced in large numbers at 77 0 K could also play a role in determining the critical resolved shear stress at that temperature

  16. Mechanisms of strain accommodation in plastically-deformed zircon under simple shear deformation conditions during amphibolite-facies metamorphism

    Science.gov (United States)

    Kovaleva, Elizaveta; Klötzli, Urs; Wheeler, John; Habler, Gerlinde

    2018-02-01

    This study documents the strain accommodation mechanisms in zircon under amphibolite-facies metamorphic conditions in simple shear. Microstructural data from undeformed, fractured and crystal-plastically deformed zircon crystals are described in the context of the host shear zone, and evaluated in the light of zircon elastic anisotropy. Our work challenges the existing model of zircon evolution and shows previously undescribed rheological characteristics for this important accessory mineral. Crystal-plastically deformed zircon grains have axis oriented parallel to the foliation plane, with the majority of deformed grains having axis parallel to the lineation. Zircon accommodates strain by a network of stepped low-angle boundaries, formed by switching between tilt dislocations with the slip systems {010} and {110} and rotation axis [001], twist dislocations with the rotation axis [001], and tilt dislocations with the slip system {001} and rotation axis [010]. The slip system {110} is newly described for zircon. Most misorientation axes in plastically-deformed zircon grains are parallel to the XY plane of the sample and have [001] crystallographic direction. Such behaviour of strained zircon lattice is caused by elastic anisotropy that has a direct geometric control on the rheology, deformation mechanisms and dominant slip systems in zircon. Young's modulus and P wave velocity have highest values parallel to zircon [001] axis, indicating that zircon is elastically strong along this direction. Poisson ratio and Shear modulus demonstrate that zircon is also most resistant to shearing along [001]. Thus, [001] axis is the most common rotation axis in zircon. The described zircon behaviour is important to take into account during structural and geochronological investigations of (poly)metamorphic terrains. Geometry of dislocations in zircon may help reconstructing the geometry of the host shear zone(s), large-scale stresses in the crust, and, possibly, the timing of

  17. 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

  18. 3D mechanical stratigraphy of a deformed multi-layer: Linking sedimentary architecture and strain partitioning

    Science.gov (United States)

    Cawood, Adam J.; Bond, Clare E.

    2018-01-01

    Stratigraphic influence on structural style and strain distribution in deformed sedimentary sequences is well established, in models of 2D mechanical stratigraphy. In this study we attempt to refine existing models of stratigraphic-structure interaction by examining outcrop scale 3D variations in sedimentary architecture and the effects on subsequent deformation. At Monkstone Point, Pembrokeshire, SW Wales, digital mapping and virtual scanline data from a high resolution virtual outcrop have been combined with field observations, sedimentary logs and thin section analysis. Results show that significant variation in strain partitioning is controlled by changes, at a scale of tens of metres, in sedimentary architecture within Upper Carboniferous fluvio-deltaic deposits. Coupled vs uncoupled deformation of the sequence is defined by the composition and lateral continuity of mechanical units and unit interfaces. Where the sedimentary sequence is characterized by gradational changes in composition and grain size, we find that deformation structures are best characterized by patterns of distributed strain. In contrast, distinct compositional changes vertically and in laterally equivalent deposits results in highly partitioned deformation and strain. The mechanical stratigraphy of the study area is inherently 3D in nature, due to lateral and vertical compositional variability. Consideration should be given to 3D variations in mechanical stratigraphy, such as those outlined here, when predicting subsurface deformation in multi-layers.

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

    Science.gov (United States)

    Matin, Abdul; Mazumdar, Sweety

    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.

  20. 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.

  1. 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.

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

    International Nuclear Information System (INIS)

    Glamheden, Rune; Maersk Hansen, Lars; Fredriksson, Anders; Bergkvist, Lars; Markstroem, Ingemar; Elfstroem, Mats

    2007-02-01

    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

  3. 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}.

  4. Study of structural changes during deformation of polycrystal vanadium

    International Nuclear Information System (INIS)

    Zubets, Yu.E.; Manilov, V.A.; Sarzhan, G.F.; Trefilov, V.I.; Firstov, S.A.

    1978-01-01

    Investigated were the polycrystalline vanadium dislocation structure formed within the range of temperatures between 20 and 1000 deg C and in the interval of deformations between 5 and 94%. The diagram of states was established in the temperature vs. degree of deformation coordinates from electron microscopy data. It was shown that a deformation of 5-7% leads to the appearance in the structure of incorrect shape dislocations with a lot of jogs and kinks. The density of relatively homogeneously distributed dislocations increases with the degree of deformation up to the latter's value of 50%. At a deformation greater than 50%, there forms a cellular structure, there remaining ranges where no cellular structure is formed. Thus, there appears a two-component texture with a different level of internal stresses. Annealing of such a material gives rise to areas of different types of cellular structure

  5. 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:...

  6. Structure and properties of copper after large strain deformation

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, Kinga; Molak, Rafal M.; Pakiela, Zbigniew

    2010-05-15

    Structure and properties of Cu in dependence on strain (from {epsilon}{proportional_to} 0.9 to {epsilon}{proportional_to} 15) during multi-axial compression processing at room temperature was investigated. The evolution of dislocation structure, misorientation distribution and crystallite size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The mechanical properties of yield strength (YS), ultimate tensile strength (UTS) and uniform elongation was performed on MTS QTest/10 machine equipped with digital image correlation method (DIC). The structure-flow stress relationship of multi-axial compression processing material at strains {epsilon}{proportional_to} 3.5 and {epsilon}{proportional_to} 5.5 is discussed. It is found that processing does not produce any drastic changes in deformation structure and the microstructural refinement is slow. These results indicate that dynamic recrystallization plays an important role during multi-axial compression process in this range of deformation (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Mechanics of deformations in terms of scalar variables

    Science.gov (United States)

    Ryabov, Valeriy A.

    2017-05-01

    Theory of particle and continuous mechanics is developed which allows a treatment of pure deformation in terms of the set of variables "coordinate-momentum-force" instead of the standard treatment in terms of tensor-valued variables "strain-stress." This approach is quite natural for a microscopic description of atomic system, according to which only pointwise forces caused by the stress act to atoms making a body deform. The new concept starts from affine transformation of spatial to material coordinates in terms of the stretch tensor or its analogs. Thus, three principal stretches and three angles related to their orientation form a set of six scalar variables to describe deformation. Instead of volume-dependent potential used in the standard theory, which requires conditions of equilibrium for surface and body forces acting to a volume element, a potential dependent on scalar variables is introduced. A consistent introduction of generalized force associated with this potential becomes possible if a deformed body is considered to be confined on the surface of torus having six genuine dimensions. Strain, constitutive equations and other fundamental laws of the continuum and particle mechanics may be neatly rewritten in terms of scalar variables. Giving a new presentation for finite deformation new approach provides a full treatment of hyperelasticity including anisotropic case. Derived equations of motion generate a new kind of thermodynamical ensemble in terms of constant tension forces. In this ensemble, six internal deformation forces proportional to the components of Irving-Kirkwood stress are controlled by applied external forces. In thermodynamical limit, instead of the pressure and volume as state variables, this ensemble employs deformation force measured in kelvin unit and stretch ratio.

  8. Effect of deformation diagram on molybdenum structure and properties

    International Nuclear Information System (INIS)

    Larin, Eh.N.; Abalikhin, A.A.; Kolikov, A.P.; Ushakova, N.E.

    1984-01-01

    Effect of deformation diagram on a tendency to lamination and mechanical properties of disks made of molybdenum alloy is studied. Investigated samples were subjected to hot rolling or forging. X-ray structural analysis of texture is carried out along with estimation of the level of mechanical properties across item cross section. Sample mechanical bending tests were conducted. Sample microstructure is also studied. It is shown that rolled molybdenum has a tendency to lamination, but forged molybdenum is free of such a tendency. Forged sample ductility is practically equal in all directionse but rolled sample ductility in a surface layer is high and decreases with depth. A conclusion is drawn that forged sample grains in a setting surface are equiaxial, but distinct deformation texture is observed for rolled samples and their grains are elongated in the direction of rolling. A conclusion is made that a flow diagram of the process of disk fabrication by forging or stamping ppovides a necessary complex of physicomechanical properties of metal as compared to polling, and metal discharge coefficient decreases sharply in this case

  9. Estimating the mechanical properties of the brittle deformation zones at Olkiluoto

    International Nuclear Information System (INIS)

    Hudson, J.A.; Cosgrove, J.W.; Johansson, E.

    2008-09-01

    In rock mechanics modelling to support repository design and safety assessment for the Olkiluoto site, it is necessary to obtain the relevant rock mechanics parameters, these being an essential pre-requisite for the modelling. The parameters include the rock stress state, the properties of the intact rock and the rock mass, and the properties of the brittle deformation zones which represent major discontinuities in the rock mass continuum. However, because of the size and irregularity of the brittle deformation zones, it is not easy to estimate their mechanical properties, i.e. their deformation and strength properties. Following Section 1 explaining the motivation for the work and the objective of the Report, in Sections 2 and 3, the types of fractures and brittle deformation zones that can be encountered are described with an indication of the mechanisms that lead to complex structures. The geology at Olkiluoto is then summarized in Section 4 within the context of this Report. The practical aspects of encountering the brittle deformation zones in outcrops, drillholes and excavations are described in Sections 5 and 6 with illustrative examples of drillhole core intersections in Section 7. The various theoretical, numerical and practical methods for estimating the mechanical properties of the brittle deformation zones are described in Section 8, together with a Table summarizing each method's advantages, disadvantages and utility in estimating the mechanical properties of the zones. We emphasise that the optimal approach to estimating the mechanical properties of the brittle deformation zones cannot be determined without a good knowledge, not only of each estimation method's capabilities and idiosyncrasies, but also of the structural geology background and the specific nature of the brittle deformation zones being characterized. Finally, in Section 9, a Table is presented outlining each method's applicability to the Olkiluoto site. A flowchart is included to

  10. The effect of microstructure on the deformation modes and mechanical properties of Ti-6Al-2Nb-1Ta-0.8Mo: Part II. Equiaxed structures

    Science.gov (United States)

    Lin, Fu-Shiong; Starke, E. A.; Gysler, A.

    1984-10-01

    The Ti-6Al-2Nb-lTa-0.8Mo alloy was processed to develop both near-basal and transverse textures. Samples were annealed at different temperatures to vary the equiaxed alpha grain size and the thick-ness of the grain boundary beta, and subsequently quenched in order to transform the beta phase to either martensite, tempered martensite, or Widmanstätten alpha + beta. The effect of microstructure and texture on tensile properties and on fracture toughness was investigated. In addition, yield locus diagrams were constructed in order to study the texture strengthening effect. The yield strength was found to be strongly dependent on the thickness and Burgers relationship of the transformed beta phase surrounding the alpha grains. A texture hardening effect as large as 60 pct was found for the basal-texture material but only 15 pct for the transverse texture material. These variations are asso-ciated with differences in deformation behavior.

  11. Competing Grain Boundary and Interior Deformation Mechanisms with Varying Sizes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [University of Tennessee (UT); Gao, Yanfei [ORNL; Nieh, T. G. [University of Tennessee, Knoxville (UTK)

    2018-01-01

    In typical coarse-grained alloys, the dominant plastic deformations are dislocation gliding or climbing, and material strengths can be tuned by dislocation interactions with grain boundaries, precipitates, solid solutions, and other defects. With the reduction of grain size, the increase of material strengths follows the classic Hall-Petch relationship up to nano-grained materials. Even at room temperatures, nano-grained materials exhibit strength softening, or called the inverse Hall-Petch effect, as grain boundary processes take over as the dominant deformation mechanisms. On the other hand, at elevated temperatures, grain boundary processes compete with grain interior deformation mechanisms over a wide range of the applied stress and grain sizes. This book chapter reviews and compares the rate equation model and the microstructure-based finite element simulations. The latter explicitly accounts for the grain boundary sliding, grain boundary diffusion and migration, as well as the grain interior dislocation creep. Therefore the explicit finite element method has clear advantages in problems where microstructural heterogeneities play a critical role, such as in the gradient microstructure in shot peening or weldment. Furthermore, combined with the Hall-Petch effect and its breakdown, the above competing processes help construct deformation mechanism maps by extending from the classic Frost-Ashby type to the ones with the dependence of grain size.

  12. Puncture mechanics of soft elastomeric membrane with large deformation by rigid cylindrical indenter

    Science.gov (United States)

    Liu, Junjie; Chen, Zhe; Liang, Xueya; Huang, Xiaoqiang; Mao, Guoyong; Hong, Wei; Yu, Honghui; Qu, Shaoxing

    2018-03-01

    Soft elastomeric membrane structures are widely used and commonly found in engineering and biological applications. Puncture is one of the primary failure modes of soft elastomeric membrane at large deformation when indented by rigid objects. In order to investigate the puncture failure mechanism of soft elastomeric membrane with large deformation, we study the deformation and puncture failure of silicone rubber membrane that results from the continuous axisymmetric indentation by cylindrical steel indenters experimentally and analytically. In the experiment, effects of indenter size and the friction between the indenter and the membrane on the deformation and puncture failure of the membrane are investigated. In the analytical study, a model within the framework of nonlinear field theory is developed to describe the large local deformation around the punctured area, as well as to predict the puncture failure of the membrane. The deformed membrane is divided into three parts and the friction contact between the membrane and indenter is modeled by Coulomb friction law. The first invariant of the right Cauchy-Green deformation tensor I1 is adopted to predict the puncture failure of the membrane. The experimental and analytical results agree well. This work provides a guideline in designing reliable soft devices featured with membrane structures, which are present in a wide variety of applications.

  13. Soft sediment deformation structures in the Maastrichtian Ajali Formation Western Flank of Anambra Basin, Southern Nigeria

    Science.gov (United States)

    Olabode, Solomon Ojo

    2014-01-01

    Soft sediment deformation structures were recognized in the Maastrichtian shallow marine wave to tide influenced regressive sediments of Ajali Formation in the western flank of Anambra basin, southern Nigerian. The soft sediment deformation structures were in association with cross bedded sands, clay and silt and show different morphological types. Two main types recognised are plastic deformations represented by different types of recumbent folds and injection structure represented by clastic dykes. Other structures in association with the plastic deformation structures include distorted convolute lamination, subsidence lobes, pillars, cusps and sand balls. These structures are interpreted to have been formed by liquefaction and fluidization mechanisms. The driving forces inferred include gravitational instabilities and hydraulic processes. Facies analysis, detailed morphologic study of the soft sediment deformation structures and previous tectonic history of the basin indicate that the main trigger agent for deformation is earthquake shock. The soft sediment deformation structures recognised in the western part of Anambra basin provide a continuous record of the tectonic processes that acted on the regressive Ajali Formation during the Maastrichtian.

  14. STRUCTURE OF ECONOMIC MECHANISM

    Directory of Open Access Journals (Sweden)

    L. I. Podderegina

    2006-01-01

    Full Text Available The paper considers and analyzes scientific approaches of economists to the essence and contents of the economic mechanism. Proposals for methodological formation of economic mechanism structure are substantiated in the paper.

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

    Directory of Open Access Journals (Sweden)

    G. Molli

    2017-07-01

    Full Text Available 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

  16. Long-term Deformation Measurements of Atypical Roof Timber Structures

    Directory of Open Access Journals (Sweden)

    Jiří Bureš

    2014-06-01

    Full Text Available The paper includes conclusions from evaluation of results obtained from long-termmeasuring of innovative atypical roof timber structures. Based on the results ofmeasurements of vertical and horizontal deformation components it is possible to analyzethe real behavior of structures in given conditions. By assessing deformations in variousstages, including particularly external and internal environment temperatures, relative airhumidity and moisture content of wood, decisive parameters for real structure behaviorcan be established. The data are processed from period 2001 – 2013.

  17. Mechanical stability of the cell nucleus: roles played by the cytoskeleton in nuclear deformation and strain recovery.

    Science.gov (United States)

    Wang, Xian; Liu, Haijiao; Zhu, Min; Cao, Changhong; Xu, Zhensong; Tsatskis, Yonit; Lau, Kimberly; Kuok, Chikin; Filleter, Tobin; McNeill, Helen; Simmons, Craig A; Hopyan, Sevan; Sun, Yu

    2018-05-18

    Extracellular forces transmitted through the cytoskeleton can deform the cell nucleus. Large nuclear deformation increases the risk of disrupting the nuclear envelope's integrity and causing DNA damage. Mechanical stability of the nucleus defines its capability of maintaining nuclear shape by minimizing nuclear deformation and recovering strain when deformed. Understanding the deformation and recovery behavior of the nucleus requires characterization of nuclear viscoelastic properties. Here, we quantified the decoupled viscoelastic parameters of the cell membrane, cytoskeleton, and the nucleus. The results indicate that the cytoskeleton enhances nuclear mechanical stability by lowering the effective deformability of the nucleus while maintaining nuclear sensitivity to mechanical stimuli. Additionally, the cytoskeleton decreases the strain energy release rate of the nucleus and might thus prevent shape change-induced structural damage to chromatin. © 2018. Published by The Company of Biologists Ltd.

  18. 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.

  19. 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

  20. 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

    Commercially pure titanium was tensile tested at different strain rates between 2.2×10−4s−1 and 6.7×10−1s−1 to characterize the strain rate dependence of plastic deformation and the dominating deformation mechanisms. From true stress-true plastic strain curves, three distinct work-hardening stages...... are identified. The work-hardening rate decreases linearly with increasing flow stress for all three stages and the work-hardening rate is the controlling factor for the transition between the different stages and mechanisms. During the initial stage (at lowest stresses) plastic deformation is carried mainly...... 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...

  1. Bicrossproduct structure and graded contractions of deformed algebras

    International Nuclear Information System (INIS)

    Perez Bueno, J.C.

    1997-01-01

    It is shown that all members in the family of deformed Hopf algebras corresponding to the graded contractions of the inhomogeneous algebras iso(p,q), p + q = N, have a bicrossproduct structure. (author)

  2. Dynamic recrystallization mechanisms and twining evolution during hot deformation of Inconel 718

    Energy Technology Data Exchange (ETDEWEB)

    Azarbarmas, M. [Faculty of Materials Science and Engineering, K.N. Toosi University of Technology, 1999143344 Tehran (Iran, Islamic Republic of); Aghaie-Khafri, M., E-mail: maghaei@kntu.ac.ir [Faculty of Materials Science and Engineering, K.N. Toosi University of Technology, 1999143344 Tehran (Iran, Islamic Republic of); Cabrera, J.M.; Calvo, J. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB – Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain)

    2016-12-15

    The hot deformation behavior of an IN718 superalloy was studied by isothermal compression tests under the deformation temperature range of 950–1100 °C and strain rate range of 0.001–1 s{sup −1} up to true strains of 0.05, 0.2, 0.4 and 0.7. Electron backscattered diffraction (EBSD) technique was employed to investigate systematically the effects of strain, strain rate and deformation temperature on the subgrain structures, local and cumulative misorientations and twinning phenomena. The results showed that the occurrence of dynamic recrystallization (DRX) is promoted by increasing strain and deformation temperature and decreasing strain rate. The microstructural changes showed that discontinuous dynamic recrystallization (DDRX), characterized by grain boundary bulging, is the dominant nucleation mechanism in the early stages of deformation in which DRX nucleation occurs by twining behind the bulged areas. Twin boundaries of nuclei lost their ∑3 character with further deformation. However, many simple and multiple twins can be also regenerated during the growth of grains. The results showed that continuous dynamic recrystallization (CDRX) is promoted at higher strains and large strain rates, and lower temperatures, indicating that under certain conditions both DDRX and CDRX can occur simultaneously during the hot deformation of IN718.

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

    OpenAIRE

    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 ...

  4. On q-deformed supersymmetric classical mechanical models

    International Nuclear Information System (INIS)

    Colatto, L.P.; Matheus Valle, J.L.

    1995-10-01

    Based on the idea of quantum groups and paragrassmann variables, we present a generalization of supersymmetric classical mechanics with a deformation parameter q=exp 2πi/k dealing with the k=3 case. The coordinates of the q-superspace are a commuting parameter t and a paragrassmann variable θ, where θ 3 =0. The generator and covariant derivative are obtained, as well as the action for some possible superfields. (author). 13 refs

  5. Statics and mechanics of structures

    CERN Document Server

    Krenk, Steen

    2013-01-01

    The statics and mechanics of structures form a core aspect of civil engineering. This book provides an introduction to the subject, starting from classic hand-calculation types of analysis and gradually advancing to a systematic form suitable for computer implementation. It starts with statically determinate structures in the form of trusses, beams and frames. Instability is discussed in the form of the column problem - both the ideal column and the imperfect column used in actual column design. The theory of statically indeterminate structures is then introduced, and the force and deformation methods are explained and illustrated. An important aspect of the book’s approach is the systematic development of the theory in a form suitable for computer implementation using finite elements. This development is supported by two small computer programs, MiniTruss and MiniFrame, which permit static analysis of trusses and frames, as well as linearized stability analysis. The book’s final section presents related ...

  6. Ligand-mediated adhesive mechanics of two static, deformed spheres.

    Science.gov (United States)

    Sircar, Sarthok; Nguyen, Giang; Kotousov, Andrei; Roberts, Anthony J

    2016-10-01

    A self-consistent model is developed to investigate attachment/detachment kinetics of two static, deformable microspheres with irregular surface and coated with flexible binding ligands. The model highlights how the microscale binding kinetics of these ligands as well as the attractive/repulsive potential of the charged surface affects the macroscale static deformed configuration of the spheres. It is shown that in the limit of smooth, neutrally charged surface (i.e., the dimensionless inverse Debye length, [Formula: see text]), interacting via elastic binders (i.e., the dimensionless stiffness coefficient, [Formula: see text]) the adhesion mechanics approaches the regime of application of the JKR theory, and in this particular limit, the contact radius, R c , scales with the particle radius, R, according to the scaling law, [Formula: see text]. We show that static, deformed, highly charged, ligand-coated surface of micro-spheres exhibit strong adhesion. Normal stress distribution within the contact area adjusts with the binder stiffness coefficient, from a maximum at the center to a maximum at the periphery of the region. Although reported in some in vitro experiments involving particle adhesion, until now a physical interpretation for this variation of the stress distribution for deformable, charged, ligand-coated microspheres is missing. Surface roughness results in a diminished adhesion with a distinct reduction in the pull-off force, larger separation gap, weaker normal stress and limited area of adhesion. These results are in agreement with the published experimental findings.

  7. Vertebral deformity arising from an accelerated "creep" mechanism.

    Science.gov (United States)

    Luo, Jin; Pollintine, Phillip; Gomm, Edward; Dolan, Patricia; Adams, Michael A

    2012-09-01

    Vertebral deformities often occur in patients who recall no trauma, and display no evident fracture on radiographs. We hypothesise that vertebral deformity can occur by a gradual creep mechanism which is accelerated following minor damage. "Creep" is continuous deformation under constant load. Forty-five thoracolumbar spine motion segments were tested from cadavers aged 42-92 years. Vertebral body areal BMD was measured using DXA. Specimens were compressed at 1 kN for 30 min, while creep in each vertebral body was measured using an optical MacReflex system. After 30 min recovery, each specimen was subjected to a controlled overload event which caused minor damage to one of its vertebrae. The creep test was then repeated. Vertebral body creep was measurable in specimens with BMD Creep was greater anteriorly than posteriorly (p creep by 800 % (anteriorly), 1,000 % (centrally) and 600 % (posteriorly). In 34 vertebrae with complete before-and-after data, anterior wedging occurring during the 1st creep test averaged 0.07° (STD 0.17°), and in the 2nd test (after minor damage) it averaged 0.79° (STD 1.03°). The increase was highly significant (P creep test was proportional to the severity of damage, as quantified by specimen height loss during the overload event (r (2) = 0.51, p creep to such an extent that it makes a substantial contribution to vertebral deformity.

  8. Structural defects in natural plastically deformed diamonds: Evidence from EPR spectroscopy

    Science.gov (United States)

    Mineeva, R. M.; Titkov, S. V.; Speransky, A. V.

    2009-06-01

    Structural defects formed as a result of plastic deformation in natural diamond crystals have been studied by EPR spectroscopy. The spectra of brown, pink-brown, black-brown, pink-purple, and gray plastically deformed diamonds of type Ia from deposits in Yakutia and the Urals were recorded. The results of EPR spectroscopy allowed us to identify various deformation centers in the structure of natural diamonds and to show that nitrogen centers were transformed under epigenetic mechanical loading. Abundant A centers, consisting of two isomorphic nitrogen atoms located in neighboring structural sites, were destroyed as a result of this process to form a series of N1, N4, W7, M2, and M3 nitrogen centers. Such centers are characterized by an anisotropic spatial distribution and a positive charge, related to the mechanism of their formation. In addition, N2 centers (probably, deformation-produced dislocations decorated by nitrogen) were formed in all plastically deformed diamonds and W10 and W35 centers (the models have not been finally ascertained) were formed in some of them. It has been established that diamonds with various types of deformation-induced color contain characteristic associations of these deformation centers. The diversity of associations of deformation centers indicates appreciable variations in conditions of disintegration of deep-seated rocks, transfer of diamonds to the Earth’s surface, and formation of kimberlitic deposits. Depending on the conditions of mechanical loading, the diamond crystals were plastically deformed by either dislocation gliding or mechanical twinning. Characteristic features of plastic deformation by dislocation gliding are the substantial prevalence of the N2 centers over other deformation centers and the occurrence of the high-spin W10 and W35 centers. The attributes of less frequent plastic deformation by mechanical twinning are unusual localization of the M2 centers and, in some cases, the N1 centers in microtwinned

  9. Displacement and deformation measurement for large structures by camera network

    Science.gov (United States)

    Shang, Yang; Yu, Qifeng; Yang, Zhen; Xu, Zhiqiang; Zhang, Xiaohu

    2014-03-01

    A displacement and deformation measurement method for large structures by a series-parallel connection camera network is presented. By taking the dynamic monitoring of a large-scale crane in lifting operation as an example, a series-parallel connection camera network is designed, and the displacement and deformation measurement method by using this series-parallel connection camera network is studied. The movement range of the crane body is small, and that of the crane arm is large. The displacement of the crane body, the displacement of the crane arm relative to the body and the deformation of the arm are measured. Compared with a pure series or parallel connection camera network, the designed series-parallel connection camera network can be used to measure not only the movement and displacement of a large structure but also the relative movement and deformation of some interesting parts of the large structure by a relatively simple optical measurement system.

  10. Deformation Mechanisms of Darreh Sary Metapelites, Sanandaj‒Sirjan Zone, Iran

    Science.gov (United States)

    Hemmati, O.; Tabatabaei Manesh, S. M.; Nadimi, A. R.

    2018-03-01

    The Darreh Sary metapelitic rocks are located in the northeast of Zagros orogenic belt and Sanandaj-Sirjan structural zone. The lithological composition of these rocks includes slate, phyllite, muscovitebiotite schist, garnet schist, staurolite-garnet schist and staurolite schist. The shale is the protolith of these metamorphic rocks, which was originated from the continental island arc tectonic setting and has been subjected to processes of Zagros orogeny. The deformation mechanisms in these rocks include bulging recrystallization (BLG), subgrain rotation recrystallization (SGR) and grain boundary migration recrystallization (GBM), which are considered as the key to estimate the deformation temperature of the rocks. The estimated ranges of deformation temperature and depth in these rocks show the temperatures of 275-375, 375-500, and >500°C and the depths of 10 to 17 km. The observed structures in these rocks such as faults, fractures and folds, often with the NW-SE direction coordinate with the structural trends of Zagros orogenic belt structures. The S-C mylonite fabrics is observed in these rocks with other microstructures such as mica fish, σ fabric and garnet deformation indicate the dextral shear deformation movements of study area. Based on the obtained results of this research, the stages of tectonic evolution of Darreh Sary area were developed.

  11. Abrasive wear mechanisms and surface layer structure of refractory materials after mechanical working

    International Nuclear Information System (INIS)

    Milman, Y.V.; Lotsko, D.V.

    1989-01-01

    The mechanisms of abrasive wear and surface layer structure formation after different kinds of mechanical working are considered in terms of fracture and plastic deformation mechanisms for various refractory materials. The principles for classification of abrasive wear mechanisms are proposed, the four types of wear mechanisms are distinguished for various combinations of fractures and plastic deformation types. The concept of characteristic deformation temperature t * (knee temperature) is used. Detailed examples are given of investigating the surface layer structures in grinded crystals of sapphire and molybdenum. The amorphisation tendency of the thinnest surface layer while mechanical polishing is discussed separately. 19 refs., 11 figs., 2 tabs. (Author)

  12. 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.......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 set...

  13. Disordered long-range internal stresses in deformed copper and the mechanisms underlying plastic deformation

    International Nuclear Information System (INIS)

    Levine, Lyle E.; Geantil, Peter; Larson, Bennett C.; Tischler, Jonathan Z.; Kassner, Michael E.; Liu, Wenjun; Stoudt, Mark R.; Tavazza, Francesca

    2011-01-01

    Highlights: → Axial elastic strains were measured from numerous individual, contiguous dislocation cell walls and cell interiors. → The mean stresses for the cell walls and cell interiors were of opposite sign, in agreement with theoretical predictions. → The separation between the mean cell wall and cell interior stresses was about 20% of the flow stress. → Broad distributions of dipolar stresses were observed that are consistent with a simple size-scaling model. - Abstract: The strength of wavy glide metals increases dramatically during deformation as dislocations multiply and entangle, forming dense dislocation wall structures. Numerous competing models have been proposed for this process but experimental validation and guidance for further model development require new experimental approaches capable of resolving local stresses within the dislocation microstructure. We use three-dimensional X-ray microscopy combining submicrometer spatial resolution with diffracted-beam masking to make direct measurements of axial elastic strain (and thus stress) in individual dislocation cell walls and their adjacent cell interiors in heavily deformed copper. These spatially resolved measurements show broad, asymmetric distributions of dipolar stresses that directly discriminate between long-standing deformation models and demonstrate that the distribution of local stresses is statistically connected to the global behavior through simple rules.

  14. Speckle photography applied to measure deformations of very large structures

    Science.gov (United States)

    Conley, Edgar; Morgan, Chris K.

    1995-04-01

    Fundamental principles of mechanics have recently been brought to bear on problems concerning very large structures. Fields of study include tectonic plate motion, nuclear waste repository vault closure mechanisms, the flow of glacier and sea ice, and highway bridge damage assessment and residual life prediction. Quantitative observations, appropriate for formulating and verifying models, are still scarce however, so the need to adapt new methods of experimental mechanics is clear. Large dynamic systems often exist in environments subject to rapid change. Therefore, a simple field technique that incorporates short time scales and short gage lengths is required. Further, the measuring methods must yield displacements reliably, and under oft-times adverse field conditions. Fortunately, the advantages conferred by an experimental mechanics technique known as speckle photography nicely fulfill this rather stringent set of performance requirements. Speckle seemed to lend itself nicely to the application since it is robust and relatively inexpensive. Experiment requirements are minimal -- a camera, high resolution film, illumination, and an optically rough surface. Perhaps most important is speckle's distinct advantage over point-by-point methods: It maps the two dimensional displacement vectors of the whole field of interest. And finally, given the method's high spatial resolution, relatively short observation times are necessary. In this paper we discuss speckle, two variations of which were used to gage the deformation of a reinforced concrete bridge structure subjected to bending loads. The measurement technique proved to be easily applied, and yielded the location of the neutral axis self consistently. The research demonstrates the feasibility of using whole field techniques to detect and quantify surface strains of large structures under load.

  15. Shear Creep Simulation of Structural Plane of Rock Mass Based on Discontinuous Deformation Analysis

    Directory of Open Access Journals (Sweden)

    Guoxin Zhang

    2017-01-01

    Full Text Available Numerical simulations of the creep characteristics of the structural plane of rock mass are very useful. However, most existing simulation methods are based on continuum mechanics and hence are unsuitable in the case of large displacements and deformations. The discontinuous deformation analysis method proposed by Genhua is a discrete one and has a significant advantage when simulating the contacting problem of blocks. In this study, we combined the viscoelastic rheological model of Burgers with the discontinuous deformation analysis (DDA method. We also derived the recurrence formula for the creep deformation increment with the time step during numerical simulations. Based on the minimum potential energy principle, the general equilibrium equation was derived, and the shear creep deformation in the structural plane was considered. A numerical program was also developed and its effectiveness was confirmed based on the curves obtained by the creep test of the structural plane of a rock mass under different stress levels. Finally, the program was used to analyze the mechanism responsible for the creep features of the structural plane in the case of the toppling deformation of the rock slope. The results showed that the extended DDA method is an effective one.

  16. Influence of Plastic Deformation on Martensitic Transformation During Hot Stamping of Complex Structure Auto Parts

    Science.gov (United States)

    Shen, Yuhan; Song, Yanli; Hua, Lin; Lu, Jue

    2017-04-01

    The ultra-high strength steel auto parts manufactured by hot stamping are widely applied for weight reduction and safety improvement. During the hot stamping process, hot forming and quenching are performed in one step wherein plastic deformation and phase transformation simultaneously take place and affect each other. Thereinto, the influence of deformation on martensitic transformation is of great importance. In the present paper, the influence of plastic deformation on martensitic transformation during hot stamping of complex structure auto parts was investigated. For this purpose, a B-pillar reinforced panel in B1500HS steel was manufactured by hot stamping, and the process was simulated by finite element software based on a thermo-mechanical-metallurgical coupled model. Considering various deformation degrees, the microstructures and mechanical properties at four typical locations of the hot stamped B-pillar reinforced panel were detected. The results show that the martensitic content and the microhardness increase with the increase in the deformation amount. There are two reasons causing this phenomenon: (1) the increase in mechanical driving force and (2) the increased probability of the martensitic nucleation at crystal defects. The x-ray diffraction analysis indicates the carbon enrichment in retained austenite which results from the carbon diffusion during the low-carbon martensite formation. Furthermore, the carbon content decreases with the increase in the deformation amount, because the deformation of austenite suppresses the carbon diffusion.

  17. 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.

  18. Mechanics of adsorption-deformation coupling in porous media

    Science.gov (United States)

    Zhang, Yida

    2018-05-01

    This work extends Coussy's macroscale theory for porous materials interacting with adsorptive fluid mixtures. The solid-fluid interface is treated as an independent phase that obeys its own mass, momentum and energy balance laws. As a result, a surface strain energy term appears in the free energy balance equation of the solid phase, which further introduces the so-called adsorption stress in the constitutive equations of the porous skeleton. This establishes a fundamental link between the adsorption characteristics of the solid-fluid interface and the mechanical response of the porous media. The thermodynamic framework is quite general in that it recovers the coupled conduction laws, Gibbs isotherm and the Shuttleworth's equation for surface stress, and imposes no constraints on the magnitude of deformation and the functional form of the adsorption isotherms. A rich variety of coupling between adsorption and deformation is recovered as a result of combining different poroelastic models (isotropic vs. anisotropic, linear vs. nonlinear) and adsorption models (unary vs. mixture adsorption, uncoupled vs. stretch-dependent adsorption). These predictions are discussed against the backdrop of recent experimental data on coal swelling subjected to CO2 and CO2sbnd CH4 injections, showing the capability and versatility of the theory in capturing adsorption-induced deformation of porous materials.

  19. 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.

  20. A deformation quantization theory for noncommutative quantum mechanics

    International Nuclear Information System (INIS)

    Costa Dias, Nuno; Prata, Joao Nuno; Gosson, Maurice de; Luef, Franz

    2010-01-01

    We show that the deformation quantization of noncommutative quantum mechanics previously considered by Dias and Prata ['Weyl-Wigner formulation of noncommutative quantum mechanics', J. Math. Phys. 49, 072101 (2008)] and Bastos, Dias, and Prata ['Wigner measures in non-commutative quantum mechanics', e-print arXiv:math-ph/0907.4438v1; Commun. Math. Phys. (to appear)] can be expressed as a Weyl calculus on a double phase space. We study the properties of the star-product thus defined and prove a spectral theorem for the star-genvalue equation using an extension of the methods recently initiated by de Gosson and Luef ['A new approach to the *-genvalue equation', Lett. Math. Phys. 85, 173-183 (2008)].

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

    International Nuclear Information System (INIS)

    Mathiazhagan, S.; Anup, S.

    2016-01-01

    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. - 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.

  2. Topological defect clustering and plastic deformation mechanisms in functionalized graphene

    Science.gov (United States)

    Nunes, Ricardo; Araujo, Joice; Chacham, Helio

    2011-03-01

    We present ab initio results suggesting that strain plays a central role in the clustering of topological defects in strained and functionalized graphene models. We apply strain onto the topological-defect graphene networks from our previous work, and obtain topological-defect clustering patterns which are in excellent agreement with recent observations in samples of reduced graphene oxide. In our models, the graphene layer, containing an initial concentration of isolated topological defects, is covered by hydrogen or hydroxyl groups. Our results also suggest a rich variety of plastic deformation mechanism in functionalized graphene systems. We acknowledge support from the Brazilian agencies: CNPq, Fapemig, and INCT-Materiais de Carbono.

  3. Formation of diapiric structure in the deformation zone, central ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    serpentinite layer existing near the base of the crust that is interpreted to have been formed at mid-ocean ... Keywords. Diffusive plate boundary; deformation zone; diapiric structure; serpentinized peridotites; crustal structure; ... calculated by applying Eotvos correction and nor- ..... trend of the basement and flat Moho, and.

  4. Production, deformation and mechanical investigation of magnetic alginate capsules

    Science.gov (United States)

    Zwar, Elena; Kemna, Andre; Richter, Lena; Degen, Patrick; Rehage, Heinz

    2018-02-01

    In this article we investigated the deformation of alginate capsules in magnetic fields. The sensitivity to magnetic forces was realised by encapsulating an oil in water emulsion, where the oil droplets contained dispersed magnetic nanoparticles. We solved calcium ions in the aqueous emulsion phase, which act as crosslinking compounds for forming thin layers of alginate membranes. This encapsulating technique allows the production of flexible capsules with an emulsion as the capsule core. It is important to mention that the magnetic nanoparticles were stable and dispersed throughout the complete process, which is an important difference to most magnetic alginate-based materials. In a series of experiments, we used spinning drop techniques, capsule squeezing experiments and interfacial shear rheology in order to determine the surface Young moduli, the surface Poisson ratios and the surface shear moduli of the magnetically sensitive alginate capsules. In additional experiments, we analysed the capsule deformation in magnetic fields. In spinning drop and capsule squeezing experiments, water droplets were pressed out of the capsules at elevated values of the mechanical load. This phenomenon might be used for the mechanically triggered release of water-soluble ingredients. After drying the emulsion-filled capsules, we produced capsules, which only contained a homogeneous oil phase with stable suspended magnetic nanoparticles (organic ferrofluid). In the dried state, the thin alginate membranes of these particles were rather rigid. These dehydrated capsules could be stored at ambient conditions for several months without changing their properties. After exposure to water, the alginate membranes rehydrated and became flexible and deformable again. During this swelling process, water diffused back in the capsule. This long-term stability and rehydration offers a great spectrum of different applications as sensors, soft actuators, artificial muscles or drug delivery systems.

  5. Microstructure Deformation and Fracture Mechanism of Highly Filled Polymer Composites under Large Tensile Deformation

    International Nuclear Information System (INIS)

    Tao Zhangjiang; Ping Songdan; Mei Zhang; Cheng Zhaipeng

    2013-01-01

    The microstructure deformation and fracture mechanisms of particulate-filled polymer composites were studied based on microstructure observations in this paper. By using in-situ tensile test system under scanning electron microscopy, three different composites composed of polymer binder filled by three different types of particles, namely Al particles, AP particles and HMX particles, with the same total filler content were tested. The roles of initial microstructure damage and particle type on the microstructure deformation and damage are highlighted. The results show that microstructure damage starts with the growth of the initial microvoids within the binders or along the binder/particle interfaces. With the increase of strain, the microstructure damages including debonding at the particle/binder interface and tearing of the binder lead to microvoid coalescence, and finally cause an abrupt fracture of the samples. Coarse particles lead to an increase of debonding at the particle/binder interface both in the initial state and during the loading process, and angular particles promote interface debonding during the loading process.

  6. Thermally assisted deformation of structural superplastics and ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    constant.) (xii) It has been suggested that the self and the solute diffusivities are enhanced and the .... In this paper, only a summary of the important experimental results that a viable theory of structural ..... Experimental verification. Mater. Sci.

  7. QuikForm: Intelligent deformation processing of structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier, R.J.; Wellman, G.W.

    1994-09-01

    There currently exists a critical need for tools to enhance the industrial competitiveness and agility of US industries involved in deformation processing of structural alloys. In response to this need, Sandia National Laboratories has embarked upon the QuikForm Initiative. The goal of this program is the development of computer-based tools to facilitate the design of deformation processing operations. The authors are currently focusing their efforts on the definition/development of a comprehensive system for the design of sheet metal stamping operations. The overall structure of the proposed QuikForm system is presented, and the focus of their thrust in each technical area is discussed.

  8. Co2 injection into oil reservoir associated with structural deformation

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    In this work, the problem of structural deformation with two-phase flow of carbon sequestration is presented. A model to simulate miscible CO2 injection with structural deformation in the aqueous phase is established. In the first part of this paper, we developed analytical solution for the problem under consideration with certain types of boundary conditions, namely, Dirichlet and Neumann boundary conditions. The second part concerns to numerical simulation using IMPDES scheme. A simulator based on cell-centered finite difference method is used to solve this equations system. Distributions of CO2 saturation, and horizontal and vertical displacements have been introduced.

  9. Measurement of deforming mode of lattice truss structures under impact loading

    Directory of Open Access Journals (Sweden)

    Zhao H.

    2012-08-01

    Full Text Available Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression and remain constant afterwards (because of significant bending. The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached, together with the strain hardening of base material.

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

    KAUST Repository

    Gurses, Ercan; El Sayed, Tamer S.

    2011-01-01

    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

  11. 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...

  12. Computational mesh generation for vascular structures with deformable surfaces

    International Nuclear Information System (INIS)

    Putter, S. de; Laffargue, F.; Breeuwer, M.; Vosse, F.N. van de; Gerritsen, F.A.; Philips Medical Systems, Best

    2006-01-01

    Computational blood flow and vessel wall mechanics simulations for vascular structures are becoming an important research tool for patient-specific surgical planning and intervention. An important step in the modelling process for patient-specific simulations is the creation of the computational mesh based on the segmented geometry. Most known solutions either require a large amount of manual processing or lead to a substantial difference between the segmented object and the actual computational domain. We have developed a chain of algorithms that lead to a closely related implementation of image segmentation with deformable models and 3D mesh generation. The resulting processing chain is very robust and leads both to an accurate geometrical representation of the vascular structure as well as high quality computational meshes. The chain of algorithms has been tested on a wide variety of shapes. A benchmark comparison of our mesh generation application with five other available meshing applications clearly indicates that the new approach outperforms the existing methods in the majority of cases. (orig.)

  13. Sensing surface mechanical deformation using active probes driven by motor proteins

    Science.gov (United States)

    Inoue, Daisuke; Nitta, Takahiro; Kabir, Arif Md. Rashedul; Sada, Kazuki; Gong, Jian Ping; Konagaya, Akihiko; Kakugo, Akira

    2016-01-01

    Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science. PMID:27694937

  14. Structured Mechanical Collage.

    Science.gov (United States)

    Huang, Zhe; Wang, Jiang; Fu, Hongbo; Lau, Rynson W H

    2014-07-01

    We present a method to build 3D structured mechanical collages consisting of numerous elements from the database given artist-designed proxy models. The construction is guided by some graphic design principles, namely unity, variety and contrast. Our results are visually more pleasing than previous works as confirmed by a user study.

  15. Features of structural response of mechanically loaded crystallites to irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Korchuganov, Aleksandr V., E-mail: avkor@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    A molecular dynamics method is employed to investigate the origin and evolution of plastic deformation in elastically deformed iron and vanadium crystallites due to atomic displacement cascades. Elastic stress states of crystallites result from different degrees of specimen deformation. Crystallites are deformed under constant-volume conditions. Atomic displacement cascades with the primary knock-on atom energy up to 50 keV are generated in loaded specimens. It is shown that irradiation may cause not only the Frenkel pair formation but also large-scale structural rearrangements outside the irradiated area, which prove to be similar to rearrangements proceeding by the twinning mechanism in mechanically loaded specimens.

  16. 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

  17. Study of inelastic deformation mechanisms in metal glass volume

    International Nuclear Information System (INIS)

    Bakaj, S.A.; Neklyudov, I.M.; Savchenko, V.I.; Ehkert, Yu.

    2001-01-01

    The results of investigations of the mechanical properties and internal friction of the bulk amorphous alloy Zr 53.5 Ti 5 Cu 17.5 Ni 14.6 Al 10.4 within the temperature range from the room temperature up to glass-transition temperature are reported. The yield stress and transition from homogeneous to inhomogeneous plastic deformation are investigated. The temperature dependence of low-frequency internal friction, Q -1 (T), in the amplitude-independent limit of oscillations is obtained. The temperature range within which the homogeneous plastic deformation is observed under compression stress is determined. The superplasticity of the amorphous alloy is revealed at the temperature which is 100K lower than the glass-transition temperature. The lowest temperature, at which the superplasticity is revealed, turns to be an edge of the temperature range where Q -1 (T) increases fast. The microscopic nature of the observed phenomena are interpreted on the base of the polycluster model of the metallic glasses

  18. 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

  19. Auxetic hexachiral structures with wavy ligaments for large elasto-plastic deformation

    Science.gov (United States)

    Zhu, Yilin; Wang, Zhen-Pei; Hien Poh, Leong

    2018-05-01

    The hexachiral structure is in-plane isotropic in small deformation. When subjected to large elasto-plastic deformation, however, the hexachiral structure tends to lose its auxeticity and/or isotropy—properties which are desirable in many potential applications. The objective of this study is to improve these two mechanical properties, without significantly compromising the effective yield stress, in the regime with significant material and geometrical nonlinearity effects. It is found that the deformation mechanisms underlying the auxeticity and isotropy properties of a hexachiral structure are largely influenced by the extent of rotation of the central ring in a unit cell. To facilitate the development of this deformation mechanism, an improved design with wavy ligaments is proposed. The improved performance of the proposed hexachiral structure is demonstrated. An initial study on possible applications as a protective material is next carried out, where the improved hexachiral design is shown to exhibit higher specific energy absorption capacity compared to the original design, as well as standard honeycomb structures.

  20. Evaluation of soft sediment deformation structures along the Fethiye ...

    Indian Academy of Sciences (India)

    Burdur city is located on lacustrine sedimentary deposits at the northeastern end of the Fethiye–Burdur Fault Zone (FBFZ) in SW Turkey. Fault steps were formed in response to vertical displacement along normal fault zones in these deposits. Soft sediment deformation structures were identified at five sitesin lacustrine ...

  1. Structure, deformation, and failure of flow-oriented semicrystalline polymers

    NARCIS (Netherlands)

    Schrauwen, B.A.G.; Breemen, van L.C.A.; Spoelstra, A.B.; Govaert, L.E.; Peters, G.W.M.; Meijer, H.E.H.

    2004-01-01

    This study deals with the influence of processing induced crystalline orientation on the macroscopic deformation and failure behavior of thin samples of polyethylene and polypropylene. Distribution and structure of flow-induced orientations were characterized by optical microscopy, X-ray diffraction

  2. Creep deformation mechanisms in a γ titanium aluminide

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, Zakaria [Institute of Structural Materials, College of Engineering, Bay Campus, Swansea University, Swansea SA18EN (United Kingdom); Ding, Rengen [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B152TT (United Kingdom); Martin, Nigel; Dixon, Mark [Rolls-Royce plc, P.O. Box 31, Derby DE248BJ (United Kingdom); Bache, Martin [Institute of Structural Materials, College of Engineering, Bay Campus, Swansea University, Swansea SA18EN (United Kingdom)

    2016-09-15

    Titanium aluminides (TiAl) are considered as potential alternatives to replace nickel-based alloys of greater density for selected components within future gas turbine aero-engines. This is attributed to the high specific strength as well as the good oxidation resistance at elevated temperatures. The gamma (γ) titanium aluminide system Ti-45Al-2Mn-2Nb has previously demonstrated promising performance in terms of its physical and mechanical properties. The main aim of the current study, which is a continuation of a previously published paper, aims at evaluating the performance of this titanium aluminide system under high temperature creep conditions. Of particular interest, the paper is strongly demonstrating the precise capability of the Wilshire Equations technique in predicting the long-term creep behaviour of this alloy. Moreover, it presents a physically meaningful understanding of the various creep mechanisms expected under various testing conditions. To achieve this, two creep specimens, tested under distinctly different stress levels at 700 °C have been extensively examined. Detailed microstructural investigations and supporting transmission electron microscopy (TEM) have explored the differences in creep mechanisms active under the two stress regimes, with the deformation mechanisms correlated to Wilshire creep life prediction curves.

  3. Soft-Sediment Deformation Structures Interpreted as Seismites in the Kolankaya Formation, Denizli Basin (SW Turkey)

    Science.gov (United States)

    Topal, Savaş; Özkul, Mehmet

    2014-01-01

    The NW-trending Denizli basin of the SW Turkey is one of the neotectonic grabens in the Aegean extensional province. It is bounded by normal faults on both southern and northern margins. The basin is filled by Neogene and Quaternary terrestrial deposits. Late Miocene- Late Pliocene aged Kolankaya formation crops out along the NW trending Karakova uplift in the Denizli basin. It is a typical fluviolacustrine succession that thickens and coarsens upward, comprising poorly consolidated sand, gravelly sand, siltstone and marl. Various soft-sediment deformation structures occur in the formation, especially in fine- to medium grained sands, silts and marls: load structures, flame structures, clastic dikes (sand and gravely-sand dike), disturbed layers, laminated convolute beds, slumps and synsedimentary faulting. The deformation mechanism and driving force for the soft-sediment deformation are related essentially to gravitational instability, dewatering, liquefaction-liquidization, and brittle deformation. Field data and the wide lateral extent of the structures as well as regional geological data show that most of the deformation is related to seismicity and the structures are interpreted as seismites. The existence of seismites in the Kolankaya Formation is evidence for continuing tectonic activity in the study area during the Neogene and is consistent with the occurrence of the paleoearthquakes of magnitude >5. PMID:25152909

  4. Diffusive, Displacive Deformations and Local Phase Transformation Govern the Mechanics of Layered Crystals: The Case Study of Tobermorite.

    Science.gov (United States)

    Tao, Lei; Shahsavari, Rouzbeh

    2017-07-19

    Understanding the deformation mechanisms underlying the mechanical behavior of materials is the key to fundamental and engineering advances in materials' performance. Herein, we focus on crystalline calcium-silicate-hydrates (C-S-H) as a model system with applications in cementitious materials, bone-tissue engineering, drug delivery and refractory materials, and use molecular dynamics simulation to investigate its loading geometry dependent mechanical properties. By comparing various conventional (e.g. shear, compression and tension) and nano-indentation loading geometries, our findings demonstrate that the former loading leads to size-independent mechanical properties while the latter results in size-dependent mechanical properties at the nanometer scales. We found three key mechanisms govern the deformation and thus mechanics of the layered C-S-H: diffusive-controlled and displacive-controlled deformation mechanisms, and strain gradient with local phase transformations. Together, these elaborately classified mechanisms provide deep fundamental understanding and new insights on the relationship between the macro-scale mechanical properties and underlying molecular deformations, providing new opportunities to control and tune the mechanics of layered crystals and other complex materials such as glassy C-S-H, natural composite structures, and manmade laminated structures.

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

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, Bo

    2014-01-01

    With high-angular resolution three-dimensional X-ray diffraction (3DXRD), quantitative information is gained about dislocation structures in individual grains in the bulk of a macroscopic specimen by acquiring reciprocal space maps. In high-resolution 3D reciprocal space maps of tensile......-deformed copper, individual, almost dislocation-free subgrains are identified from high-intensity peaks and distinguished by their unique combination of orientation and elastic strain; dislocation walls manifest themselves as a smooth cloud of lower intensity. The elastic strain shows only minor variations within...... dynamics is followed in situ during varying loading conditions by reciprocal space mapping: during uninterrupted tensile deformation, formation of subgrains is observed concurrently with broadening of Bragg reflections shortly after the onset of plastic deformation. When the traction is terminated, stress...

  6. Radiative processes as a condensation phenomenon and the physical meaning of deformed canonical structures

    International Nuclear Information System (INIS)

    Gamboa, J.; Mendez, F.; Grigorio, L.S.; Guimaraes, M.S.; Wotzasek, C.

    2008-01-01

    We study the radiative corrections of QED 3 from the dual point of view and show that this process is the exact dual to the Julia-Toulouse mechanism introduced by Quevedo and Trugenberger [F. Quevedo, C.A. Trugenberger, Nucl. Phys. B 501 (1997) 143] some years ago. We discuss the physics behind this mechanism that involves condensation of topological defects. It is shown that the dual Stuckelberg mechanism is responsible for the 'rank-jump' phenomenon that transforms the scalar field (dual to Maxwell in this dimensionality) into the vectorial self-dual field. This phenomenon is studied using the ideas of noncommutative fields theory that examines possible deformations of the canonical structure of some well-known models in (2+1)D. A deformation is constructed linking the massless scalar field theory with the self-dual theory. This is the exact dual of the known deformation connecting the Maxwell theory with the Maxwell-Chern-Simons theory. Duality, radiative corrections, the Julia-Toulouse mechanism and canonical deformations are then used to establish a web of relations between the mentioned theories and to propose a physical picture of the deformation procedure adopted

  7. A simulation model for analysing brain structure deformations

    Energy Technology Data Exchange (ETDEWEB)

    Bona, Sergio Di [Institute for Information Science and Technologies, Italian National Research Council (ISTI-8211-CNR), Via G Moruzzi, 1-56124 Pisa (Italy); Lutzemberger, Ludovico [Department of Neuroscience, Institute of Neurosurgery, University of Pisa, Via Roma, 67-56100 Pisa (Italy); Salvetti, Ovidio [Institute for Information Science and Technologies, Italian National Research Council (ISTI-8211-CNR), Via G Moruzzi, 1-56124 Pisa (Italy)

    2003-12-21

    Recent developments of medical software applications from the simulation to the planning of surgical operations have revealed the need for modelling human tissues and organs, not only from a geometric point of view but also from a physical one, i.e. soft tissues, rigid body, viscoelasticity, etc. This has given rise to the term 'deformable objects', which refers to objects with a morphology, a physical and a mechanical behaviour of their own and that reflects their natural properties. In this paper, we propose a model, based upon physical laws, suitable for the realistic manipulation of geometric reconstructions of volumetric data taken from MR and CT scans. In particular, a physically based model of the brain is presented that is able to simulate the evolution of different nature pathological intra-cranial phenomena such as haemorrhages, neoplasm, haematoma, etc and to describe the consequences that are caused by their volume expansions and the influences they have on the anatomical and neuro-functional structures of the brain.

  8. 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.

  9. Mechanical design and analysis of focal plate for gravity deformation

    Science.gov (United States)

    Wang, Jianping; Chu, Jiaru; Hu, Hongzhuan; Li, Kexuan; Zhou, Zengxiang

    2014-07-01

    The surface accuracy of astronomical telescope focal plate is a key indicator to precision stellar observation. To conduct accurate deformation measurement for focal plate in different status, a 6-DOF hexapod platform was used for attitude adjustment. For the small adjustment range of a classic 6-DOF hexapod platform, an improved structural arrangement method was proposed in the paper to achieve ultimate adjustment of the focal plate in horizontal and vertical direction. To validate the feasibility of this method, an angle change model which used ball hinge was set up for the movement and base plate. Simulation results in MATLAB suggested that the ball hinge angle change of movement and base plate is within the range of the limiting angle in the process of the platform plate adjusting to ultimate attitude. The proposed method has some guiding significance for accurate surface measurement of focal plate.

  10. Effect of large plastic deformation on microstructure and mechanical properties of a TWIP steel

    International Nuclear Information System (INIS)

    Yanushkevich, Z; Belyakov, A; Kaibyshev, R; Molodov, D

    2014-01-01

    The effect of cold rolling on the microstructure evolution and mechanical properties of a cold rolled Fe-0.3C-17Mn-1.5AI TWIP steel was studied. The plate samples were cold rolled with reductions of 20, 40, 60 and 80%. The structural changes were associated with the development of deformation twinning and shear bands. The average spacing between twin boundaries in the transverse section of the rolled plates decreased from ∼190 to 36 nm with an increase in the rolling reduction from 20 to 40%. Upon further rolling to 80% reduction the twin spacing remained at about 30 nm. The cold rolling resulted in significant increase in strength as revealed by tensile tests at an ambient temperature. The offset yield stress approached 1440 MPa, and the ultimate tensile strength increased to 1630 MPa after rolling reduction of 80%. Such significant strengthening was attributed to the development of specific structure consisting of deformation nanotwins with high dislocation density

  11. EARTHQUAKE-INDUCED DEFORMATION STRUCTURES AND RELATED TO EARTHQUAKE MAGNITUDES

    Directory of Open Access Journals (Sweden)

    Savaş TOPAL

    2003-02-01

    Full Text Available Earthquake-induced deformation structures which are called seismites may helpful to clasify the paleoseismic history of a location and to estimate the magnitudes of the potention earthquakes in the future. In this paper, seismites were investigated according to the types formed in deep and shallow lake sediments. Seismites are observed forms of sand dikes, introduced and fractured gravels and pillow structures in shallow lakes and pseudonodules, mushroom-like silts protruding laminites, mixed layers, disturbed varved lamination and loop bedding in deep lake sediments. Earthquake-induced deformation structures, by benefiting from previous studies, were ordered according to their formations and earthquake magnitudes. In this order, the lowest eartquake's record is loop bedding and the highest one is introduced and fractured gravels in lacustrine deposits.

  12. Crustal structure and tectonic deformation of the southern Ecuadorian margin

    Science.gov (United States)

    Calahorrano, Alcinoe; Collot, Jean-Yves; Sage, Françoise; Ranero, César R.

    2010-05-01

    Multichannel seismic lines acquired during the SISTEUR cruise (2000) provide new constraints on the structure and deformation of the subduction zone at the southern Ecuadorian margin, from the deformation front to the continental shelf of the Gulf of Guayaquil. The pre-stack depth migrated images allows to characterise the main structures of the downgoing and overriding plates and to map the margin stratigraphy in order to propose a chronology of the deformation, by means of integrating commercial well data and industry seismic lines located in the gulf area. The 100-km-long seismic lines show the oceanic Nazca plate underthrusting the South American plate, as well as the subduction channel and inter-plate contact from the deformation front to about 90 km landward and ~20 km depth. Based on seismic structure we identify four upper-plate units, consisting of basement and overlaying sedimentary sequences A, B and C. The sedimentary cover varies along the margin, being few hundreds of meters thick in the lower and middle slope, and ~2-3 km thick in the upper slope. Exceptionally, a ~10-km -thick basin, here named Banco Peru basin, is located on the upper slope at the southernmost part of the gulf. This basin seems to be the first evidence of the Gulf of Guayaquil opening resulting from the NE escaping of the North Andean Block. Below the continental shelf, thick sedimentary basins of ~6 to 8 km occupy most of the gulf area. Tectonic deformation across most of the upper-plate is dominated by extensional regime, locally disturbed by diapirism. Compression evidences are restricted to the deformation front and surrounding areas. Well data calibrating the seismic profiles indicate that an important portion of the total thickness of the sedimentary coverage of the overriding plate are Miocene or older. The data indicate the extensional deformation resulting from the NE motion of the North Andean Block and the opening of the Gulf of Guayaquil, evolves progressively in age

  13. Deformation Mechanism on the Northern Margin of the Tibetan Plateau Inferred from Magnetotelluric Data

    Science.gov (United States)

    Zhang, L.; Jin, S.; Wei, W.; Ye, G.; Xie, C.

    2017-12-01

    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 plateau. However, 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. 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. 2D inversions were performed to produce a preferred model of the lithospheric electrical structure. 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. 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 ° 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 extending from the upper crust to upper mantle, implying vertical coherent deformation of the lithosphere. Melt fraction of this conductive region is estimated to be as high as 10%, which might accommodates a major portion of the thrust deformation on

  14. Material heterogeneity in cancellous bone promotes deformation recovery after mechanical failure.

    Science.gov (United States)

    Torres, Ashley M; Matheny, Jonathan B; Keaveny, Tony M; Taylor, David; Rimnac, Clare M; Hernandez, Christopher J

    2016-03-15

    Many natural structures use a foam core and solid outer shell to achieve high strength and stiffness with relatively small amounts of mass. Biological foams, however, must also resist crack growth. The process of crack propagation within the struts of a foam is not well understood and is complicated by the foam microstructure. We demonstrate that in cancellous bone, the foam-like component of whole bones, damage propagation during cyclic loading is dictated not by local tissue stresses but by heterogeneity of material properties associated with increased ductility of strut surfaces. The increase in surface ductility is unexpected because it is the opposite pattern generated by surface treatments to increase fatigue life in man-made materials, which often result in reduced surface ductility. We show that the more ductile surfaces of cancellous bone are a result of reduced accumulation of advanced glycation end products compared with the strut interior. Damage is therefore likely to accumulate in strut centers making cancellous bone more tolerant of stress concentrations at strut surfaces. Hence, the structure is able to recover more deformation after failure and return to a closer approximation of its original shape. Increased recovery of deformation is a passive mechanism seen in biology for setting a broken bone that allows for a better approximation of initial shape during healing processes and is likely the most important mechanical function. Our findings suggest a previously unidentified biomimetic design strategy in which tissue level material heterogeneity in foams can be used to improve deformation recovery after failure.

  15. Two-component feedback loops and deformed mechanics

    International Nuclear Information System (INIS)

    Tourigny, David S.

    2015-01-01

    It is shown that a general two-component feedback loop can be viewed as a deformed Hamiltonian system. Some of the implications of using ideas from theoretical physics to study biological processes are discussed. - Highlights: • Two-component molecular feedback loops are viewed as q-deformed Hamiltonian systems. • Deformations are reversed using Jackson derivatives to take advantage of working in the Hamiltonian limit. • New results are derived for the particular examples considered. • General deformations are suggested to be associated with a broader class of biological processes

  16. Mechanical twinning and texture evolution in severely deformed Ti-6Al-4V at high temperatures

    International Nuclear Information System (INIS)

    Yapici, Guney Guven; Karaman, Ibrahim; Luo Zhiping

    2006-01-01

    We have investigated the deformation behavior and texture evolution of two-phase Ti-6Al-4V subjected to severe plastic deformation using equal channel angular extrusion (ECAE) at a high temperature (∼0.55T m ). Significant deformation twinning activity was observed after one and two ECAE passes in a 90 deg, die at 800 deg. C. Twinning activity at such a high temperature is a first-time observation in this material and is attributed to the high strain and stress levels imposed during ECAE. High stress levels and the stress state can affect the separation of twinning partials considerably. Resolved shear stress magnitudes on twin partials were found to be high during the ECAE process that helps the nucleation of mechanical twinning. The twinning mode was identified as the {101-bar 1} type using electron diffraction patterns which is one of the twinning modes observed in Ti at temperatures above 350 deg. C. Although only one twinning variant was mainly evident after one pass, multiple twin variants of the same mode were observed after the second pass with a significant increase in twin volume fraction. ECAE processing aligned the basal planes of the hexagonal close-packed α phase, initially having a random texture, with the ECAE shear plane. Texture evolution during ECAE was successfully predicted using a viscoplastic self-consistent crystal plasticity framework capturing the effect of the observed twinning mode on texture. Mechanical twins formed during ECAE and grain refinement led to a noteworthy improvement in flow stresses under tension and compression at room temperature. A strong directional anisotropy in yield strengths was also evident which cannot be explained only by crystallographic texture. It was speculated that the asymmetry of critical resolved shear stresses of deformation modes and the processing-induced deformation structure should play a role. With the supporting evidence from our previous works on the severe plastic deformation of other

  17. Remote sensing image stitch using modified structure deformation

    Science.gov (United States)

    Pan, Ke-cheng; Chen, Jin-wei; Chen, Yueting; Feng, Huajun

    2012-10-01

    To stitch remote sensing images seamlessly without producing visual artifact which is caused by severe intensity discrepancy and structure misalignment, we modify the original structure deformation based stitching algorithm which have two main problems: Firstly, using Poisson equation to propagate deformation vectors leads to the change of the topological relationship between the key points and their surrounding pixels, which may bring in wrong image characteristics. Secondly, the diffusion area of the sparse matrix is too limited to rectify the global intensity discrepancy. To solve the first problem, we adopt Spring-Mass model and bring in external force to keep the topological relationship between key points and their surrounding pixels. We also apply tensor voting algorithm to achieve the global intensity corresponding curve of the two images to solve the second problem. Both simulated and experimental results show that our algorithm is faster and can reach better result than the original algorithm.

  18. Intermediate size inducer pump - structural analysis and transient deformation studies

    International Nuclear Information System (INIS)

    Cheng, T.K.; Nishizaka, J.N.

    1979-05-01

    This report summarizes the structural and thermal transient deformation analysis of the Intermediate Size Inducer Pump. The analyses were performed in accordance to the requirements of N266ST310001, the specification for the ISIP. Results of stress analysis indicate that the thermal transient stress and strain are within the stress strain limits of RDT standard F9-4 which was used as a guide

  19. 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,

  20. Deformation mechanisms and irradiation effects in zirconium alloys. A multi-scale study

    International Nuclear Information System (INIS)

    Onimus, Fabien

    2015-01-01

    Zirconium alloys have been used for more than 30 years in the nuclear industry as structural materials for the fuel assemblies of pressurized water reactors. In particular, the cladding tube, made of zirconium alloys, constitutes the first barrier against the dissemination of radioactive elements. It is therefore essential to have a good understanding and prediction of the mechanical behavior of these materials in various conditions. The work presented in this dissertation deals with an experimental study and numerical simulations, at several length scales, of the deformation mechanisms and the mechanical behavior of zirconium alloys before irradiation, but also after irradiation and under irradiation. The mechanical behavior of zirconium single crystal has been determined, during an original study, using tensile test specimens containing large grains. Based on this study, crystal plasticity constitutive laws have been proposed. A polycrystalline model has also been developed to simulate the behavior of unirradiated zirconium alloys. A thorough Transmission Electron Microscopy (TEM) study has been able to clarify the deformation mechanisms of zirconium alloys occurring after irradiation. The clearing of loops by gliding dislocations leading to the dislocation channeling mechanism has been studied in details. This phenomenon has also been simulated using a dislocation dynamics code. The macroscopic consequences of this process have also been analyzed. A polycrystalline model taking into account the specificity of this mechanism has eventually been proposed. This approach has then been extended to the post-irradiation creep behavior. The recovery of radiation defects during creep tests has been characterized by TEM and modeled using cluster dynamics method. Deformation modes during creep have also been studied and a simple model for the creep behavior has eventually been proposed. Finally, the mechanism responsible for the acceleration of irradiation growth that

  1. 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

    2013-01-01

    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

  2. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    dislocation segments lie in their slip or climb planes. On the basis of this structure, a model is proposed in which glide is the principal cause of deformation but the rate-limiting process, i.e. annealing of the network, is diffusion-controlled. Theoretical estimates and experimental results agree within 1...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...

  3. An experimental study of deformation mechanism and microstructure evolution during hot deformation of Ti–6Al–2Zr–1Mo–1V alloy

    International Nuclear Information System (INIS)

    He, D.; Zhu, J.C.; Lai, Z.H.; Liu, Y.; Yang, X.W.

    2013-01-01

    Highlights: ► Isothermal tensile deformations were carried on Ti–6Al–2Zr–1Mo–1V titanium alloy. ► Deformation activations were calculated based on kinetics rate equations. ► Deformation mechanisms are dislocation creep and self-diffusion at 800 and 850 °C. ► Microstructure globularization mechanisms varied with deformation temperature. ► Recrystallization mechanism changed from CDRX to DDRX as temperature increasing. - Abstract: Isothermal tensile tests have been performed to study the deformation mechanisms and microstructure evolution of Ti–6Al–2Zr–1Mo–1V titanium alloy in the temperature range 750–850 °C and strain rate range 0.001–0.1 s −1 . The deformation activations have been calculated based on kinetics rate equation to investigate the hot deformation mechanism. Microstructures of deformed samples have been analyzed by electron backscatter diffraction (EBSD) to evaluate the influences of hot deformation parameters on the microstructure evolution and recrystallization mechanism. The results indicate that deformation mechanisms vary with deformation conditions: at medium (800 °C) and high (850 °C) temperature, the deformation is mainly controlled by the mechanisms of dislocation creep and self-diffusion, respectively. The microstructure globularization mechanisms also depend on deformation temperature: in the temperature range from 750 to 800 °C, the high angle grain boundaries are mainly formed via dislocation accumulation or subgrain boundaries sliding and subgrains rotation; while at high temperature of 850 °C, recrystallization is the dominant mechanism. Especially, the evolution of the recrystallization mechanism with the deformation temperature is first observed and investigated in TA15 titanium alloy

  4. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Modelling and Simulation of Structural Deformation of Isothermal Subsurface Flow and Carbon Dioxide Injection

    KAUST Repository

    El-Amin, Mohamed

    2011-05-15

    Injection of CO2 in hydrocarbon reservoir has double benefit. On the one hand, it is a profitable method due to issues related to global warming, and on the other hand it is an effective mechanism to enhance hydrocarbon recovery. Such injection associates complex processes involving, e.g., solute transport of dissolved materials, in addition to local changes in density of the phases. Also, increasing carbon dioxide injection may cause a structural deformation of the medium, so it is important to include such effect into the model. The structural deformation modelling in carbon sequestration is important to evaluate the medium stability to avoid CO2 leakage to the atmosphere. On the other hand, geologic formation of the medium is usually heterogeneous and consists of several layers of different permeability. In this work we conduct numerical simulation of two-phase flow in a heterogeneous porous medium domain with dissolved solute transport as well as structural deformation effects. The solute transport of the dissolved component is described by concentration equation. The structural deformation for geomechanics is derived from a general local differential balance equation with neglecting the local mass balance of solid phase and the inertial force term. The flux continuity condition is used at interfaces between different permeability layers of the heterogeneous medium. We analyze the vertical migration of a CO2 plume injected into a 2D layered reservoir. Analysis of distribution of flow field components such as saturation, pressures, velocities, and CO2 concentration are presented.

  6. 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.

  7. Deformation mechanisms in Ti/TiN multilayer under compressive loading

    International Nuclear Information System (INIS)

    Yang, Wei; Ayoub, Georges; Salehinia, Iman; Mansoor, Bilal; Zbib, Hussein

    2017-01-01

    The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit dislocations or dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the dislocation dissociation of perfect dislocation into pairs of partials dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when dislocation nucleated/transmitted in/into the TiN layer.

  8. Characteristic structures and properties of nanostructured metals prepared by plastic deformation

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2011-01-01

    This chapter focuses on describing the characteristic microstructures of nanostructured metals produced by plastic deformation to ultrahigh strains and their correlation with hardening by annealing and softening by deformation. The results suggest that optimising microstructure and the mechanical...

  9. Fast Detection of Material Deformation through Structural Dissimilarity

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Perciano, Talita; Parkinson, Dilworth

    2015-10-29

    Designing materials that are resistant to extreme temperatures and brittleness relies on assessing structural dynamics of samples. Algorithms are critically important to characterize material deformation under stress conditions. Here, we report on our design of coarse-grain parallel algorithms for image quality assessment based on structural information and on crack detection of gigabyte-scale experimental datasets. We show how key steps can be decomposed into distinct processing flows, one based on structural similarity (SSIM) quality measure, and another on spectral content. These algorithms act upon image blocks that fit into memory, and can execute independently. We discuss the scientific relevance of the problem, key developments, and decomposition of complementary tasks into separate executions. We show how to apply SSIM to detect material degradation, and illustrate how this metric can be allied to spectral analysis for structure probing, while using tiled multi-resolution pyramids stored in HDF5 chunked multi-dimensional arrays. Results show that the proposed experimental data representation supports an average compression rate of 10X, and data compression scales linearly with the data size. We also illustrate how to correlate SSIM to crack formation, and how to use our numerical schemes to enable fast detection of deformation from 3D datasets evolving in time.

  10. Microstructure and mechanical properties of precipitation hardened aluminum under high rate deformation

    International Nuclear Information System (INIS)

    Grady, D.E.; Asav, J.R.; Rohde, R.W.; Wise, J.L.

    1983-01-01

    This chapter attempts to correlate the shock compression and quasistatic deformation of 6061-T6 aluminium. Examines recovered specimens which have been shock loaded, and compares results with both static and dynamic mechanical property measurements. Discusses experimental procedures (reshock and unloading experiments, shock recovery techniques, metallographic techniques and coldwork experiments); dynamic strength and wave-profile properties (strength and shear-stress states on the Hugoniot, steady-wave risetime and viscosity); quasistatic and shock metallography studies (metallography of quasistatically deformed material; metallography of shock deformed specimens; comparison of static and shock deformation; correlation of hardness and dynamic strength measurements); and thermal trapping calculations in shocked aluminium (heterogeneous deformation and adiabatic heating in shock-wave loading; energy and risetime relations under steadywave shock compression; heterogeneous temperature calculations in aluminium). Concludes that heterogeneous shear deformation appears to play a role in the dynamic deformation process

  11. Characterization of cyclic deformation behaviour by mechanical, thermometrical and electrical methods; Bewertung zyklischer Verformungsvorgaenge metallischer Werkstoffe mit Hilfe mechanischer, thermometrischer und elektrischer Messverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Pietrowski, A. [Essen Univ. (Gesamthochschule) (Germany). Lehrstuhl fuer Werkstoffkunde; Eifler, D. [Kaiserslautern Univ. (Germany). Lehrstuhl fuer Werkstoffkunde

    1995-03-01

    Cyclic deformation causes changes in the microstructure and subsequently failure of structural parts. Mechanical, thermometrical and electrical methods can be used to characterize the deformation behaviour of metals as can be shown for normalized or heat treated steels as well as for sintered steels. (orig.)

  12. Formation of Quenching Structures in the Steel 35 by Deform Cutting

    Directory of Open Access Journals (Sweden)

    A. G. Degtyareva

    2014-01-01

    Full Text Available In industry different methods of surface hardening are widely used to increase reliability and durability of friction unit parts. Among these methods are areas of focus based on deformcutting technology (DC i.e. method of chip-free mechanical treatment.It is shown that DC method allows us to produce through- or partial-hardening surface layers of a large thickness (0,4…1.5mm on steel with no additional heat sources. The standard metal-cutting equipment and common tools are used for deform-cutting process.The significant heat generation in the deform-cutting zone and mechanical effect from the tool allow us to heat undercut layers to the phase transformation point to have the hardening structure as a result of heat removal to the cold balk. The hardening structure formation occurs at significant heating and cooling rate (106C/c with large degrees and rates of strain.The deform-cutting modes and working face tool grinding determine the type and properties of the hardening structure. To produce the hardening structure would require the heat transfer and force action augmentation while treatment.These researches deal with through- and partial surface hardening samples produced by turning steel 35 shafts. While through hardening the phase transformation carry among the whole thickness of the undercut layer; while partial hardening the hardening interlayer formed on the side of the cutting tool contact.The depth of hardening zone of samples with through hardening layers is 0,5 mm; the depth of hardening zone of partial hardening samples is 0,8 mm. Micro-hardness of the through hardening layers is 653 HV0,1 and 485 HV0,1 for the partial hardening layers. The metallographic analysis shows that the hardening zone formed while deform cutting has disperse structure; there are ferrite ghosts in it.The tempering at temperatures of 200 – 700C showed that the micro-hardness of the hardening structures formed while deform cutting is larger than the micro

  13. Mechanisms of Plastic Deformation in Collagen Networks Induced by Cellular Forces.

    Science.gov (United States)

    Ban, Ehsan; Franklin, J Matthew; Nam, Sungmin; Smith, Lucas R; Wang, Hailong; Wells, Rebecca G; Chaudhuri, Ovijit; Liphardt, Jan T; Shenoy, Vivek B

    2018-01-23

    Contractile cells can reorganize fibrous extracellular matrices and form dense tracts of fibers between neighboring cells. These tracts guide the development of tubular tissue structures and provide paths for the invasion of cancer cells. Here, we studied the mechanisms of the mechanical plasticity of collagen tracts formed by contractile premalignant acinar cells and fibroblasts. Using fluorescence microscopy and second harmonic generation, we quantified the collagen densification, fiber alignment, and strains that remain within the tracts after cellular forces are abolished. We explained these observations using a theoretical fiber network model that accounts for the stretch-dependent formation of weak cross-links between nearby fibers. We tested the predictions of our model using shear rheology experiments. Both our model and rheological experiments demonstrated that increasing collagen concentration leads to substantial increases in plasticity. We also considered the effect of permanent elongation of fibers on network plasticity and derived a phase diagram that classifies the dominant mechanisms of plasticity based on the rate and magnitude of deformation and the mechanical properties of individual fibers. Plasticity is caused by the formation of new cross-links if moderate strains are applied at small rates or due to permanent fiber elongation if large strains are applied over short periods. Finally, we developed a coarse-grained model for plastic deformation of collagen networks that can be employed to simulate multicellular interactions in processes such as morphogenesis, cancer invasion, and fibrosis. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. The mechanical deformation of superconducting BiSrCaCuO/Ag composites

    International Nuclear Information System (INIS)

    Han, Z.; Skov-Hansen, P.; Freltoft, T.

    1997-01-01

    The mechanical deformation of BiSrCaCuO/Ag composites made by the powder-in-tube method is a multi-step process. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. A key parameter is the core density, which changes during mechanical deformation. In this review, basic concepts of the classical mechanical deformation theory are briefly discussed. Simple descriptions of deformation processes like pressing, rolling, drawing and extrusion are also presented. The term 'freedom parameter', Δ f , is introduced to illustrate the influence of various constraint factors on the mass-flow behaviour. Simple pictures including mass redistribution and the powder-flow model are presented for interpreting the plastic deformation process of the composites. Experimental results are reviewed and our proposed pictures and models are applied for discussion. (author)

  15. Large Deformation of an Elastic Rod with Structural Anisotropy Subjected to Fluid Flow

    Science.gov (United States)

    Hassani, Masoud; Mureithi, Njuki; Gosselin, Frederick

    2015-11-01

    In the present work, we seek to understand the fundamental mechanisms of three-dimensional reconfiguration of plants by studying the large deformation of a flexible rod in fluid flow. Flexible rods made of Polyurethane foam and reinforced with Nylon fibers are tested in a wind tunnel. The rods have bending-torsion coupling which induces a torsional deformation during asymmetric bending. A mathematical model is also developed by coupling the Kirchhoff rod theory with a semi-empirical drag formulation. Different alignments of the material frame with respect to the flow direction and a range of structural properties are considered to study their effect on the deformation of the flexible rod and its drag scaling. Results show that twisting causes the flexible rods to reorient and bend with the minimum bending rigidity. It is also found that the drag scaling of the rod in the large deformation regime is not affected by torsion. Finally, using a proper set of dimensionless numbers, the state of a bending and twisting rod is characterized as a beam undergoing a pure bending deformation.

  16. Deformation mechanism of the Cryostat in the CADS Injector II

    Science.gov (United States)

    Yuan, Jiandong; Zhang, Bin; Wan, Yuqin; Sun, Guozhen; Bai, Feng; Zhang, Juihui; He, Yuan

    2018-01-01

    Thermal contraction and expansion of the Cryostat will affect its reliability and stability. To optimize and upgrade the Cryostat, we analyzed the heat transfer in a cryo-vacuum environment from the theoretical point first. The simulation of cryo-vacuum deformation based on a finite element method was implemented respectively. The completed measurement based on a Laser Tracker and a Micro Alignment Telescope was conducted to verify its correctness. The monitored deformations were consistent with the simulated ones. After the predictable deformations in vertical direction have been compensated, the superconducting solenoids and Half Wave Resonator cavities approached the ideal "zero" position under liquid helium conditions. These guaranteed the success of 25 MeV@170 uA continuous wave protons of Chinese accelerator driven subcritical system Injector II. By correlating the vacuum and cryo-deformation, we have demonstrated that the complete deformation was the superposition effect of the atmospheric pressure, gravity and thermal stress during both the process of cooling down and warming up. The results will benefit to an optimization for future Cryostat's design.

  17. Ocean acidification causes structural deformities in juvenile coral skeletons.

    Science.gov (United States)

    Foster, Taryn; Falter, James L; McCulloch, Malcolm T; Clode, Peta L

    2016-02-01

    Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a "business-as-usual" emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100.

  18. Fine grained 304 ASS processed by a severe plastic deformation and subsequent annealing; microstructure and mechanical properties evaluation

    Science.gov (United States)

    Salout, Shima Ahmadzadeh; Shirazi, Hasan; Nili-Ahmadabadi, Mahmoud

    2018-01-01

    The current research is an attempt to study the effect of a novel severe plastic deformation technique so called "repetitive corrugation and straightening by rolling" (RCSR) and subsequent annealing on the microstructure and mechanical properties of AISI type 304 austenitic stainless steel. In this study, RCSR process was carried out at 200 °C on the 304 austenitic stainless steel (above Md30 temperature that is about 50 °C for this stainless steel) in order to avoid the formation of martensite phase when a high density of dislocations was introduced into the austenite phase and also high density of mechanical twins was induced in the deformed 304 austenitic stainless steel. Because of relationship between deformation temperature, stacking fault energy (SFE) and mechanisms of deformation. Thereafter subsequently, annealing treatment was applied into deformed structure in order to refine the microstructure of 304 stainless s teel. The specimens were examined by means of optical microscopy (OM), scanning electron microscopy (SEM), tensile and micro-hardness tests. The results indicate that by increasing the cycles of RCSR process (increasing applied strain), further mechanical twins are induced, the hardness and in particular, the yield stress of specimens have been increased.

  19. Computational structural mechanics for engine structures

    Science.gov (United States)

    Chamis, C. C.

    1989-01-01

    The computational structural mechanics (CSM) program at Lewis encompasses: (1) fundamental aspects for formulating and solving structural mechanics problems, and (2) development of integrated software systems to computationally simulate the performance/durability/life of engine structures. It is structured to mainly supplement, complement, and whenever possible replace, costly experimental efforts which are unavoidable during engineering research and development programs. Specific objectives include: investigate unique advantages of parallel and multiprocesses for: reformulating/solving structural mechanics and formulating/solving multidisciplinary mechanics and develop integrated structural system computational simulators for: predicting structural performances, evaluating newly developed methods, and for identifying and prioritizing improved/missing methods needed. Herein the CSM program is summarized with emphasis on the Engine Structures Computational Simulator (ESCS). Typical results obtained using ESCS are described to illustrate its versatility.

  20. Quantum Mechanics on the h-deformed Quantum Plane

    OpenAIRE

    Cho, Sunggoo

    1998-01-01

    We find the covariant deformed Heisenberg algebra and the Laplace-Beltrami operator on the extended $h$-deformed quantum plane and solve the Schr\\"odinger equations explicitly for some physical systems on the quantum plane. In the commutative limit the behaviour of a quantum particle on the quantum plane becomes that of the quantum particle on the Poincar\\'e half-plane, a surface of constant negative Gaussian curvature. We show the bound state energy spectra for particles under specific poten...

  1. Strengthening mechanisms in nanostructured high-purity aluminium deformed to high strain and annealed

    DEFF Research Database (Denmark)

    Kamikawa, Naoya; Huang, Xiaoxu; Tsuji, Nobuhiro

    2009-01-01

    Samples of pure aluminium (99.99%) have been produced by accumulative roll-bonding to a large strain followed by a heat treatment, where a two-step annealing process has been used to produce samples with large variations in structural parameters such as boundary spacing, misorientation angle...... and dislocation density. These parameters have been quantified by a structural analysis applying transmission electron microscopy and electron backscatter diffraction, and the mechanical properties have been determined by tensile testing at room temperature. Strength–structure relationships have been analysed...... based on the operation of two strengthening mechanisms—grain boundary and dislocation strengthening—and good agreement with experiments has been found for the deformed sample. However, for samples where the density of dislocation sources has been reduced significantly by annealing, an additional...

  2. The effect of dispersoids on the grain refinement mechanisms during deformation of aluminium alloys to ultra-high strains

    International Nuclear Information System (INIS)

    Apps, P.J.; Berta, M.; Prangnell, P.B.

    2005-01-01

    The effect of fine dispersoids on the mechanisms and rate of grain refinement has been investigated during the severe deformation of a model aluminium alloy. A binary Al-0.2Sc alloy, containing coherent Al 3 Sc dispersoids, of ∼20 nm in diameter and ∼100 nm spacing, has been deformed by equal channel angular extrusion to an effective strain of ten. The resulting deformation structures were quantitatively analysed using high-resolution electron backscattered diffraction orientation mapping, and the results have been compared to those obtained from a single-phase Al-0.13Mg alloy, deformed under identical conditions. The presence of fine, non-shearable, dispersoids has been found to homogenise slip, retard the formation of a cellular substructure and inhibit the formation of microshear bands during deformation. These factors combine to reduce the rate of high-angle grain boundary generation at low to medium strains and, hence, retard the formation of a submicron grain structure to higher strains during severe deformation

  3. Plate boundary deformation of the Pacific plate. Two case studies. (1) Crustal structure of the northwestern Vizcaino block and Gorda escarpment, offshore northern California, and implications for postsubduction deformation of a paleoaccretionary margin. (2) A focused look at the Alpine fault, New Zealand: Seismicity, focal mechanisms and stress observations

    Science.gov (United States)

    Leitner, Beate

    Two examples of Pacific rim plate boundary deformation are presented. In the first part of the thesis crustal models are derived for the northwestern part of the Vizcaino block in California using marine seismic and gravity data collected by the Mendocino Triple Junction Seismic Experiment. A northwest-southeast trending kink in the Moho is imaged and interpreted to have formed under compression by reactivation of preexisting thrust faults in the paleoaccretionary prism at the seaward margin of the Vizcaino block. The study suggests that the deformation resulted from mainly north-south compression between the Pacific-Juan de Fuca plates across the Mendocino transform fault and predates late Pliocene Pacific-North America plate convergence. In the second part, 195 earthquakes recorded during the duration of the Southern Alps Passive Seismic Experiment (SAPSE) are analysed. Precise earthquake locations and focal mechanisms provide unprecedented detail of the seismotectonics in the central South Island. The short term (6 month) SAPSE seismicity is compared with long term (8 years) seismicity recorded by the New Zealand National Seismic network and the Lake Pukaki network. The seismicity rate of the Alpine fault is low, but comparable to locked sections of the San Andreas fault, with large earthquakes expected. Changes of the depth of the seismogenic zone, generally uniform at about 10--12 km, occur only localised over distances smaller than 30 km, suggesting that thermal perturbations must be of similar scale. This implies that the thermal effects of the uplift of the Southern Alps do not change the seismogenic depth significantly and are not in accordance with most of the present thermal models. Both the Hope and Porters Pass fault zones are seismically active and deformation is accommodated near the fault zones and in the adjacent crust. North of Mt Cook, a triangular shaped region along the Alpine fault is characterised by absence of earthquakes. We interpret this

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

    Energy Technology Data Exchange (ETDEWEB)

    Kilymis, D. A.; Delaye, J.-M., E-mail: jean-marc.delaye@cea.fr [CEA Marcoule, DEN/DTCD, Service d’Etude et Comportement des Matériaux de Conditionnement, BP17171 30207 Bagnols-sur-Cèze Cedex (France)

    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 SiO{sub 2} content of the glass, which promotes densification due to the open structure of SiO{sub 4} 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.

  5. 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.

  6. Characterization of mechanical properties of pericardium tissue using planar biaxial tension and flexural deformation.

    Science.gov (United States)

    Murdock, Kyle; Martin, Caitlin; Sun, Wei

    2018-01-01

    Flexure is an important mode of deformation for native and bioprosthetic heart valves. However, mechanical characterization of bioprosthetic leaflet materials has been done primarily through planar tensile testing. In this study, an integrated experimental and computational cantilever beam bending test was performed to characterize the flexural properties of glutaraldehyde-treated bovine and porcine pericardium of different thicknesses. A strain-invariant based structural constitutive model was used to model the pericardial mechanical behavior quantified through the bending tests of this study and the planar biaxial tests previously performed. The model parameters were optimized through an inverse finite element (FE) procedure in order to describe both sets of experimental data. The optimized material properties were implemented in FE simulations of transcatheter aortic valve (TAV) deformation. It was observed that porcine pericardium TAV leaflets experienced significantly more flexure than bovine when subjected to opening pressurization, and that the flexure may be overestimated using a constitutive model derived from purely planar tensile experimental data. Thus, modeling of a combination of flexural and biaxial tensile testing data may be necessary to more accurately describe the mechanical properties of pericardium, and to computationally investigate bioprosthetic leaflet function and design. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Radiographic Predictors for Mechanical Failure After Adult Spinal Deformity Surgery

    DEFF Research Database (Denmark)

    Hallager, Dennis W; Karstensen, Sven; Bukhari, Naeem

    2017-01-01

    spinal deformity surgery range 12% to 37% in literature. Although the importance of spinal and spino-pelvic alignment is well documented for surgical outcome and ideal alignment has been proposed as sagittal vertical axis (SVA) lordosis (LL) = pelvic incidence ± 9...

  8. 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...

  9. Evolution of the structure and the phase composition of a bainitic structural steel during plastic deformation

    Science.gov (United States)

    Nikitina, E. N.; Glezer, A. M.; Ivanov, Yu. F.; Aksenova, K. V.; Gromov, V. E.; Kazimirov, S. A.

    2017-10-01

    The evolution of the phase composition and the imperfect substructure of the 30Kh2N2MFA bainitic structural steel subjected to compressive deformation by 36% is quantitatively analyzed. It is shown that deformation is accompanied by an increase in the scalar dislocation density, a decrease in the longitudinal fragment sizes, an increase in the number of stress concentrators, the dissolution of cementite particles, and the transformation of retained austenite.

  10. Structural deformation and intertube conductance of crossed carbon nanotube

    International Nuclear Information System (INIS)

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Choi, Hyoung J.; Ihm, Jisoon; Louie, Steven G.

    2000-01-01

    We present a first-principles study of the structure and quantum electronic conductance of junctions consisting of two crossed (5,5) single-walled carbon nanotubes. The structures are determined by constrained minimization of total energy at a given force between the two tubes, simulating the effects of substrate-tube attraction or an applied force. We find that the intertube contact distance is very sensitive to the applied force in the range of 0-10 nN. The intertube conductance is sizable for realistic deformation expected from substrate interaction. The results explain the recent transport data on crossed nanotubes and show that these systems may be potentially useful as electromechanical devices

  11. Structural Deformation and Intertube Conductance of Crossed Carbon Nanotube Junctions

    International Nuclear Information System (INIS)

    Yoon, Young-Gui; Mazzoni, Mario S. C.; Choi, Hyoung Joon; Ihm, Jisoon; Louie, Steven G.

    2001-01-01

    We present a first-principles study of the structure and quantum electronic conductance of junctions consisting of two crossed (5,5) single-walled carbon nanotubes. The structures are determined by constrained minimization of total energy at a given force between the two tubes, simulating the effects of substrate-tube attraction or an applied force. We find that the intertube contact distance is very sensitive to the applied force in the range of 0--10nN. The intertube conductance is sizable for realistic deformation expected from substrate interaction. The results explain the recent transport data on crossed nanotubes and show that these systems may be potentially useful as electromechanical devices

  12. 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.

  13. The deformation twin in lamellar Ti 3Al/TiAl structure

    Science.gov (United States)

    Zhang, J. X.; Ye, H. Q.

    2003-04-01

    A Ti-48Al-2Cr (at.%) alloy consisting of γ+α 2 lamellar structure was deformed in compression at room temperature. Study by high resolution electron microscopy was carried out on the characteristic of induced γ T/α 2 interface. During deformation the γ T/α 2 interface presents a stepped structure and the γ/α 2 interface remains straight. The formation mechanism of γ T associated with misfit dislocations is proposed. 1/2[01 1¯] γ interfacial dislocation in the γ/α 2 interface can dissociate into a 1/6[ 1¯1 2¯] γ partial dislocation which glides on the ( 1¯11) γ plane and causes γ T to form.

  14. Soft tissue deformation modelling through neural dynamics-based reaction-diffusion mechanics.

    Science.gov (United States)

    Zhang, Jinao; Zhong, Yongmin; Gu, Chengfan

    2018-05-30

    Soft tissue deformation modelling forms the basis of development of surgical simulation, surgical planning and robotic-assisted minimally invasive surgery. This paper presents a new methodology for modelling of soft tissue deformation based on reaction-diffusion mechanics via neural dynamics. The potential energy stored in soft tissues due to a mechanical load to deform tissues away from their rest state is treated as the equivalent transmembrane potential energy, and it is distributed in the tissue masses in the manner of reaction-diffusion propagation of nonlinear electrical waves. The reaction-diffusion propagation of mechanical potential energy and nonrigid mechanics of motion are combined to model soft tissue deformation and its dynamics, both of which are further formulated as the dynamics of cellular neural networks to achieve real-time computational performance. The proposed methodology is implemented with a haptic device for interactive soft tissue deformation with force feedback. Experimental results demonstrate that the proposed methodology exhibits nonlinear force-displacement relationship for nonlinear soft tissue deformation. Homogeneous, anisotropic and heterogeneous soft tissue material properties can be modelled through the inherent physical properties of mass points. Graphical abstract Soft tissue deformation modelling with haptic feedback via neural dynamics-based reaction-diffusion mechanics.

  15. Concerning the problem of the plastic deformation mechanism changeover in neutron-irradiated metals and alloys

    International Nuclear Information System (INIS)

    Kolesnikov, A.N.; Krasnoselov, V.A.; Prokhorov, V.I.

    1982-01-01

    With a phenomenological model of plastic deformation instability as a basis, an analysis was made of the neutron irradition effects on the characteristics of strength and plasticity vs. structural parameters and radiation damage morphology. It was demonstrated that the enchanced plasticity in the initial stage of neutron irradiation has to do with the solid solution disintegration. Introduction of indestructible strengthening barriers enhances the stress-resistance of the neck-formation by 1.22 times. The ''big grain'' effect is observable during the deformation channel production only. Both the deformation twinning and deformation-induced martensite transformation raise the plastic flow stability

  16. Room temperature deformation mechanisms in ultrafine-grained materials processed by hot isostatic pressing

    International Nuclear Information System (INIS)

    Cao, W.Q.; Dirras, G.F.; Benyoucef, M.; Bacroix, B.

    2007-01-01

    Ultrafine-grained (uf-g) and microcrystalline-grained (mc-g) irons have been fabricated by hot isostatic pressing of nanopowders. The mechanical properties have been characterized by compressive tests at room temperature and the resulting microstructures and textures have been determined by combining electron back scatter diffraction and transmission electron microscopy. A transition of the deformation mode, from work hardening to work softening occurs for grain sizes below ∼1 μm, reflecting a transition of the deformation mode from homogeneous to localized deformation into shear bands (SBs). The homogeneous deformation is found to be lattice dislocation-based while the deformation within SBs involves lattice dislocations as well as boundary-related mechanisms, possibly grain boundary sliding accommodated by boundary opening

  17. 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

    data, and no subgrain boundaries. Secondly, garnet lattice rotation of up to 10° around rational garnet 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 <100nm inclusions are observed, whereas these are more abundant in unstrained garnet domains despite the foil being located entirely within the optically visible bleaching zone. Chlorite inclusions and formation of etch pits at dislocations at the garnet-chlorite interface demonstrate the presence of fluid along subgrain boundaries during this second bleaching process. In summary, brittle deformation in these garnets led to enhanced transport and inclusion re-equilibration by coarsening, forming inclusion trails. The precise mechanism allowing enhanced transport is still to be determined and may have involved fluid supply with or without pipe diffusion along introduced dislocations. Later ductile deformation via dislocations, concentrated at already coarsened inclusions and enhanced by fluid availability, further affected the nanoinclusion population. The inclusion trail microstructure records complex small-scale interaction between deformation and reaction, shedding light on the mechanisms by which re-equilibration and strain localisation can influence each other in deforming host-inclusion systems. Bestmann et al. (2008) Journal of Structural Geology 30: 777-790

  18. Investigation of mechanical properties and operative deformation mechanism in nano-crystalline Ni–Co/SiC electrodeposits

    International Nuclear Information System (INIS)

    Lari Baghal, S.M.; Amadeh, A.; Heydarzadeh Sohi, M.

    2012-01-01

    Highlights: ► The tensile properties of Ni–Co and Ni–Co/SiC deposits were investigated. ► The SiC particles enhanced tensile strength and ductility of nano-structured composites. ► The deformation mechanism at low and high strain rates were studied. - Abstract: Ni–Co/SiC nano-composites were prepared via electrodeposition from a modified Watts bath containing SiC particles with average particle size of 50 nm, SDS as surfactant and saccharin as grain refiner in appropriate amounts. The effect of nano-particle incorporation on microstructure, mechanical properties and deformation mechanism of electrodeposits were investigated. The mechanical properties of electrodeposits were investigated by Vickers microhardness and tensile tests. The results indicated that incorporation of SiC particles into a 15 nm Ni–Co matrix had no considerable effect on its microhardness and yield strength, that is, dispersion hardening did not operate in this range of grain size. However it was observed that co-deposition of uniform distributed SiC particles can significantly improve the ultimate tensile strength and elongation to failure of the deposits. Calculation of apparent activation volume from tensile test results at different strain rates proved that incorporation of SiC nano-particles are responsible for stress-assisted activation of GB atoms mechanism that can significantly increase the plasticity. Nano-crystalline Ni–Co matrix showed a mixed mod behavior of ductile and brittle fracture whereas incorporation of SiC particles and increasing the strain rate promoted ductile fracture mode.

  19. Correlation between locally deformed structure and oxide film properties in austenitic stainless steel irradiated with neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Chimi, Yasuhiro, E-mail: chimi.yasuhiro@jaea.go.jp [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kitsunai, Yuji [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Kasahara, Shigeki [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Chatani, Kazuhiro; Koshiishi, Masato [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Nishiyama, Yutaka [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2016-07-15

    To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%–2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps. - Highlights: • Visible step structures depend on the neutron dose and the applied strain. • Local strain at grain boundaries was accumulated with the neutron dose. • Oxide thickness increases with neutron dose and local strain at grain boundaries. • No penetrative oxidation was observed along grain boundaries or surface steps.

  20. Mechanical properties and deformation mechanism of Mg-Al-Zn alloy with gradient microstructure in grain size and orientation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Liu; Yuan, Fuping; Jiang, Ping; Xie, Jijia; Wu, Xiaolei, E-mail: xlwu@imech.ac.cn

    2017-05-10

    The surface mechanical attrition treatment was taken to fabricate the gradient structure in AZ31 magnesium alloy sheet. Microstructural investigations demonstrate the formation of dual gradients with respect to grain size and orientation, where the microstructural sizes decreased from several microns to about 200 nm from center area to treated surface, while the c-axis gradually inclined from being vertical to treated plane towards parallel with it. According to tensile results, the gradient structured sample has yield strength of 305 MPa in average, which is increased by about 4 times when compared with its coarse-grained counterpart. Meanwhile, contrary to quickly failure after necking in most traditional magnesium alloys, the failure process of gradient structure appears more gently, which makes it has 6.5% uniform elongation but 11.5% total elongation. The further comparative tensile tests for separated gradient layers and corresponding cores demonstrate that the gradient structured sample has higher elongation either in uniform or in post-uniform stages. In order to elucidate the relationship between mechanical properties and deformation mechanisms for this dual gradient structure, the repeated stress relaxation tests and pole figure examinations via X-ray diffraction were conducted in constituent gradient layer and corresponding core, as well as gradient structured sample. The results show that the pyramidal dislocations in dual gradient structure are activated through the whole thickness of sample. Together with the contribution of grain-size gradient, more dislocations are activated in dual gradient structure under tensile loading, which results in stronger strain hardening and hence higher tensile ductility.

  1. Mechanical properties and deformation mechanism of Mg-Al-Zn alloy with gradient microstructure in grain size and orientation

    International Nuclear Information System (INIS)

    Chen, Liu; Yuan, Fuping; Jiang, Ping; Xie, Jijia; Wu, Xiaolei

    2017-01-01

    The surface mechanical attrition treatment was taken to fabricate the gradient structure in AZ31 magnesium alloy sheet. Microstructural investigations demonstrate the formation of dual gradients with respect to grain size and orientation, where the microstructural sizes decreased from several microns to about 200 nm from center area to treated surface, while the c-axis gradually inclined from being vertical to treated plane towards parallel with it. According to tensile results, the gradient structured sample has yield strength of 305 MPa in average, which is increased by about 4 times when compared with its coarse-grained counterpart. Meanwhile, contrary to quickly failure after necking in most traditional magnesium alloys, the failure process of gradient structure appears more gently, which makes it has 6.5% uniform elongation but 11.5% total elongation. The further comparative tensile tests for separated gradient layers and corresponding cores demonstrate that the gradient structured sample has higher elongation either in uniform or in post-uniform stages. In order to elucidate the relationship between mechanical properties and deformation mechanisms for this dual gradient structure, the repeated stress relaxation tests and pole figure examinations via X-ray diffraction were conducted in constituent gradient layer and corresponding core, as well as gradient structured sample. The results show that the pyramidal dislocations in dual gradient structure are activated through the whole thickness of sample. Together with the contribution of grain-size gradient, more dislocations are activated in dual gradient structure under tensile loading, which results in stronger strain hardening and hence higher tensile ductility.

  2. Mechanical behaviour of Zn–Al–Cu–Mg alloys: Deformation mechanisms of as-cast microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhicheng; Sandlöbes, Stefanie; Wu, Liang; Hu, Weiping; Gottstein, Günter; Korte-Kerzel, Sandra, E-mail: Korte-Kerzel@imm.rwth-aachen.de

    2016-01-10

    We study the effects of dilute Mg addition on the microstructure formation and mechanical properties of a ZnAl4Cu1 alloy. On the basis of the composition of the commercial alloy Z410 (4 wt% Al, 1 wt% Cu, and 0.04 wt% Mg), three laboratory alloys with different Mg contents (0.04 wt%, 0.21 wt% and 0.31 wt%) are characterised in terms of their mechanical properties and microstructures using ex-situ and in-situ tensile tests in conjunction with scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Increasing Mg content causes the precipitation of Mg{sub 2}Zn{sub 11} phase precipitates and refined lamellar spacings in the eutectoid phase. The alloy with a medium Mg content (0.21 wt%) exhibits the highest yield strength both at room temperature and at elevated temperatures. Further, we show that dilute Mg alloying causes an improvement of the ductility of ZnAl4Cu1 base-alloys, especially at elevated temperatures. In addition, the alloys reveal two distinct deformation regimes distinguishable close to room temperature and at commonly employed strain rates, with work hardening and brittle fracture exhibited at room temperature and/or elevated strain rate (5×10{sup −4} s{sup −1}), and work softening and ductile fracture at elevated temperature and/or low strain rate (6×10{sup −6} s{sup −1}). The deformation mechanisms and fracture behaviour in both regimes are investigated and the underlying physical mechanisms of the observed phenomena are discussed.

  3. Mechanical behaviour of Zn–Al–Cu–Mg alloys: Deformation mechanisms of as-cast microstructures

    International Nuclear Information System (INIS)

    Wu, Zhicheng; Sandlöbes, Stefanie; Wu, Liang; Hu, Weiping; Gottstein, Günter; Korte-Kerzel, Sandra

    2016-01-01

    We study the effects of dilute Mg addition on the microstructure formation and mechanical properties of a ZnAl4Cu1 alloy. On the basis of the composition of the commercial alloy Z410 (4 wt% Al, 1 wt% Cu, and 0.04 wt% Mg), three laboratory alloys with different Mg contents (0.04 wt%, 0.21 wt% and 0.31 wt%) are characterised in terms of their mechanical properties and microstructures using ex-situ and in-situ tensile tests in conjunction with scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Increasing Mg content causes the precipitation of Mg_2Zn_1_1 phase precipitates and refined lamellar spacings in the eutectoid phase. The alloy with a medium Mg content (0.21 wt%) exhibits the highest yield strength both at room temperature and at elevated temperatures. Further, we show that dilute Mg alloying causes an improvement of the ductility of ZnAl4Cu1 base-alloys, especially at elevated temperatures. In addition, the alloys reveal two distinct deformation regimes distinguishable close to room temperature and at commonly employed strain rates, with work hardening and brittle fracture exhibited at room temperature and/or elevated strain rate (5×10"−"4 s"−"1), and work softening and ductile fracture at elevated temperature and/or low strain rate (6×10"−"6 s"−"1). The deformation mechanisms and fracture behaviour in both regimes are investigated and the underlying physical mechanisms of the observed phenomena are discussed.

  4. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    Science.gov (United States)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X. Q.

    2013-12-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures.

  5. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    International Nuclear Information System (INIS)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X Q

    2013-01-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures. (paper)

  6. A mechanical deformation model of metallic fuel pin under steady state conditions

    International Nuclear Information System (INIS)

    Lee, D. W.; Lee, B. W.; Kim, Y. I.; Han, D. H.

    2004-01-01

    As a mechanical deformation model of the MACSIS code predicts the cladding deformation due to the simple thin shell theory, it is impossible to predict the FCMI(Fuel-Cladding Mechanical Interaction). Therefore, a mechanical deformation model used the generalized plane strain is developed. The DEFORM is a mechanical deformation routine which is used to analyze the stresses and strains in the fuel and cladding of a metallic fuel pin of LMRs. The accuracy of the program is demonstrated by comparison of the DEFORM predictions with the result of another code calculations or experimental results in literature. The stress/strain distributions of elastic part under free thermal expansion condition are completely matched with the results of ANSYS code. The swelling and creep solutions are reasonably well agreed with the simulations of ALFUS and LIFE-M codes, respectively. The predicted cladding strains are under estimated than experimental data at the range of high burnup. Therefore, it is recommended that the fine tuning of the DEFORM based on various range of experimental data

  7. Structural mechanics simulations

    International Nuclear Information System (INIS)

    Biffle, J.H.

    1992-01-01

    Sandia National Laboratory has a very broad structural capability. Work has been performed in support of reentry vehicles, nuclear reactor safety, weapons systems and components, nuclear waste transport, strategic petroleum reserve, nuclear waste storage, wind and solar energy, drilling technology, and submarine programs. The analysis environment contains both commercial and internally developed software. Included are mesh generation capabilities, structural simulation codes, and visual codes for examining simulation results. To effectively simulate a wide variety of physical phenomena, a large number of constitutive models have been developed

  8. Analysis of temperature profiles and the mechanism of silicon substrate plastic deformation under epitaxial growth

    International Nuclear Information System (INIS)

    Mirkurbanov, H.A.; Sazhnev, S.V.; Timofeev, V.N.

    2004-01-01

    Full text: Thermal treatment of silicon wafers holds one of the major place in the manufacturing of semi-conductor devices. Thermal treatment includes wafer annealing, thermal oxidation, epitaxial growing etc. Quality of wafers in the high-temperature processes (900-1200 deg C) is estimated by the density of structural defects, including areas of plastic deformation, which are shown as the slip lines appearance. Such areas amount to 50-60 % of total wafer surface. The plastic deformation is caused by the thermal stresses. Experimental and theoretical researches allowed to determine thermal balance and to construct a temperature profiles throughout the plate surface. Thermal stresses are caused by temperature drop along the radius of a wafer and at the basic peripheral ring. The threshold temperature drop between center f a wafer and its peripherals (ΔT) for slip lines appearance, amounts to 15-17 deg. C. At the operating temperature of 900-1200 deg. C and ΔT>20 deg. C, the stresses reach the silicon yield point. According to the results of the researches of structure and stress profiles in a wafer, the mechanism of slip lines formation has been constructed. A source of dislocations is the rear broken layer of thickness 8-10 microns, formed after polishing. The micro-fissures with a density 10 5 -10 6 cm -2 are the sources of dislocations. Dislocations move on a surface of a wafer into a slip plane (111). On a wafer surface with orientation (111) it is possible to allocate zones where the tangential stress vector is most favorably directed with respect to a slip plane leaving on a surface, i.e. the shift stresses are maximal in the slip plane. The way to eliminate plastic deformation is to lower the temperature drop to a level of <15 deg. C and elimination of the broken layer in wafer

  9. Modeling level structures of odd-odd deformed nuclei

    International Nuclear Information System (INIS)

    Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.

    1984-01-01

    A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for 238 Np, 244 Am, and 250 Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed. 18 refs., 5 figs., 4 tabs

  10. A study of the deformability of composite rods with end fittings for truss structures

    Energy Technology Data Exchange (ETDEWEB)

    Stepanychev, E I; Novikov, V V; Sukhanov, A V; Lapotkin, V A; Postnov, A N [Moskovskii Aviatsionnyi Tekhnologicheskii Institut, Moscow (USSR)

    1989-04-01

    A method is proposed for studying the deformability characteristics of composite rods with end fittings under static loading. Three types of connectors for tubular composite rods are examined from the standpoint of deformability, and differences in the deformability of the central part of a rod and of the connection zone are discussed. The effect of thermal cycling on the deformability of structures of this type is analyzed. 7 refs.

  11. Mechanics of Failure Mechanisms in Structures

    CERN Document Server

    Carlson, R L; Craig, J I

    2012-01-01

    This book focuses on the mechanisms and underlying mechanics of failure in various classes of materials such as metallic, ceramic, polymeric, composite and bio-material.  Topics include tensile and compressive fracture, crack initiation and growth, fatigue and creep rupture in metallic materials, matrix cracking and delamination and environmental degradation in polymeric composites, failure of bio-materials such as prosthetic heart valves and prosthetic hip joints, failure of ceramics and ceramic matrix composites, failure of metallic matrix composites, static and dynamic buckling failure, dynamic excitations and creep buckling failure in structural systems. Chapters are devoted to failure mechanisms that are characteristic of each of the materials.  The work also provides the basic elements of fracture mechanics and studies in detail several niche topics such as the effects of toughness gradients, variable amplitude loading effects in fatigue, small fatigue cracks, and creep induced brittleness. Furthe...

  12. Micro-mechanisms of Surface Defects Induced on Aluminum Alloys during Plastic Deformation at Elevated Temperatures

    Science.gov (United States)

    Gali, Olufisayo A.

    Near-surface deformed layers developed on aluminum alloys significantly influence the corrosion and tribological behavior as well as reduce the surface quality of the rolled aluminum. The evolution of the near-surface microstructures induced on magnesium containing aluminum alloys during thermomechanical processing has been investigated with the aim generating an understanding of the influence of individual forming parameters on its evolution and examine the microstructure of the roll coating induced on the mating steel roll through material transfer during rolling. The micro-mechanisms related to the various features of near-surface microstructure developed during tribological conditions of the simulated hot rolling process were identified. Thermomechanical processing experiments were performed with the aid of hot rolling (operating temperature: 550 to 460 °C, 4, 10 and 20 rolling pass schedules) and hot forming (operating temperature: 350 to 545 °C, strain rate: 4 x 10-2 s-1) tribo-simulators. The surface, near-surface features and material transfer induced during the elevated temperature plastic deformation were examined and characterized employing optical interferometry, SEM/EDS, FIB and TEM. Near-surface features characterized on the rolled aluminum alloys included; cracks, fractured intermetallic particles, aluminum nano-particles, oxide decorated grain boundaries, rolled-in oxides, shingles and blisters. These features were related to various individual rolling parameters which included, the work roll roughness, which induced the formation of shingles, rolling marks and were responsible for the redistribution of surface oxide and the enhancements of the depth of the near-surface damage. The enhanced stresses and strains experienced during rolling were related to the formation and propagation of cracks, the nanocrystalline structure of the near-surface layers and aluminum nano-particles. The mechanism of the evolution of the near-surface microstructure were

  13. 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.

  14. Mechanism for microstructural evolution induced by high temperature deformation in Zr-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Cheng, Sirui; Wang, Chunju; Ma, Mingzhen; Shan, Debin; Guo, Bin

    2016-01-01

    In the Zr_4_1_._2Ti_1_3_._8Cu_1_2_._5Ni_1_0Be_2_2_._5 (Vit1) alloy undergoing high temperature deformation, its thermal properties and microstructure are quite different from those in the annealing alloy. In order to research the coupled effect of temperature and plastic strain on microstructural evolution of Zr-based amorphous, uniaxial compression test of Vit1 alloy with good amorphous nature has been performed, and then the structural state and thermal properties of Vit1 alloy after thermal deformation and isothermal annealing in the supercooled liquid region were investigated. It is revealed that the deformed specimens possess higher characteristic temperature and lower enthalpy change of microstructural relaxation. In addition, the smaller inter-atomic distance and higher order degree of atomic arrangement can be observed in those deformed Vit1 alloy. That can be deduced that thermal deformation is in favor of the microstructural evolution from a metastable amorphous state to stable crystallization state, because plastic strain promotes the annihilation of free volume and provide excess driving force of atomic diffusion. However, upon increasing the ambient temperature, the influence of plastic deformation on microstructure gradually decreased owing to the decreasing proportion of the plastic deformation-induced annihilation of free volume during the whole thermal deformation process. - Highlights: • The deformed specimens possess closer microstructure and higher characteristic temperatures. • The order degree of microstructures in deformed specimens is higher than that in annealed specimens. • Thermal deformation accelerates the microstructural evolution of Zr-based BMGs. • The influence of thermal deformation on microstructure decreases with the temperature increasing.

  15. Mechanism for microstructural evolution induced by high temperature deformation in Zr-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Sirui [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Chunju [Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150080 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Mingzhen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Shan, Debin, E-mail: shandebin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150080 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Bin [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2016-08-15

    In the Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (Vit1) alloy undergoing high temperature deformation, its thermal properties and microstructure are quite different from those in the annealing alloy. In order to research the coupled effect of temperature and plastic strain on microstructural evolution of Zr-based amorphous, uniaxial compression test of Vit1 alloy with good amorphous nature has been performed, and then the structural state and thermal properties of Vit1 alloy after thermal deformation and isothermal annealing in the supercooled liquid region were investigated. It is revealed that the deformed specimens possess higher characteristic temperature and lower enthalpy change of microstructural relaxation. In addition, the smaller inter-atomic distance and higher order degree of atomic arrangement can be observed in those deformed Vit1 alloy. That can be deduced that thermal deformation is in favor of the microstructural evolution from a metastable amorphous state to stable crystallization state, because plastic strain promotes the annihilation of free volume and provide excess driving force of atomic diffusion. However, upon increasing the ambient temperature, the influence of plastic deformation on microstructure gradually decreased owing to the decreasing proportion of the plastic deformation-induced annihilation of free volume during the whole thermal deformation process. - Highlights: • The deformed specimens possess closer microstructure and higher characteristic temperatures. • The order degree of microstructures in deformed specimens is higher than that in annealed specimens. • Thermal deformation accelerates the microstructural evolution of Zr-based BMGs. • The influence of thermal deformation on microstructure decreases with the temperature increasing.

  16. Intraplate Crustal Deformation Within the Northern Sinai Microplate: Evidence from Paleomagnetic Directions and Mechanical Modeling

    Science.gov (United States)

    Dembo, N.; Granot, R.; Hamiel, Y.

    2017-12-01

    The intraplate crustal deformation found in the northern part of the Sinai Microplate, located near the northern Dead Sea Fault plate boundary, is examined. Previous studies have suggested that distributed deformation in Lebanon is accommodated by regional uniform counterclockwise rigid block rotations. However, remanent magnetization directions observed near the Lebanese restraining bend are not entirely homogeneous suggesting that an unexplained and complex internal deformation pattern exists. In order to explain the variations in the amount of vertical-axis rotations we construct a mechanical model of the major active faults in the region that simulates the rotational deformation induced by motion along these faults. The rotational pattern calculated by the mechanical modeling predicts heterogeneous distribution of rotations around the faults. The combined rotation field that considers both the fault induced rotations and the already suggested regional block rotations stands in general agreement with the observed magnetization directions. Overall, the modeling results provide a more detailed and complete picture of the deformation pattern in this region and show that rotations induced by motion along the Dead Sea Fault act in parallel to rigid block rotations. Finally, the new modeling results unravel important insights as to the fashion in which crustal deformation is distributed within the northern part of the Sinai Microplate and propose an improved deformational mechanism that might be appropriate for other plate margins as well.

  17. Strengthening mechanisms and deformation behavior of cryomilled Al–Cu–Mg–Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kurmanaeva, Lilia, E-mail: lkurmanaeva@ucdavis.com [Department of Chemical Engineering & Materials Science, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Topping, Troy D. [Department of Chemical Engineering & Materials Science, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); California State University, Sacramento, 6000 J Street, Sacramento, CA 95819 (United States); Wen, Haiming; Sugahara, Haruka; Yang, Hanry; Zhang, Dalong; Schoenung, Julie M.; Lavernia, Enrique J. [Department of Chemical Engineering & Materials Science, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States)

    2015-05-25

    Highlights: • Ultra-fine and coarse grained Al–Cu–Mg–Ag alloy samples were processed by methods of powder metallurgy. • Despite thermal exposure during consolidation,cryomilled materials retain an ultra-fine grained structure due to the presence of nano-dispersoids at grain boundaries. • Cryomilling results in a change in precipitation kinetics, due to the depletion of Mg atoms at the grain interiors and segregation of Mg, Cu and Ag atoms at grain boundaries. • Dominant deformation mechanisms in cryomilled samples were grain boundary strengthening and dispersion strengthening from oxides and nitrides. - Abstract: In the last decade, the commercially available heat-treatable aluminum alloy (AA) 2139 (Al–Cu–Mg–Ag) has generated interest within the aerospace and defense communities because of its high strength and damage tolerance as compared to those of other AA 2XXX alloys. In this work we investigate the possibility of enhancing the performance of AA 2139 via a nanostructuring approach involving the consolidation of cryomilled powders. For comparison purposes, two types of feedstock powders (cryomilled and unmilled, gas-atomized powder), were consolidated via dual mode dynamic forging. Our results show that, following heat treatment (HT), the strength of the cryomilled material increases in the range of ∼25% to ∼200% relative to that of the unmilled counterparts, depending on specific processing parameters. We present microstructural data, including grain size and precipitate chemistry, to provide insight into the underlying strengthening mechanisms. Vickers microhardess tests are used to evaluate peak heat treatments, and tensile testing is performed to characterize mechanical behavior. The kinetics of precipitation, strengthening mechanisms and deformation behavior are discussed. It is proposed that the combination of elemental segregation with the presence of oxides along grain boundaries, both facilitated by enhanced diffusion paths, are

  18. Structure of deformed wing virus, a major honey bee pathogen.

    Science.gov (United States)

    Škubník, Karel; Nováček, Jiří; Füzik, Tibor; Přidal, Antonín; Paxton, Robert J; Plevka, Pavel

    2017-03-21

    The worldwide population of western honey bees ( Apis mellifera ) is under pressure from habitat loss, environmental stress, and pathogens, particularly viruses that cause lethal epidemics. Deformed wing virus (DWV) from the family Iflaviridae , together with its vector, the mite Varroa destructor , is likely the major threat to the world's honey bees. However, lack of knowledge of the atomic structures of iflaviruses has hindered the development of effective treatments against them. Here, we present the virion structures of DWV determined to a resolution of 3.1 Å using cryo-electron microscopy and 3.8 Å by X-ray crystallography. The C-terminal extension of capsid protein VP3 folds into a globular protruding (P) domain, exposed on the virion surface. The P domain contains an Asp-His-Ser catalytic triad that is, together with five residues that are spatially close, conserved among iflaviruses. These residues may participate in receptor binding or provide the protease, lipase, or esterase activity required for entry of the virus into a host cell. Furthermore, nucleotides of the DWV RNA genome interact with VP3 subunits. The capsid protein residues involved in the RNA binding are conserved among honey bee iflaviruses, suggesting a putative role of the genome in stabilizing the virion or facilitating capsid assembly. Identifying the RNA-binding and putative catalytic sites within the DWV virion structure enables future analyses of how DWV and other iflaviruses infect insect cells and also opens up possibilities for the development of antiviral treatments.

  19. Nuclear structure at high-spin and large-deformation

    International Nuclear Information System (INIS)

    Shimizu, Yoshifumi R.

    2000-01-01

    Atomic nucleus is a finite quantal system and shows various marvelous features. One of the purposes of the nuclear structure study is to understand such features from a microscopic viewpoint of nuclear many-body problem. Recently, it is becoming possible to explore nuclear states under 'extreme conditions', which are far different from the usual ground states of stable nuclei, and new aspects of such unstable nuclei attract our interests. In this lecture, I would like to discuss the nuclear structure in the limit of rapid rotation, or the extreme states with very large angular momenta, which became accessible by recent advent of large arrays of gamma-ray detecting system; these devices are extremely useful to measure coincident multiple γ-rays following heavy-ion fusion reactions. Including such experimental aspects as how to detect the nuclear rotational states, I review physics of high-spin states starting from the elementary subjects of nuclear structure study. In would like also to discuss the extreme states with very large nuclear deformation, which are easily realized in rapidly rotating nuclei. (author)

  20. Influence of preliminary plastic deformation on plasticity characteristics and structure of armco-iron

    International Nuclear Information System (INIS)

    Vergazov, A.N.; Rybin, V.V.; Meshkov, Yu.Ya.; Moskvina, V.A.; Serditova, T.N.

    1990-01-01

    Effect of preliminary plastic deformation (PPD) by drawing on the maximum plasticity characteristics (critical rupture strain) ε c , general δ and uniform δ p relative elongation and on the structure of armco-iron in a wide range of PPD degree change (e=0-4.6) is studied. It is ascertained that with e growth the metal plastic properties at T test =77 and 293 K change in a different way. In particular, the critical strain ε c increases monotonously at 77 K and reduces at 293 K. It is shown that all changes of mechanical characteristics observed with e increase are conditioned by the development of fragmentation process in armco-iron. The data obtained are discussed from the veiwpoint of the developed plastic deformation physics concepts

  1. Tensile Deformation Temperature Impact on Microstructure and Mechanical Properties of AISI 316LN Austenitic Stainless Steel

    Science.gov (United States)

    Xiong, Yi; He, Tiantian; Lu, Yan; Ren, Fengzhang; Volinsky, Alex A.; Cao, Wei

    2018-03-01

    Uniaxial tensile tests were conducted on AISI 316LN austenitic stainless steel from - 40 to 300 °C at a rate of 0.5 mm/min. Microstructure and mechanical properties of the deformed steel were investigated by optical, scanning and transmission electron microscopies, x-ray diffraction, and microhardness testing. The yield strength, ultimate tensile strength, elongation, and microhardness increase with the decrease in the test temperature. The tensile fracture morphology has the dimple rupture feature after low-temperature deformations and turns to a mixture of transgranular fracture and dimple fracture after high-temperature ones. The dominating deformation microstructure evolves from dislocation tangle/slip bands to large deformation twins/slip bands with temperature decrease. The deformation-induced martensite transformation can only be realized at low temperature, and its quantity increases with the decrease in the temperature.

  2. 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.

  3. Mechanical properties along interfaces of bonded structures in fusion reactors

    International Nuclear Information System (INIS)

    Hassan, M.H.; Kulcinski, G.L.

    1993-01-01

    Proper assessment of the mechanical properties along interfaces of bonded structures currently used in many fusion reactor designs is essential to compare the different fabrication techniques. A Mechanical Properties Microprobe (MPM) was used to measure hardness and Young's modules along the interfaces of Be/Cu bonded structure. The MPM was able to distinguish different fabrication techniques by a direct measurement of the hardness, Young's modules, and H/E 2 which reflects the ability of deformation of the interfacial region

  4. Deformation Mechanism and Recrystallization Relationships in Galfenol Single Crystals: On the Origin of Goss and Cube Orientations

    Science.gov (United States)

    Na, Suok-Min; Smith, Malcolm; Flatau, Alison B.

    2018-06-01

    In this work, deformation mechanism related to recrystallization behavior in single-crystal disks of Galfenol (Fe-Ga alloy) was investigated to gain insights into the influence of crystal orientations on structural changes and selective grain growth that take place during secondary recrystallization. We started with the three kinds of single-crystal samples with (011)[100], (001)[100], and (001)[110] orientations, which were rolled and annealed to promote the formation of different grain structures and texture evolutions. The initial Goss-oriented (011)[100] crystal mostly rotated into {111} orientations with twofold symmetry and shear band structures by twinning resulted in the exposure of rolled surface along {001} orientation during rolling. In contrast, the Cube-oriented (001)[100] single crystal had no change in texture during rolling with the thickness reduction up to 50 pct. The {123} slip systems were preferentially activated in these single crystals during deformation as well as {112} slip systems that are known to play a role in primary slip of body-centered cubic (BCC) materials such as α-iron and Fe-Si alloys. After annealing, the deformed Cube-oriented single crystal had a small fraction ( orientation, associated with {123} slip systems as well. This was expected to provide potential sites of nucleation for secondary recrystallization; however, no Goss- and Cube-oriented components actually developed in this sample during secondary recrystallization. Those results illustrated how the recrystallization behavior can be influenced by deformed structure and the slip systems.

  5. Thermal-mechanical deformation modelling of soft tissues for thermal ablation.

    Science.gov (United States)

    Li, Xin; Zhong, Yongmin; Jazar, Reza; Subic, Aleksandar

    2014-01-01

    Modeling of thermal-induced mechanical behaviors of soft tissues is of great importance for thermal ablation. This paper presents a method by integrating the heating process with thermal-induced mechanical deformations of soft tissues for simulation and analysis of the thermal ablation process. This method combines bio-heat transfer theories, constitutive elastic material law under thermal loads as well as non-rigid motion dynamics to predict and analyze thermal-mechanical deformations of soft tissues. The 3D governing equations of thermal-mechanical soft tissue deformation are discretized by using the finite difference scheme and are subsequently solved by numerical algorithms. Experimental results show that the proposed method can effectively predict the thermal-induced mechanical behaviors of soft tissues, and can be used for the thermal ablation therapy to effectively control the delivered heat energy for cancer treatment.

  6. Effect of cold deformation on latent energy value and high-temperature mechanical properties of 12Cr18Ni10Ti steel

    International Nuclear Information System (INIS)

    Maksimkin, O.P.; Shiganakov, Sh.B.; Gusev, M.N.

    1997-01-01

    Energetic and magnetic characteristics and also the high-temperature mechanical properties depending on the preliminary cold deformation of 12Cr18Ni10Ti steel are presented. It is shown that the value of storage energy in the steel has being grown with increase of the deformation. The rate of its growth has been increased after beginning of martensitic γ→α'- transformation when value of comparative storage energy at first decreased and then has been stay practically constant. Level of mechanical properties of the steel at 1073 K has been determined not only by value of cold deformation but and structural reconstruction corresponding to deformations 35-45% and accompanying with α'-phase martensite formation and change of energy accumulating rate. Preliminary cold deformation (40-60 %) does not improve high- temperature plasticity of steel samples implanted by helium. refs. 7, figs. 2

  7. 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.

  8. 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.

  9. Evidence for cross rift structural controls on deformation and seismicity at a continental rift caldera

    Science.gov (United States)

    Lloyd, Ryan; Biggs, Juliet; Wilks, Matthew; Nowacki, Andy; Kendall, J.-Michael; Ayele, Atalay; Lewi, Elias; Eysteinsson, Hjálmar

    2018-04-01

    In continental rifts structural heterogeneities, such as pre-existing faults and foliations, are thought to influence shallow crustal processes, particularly the formation of rift faults, magma reservoirs and surface volcanism. We focus on the Corbetti caldera, in the southern central Main Ethiopian Rift. We measure the surface deformation between 22nd June 2007 and 25th March 2009 using ALOS and ENVISAT SAR interferograms and observe a semi-circular pattern of deformation bounded by a sharp linear feature cross-cutting the caldera, coincident with the caldera long axis. The signal reverses in sign but is not seasonal: from June to December 2007 the region south of this structure moves upwards 3 cm relative to the north, while from December 2007 until November 2008 it subsides by 2 cm. Comparison of data taken from two different satellite look directions show that the displacement is primarily vertical. We discuss potential mechanisms and conclude that this deformation is associated with pressure changes within a shallow (statistically consistent with this fault structure, indicating that the fault has also controlled the migration of magma from a reservoir to the surface over tens of thousands of years. Spatial patterns of seismicity are consistent with a cross-rift structure that extents outside the caldera and to a depth of ∼30 km, and patterns of seismic anisotropy suggests stress partitioning occurs across the structure. We discuss the possible nature of this structure, and conclude that it is most likely associated with the Goba-Bonga lineament, which cross-cuts and pre-dates the current rift. Our observations show that pre-rift structures play an important role in magma transport and shallow hydrothermal processes, and therefore they should not be neglected when discussing these processes.

  10. Microstructure evolution and deformation mechanism change in 0.98C-8.3Mn-0.04N steel during compressive deformation

    International Nuclear Information System (INIS)

    Wang, T.S.; Hou, R.J.; Lv, B.; Zhang, M.; Zhang, F.C.

    2007-01-01

    The microstructure evolution and the deformation mechanism change in 0.98C-8.3Mn-0.04N steel during compressive deformation at room temperature have been studied as a function of the reduction in the range of 20-60%. Experimental results show that with the reduction increasing the microstructure of the deformed sample changes from dislocation substructures into the dominant twins plus dislocations. This suggests that the plastic deformation mechanism changes from the dislocation slip to the dominant deformation twinning. The minimum reduction for deformation twins starting is estimated to be at between 30 and 40%. With the reduction further increases to more than 40%, the deformation twinning is operative and the thickness of deformation twins gradually decreases to nanoscale and shear bands occur. These high-density twins can be curved by the formation of shear bands. In addition, both transmission electron microscopy and X-ray diffraction examinations confirm the inexistence of deformation-induced martensites in these deformed samples

  11. Translation-rotation plasticity as basic mechanism of plastic deformation in macro-, micro- and nanoindentation processes

    International Nuclear Information System (INIS)

    Grabco, D; Shikimaka, O; Harea, E

    2008-01-01

    This paper presents a brief review of multilateral examinations for the purpose of detection of interrelation between processes occuring in solids at different levels of action of exterior loading, namely, at macro-, micro- and nanoindentation. Convincing arguments supporting the rotation deformation mechanism alongside the recognized dislocation one are adduced. It has been shown that the decrease in dislocation mobility leads at all scales to the intensification of rotation plasticity and to the involvement of other plastic deformation mechanisms, such as appearance and interaction of disclinations, twinning, phase transition and compression of material. The conversion from translation plasticity to the rotation-translation one means transition to the higher level of plastic deformation, the mesolevel, when the possibilities of the previous microscopic level are exhausted. It was established that the plastic deformation zone in the vicinity of indentations could be separated into two main specific regions: (i) peripheral region predominantly with the dislocation deformation mechanism; otherwise, translation mechanism: microlevel, and (ii) quasidestructured region mainly with the disclination or the intergranular sliding mechanism: rotation mechanism, mesolevel

  12. Materials and noncoplanar mesh designs for integrated circuits with linear elastic responses to extreme mechanical deformations.

    Science.gov (United States)

    Kim, Dae-Hyeong; Song, Jizhou; Choi, Won Mook; Kim, Hoon-Sik; Kim, Rak-Hwan; Liu, Zhuangjian; Huang, Yonggang Y; Hwang, Keh-Chih; Zhang, Yong-wei; Rogers, John A

    2008-12-02

    Electronic systems that offer elastic mechanical responses to high-strain deformations are of growing interest because of their ability to enable new biomedical devices and other applications whose requirements are impossible to satisfy with conventional wafer-based technologies or even with those that offer simple bendability. This article introduces materials and mechanical design strategies for classes of electronic circuits that offer extremely high stretchability, enabling them to accommodate even demanding configurations such as corkscrew twists with tight pitch (e.g., 90 degrees in approximately 1 cm) and linear stretching to "rubber-band" levels of strain (e.g., up to approximately 140%). The use of single crystalline silicon nanomaterials for the semiconductor provides performance in stretchable complementary metal-oxide-semiconductor (CMOS) integrated circuits approaching that of conventional devices with comparable feature sizes formed on silicon wafers. Comprehensive theoretical studies of the mechanics reveal the way in which the structural designs enable these extreme mechanical properties without fracturing the intrinsically brittle active materials or even inducing significant changes in their electrical properties. The results, as demonstrated through electrical measurements of arrays of transistors, CMOS inverters, ring oscillators, and differential amplifiers, suggest a valuable route to high-performance stretchable electronics.

  13. Nonlinear structural mechanics theory, dynamical phenomena and modeling

    CERN Document Server

    Lacarbonara, Walter

    2013-01-01

    Nonlinear Structural Mechanics: Theory, Dynamical Phenomena and Modeling offers a concise, coherent presentation of the theoretical framework of nonlinear structural mechanics, computational methods, applications, parametric investigations of nonlinear phenomena and their mechanical interpretation towards design. The theoretical and computational tools that enable the formulation, solution, and interpretation of nonlinear structures are presented in a systematic fashion so as to gradually attain an increasing level of complexity of structural behaviors, under the prevailing assumptions on the geometry of deformation, the constitutive aspects and the loading scenarios. Readers will find a treatment of the foundations of nonlinear structural mechanics towards advanced reduced models, unified with modern computational tools in the framework of the prominent nonlinear structural dynamic phenomena while tackling both the mathematical and applied sciences. Nonlinear Structural Mechanics: Theory, Dynamical Phenomena...

  14. Mechanical properties and deformation of polycrystalline lithium orthosilicate

    International Nuclear Information System (INIS)

    Bar, K.; Chu, C.Y.; Singh, J.P.; Goretta, K.C.; Routbort, J.L.; Billone, M.C.; Poeppel, R.B.

    1988-02-01

    Room-temperature strength, fracture toughness, Young's modulus, and thermal-shock resistance were determined for 68--98% dense lithium orthosilicate (Li 4 SiO 4 ) specimens. In the low-density regime, both strength and fracture toughness were controlled by the density of the specimen. At high density, the strength depends on grain size. Young's modulus values ranged from 30--103 GPa at densities between 68 and 98% TD. A critical quenching temperature difference in the range of 150--170/degree/C was observed in thermal-shock tests of bar specimens. Steady-state creep tests indicated 90% dense Li 4 SiO 4 fractures at T ≤ 800/degree/C before reaching steady state and deforms plastically at 900/degree/C. It is more creep-resistant at 900/degree/C than Li 2 O, about equal to Li 2 Zr) 3 , and less than LiA10 2 . 13 refs., 4 figs., 1 tab

  15. 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.

  16. Cold deformation effect on the microstructures and mechanical properties of AISI 301LN and 316L stainless steels

    International Nuclear Information System (INIS)

    Silva, Paulo Maria de O.; Abreu, Hamilton Ferreira G. de; Albuquerque, Victor Hugo C. de; Neto, Pedro de Lima; Tavares, Joao Manuel R.S.

    2011-01-01

    As austenitic stainless steels have an adequate combination of mechanical resistance, conformability and resistance to corrosion they are used in a wide variety of industries, such as the food, transport, nuclear and petrochemical industries. Among these austenitic steels, the AISI 301LN and 316L steels have attracted prominent attention due to their excellent mechanical resistance. In this paper a microstructural characterization of AISI 301LN and 316L steels was made using various techniques such as metallography, optical microscopy, scanning electronic microscopy and atomic force microscopy, in order to analyze the cold deformation effect. Also, the microstructural changes were correlated with the alterations of mechanical properties of the materials under study. One of the numerous uses of AISI 301LN and 316L steels is in the structure of wagons for metropolitan surface trains. For this type of application it is imperative to know their microstructural behavior when subjected to cold deformation and correlate it with their mechanical properties and resistance to corrosion. Microstructural analysis showed that cold deformation causes significant microstructural modifications in these steels, mainly hardening. This modification increases the mechanical resistance of the materials appropriately for their foreseen application. Nonetheless, the materials become susceptible to pitting corrosion.

  17. Polycrystal deformation and single crystal deformation: Dislocation structure and flow stress in copper

    DEFF Research Database (Denmark)

    Huang, X.; Borrego, A.; Pantleon, W.

    2001-01-01

    of microstructures have been identified. A correlation is found between microstructure and grain orientation, which agrees well with earlier observations in tensile deformed aluminum polycrystals and copper single crystals. The stress–strain curve of the copper polycrystal is calculated with good accuracy from...

  18. Hamiltonian structure of isospectral deformation equation and semi-classical approximation to factorized S-matrices

    International Nuclear Information System (INIS)

    Chudnovsky, D.V.; Chudnovsky, G.V.

    1980-01-01

    We consider semi-classical approximation to factorized S-matrices. We show that this new class of matrices, called s-matrices, defines Hamiltonian structures for isospectral deformation equations. Concrete examples of factorized s-matrices are constructed and they are used to define Hamiltonian structure for general two-dimensional isospectral deformation systems. (orig.)

  19. Structural Changes in Deformed Soft Magnetic Ni-Based Metallic Glass

    NARCIS (Netherlands)

    Jurikova, A.; Csach, K.; Miskuf, J.; Ocelik, V.

    The effects of intensive plastic deformation of the soft magnetic metallic glass Ni Si 13 on the structural relaxation were examined. The enthalpy changes studied by differential scanning calorimetry revealed that the intensive plastic deformation was associated with the partial structural

  20. Structural aspects of elastic deformation of a metallic glass

    International Nuclear Information System (INIS)

    Hufnagel, T. C.; Ott, R. T.; Almer, J.

    2006-01-01

    We report the use of high-energy x-ray scattering to measure strain in a Zr 57 Ti 5 Cu 20 Ni 8 Al 10 bulk metallic glass in situ during uniaxial compression in the elastic regime up to stresses of approximately 60% of the yield stress. The strains extracted in two ways--directly from the normalized scattering data and from the pair correlation functions--are in good agreement with each other for length scales greater than 4 A. The elastic modulus calculated on the basis of this strain is in good agreement with that reported for closely related amorphous alloys based on macroscopic measurements. The strain measured for atoms in the nearest-neighbor shell, however, is smaller than that for more distant shells, and the effective elastic modulus calculated from the strain on this scale is therefore larger, comparable to crystalline alloys of similar composition. These observations are in agreement with previously proposed models in which the nominally elastic deformation of a metallic glass has a significant anelastic component due to atomic rearrangements in topologically unstable regions of the structure. We also observe that the distribution of the atomic-level stresses in the glass becomes more uniform during loading. This implies that the stiffness of metallic glasses may have an entropic contribution, analogous to the entropic contribution in rubber elasticity

  1. Exploring of PST-TBPM in Monitoring Dynamic Deformation of Steel Structure in Vibration

    Science.gov (United States)

    Chen, Mingzhi; Zhao, Yongqian; Hai, Hua; Yu, Chengxin; Zhang, Guojian

    2018-01-01

    In order to monitor the dynamic deformation of steel structure in the real-time, digital photography is used in this paper. Firstly, the grid method is used correct the distortion of digital camera. Then the digital cameras are used to capture the initial and experimental images of steel structure to obtain its relative deformation. PST-TBPM (photographing scale transformation-time baseline parallax method) is used to eliminate the parallax error and convert the pixel change value of deformation points into the actual displacement value. In order to visualize the deformation trend of steel structure, the deformation curves are drawn based on the deformation value of deformation points. Results show that the average absolute accuracy and relative accuracy of PST-TBPM are 0.28mm and 1.1‰, respectively. Digital photography used in this study can meet accuracy requirements of steel structure deformation monitoring. It also can warn the safety of steel structure and provide data support for managers’ safety decisions based on the deformation curves on site.

  2. Crustal deformation mechanism in southeastern Tibetan Plateau: Insights from numerical modeling

    Science.gov (United States)

    Li, Y.; Liu, S.; Chen, L.

    2017-12-01

    The Indo-Asian collision developed the complicated crustal deformation around the southeastern Tibetan plateau. Numerous models have proposed to explain the crustal deformation, but the mechanism remains controversial, especially the increasing multi-geophysics data, which demonstrate the existence of lower velocity, lower resistivity and high conductivity, implying that lower crustal flow is responsible for the crustal deformation, arguing for the lower crust flow model. To address the relations between the crust flow and the surface deformation, we employ a three-dimensional viscoelastic finite model to investigate the possible influence on the surface deformation, and discuss the stress field distribution under the model. Our preliminary results suggest that lower crustal flow plays an important role in crustal deformation in southeastern Tibetan plateau. 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. 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 predicted match observations well, especially for the magnitude within the South China block. The maximum principal stress field 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.

  3. Influence of the Strain History on TWIP Steel Deformation Mechanisms in the Deep-Drawing Process

    Science.gov (United States)

    Lapovok, R.; Timokhina, I.; Mester, A.-K.; Weiss, M.; Shekhter, A.

    2018-06-01

    A study of preferable deformation modes on strain path and strain level in a TWIP steel sheet was performed. Different strain paths were obtained by stretch forming of specimens with various shapes and tensile tests. TEM analysis was performed on samples cut from various locations in the deformed specimens, which had different strain paths and strain levels and the preferable deformation modes were identified. Stresses caused by various strain paths were considered and an analytical analysis performed to identify the preferable deformation modes for the case of single crystal. For a single crystal, in assumption of the absence of lattice rotation, the strain path and the level of accumulated equivalent strain define the preferable deformation mode. For a polycrystalline material, such analytical analysis is not possible due to the large number of grains and, therefore, numerical simulation was employed. For the polycrystalline material, the role of strain path diminishes due to the presence of a large number of grains with random orientations and the effect of accumulated strain becomes dominant. However, at small strains the strain path still defines the level of twinning activity. TEM analysis experimentally confirmed that various deformation modes lead to different deformation strengthening mechanisms.

  4. Mechanisms of Photo-Induced Deformations of Liquid Crystal Elastomers

    Science.gov (United States)

    Dawson, Nathan; Kuzyk, Mark; Neal, Jeremy; Luchette, Paul; Palffy-Muhoray, Peter

    2010-03-01

    Over a century ago, Alexander Graham Bell invented the photophone, which he used to transmit mechanical information on a beam of light. We report on the use of an active Fabry-Perot interferometer to encode and detect mechanical information using the photomechanical effect of a liquid crystal elastomer (LCE) that is placed at a critical point between the reflectors. These are the first steps in the creation of ultra smart materials which require a large photomechanical response. Thus, understanding the underlying mechanisms is critical. Only limited studies of the mechanisms of the photomechanical effect, such as photo-isomerization, photo-reorientation and thermal effects have been studied in azo-dye-doped LCEs and in azo-dye-doped polymer fibers have been reported. The focus of our present work is to use the Fabry-Perot transducer geometry to study the underlying mechanisms and to determine the relevant material parameters that are used to develop theoretical models of the response. We use various intensity-modulated optical wave forms to determine the frequency response of the material, which are used to predict the material response.

  5. Complex structure-induced deformations of σ-models

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, Dmitri [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany); Steklov Mathematical Institute of Russ. Acad. Sci.,Gubkina str. 8, 119991 Moscow (Russian Federation)

    2017-03-24

    We describe a deformation of the principal chiral model (with an even-dimensional target space G) by a B-field proportional to the Kähler form on the target space. The equations of motion of the deformed model admit a zero-curvature representation. As a simplest example, we consider the case of G=S{sup 1}×S{sup 3}. We also apply a variant of the construction to a deformation of the AdS{sub 3}×S{sup 3}×S{sup 1} (super-)σ-model.

  6. 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.

  7. 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.

  8. Three-dimensional printing and deformation behavior of low-density target structures by two-photon polymerization

    Science.gov (United States)

    Liu, Ying; Stein, Ori; Campbell, John H.; Jiang, Lijia; Petta, Nicole; Lu, Yongfeng

    2017-08-01

    Two-photon polymerization (2PP), a 3D nano to microscale additive manufacturing process, is being used for the first time to fabricate small custom experimental packages ("targets") to support laser-driven high-energy-density (HED) physics research. Of particular interest is the use of 2PP to deterministically print low-density, low atomic-number (CHO) polymer matrices ("foams") at millimeter scale with sub-micrometer resolution. Deformation during development and drying of the foam structures remains a challenge when using certain commercial photo-resins; here we compare use of acrylic resins IP-S and IP-Dip. The mechanical strength of polymeric beam and foam structures is examined particularly the degree of deformation that occurs during the development and drying processes. The magnitude of the shrinkage in the two resins in quantified by printing sample structures and by use of FEA to simulate the deformation. Capillary drying forces are shown to be small and likely below the elastic limit of the core foam structure. In contrast the substantial shrinkage in IP-Dip ( 5-10%) cause large shear stresses and associated plastic deformation particularly near constrained boundaries such as the substrate and locations with sharp density variation. The inherent weakness of stitching boundaries is also evident and in certain cases can lead to delamination. Use of IP-S shows marked reduction in deformation with a minor loss of print resolution

  9. 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.

    2011-04-01

    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.

  10. Mechanical characterization of the P56 mouse brain under large-deformation dynamic indentation

    Science.gov (United States)

    MacManus, David B.; Pierrat, Baptiste; Murphy, Jeremiah G.; Gilchrist, Michael D.

    2016-02-01

    The brain is a complex organ made up of many different functional and structural regions consisting of different types of cells such as neurons and glia, as well as complex anatomical geometries. It is hypothesized that the different regions of the brain exhibit significantly different mechanical properties, which may be attributed to the diversity of cells and anisotropy of neuronal fibers within individual brain regions. The regional dynamic mechanical properties of P56 mouse brain tissue in vitro and in situ at velocities of 0.71-4.28 mm/s, up to a deformation of 70 μm are presented and discussed in the context of traumatic brain injury. The experimental data obtained from micro-indentation measurements were fit to three hyperelastic material models using the inverse Finite Element method. The cerebral cortex elicited a stiffer response than the cerebellum, thalamus, and medulla oblongata regions for all velocities. The thalamus was found to be the least sensitive to changes in velocity, and the medulla oblongata was most compliant. The results show that different regions of the mouse brain possess significantly different mechanical properties, and a significant difference also exists between the in vitro and in situ brain.

  11. Analyzing the Mechanical Behavior of Polymer and Composite Materials by Means of Unique Method of Deformation Calorimetry

    Science.gov (United States)

    Bessonova, N. P.; Chvalun, S. N.

    2018-06-01

    Results are presented from long-term investigations of a wide range of polymer systems, varying from elastomers and thermoplastic elastomers to plastics and fibers. The thermophysical properties of both initial and modifying additive-containing polysiloxanes, block copolymers, and poleolefins that differ in chemical nature, structure, and composition are analyzed. It is shown that deformation calorimetry allows the simultaneous registration of mechanical (from 5 × 10-3 kg) and thermal effects (at a sensitivity of 2 × 10‒7 J/s), and the determination of changes in enthalpy, internal energy, and intra- and intermolecular contributions to the formation of the tensile stress response. In other words, it provides a unique opportunity to analyze the deformation mechanism of investigated systems and its dependence on the changing parameters.

  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. On temperature dependence of deformation mechanism and the brittle - ductile transition in semiconductors

    International Nuclear Information System (INIS)

    Pirouz, P.; Samant, A.V.; Hong, M.H.; Moulin, A.; Kubin, L.P.

    1999-01-01

    Recent deformation experiments on semiconductors have shown the occurrence of a break in the variation of the critical resolved shear stress of the crystal as a function of temperature. These and many other examples in the literature evidence a critical temperature at which a transition occurs in the deformation mechanism of the crystal. In this paper, the occurrence of a similar transition in two polytypes of SiC is reported and correlated to the microstructure of the deformed crystals investigated by transmission electron microscopy, which shows evidence for partial dislocations carrying the deformation at high stresses and low temperatures. Based on these results and data in the literature, the explanation is generalized to other semiconductors and a possible relationship to their brittle-ductile transition is proposed. copyright 1999 Materials Research Society

  14. Soft-sediment deformations (convolute lamination and load structures) in turbidites as indicators of flow reflections against bounding slopes

    Science.gov (United States)

    Tinterri, Roberto; Muzzi Magalhaes, Pierre; Tagliaferri, Alessio; Cunha, Rogerio S.; Laporta, Michele

    2015-04-01

    Soft-sediment deformations, such as convolute laminations, load structures and water escapes are very rapid deformations that occur in unconsolidated sediments near the depositional surface during or shortly after deposition and before significant diagenesis. These types of deformations develop when primary stratifications are deformed by a system of driving forces, while the sediment is temporarily in a weakened state due to the action of a deformation mechanism know as liquidization. This deformation occurs if the applied stress exceeds the sediment strength, either through an increase in the applied stress or through a temporary reduction in sediment strength. Liquidization mechanisms can be triggered by several agents, such as seismic shaking, rapid sedimentation with high-fallout rates or cyclic-pressure variations associated with storm waves or breaking waves. Consequently, soft-sediment deformations can be produced by different processes and form ubiquitous sedimentary structures characterizing many sedimentary environments. However, even though these types of structures are relatively well-known in terms of geometry and sedimentary characteristics, many doubts arise when the understanding of deformation and trigger mechanisms is attempted. As stressed also by the recent literature, the main problem lies in the fact that the existing approaches for the identification of triggering agents rely on criteria that are not diagnostic or not applicable to outcrop-based studies, because they are not always based on detailed facies analysis related to a paleoenvironmental-context approach. For this reason, this work discusses the significance of particular types of soft-sediment deformations that are very common in turbidite deposits, namely convolute laminations and load structures, especially on the basis of a deep knowledge of the stratigraphic framework and geological setting in which these structures are inserted. More precisely, detailed facies analyses of the

  15. High temperature deformation mechanisms of L12-containing Co-based superalloys

    Science.gov (United States)

    Titus, Michael Shaw

    Ni-based superalloys have been used as the structural material of choice for high temperature applications in gas turbine engines since the 1940s, but their operating temperature is becoming limited by their melting temperature (Tm =1300degrees C). Despite decades of research, no viable alternatives to Ni-based superalloys have been discovered and developed. However, in 2006, a ternary gamma' phase was discovered in the Co-Al-W system that enabled a new class of Co-based superalloys to be developed. These new Co-based superalloys possess a gamma-gamma' microstructure that is nearly identical to Ni-based superalloys, which enables these superalloys to achieve extraordinary high temperature mechanical properties. Furthermore, Co-based alloys possess the added benefit of exhibiting a melting temperature of at least 100degrees C higher than commercial Ni-based superalloys. Superalloys used as the structural materials in high pressure turbine blades must withstand large thermomechanical stresses imparted from the rotating disk and hot, corrosive gases present. These stresses induce time-dependent plastic deformation, which is commonly known as creep, and new superalloys must possess adequate creep resistance over a broad range of temperature in order to be used as the structural materials for high pressure turbine blades. For these reasons, this research focuses on quantifying high temperature creep properties of new gamma'-containing Co-based superalloys and identifying the high temperature creep deformation mechanisms. The high temperature creep properties of new Co- and CoNi-based alloys were found to be comparable to Ni-based superalloys with respect to minimum creep rates and creep-rupture lives at 900degrees C up to the solvus temperature of the gamma' phase. Co-based alloys exhibited a propensity for extended superlattice stacking fault formation in the gamma' precipitates resulting from dislocation shearing events. When Ni was added to the Co-based compositions

  16. String field theory. Algebraic structure, deformation properties and superstrings

    International Nuclear Information System (INIS)

    Muenster, Korbinian

    2013-01-01

    This thesis discusses several aspects of string field theory. The first issue is bosonic open-closed string field theory and its associated algebraic structure - the quantum open-closed homotopy algebra. We describe the quantum open-closed homotopy algebra in the framework of homotopy involutive Lie bialgebras, as a morphism from the loop homotopy Lie algebra of closed string to the involutive Lie bialgebra on the Hochschild complex of open strings. The formulation of the classical/quantum open-closed homotopy algebra in terms of a morphism from the closed string algebra to the open string Hochschild complex reveals deformation properties of closed strings on open string field theory. In particular, we show that inequivalent classical open string field theories are parametrized by closed string backgrounds up to gauge transformations. At the quantum level the correspondence is obstructed, but for other realizations such as the topological string, a non-trivial correspondence persists. Furthermore, we proof the decomposition theorem for the loop homotopy Lie algebra of closed string field theory, which implies uniqueness of closed string field theory on a fixed conformal background. Second, the construction of string field theory can be rephrased in terms of operads. In particular, we show that the formulation of string field theory splits into two parts: The first part is based solely on the moduli space of world sheets and ensures that the perturbative string amplitudes are recovered via Feynman rules. The second part requires a choice of background and determines the real string field theory vertices. Each of these parts can be described equivalently as a morphism between appropriate cyclic and modular operads, at the classical and quantum level respectively. The algebraic structure of string field theory is then encoded in the composition of these two morphisms. Finally, we outline the construction of type II superstring field theory. Specific features of the

  17. Formality theory from Poisson structures to deformation quantization

    CERN Document Server

    Esposito, Chiara

    2015-01-01

    This book is a survey of the theory of formal deformation quantization of Poisson manifolds, in the formalism developed by Kontsevich. It is intended as an educational introduction for mathematical physicists who are dealing with the subject for the first time. The main topics covered are the theory of Poisson manifolds, star products and their classification, deformations of associative algebras and the formality theorem. Readers will also be familiarized with the relevant physical motivations underlying the purely mathematical construction.

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

    International Nuclear Information System (INIS)

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

    1996-01-01

    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

  19. Adsorption-Induced Deformation of Hierarchically Structured Mesoporous Silica-Effect of Pore-Level Anisotropy.

    Science.gov (United States)

    Balzer, Christian; Waag, Anna M; Gehret, Stefan; Reichenauer, Gudrun; Putz, Florian; Hüsing, Nicola; Paris, Oskar; Bernstein, Noam; Gor, Gennady Y; Neimark, Alexander V

    2017-06-06

    The goal of this work is to understand adsorption-induced deformation of hierarchically structured porous silica exhibiting well-defined cylindrical mesopores. For this purpose, we performed an in situ dilatometry measurement on a calcined and sintered monolithic silica sample during the adsorption of N 2 at 77 K. To analyze the experimental data, we extended the adsorption stress model to account for the anisotropy of cylindrical mesopores, i.e., we explicitly derived the adsorption stress tensor components in the axial and radial direction of the pore. For quantitative predictions of stresses and strains, we applied the theoretical framework of Derjaguin, Broekhoff, and de Boer for adsorption in mesopores and two mechanical models of silica rods with axially aligned pore channels: an idealized cylindrical tube model, which can be described analytically, and an ordered hexagonal array of cylindrical mesopores, whose mechanical response to adsorption stress was evaluated by 3D finite element calculations. The adsorption-induced strains predicted by both mechanical models are in good quantitative agreement making the cylindrical tube the preferable model for adsorption-induced strains due to its simple analytical nature. The theoretical results are compared with the in situ dilatometry data on a hierarchically structured silica monolith composed by a network of mesoporous struts of MCM-41 type morphology. Analyzing the experimental adsorption and strain data with the proposed theoretical framework, we find the adsorption-induced deformation of the monolithic sample being reasonably described by a superposition of axial and radial strains calculated on the mesopore level. The structural and mechanical parameters obtained from the model are in good agreement with expectations from independent measurements and literature, respectively.

  20. Investigation of creep deformation mechanisms at intermediate temperatures in Rene 88 DT

    International Nuclear Information System (INIS)

    Viswanathan, G.B.; Sarosi, P.M.; Henry, M.F.; Whitis, D.D.; Milligan, W.W.; Mills, M.J.

    2005-01-01

    Creep deformation substructures in the superalloy Rene 88 DT have been investigated after small-strain (0.2-0.5%) creep at 650 deg C using conventional and high resolution transmission electron microscopy. Clear differences in creep strength and deformation mechanisms have been observed as a function of applied stress and precipitate microstructure. Both coarse and fine bimodal precipitate microstructures have been tested, produced by relatively slow and fast cooling from the supersolvus solutionizing temperature. The finer γ' microstructure exhibited significantly lower creep rates. It has been established that microtwinning caused by the passage of Shockley partial dislocations on successive {1 1 1} planes is the dominant deformation process at low applied stress, and changes to shearing by 1/2[1 1 0] dislocations and Orowan looping around the larger secondary precipitates at higher applied stress. In the coarser microstructure, the dominant deformation mode is isolated faulting where 1/2[1 1 0] dislocations shear the matrix while superlattice extrinsic stacking faults are created in the secondary γ' particles. The detailed mechanisms by which these deformation modes proceed are discussed, leading to the proposition that the thermally activated process for both microtwinning and isolated faulting is similar, involving diffusion-mediated re-ordering within the γ' particles in the wake of shearing 1/6 Shockley partials. Based on the present evidence, it is proposed that the tertiary γ' volume fraction is crucial in dictating the transition in mechanism and the creep strength of these alloys

  1. Impact of silver metallization and electron irradiation on the mechanical deformation of polyimide films

    Science.gov (United States)

    Muradov, A. D.; Mukashev, K. M.; Yar-Mukhamedova, G. Sh.; Korobova, N. E.

    2017-11-01

    The impact of silver metallization and electron irradiation on the physical and mechanical properties of polyimide films has been studied. The metal that impregnated the structure of the polyimide substrate was 1-5 μm. The surface coatings contained 80-97% of the relative silver mirror in the visible and infrared regions. Irradiation was performed at the ELU-6 linear accelerator with an average beam electron energy of 2 MeV, an integral current of up to 1000 μA, a pulse repetition rate of 200 Hz, and a pulse duration of 5 μs. The absorbed dose in the samples was 10, 20, 30, and 40 MGy. The samples were deformed at room temperature under uniaxial tension on an Instron 5982 universal testing system. The structural changes in the composite materials that result from the impact of the physical factors were studied using an X-ray diffractometer DRON-2M in air at 293 K using Cu K α radiation (λαCu = 1.5418 Å). A substantial growth of mechanical characteristics resulting from the film metallization, as compared to the pure film, was observed. The growth of the ultimate strength by Δσ = 105 MPa and the plasticity by Δɛ = 75% is connected with the characteristics of the change of structure of the metallized films and the chemical etching conditions. The electron irradiation of the metallized polyimide film worsens its elastic and strength characteristics due to the formation of new phases in the form of silver oxide in the coating. The concentration of these phases increased with increasing dose, which was also the result of the violation of the ordered material structure, namely, the rupture of polyimide macromolecule bonds and the formation of new phases of silver in the coating. A mathematical model was obtained that predicts the elastic properties of silver metallized polyimide films. This model agrees with the experimental data.

  2. Tunable Mechanical Metamaterials through Hybrid Kirigami Structures.

    Science.gov (United States)

    Hwang, Doh-Gyu; Bartlett, Michael D

    2018-02-21

    Inspired by the art of paper cutting, kirigami provides intriguing tools to create materials with unconventional mechanical and morphological responses. This behavior is appealing in multiple applications such as stretchable electronics and soft robotics and presents a tractable platform to study structure-property relationships in material systems. However, mechanical response is typically controlled through a single or fractal cut type patterned across an entire kirigami sheet, limiting deformation modes and tunability. Here we show how hybrid patterns of major and minor cuts creates new opportunities to introduce boundary conditions and non-prismatic beams to enable highly tunable mechanical responses. This hybrid approach reduces stiffness by a factor of ~30 while increasing ultimate strain by a factor of 2 (up to 750% strain) relative to single incision patterns. We present analytical models and generate general design criteria that is in excellent agreement with experimental data from nanoscopic to macroscopic systems. These hybrid kirigami materials create new opportunities for multifunctional materials and structures, which we demonstrate with stretchable kirigami conductors with nearly constant electrical resistance up to >400% strain and magnetoactive actuators with extremely rapid response (>10,000% strain s -1 ) and high, repeatable elongation (>300% strain).

  3. 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.

  4. Structural evolution of a deformed Σ=9 (122) grain boundary in silicon. A high resolution electron microscopy study

    International Nuclear Information System (INIS)

    Putaux, Jean-Luc

    1991-01-01

    This research thesis addresses the study by high resolution electron microscopy of the evolution of a silicon bi-crystal under deformation at different temperatures. The author notably studied the structural evolution of the boundary as well as that of grains at the vicinity of the boundary. Two observation scales have been used: the evolution of sub-structures of dislocations induced by deformation in grains and in boundary, and the structure of all defects at an atomic scale. After a presentation of experimental tools (the necessary perfect quality of the electronic optics is outlined), the author recalls some descriptive aspects of grain boundaries (geometric network concepts to describe coinciding networks, concepts of delimiting boundaries and of structural unit to describe grain boundary atomic structure), recalls the characteristics of the studied bi-crystal, and the conditions under which it is deformed. He presents the structures of all perfectly coinciding boundaries, describes defects obtained by deformation at the vicinity of the boundary, describes the entry of dissociated dislocations into the boundaries, and discusses the characterization of boundary dislocations (the notion of Burgers vector is put into question again), and the atomic mechanism of displacement of dislocations in boundaries [fr

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    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. High Strain Rate Deformation Mechanisms of Body Centered Cubic Material Subjected to Impact Loading

    Science.gov (United States)

    Visser, William

    Low carbon steel is the most common grade of structural steel used; it has carbon content of 0.05% to 0.25% and very low content of alloying elements. It is produced in great quantities and provides material properties that are acceptable for many engineering applications, particularly in the construction industry in which low carbon steel is widely used as the strengthening phase in civil structures. The overall goal of this dissertation was to investigate the deformation response of A572 grade 50 steel when subjected to impact loading. This steel has a 0.23% by weight carbon content and has less than 2% additional alloying elements. The deformation mechanisms of this steel under shock loading conditions include both dislocation motion and twin formation. The goal of this work was achieved by performing experimental, analytical and numerical research in three integrated tasks. The first is to determine the relationship between the evolution of deformation twins and the impact pressure. Secondly, a stress criterion for twin nucleation during high strain rate loading was developed which can account for the strain history or initial dislocation density. Lastly, a method was applied for separating the effects of dislocations and twins generated by shock loading in order to determine their role in controlling the flow stress of the material. In this regard, the contents of this work have been categorically organized. First, the active mechanisms in body centered cubic (BCC) low carbon steel during shock loading have been determined as being a composed of the competing mechanisms of dislocations and deformation twins. This has been determined through a series of shock loading tests of the as-received steel. The shock loading tests were done by plate impact experiments at several impact pressures ranging from 2GPa up to 13GPa using a single stage light gas gun. A relationship between twin volume fraction and impact pressure was determined and an analytical model was

  7. Deformation behavior of carbon-fiber reinforced shape-memory-polymer composites used for deployable structures (Conference Presentation)

    Science.gov (United States)

    Lan, Xin; Liu, Liwu; Li, Fengfeng; Pan, Chengtong; Liu, Yanju; Leng, Jinsong

    2017-04-01

    Shape memory polymers (SMPs) are a new type of smart material, they perform large reversible deformation with a certain external stimulus (e.g., heat and electricity). The properties (e.g., stiffness, strength and other mechanically static or quasi-static load-bearing capacity) are primarily considered for conventional resin-based composite materials which are mainly used for structural materials. By contrast, the mechanical actuating performance with finite deformation is considered for the shape memory polymers and their composites which can be used for both structural materials and functional materials. For shape memory polymers and their composites, the performance of active deformation is expected to further promote the development in smart active deformation structures, such as deployable space structures and morphing wing aircraft. The shape memory polymer composites (SMPCs) are also one type of High Strain Composite (HSC). The space deployable structures based on carbon fiber reinforced shape memory polymer composites (SMPCs) show great prospects. Considering the problems that SMPCs are difficult to meet the practical applications in space deployable structures in the recent ten years, this paper aims to research the mechanics of deformation, actuation and failure of SMPCs. In the overall view of the shape memory polymer material's nonlinearity (nonlinearity and stress softening in the process of pre-deformation and recovery, relaxation in storage process, irreversible deformation), by the multiple verifications among theory, finite element and experiments, one obtains the deformation and actuation mechanism for the process of "pre-deformation, energy storage and actuation" and its non-fracture constraint domain. Then, the parameters of SMPCs will be optimized. Theoretical analysis is realized by the strain energy function, additionally considering the interaction strain energy between the fiber and the matrix. For the common resin-based or soft

  8. Mechanisms of plastic deformation (cyclic and monotonous) of Inconel X750

    International Nuclear Information System (INIS)

    Randrianarivony, H.

    1992-01-01

    Plastic deformation mechanisms under cyclic or monotonous solicitations, are analysed in function of Inconel X750 initial macrostructure. Two heat treated Inconel (first one is treated at 1366 K one hour, air cooled, aged at 977 K 20 hours, and air cooled, the second alloy is aged at 1158 K 24 hours, air cooled, aged at 977 K 20 hours, and air cooled), are characterized respectively by a fine and uniform precipitation of the γ' phase (approximative formulae: Ni 3 (Al,Ti)), and by a bimodal distribution of γ' precipitates. In both alloys, dislocations pairs (characteristic of a shearing by antiphase wall creation) are observed, and the crossing mechanism of the γ' precipitates by creation of overstructure pile defects is the same. But, glissile loops dislocations are less numerous than dislocations pairs in the first alloy, involving denser bands structure for this alloy (dislocations loops are always observed around γ' precipitates). Some comportment explications of Inconel X750 in PWR medium are given. (A.B.). refs., figs., tabs

  9. Morphology, deformation, and defect structures of TiCr2 in Ti-Cr alloys

    International Nuclear Information System (INIS)

    Chen, K.C.; Allen, S.M.; Livingston, J.D.

    1992-01-01

    The morphologies and defect structures of TiCr 2 in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr 2 . The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking fault, and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability

  10. Studying physical properties of deformed intact and fractured rocks by micro-scale hydro-mechanical-seismicity model

    Science.gov (United States)

    Raziperchikolaee, Samin

    The pore pressure variation in an underground formation during hydraulic stimulation of low permeability formations or CO2 sequestration into saline aquifers can induce microseismicity due to fracture generation or pre-existing fracture activation. While the analysis of microseismic data mainly focuses on mapping the location of fractures, the seismic waves generated by the microseismic events also contain information for understanding of fracture mechanisms based on microseismic source analysis. We developed a micro-scale geomechanics, fluid-flow and seismic model that can predict transport and seismic source behavior during rock failure. This model features the incorporation of microseismic source analysis in fractured and intact rock transport properties during possible rock damage and failure. The modeling method considers comprehensive grains and cements interaction through a bonded-particle-model. As a result of grain deformation and microcrack development in the rock sample, forces and displacements in the grains involved in the bond breakage are measured to determine seismic moment tensor. In addition, geometric description of the complex pore structure is regenerated to predict fluid flow behavior of fractured samples. Numerical experiments are conducted for different intact and fractured digital rock samples, representing various mechanical behaviors of rocks and fracture surface properties, to consider their roles on seismic and transport properties of rocks during deformation. Studying rock deformation in detail provides an opportunity to understand the relationship between source mechanism of microseismic events and transport properties of damaged rocks to have a better characterizing of fluid flow behavior in subsurface formations.

  11. Statics and Mechanics of Structures

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    The statics and mechanics of structures form a core aspect of civil engineering. This book provides an introduction to the subject, starting from classic hand-calculation types of analysis and gradually advancing to a systematic form suitable for computer implementation. It starts with statically...

  12. Induced deformation of the canonical structure and UV/IR duality in (1+1)D

    International Nuclear Information System (INIS)

    Grigorio, L. S.; Guimaraes, M. S.; Wotzasek, C.

    2008-01-01

    The purpose of this work is twofold. Working in the framework of (1+1)D Lorentz violating field theories, we will investigate first the general claim that fermionic interactions may be equivalent to a deformation of the canonical structure of the theory. Second, the deformed theory will be studied using duality reasoning to address the behavior of the infrared and ultraviolet regimes

  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. 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...

  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,

  16. Elasto-capillarity: deforming an elastic structure with a liquid droplet

    International Nuclear Information System (INIS)

    Roman, B; Bico, J

    2010-01-01

    Although negligible at macroscopic scales, capillary forces become dominant as the sub-millimetric scales of micro-electro-mechanical systems (MEMS) are considered. We review various situations, not limited to micro-technologies, where capillary forces are able to deform elastic structures. In particular, we define the different length scales that are relevant for 'elasto-capillary' problems. We focus on the case of slender structures (lamellae, rods and sheets) and describe the size of a bundle of wet hair, the condition for a flexible rod to pierce a liquid interface or the fate of a liquid droplet deposited on a flexible thin sheet. These results can be generalized to similar situations involving adhesion or fracture energy, which widens the scope of possible applications from biological systems, to stiction issues in micro-fabrication processes, the manufacturing of 3D microstructures or the formation of blisters in thin film coatings. (topical review)

  17. Structural mechanics and reactor safety

    International Nuclear Information System (INIS)

    Brandes, K.

    1983-01-01

    Operational safety and reliability of nuclear power plants widely depend on the mechanical behaviour of their structural components and their resistance to the various and complex influences. Durability and consistency of structural components are determined by the kind of strain - during the life - and by environmental conditions. The Conferences on Structural Mechanics in Reactor Technology (SMiRT) are dedicated to the discussion of such questions. The 7th of these Conferences taking place in 2-year increments was held in Chicago in August 1983. The number of contributions again increased, the number of participants slightly decreased. There are some trends in this field worth mentioning, in particular the fact that experience from design and operation of nuclear power plants now available is more and more made use of, and that more and more attention is given the problems of fusion reactors. (orig./HP) [de

  18. Determination of Velocity And Acceleration of Structural Deformation ...

    African Journals Online (AJOL)

    This paper outlines the procedure of geodetic monitoring system of circular oil storage ... In this study, only tank 6 was used as case study scenario for the determination of ... In this study, deformation analysis by Kalman Filter technique of the ...

  19. [Application of tibial mechanical axis locator in tibial extra-articular deformity in total knee arthroplasty].

    Science.gov (United States)

    Li, Guoliang; Han, Guangpu; Zhang, Jinxiu; Ma, Shiqiang; Guo, Donghui; Yuan, Fulu; Qi, Bingbing; Shen, Runbin

    2013-07-01

    To explore the application value of self-made tibial mechanical axis locator in tibial extra-articular deformity in total knee arthroplasty (TKA) for improving the lower extremity force line. Between January and August 2012, 13 cases (21 knees) of osteoarthritis with tibial extra-articular deformity were treated, including 5 males (8 knees) and 8 females (13 knees) with an average age of 66.5 years (range, 58-78 years). The disease duration was 2-5 years (mean, 3.5 years). The knee society score (KSS) was 45.5 +/- 15.5. Extra-articular deformities included 1 case of knee valgus (2 knees) and 12 cases of knee varus (19 knees). Preoperative full-length X-ray films of lower extremities showed 10-21 degrees valgus or varus deformity of tibial extra joint. Self-made tibial mechanical axis locator was used to determine and mark coronal tibial mechanical axis under X-ray before TKA, and then osteotomy was performed with extramedullary positioning device according to the mechanical axis marker.' All incisions healed by first intention, without related complications of infection and joint instability. All patients were followed up 5-12 months (mean, 8.3 months). The X-ray examination showed case of 2.9 degrees knee deviation angle at 3 days after operation, and the accurate rate was 95.2%. No loosening or instability of prosthesis occurred during follow-up. KSS score was 85.5 +/- 15.0 at last follow-up, showing significant difference when compared with preoperative score (t=12.82, P=0.00). The seft-made tibial mechanical axis locator can improve the accurate rate of the lower extremity force line in TKA for tibia extra-articular deformity.

  20. Phase diagram of tetradecyltrimethylammonium bromide (TTAB) + water + octanol system with application of mechanical deformation

    Science.gov (United States)

    Yavuz, Aykut Evren; Masalci, Özgür; Kazanci, Nadide

    2014-11-01

    Morphological properties of tetradecyltrimethylammonium bromide (TTAB) + water + octanol system in different concentrations have been studied. In the process, isotropic phase (L1) and nematic calamitic (NC), nematic discotic (ND), hexagonal E and lamellar D anizotropic mesophases have been determined by polarizing microscopy method and partial ternary phase diagram of the system set up. Textural properties of the anisotropic mesophases of the system have been discussed and their birefringence values measured. Mechanical deformation has been applied to the mesophases. The textural properties and the birefringence values have been observed to be changed by the deformation, after and before which changes have been compared.

  1. 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

  2. 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'allongement, les monocristaux se

  3. Simulation of CO2 Injection in Porous Media with Structural Deformation Effect

    KAUST Repository

    Negara, Ardiansyah

    2011-06-18

    Carbon dioxide (CO2) sequestration is one of the most attractive methods to reduce the amount of CO2 in the atmosphere by injecting it into the geological formations. Furthermore, it is also an effective mechanism for enhanced oil recovery. Simulation of CO2 injection based on a suitable modeling is very important for explaining the fluid flow behavior of CO2 in a reservoir. Increasing of CO2 injection may cause a structural deformation of the medium. The structural deformation modeling in carbon sequestration is useful to evaluate the medium stability to avoid CO2 leakage to the atmosphere. Therefore, it is important to include such effect into the model. The purpose of this study is to simulate the CO2 injection in a reservoir. The numerical simulations of two-phase flow in homogeneous and heterogeneous porous media are presented. Also, the effects of gravity and capillary pressure are considered. IMplicit Pressure Explicit Saturation (IMPES) and IMplicit Pressure-Displacements and an Explicit Saturation (IMPDES) schemes are used to solve the problems under consideration. Various numerical examples were simulated and divided into two parts of the study. The numerical results demonstrate the effects of buoyancy and capillary pressure as well as the permeability value and its distribution in the domain. Some conclusions that could be derived from the numerical results are the buoyancy of CO2 is driven by the density difference, the CO2 saturation profile (rate and distribution) are affected by the permeability distribution and its value, and the displacements of the porous medium go to constant values at least six to eight months (on average) after injection. Furthermore, the simulation of CO2 injection provides intuitive knowledge and a better understanding of the fluid flow behavior of CO2 in the subsurface with the deformation effect of the porous medium.

  4. Effects of mechanical deformation on energy conversion efficiency of piezoelectric nanogenerators

    International Nuclear Information System (INIS)

    Yoo, Jinho; Kim, Wook; Choi, Dukhyun; Cho, Seunghyeon; Kim, Chang-Wan; Kwon, Jang-Yeon; Kim, Hojoong; Kim, Seunghyun; Chang, Yoon-Suk

    2015-01-01

    Piezoelectric nanogenerators (PNGs) are capable of converting energy from various mechanical sources into electric energy and have many attractive features such as continuous operation, replenishment and low cost. However, many researchers still have studied novel material synthesis and interfacial controls to improve the power production from PNGs. In this study, we report the energy conversion efficiency (ECE) of PNGs dependent on mechanical deformations such as bending and twisting. Since the output power of PNGs is caused by the mechanical strain of the piezoelectric material, the power production and their ECE is critically dependent on the types of external mechanical deformations. Thus, we examine the output power from PNGs according to bending and twisting. In order to clearly understand the ECE of PNGs in the presence of those external mechanical deformations, we determine the ECE of PNGs by the ratio of output electrical energy and input mechanical energy, where we suggest that the input energy is based only on the strain energy of the piezoelectric layer. We calculate the strain energy of the piezoelectric layer using numerical simulation of bending and twisting of the PNG. Finally, we demonstrate that the ECE of the PNG caused by twisting is much higher than that caused by bending due to the multiple effects of normal and lateral piezoelectric coefficients. Our results thus provide a design direction for PNG systems as high-performance power generators. (paper)

  5. Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

    NARCIS (Netherlands)

    Simons, Frederik J.; Hilst, R.D. van der

    2003-01-01

    We interpret the three-dimensional seismic wave-speed structure of the Australian upper mantle by comparing its azimuthal anisotropy to estimates of past and present lithospheric deformation. We infer the fossil strain field from the orientation of gravity anomalies relative to topography,

  6. Imprinting of slip bands in mechanically deformed MgO crystals using lithium impurities

    Energy Technology Data Exchange (ETDEWEB)

    Orera, V M; Chen, Y; Abraham, M M

    1980-01-01

    Lithium impurities in MgO can be used to imprint slip bands produced by plastic deformation. The imprinting is obtained by means of (Li)/sup 0/ defects (subtitutional Li/sup +/ ions each with an adjacent O/sup -/ ion) which absorb light at 680 nm (1.8 eV). Slip bands are observed as discolored regions against the background of dark blue coloration due to these defects. The decoloration can be achieved by two different processes: either by oxidation at 1275 K of a deformed crystal, or by the reverse procedure - deformation of a previously oxidized crystal. The mechanisms involved in the decoloration are different; the former is due to ionic motion, and the latter is an electronic effect. Similar procedures involving surface indentation by sharp objects also result in decoloration patterns.

  7. Control of thermal deformation in dielectric mirrors using mechanical design and atomic layer deposition.

    Science.gov (United States)

    Gabriel, Nicholas T; Kim, Sangho S; Talghader, Joseph J

    2009-07-01

    A mechanical design technique for optical coatings that simultaneously controls thermal deformation and optical reflectivity is reported. The method requires measurement of the refractive index and thermal stress of single films prior to the design. Atomic layer deposition was used for deposition because of the high repeatability of the film constants. An Al2O3/HfO2 distributed Bragg reflector was deposited with a predicted peak reflectivity of 87.9% at 542.4 nm and predicted edge deformation of -360 nm/K on a 10 cm silicon substrate. The measured peak reflectivity was 85.7% at 541.7 nm with an edge deformation of -346 nm/K.

  8. 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.

  9. Coal Matrix Deformation and Pore Structure Change in High-Pressure Nitrogen Replacement of Methane

    Directory of Open Access Journals (Sweden)

    Xiaofeng Ji

    2018-01-01

    Full Text Available Coal matrix deformation is one of the main controlling factors for coal reservoir permeability changes in nitrogen foam fracturing. The characteristics and mechanism of coal matrix deformation during the process of adsorption/desorption were studied by isothermal adsorption/desorption experiments with methane and nitrogen. Based on the free-energy theories, the Langmuir equation, and elastic mechanics, mathematical models of coal matrix deformation were developed and the deformation characteristics in adsorption/desorption processes were examined. From the study, we deduced that the coal matrix swelling, caused by methane adsorption, was a Langmuir-type relationship with the gas pressure, and exponentially increased as the adsorption quantity increased. Then, the deformation rate and amplitude of the coal matrix decreased gradually with the increase of the pressure. At the following stage, where nitrogen replaces methane, the coal matrix swelling continued but the deformation amplitude decreased, which was only 19.60% of the methane adsorption stage. At the mixed gas desorption stage, the coal matrix shrank with the reduction of pressure and the shrinkage amount changed logarithmically with the pressure, which had the hysteresis effect when compared with the swelling in adsorption. The mechanism of coal matrix deformation was discussed through a comparison of the change of micropores, mesopores, and also part macropores in the adsorption process.

  10. Numerical investigation of the deformation mechanism of a bubble or a drop rising or falling in another fluid

    International Nuclear Information System (INIS)

    Wang Han; Yang Yongming; Hu Yüe; Zhang Huisheng; Zhang Zhenyu

    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. (condensed matter: structure, thermal and mechanical properties)

  11. Contraction and elongation: Mechanics underlying cell boundary deformations in epithelial tissue.

    Science.gov (United States)

    Hara, Yusuke

    2017-06-01

    The cell-cell boundaries of epithelial cells form cellular frameworks at the apical side of tissues. Deformations in these boundaries, for example, boundary contraction and elongation, and the associated forces form the mechanical basis of epithelial tissue morphogenesis. In this review, using data from recent Drosophila studies on cell boundary contraction and elongation, I provide an overview of the mechanism underlying the bi-directional deformations in the epithelial cell boundary, that are sustained by biased accumulations of junctional and apico-medial non-muscle myosin II. Moreover, how the junctional tensions exist on cell boundaries in different boundary dynamics and morphologies are discussed. Finally, some future perspectives on how recent knowledge about single cell boundary-level mechanics will contribute to our understanding of epithelial tissue morphogenesis are discussed. © 2017 Japanese Society of Developmental Biologists.

  12. 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.  

  13. 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.

  14. Cracking in reinforced concrete structures due to imposed deformations

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, A.

    1997-04-01

    This thesis is concerned with modeling of the cracking process in reinforced concrete due to imposed deformations. Cracking is investigated both at early ages, during hydration, and at mature age when the final properties of the concrete are reached. One of the most important material characteristics of the concrete at early ages, the Young`s modulus is determined by means of a dynamic method called the resonance frequency method. 40 refs

  15. 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.

  16. Fluid-Structure Interaction Mechanisms for Close-In Explosions

    Directory of Open Access Journals (Sweden)

    Andrew B. Wardlaw Jr.

    2000-01-01

    Full Text Available This paper examines fluid-structure interaction for close-in internal and external underwater explosions. The resulting flow field is impacted by the interaction between the reflected explosion shock and the explosion bubble. This shock reflects off the bubble as an expansion that reduces the pressure level between the bubble and the target, inducing cavitation and its subsequent collapse that reloads the target. Computational examples of several close-in interaction cases are presented to document the occurrence of these mechanisms. By comparing deformable and rigid body simulations, it is shown that cavitation collapse can occur solely from the shock-bubble interaction without the benefit of target deformation. Addition of a deforming target lowers the flow field pressure, facilitates cavitation and cavitation collapse, as well as reducing the impulse of the initial shock loading.

  17. THE ANALYSIS OF INTENSE-DEFORMED MONOLITHIC CONCRETE STRIP STATE OF UNDERGROUND STRUCTURES OF NONCIRCULAR OUTLINE

    Directory of Open Access Journals (Sweden)

    Maria Aleksandrovna Bauer

    2017-12-01

    Full Text Available The research results of intense deformed state (IDS of the crepe and soil massif of un-derground structures having a non-circular outline with a depth of laying up to 50 m in unstable al-luvial rocks with dumps from 0.3 to 0.7 m are presented. The study was carried out by means of modeling the IDS of the soil massif and the hardening concrete of the monolithic support, erected after slaughter moving. To implement the proposed technological solutions ensuring the fixing of underground structures with monolithic concrete, it is necessary to use particularly fast solidifying compounds to exclude the use of temporary crepe. Based on the studies of a number of modifiers, various changes in mechanical properties of the most effective compositions have been established, which are used to simulate the concrete crepe of structures with time-varying characteristics. Purpose: the basis for using resource-saving technology for the construction of underground structures in a non-circular outline in a soil massif. Methods and methodology of the work: the studies were carried out by means of the finite element method (FEM using the optimal design of the experiment. Results: stress distributions were obtained in the hardening concrete crepe structures, stress concentration zones were established, displacement values in the soil massif and their spread on the surface were recieved. Areas of the result application: the results of research work can be used in the design of options for the construction of underground structures.

  18. 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.

  19. The Effect of Bedding Structure on Mechanical Property of Coal

    Directory of Open Access Journals (Sweden)

    Zetian Zhang

    2014-01-01

    Full Text Available The mechanical property of coal, influencing mining activity considerably, is significantly determined by the natural fracture distributed within coal mass. In order to study the effecting mechanism of bedding structure on mechanical property of coal, a series of uniaxial compression tests and mesoscopic tests have been conducted. The experimental results show that the distribution characteristic of calcite particles, which significantly influences the growth of cracks and the macroscopic mechanical properties of coal, is obviously affected by the bedding structure. Specifically, the uniaxial compression strength of coal sample is mainly controlled by bedding structure, and the average peak stress of specimens with axes perpendicular to the bedding planes is 20.00 MPa, which is 2.88 times the average amount of parallel ones. The test results also show a close relationship between the bedding structure and the whole deformation process under uniaxial loading.

  20. 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. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Mechanical and microstructural aspects of severe plastic deformation of austenitic steel

    Science.gov (United States)

    Rodak, K.; Pawlicki, J.; Tkocz, M.

    2012-05-01

    The paper presents the effects of severe plastic deformation by multiple compression in the orthogonal directions on the microstructure and the mechanical properties of austenitic steel. Several deformation variants were conducted with different number of passes. FEM simulations were performed in order to evaluate the actual values of the effective strain in the examined, central parts of the compressed samples. The deformed microstructure was investigated by means of the scanning transmission electron microscopy (STEM) and the scanning electron microscopy (SEM) supported by the electron back scattered diffraction (EBSD). X-ray phase analysis was performed to evaluate the martensite volume fraction. The mechanical properties were determined by means of the digital image correlation method and hardness testing. It is shown that the applied forming technique leads to strong grain refinement in the austenitic steel. Moreover, deformation induces the martensitic γ- α' transformation. The microstructural changes cause an improvement in the strength properties. The material exhibits the ultimate tensile strength of 1560 MPa and the yield stress of 1500 MPa after reaching the effective strain of 10.

  2. Mechanical and microstructural aspects of severe plastic deformation of austenitic steel

    International Nuclear Information System (INIS)

    Rodak, K; Pawlicki, J; Tkocz, M

    2012-01-01

    The paper presents the effects of severe plastic deformation by multiple compression in the orthogonal directions on the microstructure and the mechanical properties of austenitic steel. Several deformation variants were conducted with different number of passes. FEM simulations were performed in order to evaluate the actual values of the effective strain in the examined, central parts of the compressed samples. The deformed microstructure was investigated by means of the scanning transmission electron microscopy (STEM) and the scanning electron microscopy (SEM) supported by the electron back scattered diffraction (EBSD). X-ray phase analysis was performed to evaluate the martensite volume fraction. The mechanical properties were determined by means of the digital image correlation method and hardness testing. It is shown that the applied forming technique leads to strong grain refinement in the austenitic steel. Moreover, deformation induces the martensitic γ– α' transformation. The microstructural changes cause an improvement in the strength properties. The material exhibits the ultimate tensile strength of 1560 MPa and the yield stress of 1500 MPa after reaching the effective strain of 10.

  3. Internal deformation in layered Zechstein-III K-Mg salts. Structures formed by complex deformation and high contrasts in viscosity observed in drill cores.

    Science.gov (United States)

    Raith, Alexander; Urai, Janos L.

    2016-04-01

    During the evaporation of a massive salt body, alternations of interrupted and full evaporation sequences can form a complex layering of different lithologies. Viscosity contrasts of up to five orders of magnitude between these different lithologies are possible in this environment. During the late stage of an evaporation cycle potassium and magnesium (K-Mg) salts are precipitated. These K-Mg salts are of economic interest but also a known drilling hazard due to their very low viscosity. How up to 200m thick layers of these evaporites affect salt deformation at different scales is not well known. A better understanding of salt tectonics with extreme mechanical stratification is needed for better exploration and production of potassium-magnesium salts and to predict the internal structure of potential nuclear waste repositories in salt. To gain a better understanding of the internal deformation of these layers we analyzed K-Mg salt rich drill cores out of the Zechstein III-1b subunit from the Veendam Pillow 10 km southeast of Groningen, near the city Veendam in the NE Netherlands. The study area has a complex geological history with multiple tectonic phases of extension and compression forming internal deformation in the pillow but also conserving most of the original layering. Beside halite the most common minerals in the ZIII-1b are carnallite, kieserite, anhydrite and bischofite alternating in thin layers of simple composition. Seismic interpretation revealed that the internal structure of the Veendam Pillow shows areas, in which the K-Mg salt rich ZIII 1b layer is much thicker than elsewhere, as a result of salt deformation. The internal structure of the ZIII-1b on the other hand, remains unknown. The core analysis shows a strong strain concentration in the weaker Bischofite (MgCl2*6H20) and Carnallite (KMgCl3*6H20) rich layers producing tectonic breccias and highly strained layers completely overprinting the original layering. Layers formed by alternating beds

  4. A MRI-Compatible Combined Mechanical Loading and MR Elastography Setup to Study Deformation-Induced Skeletal Muscle Damage in Rats

    NARCIS (Netherlands)

    Nelissen, Jules L.; de Graaf, Larry; Traa, Willeke A.; Schreurs, Tom J. L.; Moerman, Kevin M.; Nederveen, Aart J.; Sinkus, Ralph; Oomens, Cees W. J.; Nicolay, Klaas; Strijkers, Gustav J.

    2017-01-01

    Deformation of skeletal muscle in the proximity of bony structures may lead to deep tissue injury category of pressure ulcers. Changes in mechanical properties have been proposed as a risk factor in the development of deep tissue injury and may be useful as a diagnostic tool for early detection. MRE

  5. Dislocations structure in copper cyclically deformed in low amplitude of deformation

    International Nuclear Information System (INIS)

    Lopes, L.C.R.

    1982-07-01

    The evolution of the dislocation structure during the fatigue life of copper, was observed. Fatigue tests were performed, in annealed polycristals, with constant plastic strain amplitude, and interrupted at different percentages of their fatigue lives. Optical and Scanning Electron Microscopy were used for surface analysis and Transmission Electron Microscopy for structural observations. (E.G.) [pt

  6. Correlation between fuel structure and mechanical properties of UO2

    International Nuclear Information System (INIS)

    Blank, H.; Mandler, R.; Matzke, H.; Routbort, J.; Werner, P.

    1982-10-01

    The relation between the structure of a UO 2 fuel and its mechanical properties are discussed and illustrated for particular types of UO 2 by measurements of fracture surface energy, hardness, fracture stress and of compressive deformation at 1870 and 1970 0 K. This gives the background for treating the question whether it is possible to find a simple experimental method for correlating the mechanical properties of UO 2 before irradiation with those after various irradiation histories. Hardness measurements might be such a method if combined with a detailed structural analysis and sufficient knowledge about the irradiation history

  7. Effect of Cooling Mode on Microstructure and Mechanical Properties of Pipeline Steel for Strain Based Design and Research on its Deformation Mechanism

    Science.gov (United States)

    Hesong, Zhang; Yonglin, Kang

    With the rapid development of oil and gas industry long distance pipelines inevitably pass through regions with complex geological activities. In order to avoid large deformation the pipelines must be designed based on strain criteria. In this paper the alloy system of X80 high deformability pipeline steel was designed which was 0.25%Mo-0.05%C-1.75%Mn. The effect of controlled cooling process on microstructure and mechanical properties of X80 high deformability pipeline steel were systematically investigated. Through the two-stage controlled cooling process the microstructure of the X80 high deformability pipeline steel were ferrite, bainite and M/A island. There were two kinds of ferrite which were polygonal ferrite (PF) and quasi-polygonal ferrite (QF). The bainite was granular bainite ferrite (GF). Along with the decrease of the start cooling temperature, the volume fraction of ferrite and M/A both increased, the yield ratio (Y/T) decreased, the uniform elongation (uEl) increased firstly with the content of ferrite increased but then decreased with the content and size of M/A increased. When the finish cooling temperature decreasing, the size of M/A became finer. As the start cooling temperature was 690 °C and the finish cooling temperature was 450 °C the volume fraction of ferrite was 23%, the size of ferrite grain was 5μm, the size of M/A island was below 1μm and the structure uniformity was the best. The deformation mechanism of X80 high deformability pipeline steel was analyzed. The best way to improve the work hardening rate was reducing the size of M/A islands on the premise of a certain volume fraction. The decreasing path of instantaneous strain hardening index (n*-value) showed three stages in the deformation process. The n*-value kept stable in the second stage, the reason was that the retained austenite transformed into martensite and the phase transition improved the strain hardening ability of the microstructure. This phenomenon was called

  8. Mechanical and microstructural characteristics of an Al-Li-Cu-Zr alloy during superplastic deformation

    International Nuclear Information System (INIS)

    Ren, B.

    1991-01-01

    If the above alloys are heavily cold- or warm-worked prior to superplastic deformation, they are resistant to static recrystallization but dynamically recrystallize with a clear strain dependence, and are superplastic deformable at relative high strain rates in the approximate range of 10 -3 to 10 -1 s -1 . The microstructural source of superplasticity has been the subject of less-detailed study than the more classical fully recrystallized materials. In this study, an effort was made to provide a somewhat greater insight into the mechanical behavior during the dynamic recrystallization of an Al-Li-Cu-Zr alloy, and to relate the mechanical behavior to the microstructure and its evolution. As part of the study, internal stresses were measured by the strain dip test, and effective stresses and their development were determined over a range of temperatures and strain rates. mechanisms for the superplastic flow and the internal-stress development during the initial stage of deformation were suggested. A variable-strain-rate model was developed based on the understanding of the mechanical behavior of this material

  9. Acoustic emission generated by dislocation mechanisms during the deformation of metals

    Energy Technology Data Exchange (ETDEWEB)

    Heiple, C.R.

    1978-01-01

    Acoustic emission is a transient elastic wave generated by the rapid release of energy within a material. A wide variety of mechanisms have been proposed as possible sources of acoustic emission. Proposed mechanisms have included crack propagation, precipitate fracture, twin formation, martensite formation, dislocation motion and/or multiplication. This paper is concerned with acoustic emission generated by dislocation mechanisms operating during plastic deformation. Twinning and martensitic phase transformations are excluded even though dislocation motion is involved in the nucleation and growth of twins and the growth of martensite.

  10. Acoustic emission generated by dislocation mechanisms during the deformation of metals

    International Nuclear Information System (INIS)

    Heiple, C.R.

    1978-01-01

    Acoustic emission is a transient elastic wave generated by the rapid release of energy within a material. A wide variety of mechanisms have been proposed as possible sources of acoustic emission. Proposed mechanisms have included crack propagation, precipitate fracture, twin formation, martensite formation, dislocation motion and/or multiplication. This paper is concerned with acoustic emission generated by dislocation mechanisms operating during plastic deformation. Twinning and martensitic phase transformations are excluded even though dislocation motion is involved in the nucleation and growth of twins and the growth of martensite

  11. Collapse Mechanisms Of Masonry Structures

    International Nuclear Information System (INIS)

    Zuccaro, G.; Rauci, M.

    2008-01-01

    The paper outlines a possible approach to typology recognition, safety check analyses and/or damage measuring taking advantage by a multimedia tool (MEDEA), tracing a guided procedure useful for seismic safety check evaluation and post event macroseismic assessment. A list of the possible collapse mechanisms observed in the post event surveys on masonry structures and a complete abacus of the damages are provided in MEDEA. In this tool a possible combination between a set of damage typologies and each collapse mechanism is supplied in order to improve the homogeneity of the damages interpretation. On the other hand recent researches of one of the author have selected a number of possible typological vulnerability factors of masonry buildings, these are listed in the paper and combined with potential collapse mechanisms to be activated under seismic excitation. The procedure takes place from simple structural behavior models, derived from the Umbria-Marche earthquake observations, and tested after the San Giuliano di Puglia event; it provides the basis either for safety check analyses of the existing buildings or for post-event structural safety assessment and economic damage evaluation. In the paper taking advantage of MEDEA mechanisms analysis, mainly developed for the post event safety check surveyors training, a simple logic path is traced in order to approach the evaluation of the masonry building safety check. The procedure starts from the identification of the typological vulnerability factors to derive the potential collapse mechanisms and their collapse multipliers and finally addresses the simplest and cheapest strengthening techniques to reduce the original vulnerability. The procedure has been introduced in the Guide Lines of the Regione Campania for the professionals in charge of the safety check analyses and the buildings strengthening in application of the national mitigation campaign introduced by the Ordinance of the Central Government n. 3362

  12. Emergence of coherent localized structures in shear deformations of temperature dependent fluids

    KAUST Repository

    Katsaounis, Theodoros

    2016-11-25

    Shear localization occurs in various instances of material instability in solid mechanics and is typically associated with Hadamard-instability for an underlying model. While Hadamard instability indicates the catastrophic growth of oscillations around a mean state, it does not by itself explain the formation of coherent structures typically observed in localization. The latter is a nonlinear effect and its analysis is the main objective of this article. We consider a model that captures the main mechanisms observed in high strain-rate deformation of metals, and describes shear motions of temperature dependent non-Newtonian fluids. For a special dependence of the viscosity on the temperature, we carry out a linearized stability analysis around a base state of uniform shearing solutions, and quantitatively assess the effects of the various mechanisms affecting the problem: thermal softening, momentum diffusion and thermal diffusion. Then, we turn to the nonlinear model, and construct localized states - in the form of similarity solutions - that emerge as coherent structures in the localization process. This justifies a scenario for localization that is proposed on the basis of asymptotic analysis in \\\\cite{KT}.

  13. Emergence of coherent localized structures in shear deformations of temperature dependent fluids

    KAUST Repository

    Katsaounis, Theodoros; Olivier, Julien; Tzavaras, Athanasios

    2016-01-01

    Shear localization occurs in various instances of material instability in solid mechanics and is typically associated with Hadamard-instability for an underlying model. While Hadamard instability indicates the catastrophic growth of oscillations around a mean state, it does not by itself explain the formation of coherent structures typically observed in localization. The latter is a nonlinear effect and its analysis is the main objective of this article. We consider a model that captures the main mechanisms observed in high strain-rate deformation of metals, and describes shear motions of temperature dependent non-Newtonian fluids. For a special dependence of the viscosity on the temperature, we carry out a linearized stability analysis around a base state of uniform shearing solutions, and quantitatively assess the effects of the various mechanisms affecting the problem: thermal softening, momentum diffusion and thermal diffusion. Then, we turn to the nonlinear model, and construct localized states - in the form of similarity solutions - that emerge as coherent structures in the localization process. This justifies a scenario for localization that is proposed on the basis of asymptotic analysis in \\cite{KT}.

  14. Dislocation structure evolution and characterization in the compression deformed Mn-Cu alloy

    International Nuclear Information System (INIS)

    Zhong, Y.; Yin, F.; Sakaguchi, T.; Nagai, K.; Yang, K.

    2007-01-01

    Dislocation densities and dislocation structure arrangements in cold compressed polycrystalline commercial M2052 (Mn-20Cu-5Ni-2Fe) high damping alloy with various strains were determined in scanning mode by X-ray peak profile analysis and electron backscatter diffraction (EBSD). The results indicate that the Mn-Cu-Ni-Fe alloy has an evolution behavior quite similar to the dislocation structure in copper. The dislocation arrangement parameter shows a local minimum in the transition range between stages III and IV that can be related to the transformation of the dislocation arrangement in the cell walls from a polarized dipole wall (PDW) into a polarized tile wall (PTW) structure. This evolution is further confirmed by the results of local misorientation determined by EBSD. In addition, during deformation, the multiplication of dislocation densities in the MnCu alloy is significantly slower than that in copper, and the transition of the dislocation structure is strongly retarded in the MnCu alloy compared with copper. These results can be explained by the mechanism of elastic anisotropy on the dislocation dynamics, as the elastic anisotropy in the MnCu alloy is larger than that in copper, which can strongly retard the multiplication of the dislocation population and the transformation of the dislocation structure. These results are important for research into the plastic working behavior of Mn-Cu-Ni-Fe high damping alloy

  15. Illustrating the Molecular Origin of Mechanical Stress in Ductile Deformation of Polymer Glasses

    Science.gov (United States)

    Li, Xiaoxiao; Liu, Jianning; Liu, Zhuonan; Tsige, Mesfin; Wang, Shi-Qing

    2018-02-01

    New experiments show that tensile stress vanishes shortly after preyield deformation of polymer glasses while tensile stress after postyield deformation stays high and relaxes on much longer time scales, thus hinting at a specific molecular origin of stress in ductile cold drawing: chain tension rather than intersegmental interactions. Molecular dynamics simulation based on a coarse-grained model for polystyrene confirms the conclusion that the chain network plays an essential role, causing the glassy state to yield and to respond with a high level of intrachain retractive stress. This identification sheds light on the future development regarding an improved theoretical account for molecular mechanics of polymer glasses and the molecular design of stronger polymeric materials to enhance their mechanical performance.

  16. Effect of deformation and annealing on mechanical properties of nickel-rhenium alloys

    International Nuclear Information System (INIS)

    Mashkova, V.M.

    1978-01-01

    Studied have been the mechanical properties of nickel-rhenium alloys, depending on the extent of deformation and heat treatment leading to softening. The mechanical properties of the alloys have been estimated by the results of the tensile tests of wire samples. The softening of the alloy at different temperatures is judged about by the variation in hardness. The results of the study indicate that the most abrupt reduction in the hardness of the cold-hardened metal occurs at 900-1,000 deg C and the hold-time of 1 min. Increase in the hold-time at such temperature almost does not reduce the hardness. It is established that in order to soften nickel-rhenium alloys in the process of the cold-deformation at brief annealings in the air the hold-time should not exceed 5 min at 800-900 deg C

  17. Illustrating the Molecular Origin of Mechanical Stress in Ductile Deformation of Polymer Glasses.

    Science.gov (United States)

    Li, Xiaoxiao; Liu, Jianning; Liu, Zhuonan; Tsige, Mesfin; Wang, Shi-Qing

    2018-02-16

    New experiments show that tensile stress vanishes shortly after preyield deformation of polymer glasses while tensile stress after postyield deformation stays high and relaxes on much longer time scales, thus hinting at a specific molecular origin of stress in ductile cold drawing: chain tension rather than intersegmental interactions. Molecular dynamics simulation based on a coarse-grained model for polystyrene confirms the conclusion that the chain network plays an essential role, causing the glassy state to yield and to respond with a high level of intrachain retractive stress. This identification sheds light on the future development regarding an improved theoretical account for molecular mechanics of polymer glasses and the molecular design of stronger polymeric materials to enhance their mechanical performance.

  18. On the dynamic mechanical property and deformation mechanism of as-extruded Mg-Sn-Ca alloys under tension

    International Nuclear Information System (INIS)

    Huang, Qiuyan; Pan, Hucheng; Tang, Aitao; Ren, Yuping; Song, Bo; Qin, Gaowu; Zhang, Mingxing; Pan, Fusheng

    2016-01-01

    To further understand the deformation mechanism of magnesium alloys and expand their applications under dynamic conditions, the newly developed Mg-2Sn-1Ca alloy (TX21) is selected as the representative sample and tested under wide loading rate ranging from quasi-static to dynamic level (10"−"3–500/s). Both ultimate tensile strength and elongation of the as-extruded TX21 alloys increase with strain rate. Although twinning is accompanied due to the enhanced activity at higher strain rate, the preferential activation of dislocations is readily clarified and confirmed as the dominant deformation modes. Active interactions of pyramidal dislocations result in the higher strain hardening ability and could be correlated to the obviously positive strain-rate sensitivity for mechanical properties. Moreover, it is observed that the larger grain size and higher content of solute atoms dissolved in matrix would lead to the more active dislocations and twinning formations. The present results would provide insight into further understanding the deformation mechanism under dynamic rate loading and designing Mg alloy suitable for impact conditions.

  19. On the dynamic mechanical property and deformation mechanism of as-extruded Mg-Sn-Ca alloys under tension

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qiuyan [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Pan, Hucheng [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Tang, Aitao, E-mail: tat@cqu.edu.cn [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Ren, Yuping [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Song, Bo [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Qin, Gaowu, E-mail: qingw@smm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Zhang, Mingxing [School of Mechanical and Mining Engineering, University of Queensland, St Lucia, QLD 4072 (Australia); Pan, Fusheng [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

    2016-05-10

    To further understand the deformation mechanism of magnesium alloys and expand their applications under dynamic conditions, the newly developed Mg-2Sn-1Ca alloy (TX21) is selected as the representative sample and tested under wide loading rate ranging from quasi-static to dynamic level (10{sup −3}–500/s). Both ultimate tensile strength and elongation of the as-extruded TX21 alloys increase with strain rate. Although twinning is accompanied due to the enhanced activity at higher strain rate, the preferential activation of dislocations is readily clarified and confirmed as the dominant deformation modes. Active interactions of pyramidal dislocations result in the higher strain hardening ability and could be correlated to the obviously positive strain-rate sensitivity for mechanical properties. Moreover, it is observed that the larger grain size and higher content of solute atoms dissolved in matrix would lead to the more active dislocations and twinning formations. The present results would provide insight into further understanding the deformation mechanism under dynamic rate loading and designing Mg alloy suitable for impact conditions.

  20. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. 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.

  2. Earthquake-induced soft-sediment deformation structures in Late Pleistocene lacustrine deposits of Issyk-Kul lake (Kyrgyzstan)

    Science.gov (United States)

    Gladkov, A. S.; Lobova, E. U.; Deev, E. V.; Korzhenkov, A. M.; Mazeika, J. V.; Abdieva, S. V.; Rogozhin, E. A.; Rodkin, M. V.; Fortuna, A. B.; Charimov, T. A.; Yudakhin, A. S.

    2016-10-01

    This paper discusses the composition and distribution of soft-sediment deformation structures induced by liquefaction in Late Pleistocene lacustrine terrace deposits on the southern shore of Issyk-Kul Lake in the northern Tien Shan mountains of Kyrgyzstan. The section contains seven deformed beds grouped in two intervals. Five deformed beds in the upper interval contain load structures (load casts and flame structures), convolute lamination, ball-and-pillow structures, folds and slumps. Deformation patterns indicate that a seismic trigger generated a multiple slump on a gentle slope. The dating of overlying subaerial deposits suggests correlation between the deformation features and strong earthquakes in the Late Pleistocene.

  3. Hot deformation of polycrystalline uranium dioxide: from microscopic mechanisms to macroscopic behaviour

    International Nuclear Information System (INIS)

    Dherbey, Francine

    2000-01-01

    The improvement of nuclear fuels performances in PWR requires in particular an enhancement of creep ability of uranium dioxide in order to minimise rupture risks of the cladding material during interactions between pellets and cladding. The aim of this study is to investigate the link between the ceramic macroscopic thermo-mechanical behaviour and the changes in the fuel microstructure during deformation. Stoichiometric UO 2 pellets with various grains sizes from 9 pm to 36 μm have been deformed by compression at intermediate temperatures, i.e. near T M /2, and quenched under stress. The damage is characterised by the presence of cavities at low stresses and cracks at high stresses, both along grain boundaries parallel to the compression axis. Inside grains, dislocations organise themselves into cellular substructures in which sub-boundaries are made of dislocation hexagonal networks. In these conditions, uranium dioxide deformation is described by grain boundary sliding, which is the main origin of material damage, partially accommodated by dislocational creep inside grains. A steady-state creep model is proposed on a physical basis. It accounts for the almost similar contributions of two mechanisms which are grain boundaries sliding and intragranular creep, and takes into account the grain boundary roughness. In contrast with phenomenological descriptions used up to now, this picture leads to a unique creep law on the whole range of stresses explored here, from 10 MPa to 80 MPa. The creep rate controlling mechanism seems to be the migration of sub-boundaries. The deformation at constant strain rate is controlled by the same mechanisms as creep. (author) [fr

  4. Chapter 4. Fundamental mechanisms of the low temperature plastic deformation of metals

    International Nuclear Information System (INIS)

    Fouquet, J. de

    1976-01-01

    The influence of microstructure, grain boundaries, and strain hardening, on the low temperature plasticity of polycristals is studied. The experimental data on flow stress, work hardening, temperature and strain rate effects, alloying elements and grain size effect are firstly considered, on a macroscopic scale. The mechanisms of the low temperature plastic deformation, and the strain-stress relations are then described in terms of slip modes, mobility, configuration and distributions and interactions of dislocations [fr

  5. Quasi-static and dynamic compressive deformation of a bulk nanolayered Ag–Cu eutectic alloy: Macroscopic response and dominant deformation mechanisms

    International Nuclear Information System (INIS)

    Kingstedt, O.T.; Eftink, B.; Lambros, J.; Robertson, I.M.

    2014-01-01

    Nanostructured multilayered material systems offer an attractive method of increasing material strength. This work examines the response of a bulk eutectic silver–copper material (Ag 60 Cu 40 , subscripts indicating atomic percent) which has a hierarchical structure of alternating Ag and Cu layers with thicknesses down to 50 nm. The hierarchical structure consists of two primary arrangements of layers, eutectic colonies of parallel layers, most commonly found at the material interior, and “grains” consisting of alternating Ag and Cu layers which emanate from a central region in a radial pattern, most commonly found at the material exterior surface. We show that the hierarchical structure causes a significant increase in the measured strength response when comparing the Ag 60 Cu 40 response to that of the constituent materials in their bulk nanograined or micrograined form. The deformation mechanisms of this material are studied under compressive loading over the quasi-static and dynamic regime (10 −3 –10 3 s −1 ) with strain between 5% and 50%

  6. Fluid-structure interaction analysis of deformation of sail of 30-foot yacht

    Science.gov (United States)

    Bak, Sera; Yoo, Jaehoon; Song, Chang Yong

    2013-06-01

    Most yacht sails are made of thin fabric, and they have a cambered shape to generate lift force; however, their shape can be easily deformed by wind pressure. Deformation of the sail shape changes the flow characteristics over the sail, which in turn further deforms the sail shape. Therefore, fluid-structure interaction (FSI) analysis is applied for the precise evaluation or optimization of the sail design. In this study, fluid flow analyses are performed for the main sail of a 30-foot yacht, and the results are applied to loading conditions for structural analyses. By applying the supporting forces from the rig, such as the mast and boom-end outhaul, as boundary conditions for structural analysis, the deformed sail shape is identified. Both the flow analyses and the structural analyses are iteratively carried out for the deformed sail shape. A comparison of the flow characteristics and surface pressures over the deformed sail shape with those over the initial shape shows that a considerable difference exists between the two and that FSI analysis is suitable for application to sail design.

  7. Fluid-structure interaction analysis of deformation of sail of 30-foot yacht

    Directory of Open Access Journals (Sweden)

    Sera Bak

    2013-06-01

    Full Text Available Most yacht sails are made of thin fabric, and they have a cambered shape to generate lift force; however, their shape can be easily deformed by wind pressure. Deformation of the sail shape changes the flow characteristics over the sail, which in turn further deforms the sail shape. Therefore, fluid-structure interaction (FSI analysis is applied for the precise evaluation or optimization of the sail design. In this study, fluid flow analyses are performed for the main sail of a 30-foot yacht, and the results are applied to loading conditions for structural analyses. By applying the supporting forces from the rig, such as the mast and boom-end outhaul, as boundary conditions for structural analysis, the deformed sail shape is identified. Both the flow analyses and the structural analyses are iteratively carried out for the deformed sail shape. A comparison of the flow characteristics and surface pressures over the deformed sail shape with those over the initial shape shows that a considerable difference exists between the two and that FSI analysis is suitable for application to sail design.

  8. Synthetically chemical-electrical mechanism for controlling large scale reversible deformation of liquid metal objects

    Science.gov (United States)

    Zhang, Jie; Sheng, Lei; Liu, Jing

    2014-11-01

    Reversible deformation of a machine holds enormous promise across many scientific areas ranging from mechanical engineering to applied physics. So far, such capabilities are still hard to achieve through conventional rigid materials or depending mainly on elastomeric materials, which however own rather limited performances and require complicated manipulations. Here, we show a basic strategy which is fundamentally different from the existing ones to realize large scale reversible deformation through controlling the working materials via the synthetically chemical-electrical mechanism (SCHEME). Such activity incorporates an object of liquid metal gallium whose surface area could spread up to five times of its original size and vice versa under low energy consumption. Particularly, the alterable surface tension based on combination of chemical dissolution and electrochemical oxidation is ascribed to the reversible shape transformation, which works much more flexible than many former deformation principles through converting electrical energy into mechanical movement. A series of very unusual phenomena regarding the reversible configurational shifts are disclosed with dominant factors clarified. This study opens a generalized way to combine the liquid metal serving as shape-variable element with the SCHEME to compose functional soft machines, which implies huge potential for developing future smart robots to fulfill various complicated tasks.

  9. Experiment study on failure mechanism of Bai Huichang landslide and analysis on time effect of deformation

    Energy Technology Data Exchange (ETDEWEB)

    Ronghua, Fu; Baokui, Yao; Yuke, Sun

    1985-01-01

    Bai Huichang landslide is a large scale landslide which is of the character of leveled pushing slide and collapse. To study the failure mechanism of the landslide, to analyse the reasons for failure of the landslide, to evaluate and to predict the stability of the slope, systematic tests of physico-mechanical properties of the clay rock on the sliding surface and analysis of the constituents of the substances are made. Tests on slope models made of photo-elastic material and of blocks are made. The results show that the landslide is a typical one with leveled pushing slide and collapse character, and the main reason for the landslide is the poor physico-mechanical properties and the poor water-stable properties of the clay rock which contain a vast amount of the montmorillonite. The deformation of the slope model is very similar to that of the actual slope. Regression analysis of the observed deformation of the slope indicates that the deformation decays at a rate about 70% each year. It means that the landslide will tend to be stable and no serious landslide will occur which will endanger the safety of Changhangou Colliery. 3 references.

  10. Analytical magmatic source modelling from a joint inversion of ground deformation and focal mechanisms data

    Science.gov (United States)

    Cannavo', Flavio; Scandura, Danila; Palano, Mimmo; Musumeci, Carla

    2014-05-01

    Seismicity and ground deformation represent the principal geophysical methods for volcano monitoring and provide important constraints on subsurface magma movements. The occurrence of migrating seismic swarms, as observed at several volcanoes worldwide, are commonly associated with dike intrusions. In addition, on active volcanoes, (de)pressurization and/or intrusion of magmatic bodies stress and deform the surrounding crustal rocks, often causing earthquakes randomly distributed in time within a volume extending about 5-10 km from the wall of the magmatic bodies. Despite advances in space-based, geodetic and seismic networks have significantly improved volcano monitoring in the last decades on an increasing worldwide number of volcanoes, quantitative models relating deformation and seismicity are not common. The observation of several episodes of volcanic unrest throughout the world, where the movement of magma through the shallow crust was able to produce local rotation of the ambient stress field, introduces an opportunity to improve the estimate of the parameters of a deformation source. In particular, during these episodes of volcanic unrest a radial pattern of P-axes of the focal mechanism solutions, similar to that of ground deformation, has been observed. Therefore, taking into account additional information from focal mechanisms data, we propose a novel approach to volcanic source modeling based on the joint inversion of deformation and focal plane solutions assuming that both observations are due to the same source. The methodology is first verified against a synthetic dataset of surface deformation and strain within the medium, and then applied to real data from an unrest episode occurred before the May 13th 2008 eruption at Mt. Etna (Italy). The main results clearly indicate as the joint inversion improves the accuracy of the estimated source parameters of about 70%. The statistical tests indicate that the source depth is the parameter with the highest

  11. Lifetime Reliability Estimate and Extreme Permanent Deformations of Randomly Excited Elasto-Plastic Structures

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1983-01-01

    plastic deformation during several loadings can be modelled as a filtered Poisson process. Using the Markov property of this quantity the considered first-passage problem as well as the related extreme distribution problems are then solved numerically, and the results are compared to simulation studies.......A method is presented for life-time reliability' estimates of randomly excited yielding systems, assuming the structure to be safe, when the plastic deformations are confined below certain limits. The accumulated plastic deformations during any single significant loading history are considered...

  12. Mechanical instability in non-uniform atomic structure: Application to amorphous metal

    International Nuclear Information System (INIS)

    Umeno, Yoshitaka; Kitamura, Takayuki; Tagawa, Motoki

    2007-01-01

    It is important to reveal the deformation of amorphous metal in the atomistic scale level as materials with non-crystal structure have been attracting attention with their prominent functions. In this paper atomistic simulations of tensile deformation of an amorphous model are conducted and local mechanical instability is analyzed to clarify the deformation mechanism of the amorphous structure. Instability causing sharp stress drop is associated with unstable motion of atoms within local region. The size of the region where the unstable atomic motion occurs corresponds to the magnitude of total stress decrease. At instability with large stress decrease the deformation at the onset of the instability propagates to surrounding region, which gives rise to a hysteresis loop in the stress-strain relation. This manifests the microscopic mechanism of the plasticity of amorphous structure

  13. A Structural Analysis of a Mechanical Heart Valve Prosthesis with Flat Leaflet

    Science.gov (United States)

    Kwon, Young Joo

    This paper addresses the basic concept of MDO methodology and the structural analysis that should be performed in the design process of a mechanical heart valve prosthesis with flat leaflet using MDO methodology. In the structural design of the mechanical heart valve (MHV) prosthesis, the fluid mechanics analysis is executed for the blood flow passing through the leaflets of a mechanical heart valve prosthesis. Thereafter, the rigid body dynamics analysis of the leaflet motion is performed to obtain the structural condition for the structural mechanics analysis of the deformed leaflet. Then the structural mechanics analysis of the deformed leaflet follows to confirm the minimum thickness of the leaflet for the structural durability of the mechanical heart valve prosthesis. This paper shows that the minimum leaflet thickness can be evaluated to be 0.6mm among the suggested thicknesses.

  14. Micro-structural evolution in plastically deformed crystalline materials

    DEFF Research Database (Denmark)

    Nellemann, Christopher

    predictions for the two models to be obtained. Application of the two models to the pure shear boundary value problem is used to characterize plastic behavior, which also allows for the identification of inherent properties through closed form expressions. Single crystal Monazite containing a void is studied......Two rate-independent strain gradient crystal plasticity models are developed and applied in numerical studies designed to identify the properties inherent to model predictions of plastic deformation. The two models incorporate gradients of slip into the framework of conventional crystal plasticity...... in order to model size-dependent plasticity effects. This gradient dependence is achieved by relating a slip measure which combines both slip and their gradients to a shear hardening curve, as commonly done in conventional plasticity theories. Finite element codes are implemented which allow for numerical...

  15. A unified approach to the analysis and design of elasto-plastic structures with mechanical contact

    Science.gov (United States)

    Bendsoe, Martin P.; Olhoff, Niels; Taylor, John E.

    1990-01-01

    With structural design in mind, a new unified variational model has been developed which represents the mechanics of deformation elasto-plasticity with unilateral contact conditions. For a design problem formulated as maximization of the load carrying capacity of a structure under certain constraints, the unified model allows for a simultaneous analysis and design synthesis for a whole range of mechanical behavior.

  16. Influence of deformation on structural-phase state of weld material in St3 steel

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Alexander, E-mail: galvas.kem@gmail.ru; Ababkov, Nicolay, E-mail: n.ababkov@rambler.ru; Ozhiganov, Yevgeniy, E-mail: zhigan84@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); LLC “Kuzbass Center of Welding and Control”, 33/2, Lenin Str., 650055, Kemerovo (Russian Federation); Kozlov, Eduard, E-mail: kozlov@tsuab.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Zboykova, Nadezhda, E-mail: tezaurusn@gmail.com; Koneva, Nina, E-mail: koneva@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation)

    2016-01-15

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn’t lead to the internal stresses that can destroy the sample.

  17. Mechanism of texture formation by hot deformation in rapidly quenched FeNdB

    International Nuclear Information System (INIS)

    Li, L.; Graham, C.D. Jr.

    1990-01-01

    The development of crystallographic texture in rapidly quenched Fe 14 Nd 2 B has been investigated by hot deformation. The method was to catch the process in a state of partial completion, and then use transmission electron microscopy to examine the structure. The degree of texture formation was determined by x-ray diffraction and by magnetic measurements, and the hardness and the anisotropy in hardness were measured up to 600 degree C. It was concluded, in agreement with others but with additional evidence, that preferential growth of favorably oriented grains during plastic deformation produces the texture. The nature of the plastic deformation remains unclear, since no dislocations are observed in Fe 14 Nd 2 B. It was found that when samples are compressed at temperatures near 600 degree C under low stresses for long times, they become Nd rich at the bottom, presumably because of flow of the Nd-rich liquid phase under the influence of gravity. In such samples, plastic deformation and crystallographic orientation occurs preferentially at the Nd-rich end

  18. Microscale experimental investigation of deformation and damage of argillaceous rocks under cyclic hydric and mechanical loads

    International Nuclear Information System (INIS)

    Wang, Linlin; Yang, Diansen; Heripre, Eva; Chanchole, Serge; Bornert, Michel; Pouya, Ahmad; Halphen, Bernard

    2012-01-01

    Document available in abstract form only. Argillaceous rocks are possible host rocks for underground nuclear waste repositories. They exhibit complex coupled thermo-hydro-chemo-mechanical behavior, the description of which would strongly benefit from an improved experimental insight on their deformation and damage mechanisms at microscale. We present some recent observations of the evolution of these rocks at the scale of their composite microstructure, essentially made of a clay matrix with embedded carbonates and quartz particles with sizes ranging from a few to several tens of micrometers, when they are subjected to cyclic variations of relative humidity and mechanical loading. They are based on the combination of high definition and high resolution imaging in an environmental scanning electron microscope (ESEM), in situ hydro-mechanical loading of the samples, and digital image correlation techniques. Samples, several millimeters in diameter, are held at a constant temperature of 2 deg. Celsius while the vapor pressure in the ESEM chamber is varied from a few to several hundreds of Pascals, generating a relative humidity ranging from about 10% up to 90%. Results show a strongly heterogeneous deformation field at microscale, which is the result of complex hydro-mechanical interactions. In particular, it can be shown that local swelling incompatibilities can generate irreversible deformations in the clay matrix, even if the overall hydric deformations seem reversible. In addition, local damage can be generated, in the form of a network of microcracks, located in the bulk of the clay matrix and/or at the interface between clay and other mineral particles. The morphology of this network, described in terms of crack length, orientation and preferred location, has been observed to be dependent on the speed of the variation of the relative humidity, and is different in a saturation or desaturation process. Besides studying the deformation and damage under hydric

  19. 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.

  20. Quantifying the Mechanical Properties of Materials and the Process of Elastic-Plastic Deformation under External Stress on Material

    Directory of Open Access Journals (Sweden)

    Jan Valíček

    2015-11-01

    Full Text Available The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ, especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ.

  1. Quantifying the Mechanical Properties of Materials and the Process of Elastic-Plastic Deformation under External Stress on Material

    Science.gov (United States)

    Valíček, Jan; Harničárová, Marta; Öchsner, Andreas; Hutyrová, Zuzana; Kušnerová, Milena; Tozan, Hakan; Michenka, Vít; Šepelák, Vladimír; Mitaľ, Dušan; Zajac, Jozef

    2015-01-01

    The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ), especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ. PMID:28793645

  2. Mechanism of magnetic recovery in the disorder-order transformation of Fe70Al30 mechanically deformed alloys

    International Nuclear Information System (INIS)

    Rodriguez, D. Martin; Apinaniz, E.; Plazaola, F.; Garitaonandia, J.S.; Jimenez, J.A.; Schmool, D.S.; Cuello, G.J.

    2005-01-01

    The degree of order in Fe-Al intermetallic alloys has an important influence on their magnetic properties. Moreover, the deformation of ordered alloys causes a dramatic increase of magnetization. If deformed alloys are heated, their magnetic properties decrease again. The reordering process was monitored by neutron diffraction, Moessbauer spectroscopy, and calorimetric measurements on the Fe 70 Al 30 crushed alloy. This indicates that the reordering process occurs in two stages. In the first (150-200 deg. C) new small B2 phase domains are nucleated due to vacancy migration. A second reordering stage occurs between 300 and 450 deg. C, where dislocation motion induces B2 domain growth and A2 phase elimination. The main mechanism responsible for this decrease of magnetization during the reordering process is the decrease of the disordered A2 phase content in the alloy

  3. 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.

  4. Impact of solid second phases on deformation mechanisms of naturally deformed salt rocks (Kuh-e-Namak, Dashti, Iran) and rheological stratification of the Hormuz Salt Formation

    Science.gov (United States)

    Závada, P.; Desbois, G.; Urai, J. L.; Schulmann, K.; Rahmati, M.; Lexa, O.; Wollenberg, U.

    2015-05-01

    Viscosity contrasts displayed in flow structures of a mountain namakier (Kuh-e-Namak - Dashti), between 'weak' second phase bearing rock salt and 'strong' pure rock salt types are studied for deformation mechanisms using detailed quantitative microstructural study. While the solid inclusions rich ("dirty") rock salts contain disaggregated siltstone and dolomite interlayers, "clean" salts reveal microscopic hematite and remnants of abundant fluid inclusions in non-recrystallized cores of porphyroclasts. Although the flow in both, the recrystallized "dirty" and "clean" salt types is accommodated by combined mechanisms of pressure-solution creep (PS), grain boundary sliding (GBS), transgranular microcracking and dislocation creep accommodated grain boundary migration (GBM), their viscosity contrasts observed in the field outcrops are explained by: 1) enhanced ductility of "dirty" salts due to increased diffusion rates along the solid inclusion-halite contacts than along halite-halite contacts, and 2) slow rates of intergranular diffusion due to dissolved iron and inhibited dislocation creep due to hematite inclusions for "clean" salt types Rheological contrasts inferred by microstructural analysis between both salt rock classes apply in general for the "dirty" salt forming Lower Hormuz and the "clean" salt forming the Upper Hormuz of the Hormuz Formation and imply strain rate gradients or decoupling along horizons of mobilized salt types of different composition and microstructure.

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

    International Nuclear Information System (INIS)

    Ye, Y.X.; Feng, Y.Y.; Lian, Z.C.; Hua, Y.Q.

    2014-01-01

    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.

  6. Influence of pulsed current on deformation mechanism of AZ31B sheets during tension

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kai [National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, 1954 Hua Shan Road, Shanghai 200030 (China); Dong, Xianghuai, E-mail: dongxh@sjtu.edu.cn [National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, 1954 Hua Shan Road, Shanghai 200030 (China); Xie, Huanyang [Shanghai Superior Die Technology Co., Ltd, 775 Jinsui Road, Shanghai 201209 (China); Wu, Yunjian; Peng, Fang [National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, 1954 Hua Shan Road, Shanghai 200030 (China)

    2016-08-15

    The tensile tests of AZ31B sheets were carried out under pulsed current (PC) of different frequencies, and then the deformation mechanism at different conditions was analyzed by X-Ray Diffraction. The results show that PC does not change the initial yield stress, but reduces the work hardening rate and induces softening effect. Furthermore, electroplasticity effect is controlled by thermal activation. When Z (Zener-Hollomon parameter) is high, the effect of PC is limited, causing a relatively weak electroplasticity effect. With the increasing of Z, the effect of PC strengthens. When Z reaches the critical condition, the activated slip systems obviously change because of PC, which induces the change of texture evolution and the discontinuous change of the intensity of electroplasticity. When Z is low, electroplasticity effect reaches a saturate condition and does not change with Z. Moreover, higher frequency contributes to the dislocation annihilation at all the slip systems, and then increasing frequency can strengthen the extra softening effect of PC. - Highlights: • Pulsed current does not change the initial yield stress, but reduce the work hardening rate and cause softening effect. • Increasing frequency can strengthen the softening effect. • The rules of the softening effect at different deformation condition are different. • The influence of current on deformation mechanism was analyzed by XRD.

  7. Mechanical properties and deformation behavior of Al/Al7075, two-phase material

    International Nuclear Information System (INIS)

    Sherafat, Z.; Paydar, M.H.; Ebrahimi, R.; Sohrabi, S.

    2010-01-01

    In the present study, mechanical properties and deformation behavior of Al/Al7075, two-phase material were investigated. The two-phase materials were fabricated by mixing commercially pure Al powder with Al7075 chips and consolidating the mixture through hot extrusion process at 500 o C. Mechanical properties and deformation behavior of the fabricated samples were evaluated using tensile and compression tests. A scanning electron microscope was used to study the fracture surface of the samples including different amount of Al powder, after they were fractured in tensile test. The results of the tensile and compression tests showed that with decreasing the amount of Al powder, the strength increases and ductility decreases. Calculation of work hardening exponent (n) indicated that deformation behavior does not follow a regular trend. In a way that the n value was approved to be variable and a strong function of strain and Al powder wt% of the sample. The results of the fractography studies indicate that the type of fracture happened changes from completely ductile to nearly brittle by decreasing the wt% of Al powder from 90% to 40%.

  8. Deformation mechanisms induced under high cycle fatigue tests in a metastable austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Roa, J.J., E-mail: joan.josep.roa@upc.edu [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain); CRnE, Campus Diagonal Sud, Edificio C’, Universitat Politècnica de Catalunya, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Fargas, G. [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain); Jiménez-Piqué, E. [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain); CRnE, Campus Diagonal Sud, Edificio C’, Universitat Politècnica de Catalunya, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Mateo, A. [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain)

    2014-03-01

    Advanced techniques were used to study the deformation mechanisms induced by fatigue tests in a metastable austenitic stainless steel AISI 301LN. Observations by Atomic Force Microscopy were carried out to study the evolution of a pre-existing martensite platelet at increasing number of cycles. The sub-superficial deformation mechanisms of the austenitic grains were studied considering the cross-section microstructure obtained by Focused Ion Beam and analysed by Scanning Electron Microscopy and Transmission Electron Microscopy. The results revealed no deformation surrounding the pre-existing martensitic platelet during fatigue tests, only the growth on height was observed. Martensite formation was associated with shear bands on austenite, mainly in the {111} plane, and with the activation of the other intersecting austenite {111}〈110〉 slip system. Furthermore, transmission electron microscopy results showed that the nucleation of ε-martensite follows a two stages phase transformation (γ{sub fcc}→ε{sub hcp}→α'{sub bcc})

  9. Quantification of local matrix deformations and mechanical properties during capillary morphogenesis in 3D.

    Science.gov (United States)

    Kniazeva, Ekaterina; Weidling, John W; Singh, Rahul; Botvinick, Elliot L; Digman, Michelle A; Gratton, Enrico; Putnam, Andrew J

    2012-04-01

    Reciprocal mechanical interactions between cells and the extracellular matrix (ECM) are thought to play important instructive roles in branching morphogenesis. However, most studies to date have failed to characterize these interactions on a length scale relevant to cells, especially in three-dimensional (3D) matrices. Here we utilized two complementary methods, spatio-temporal image correlation spectroscopy (STICS) and laser optical tweezers-based active microrheology (AMR), to quantify endothelial cell (EC)-mediated deformations of individual ECM elements and the local ECM mechanical properties, respectively, during the process of capillary morphogenesis in a 3D cell culture model. In experiments in which the ECM density was systematically varied, STICS revealed that the rate at which ECs deformed individual ECM fibers on the microscale positively correlated with capillary sprouting on the macroscale. ECs expressing constitutively active V14-RhoA displaced individual matrix fibers at significantly faster rates and displayed enhanced capillary sprouting relative to wild-type cells, while those expressing dominant-negative N19-RhoA behaved in an opposite fashion. In parallel, AMR revealed a local stiffening of the ECM proximal to the tips of sprouting ECs. By quantifying the dynamic physical properties of the cell-ECM interface in both space and time, we identified a correlation linking ECM deformation rates and local ECM stiffening at the microscale with capillary morphogenesis at the macroscale. This journal is © The Royal Society of Chemistry 2012

  10. Quantification of local matrix deformations and mechanical properties during capillary morphogenesis in 3D†‡

    Science.gov (United States)

    Kniazeva, Ekaterina; Weidling, John W.; Singh, Rahul; Botvinick, Elliot L.; Digman, Michelle A.; Gratton, Enrico

    2013-01-01

    Reciprocal mechanical interactions between cells and the extracellular matrix (ECM) are thought to play important instructive roles in branching morphogenesis. However, most studies to date have failed to characterize these interactions on a length scale relevant to cells, especially in three-dimensional (3D) matrices. Here we utilized two complementary methods, spatio-temporal image correlation spectroscopy (STICS) and laser optical tweezers-based active microrheology (AMR), to quantify endothelial cell (EC)-mediated deformations of individual ECM elements and the local ECM mechanical properties, respectively, during the process of capillary morphogenesis in a 3D cell culture model. In experiments in which the ECM density was systematically varied, STICS revealed that the rate at which ECs deformed individual ECM fibers on the microscale positively correlated with capillary sprouting on the macroscale. ECs expressing constitutively active V14-RhoA displaced individual matrix fibers at significantly faster rates and displayed enhanced capillary sprouting relative to wild-type cells, while those expressing dominant-negative N19-RhoA behaved in an opposite fashion. In parallel, AMR revealed a local stiffening of the ECM proximal to the tips of sprouting ECs. By quantifying the dynamic physical properties of the cell-ECM interface in both space and time, we identified a correlation linking ECM deformation rates and local ECM stiffening at the microscale with capillary morphogenesis at the macroscale. PMID:22281872

  11. Deformable meshes for medical image segmentation accurate automatic segmentation of anatomical structures

    CERN Document Server

    Kainmueller, Dagmar

    2014-01-01

    ? Segmentation of anatomical structures in medical image data is an essential task in clinical practice. Dagmar Kainmueller introduces methods for accurate fully automatic segmentation of anatomical structures in 3D medical image data. The author's core methodological contribution is a novel deformation model that overcomes limitations of state-of-the-art Deformable Surface approaches, hence allowing for accurate segmentation of tip- and ridge-shaped features of anatomical structures. As for practical contributions, she proposes application-specific segmentation pipelines for a range of anatom

  12. On the modelling of the dynamics of elastically deformable floating structures

    DEFF Research Database (Denmark)

    Seng, Sopheak; Malenica, Sime; Jensen, Jørgen Juncher

    2015-01-01

    In this paper we are reexamining the dynamic equations of an elastically deformable floating structure to identify and evaluate the contribution from the inertia cross coupling terms which commonly have been neglected due to the assumption of small structural deformation. Numerical experiments...... on two vessels, a flexible barge, and a full scale ultra large container vessel, are designed for revealing the magnitude of errors introduced into the numerical solutions when these inertia cross coupling terms have been ignored. The results shows that in realistic conditions with strong structural...

  13. Multimodal Nanoscale Characterization of Transformation and Deformation Mechanisms in Several Nickel Titanium Based Shape Memory Alloys

    Science.gov (United States)

    Casalena, Lee

    The development of viable high-temperature shape memory alloys (HTSMAs) demands a coordinated multimodal characterization effort linking nanoscale crystal structure to macroscale thermomechanical properties. In this work, several high performance NiTi-based shape memory alloys are comprehensively explored with the goal of gaining insight into the complex transformation and deformation mechanisms responsible for their remarkable behavior. Through precise control of alloying and aging parameters, microstructures are optimized to enhance properties such as high-temperature strength and stability. These are crucial requirements for the development of advanced applications such as actuators and adaptive components that operate in demanding automotive and aerospace environments. An array of NiTiHf and NiTiAu alloys are at the core of this effort, offering the possibility of increased capability over traditional pneumatic and hydraulic systems, while simultaneously reducing weight and energy requirements. NiTi-20Hf alloys exhibit a favorable balance of properties, including high strength, stability, and work output at temperatures in excess of 150 °C. The raw material cost of Hf is also much lower compared with Pt, Pd, and Au containing counterparts. Advanced scanning transmission electron microscopy (STEM) and synchrotron X-ray characterization techniques are used to explore unusual nanoscale effects of precipitate-matrix interactions, coherency strain, and dislocation activity in these alloys. Novel use of the 4D STEM strain mapping technique is used to quantify strain fields associated with precipitates, which are being coupled with new phase field modeling approaches to particle/defect interactions. Volume fractions of nanoscale precipitates are measured using STEM-based tomography techniques, atom probe tomography, and synchrotron diffraction of bulk samples. Plastic deformation of the HTSMA austenite phase is shown to occur through B2 type slip for the first time

  14. Characterization of strengthening mechanism and hot deformation behavior of powder metallurgy molybdenum

    International Nuclear Information System (INIS)

    Xiao, Meili; Li, Fuguo; Xie, Hangfang; Wang, Yufeng

    2012-01-01

    Highlights: → Dynamic recrystallization of powder metallurgy molybdenum occurs in the temperature region (1200-1450 o C). → The value of strain hardening index n decreases along with the temperature rising. → The value of strain-rate sensitivity exponent m increases slowly at first and achieves a peak value at 1350 o C. → Deformation strengthening is the main strengthening mechanism at low temperature. → Rheological strengthening becomes the primary strengthening mechanism at high temperature. -- Abstract: The high-temperature deformation behavior of powder metallurgy molybdenum has been investigated based on a series of isothermal hot compression tests, which were carried out on a Gleeble-1500 thermal mechanical simulator in a wide range of temperatures (900-1450 o C) and strain rates (0.01-10 s -1 ). Through the research on the experimental stress-strain curves, it reveals that dynamic recrystallization softening effect of powder metallurgy molybdenum occurs in the temperature range from 1200 o C to 1450 o C, in which the flow stress is significantly sensitive to temperature. In comparison with the value of strain hardening index n which decreases along with the temperature rising, the value of strain-rate sensitivity exponent m does not change obviously; however, it increases slowly with the increasing of temperature at first and achieves a peak value at 1350 o C. Furthermore, relying on the comparison of mean value of n and m, it is suggested that deformation strengthening is the main strengthening mechanism at low temperature while the rheological strengthening changes into the primary strengthening mechanism at high temperature.

  15. Mechanical behaviour of structural ceramics

    Directory of Open Access Journals (Sweden)

    Bueno, S.

    2007-06-01

    Full Text Available The use of ceramic materials in structural applications is limited by the lack of reliability associated with brittle fracture behaviour. In order to extend the structural use of ceramics, the design of microstructures which exhibit flaw tolerance due to toughening mechanisms which produce an increase in crack growth resistance during crack propagation has been proposed. This work is a review of the mechanical behaviour of structural ceramic materials and its characterisation. Firstly, the basic brittle fracture parameters and the statistical criteria to determine the probability of exceeding the safety factors demanded for a particular application are analysed. Then, the toughening mechanisms which can be developed in the materials through microstructural design as well as the mechanical characterisation of toughened ceramics are discussed. The experimental values of linear elastic fracture toughness parameters (critical stress intensity factor, KIC, and critical energy release rate, GIC are not intrinsic properties for toughened materials and depend on crack length and the loading system. In this work, the different mechanical parameters proposed to characterise such materials are reviewed. The following fracture parameters are analysed: work of fracture (γWOF, critical J-integral value (JIC and R-curve. For the determination, stable fracture tests are proposed in order to ensure that the energy provided during the test is no more than the necessary one for crack propagation.

    El uso de los materiales cerámicos en aplicaciones estructurales está limitado por la falta de fiabilidad asociada a su comportamiento frágil durante la fractura. Para extender su aplicación se ha propuesto el diseño de microestructuras que presenten tolerancia a los defectos debido a la actuación de mecanismos de refuerzo. Este trabajo es una puesta al día sobre el estudio del comportamiento mecánico de los materiales cerámicos estructurales y su

  16. Deformation mechanisms at intermediate creep temperatures in the Ni-base superalloy Rene 88 DT

    International Nuclear Information System (INIS)

    Viswanathan, G.B.; Sarosi, Peter M.; Whitis, Deborah H.; Mills, Michael J.

    2005-01-01

    Creep deformation substructures in superalloy Rene 88 DT have been investigated at two applied stress levels after small-strain (0.5%) creep at 650 deg. C using conventional and high resolution transmission electron microscopy. Clear differences in creep strength and substructures have been observed as a function of applied stress. It has been established that at intermediate temperatures microtwinning caused by the passage of Shockley partial dislocations on successive {1 1 1} planes is the dominant deformation process at low applied stress. At higher applied stress the mechanism changes to planar shearing of the matrix by 1/2 unit dislocations and Orowan looping of the precipitates. Detailed experimental evidences for these operating processes are shown and possible explanation is provided

  17. Coupling analysis of frictional heat of fluid film and thermal deformation of mechanical seal end faces

    International Nuclear Information System (INIS)

    Zhou Jianfeng; Gu Boqin

    2007-01-01

    The heat transfer model of the rotating ring and the stationary ring of mechanical seal was built. The method to calculate the frictional heat that transferred by the rings was given. the coupling analysis of the frictional heat of fluid film and thermal deformation of end faces was carried out by using FEA and BP ANN, and the relationship among the rotational speed ω, the fluid film thickness h i on the inner diameter of sealing face and the radial separation angle β of deformed end faces was obtained. Corresponding to a given ω, h i and β can be obtained by the equilibrium condition between the closing force and the bearing force of fluid film. The relationship between the leakage rate and the closing force was analyzed, and the fundamental of controlling the leakage rate by regulating the closing force was also discussed. (authors)

  18. Deformation mechanisms and grain size evolution in the Bohemian granulites - a computational study

    Science.gov (United States)

    Maierova, Petra; Lexa, Ondrej; Jeřábek, Petr; Franěk, Jan; Schulmann, Karel

    2015-04-01

    A dominant deformation mechanism in crustal rocks (e.g., dislocation and diffusion creep, grain boundary sliding, solution-precipitation) depends on many parameters such as temperature, major minerals, differential stress, strain rate and grain size. An exemplary sequence of deformation mechanisms was identified in the largest felsic granulite massifs in the southern Moldanubian domain (Bohemian Massif, central European Variscides). These massifs were interpreted to result from collision-related forced diapiric ascent of lower crust and its subsequent lateral spreading at mid-crustal levels. Three types of microstructures were distinguished. The oldest relict microstructure (S1) with large grains (>1000 μm) of feldspar deformed probably by dislocation creep at peak HT eclogite facies conditions. Subsequently at HP granulite-facies conditions, chemically- and deformation- induced recrystallization of feldspar porphyroclasts led to development of a fine-grained microstructure (S2, ~50 μm grain size) indicating deformation via diffusion creep, probably assisted by melt-enhanced grain-boundary sliding. This microstructure was associated with flow in the lower crust and/or its diapiric ascent. The latest microstructure (S3, ~100 μm grain size) is related to the final lateral spreading of retrograde granulites, and shows deformation by dislocation creep at amphibolite-facies conditions. The S2-S3 switch and coarsening was interpreted to be related with a significant decrease in strain rate. From this microstructural sequence it appears that it is the grain size that is critically linked with specific mechanical behavior of these rocks. Thus in this study, we focused on the interplay between grain size and deformation with the aim to numerically simulate and reinterpret the observed microstructural sequence. We tested several different mathematical descriptions of the grain size evolution, each of which gave qualitatively different results. We selected the two most

  19. Structural and mechanical behaviour of LLDPE/HNT nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Čermák, M.; Kadlec, P. [Department of Technologies and Measurement, Faculty of Electrical Engineering University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic); Šutta, P. [New Technologies - Research Centre University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic); Polanský, R. [Regional Innovative Centre for Electrical Engineering University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic)

    2016-03-09

    The paper briefly describes structural and mechanical influences of Halloysite nanotubes (HNT) in different level of fulfilment (0, 1, 3, 7 wt%) in the LLDPE commonly used in the cable industry. The influence of HNT on the polymer has been observed and evaluated through the average crystallite size and the micro- deformation by X-Ray diffractometry and the imaging of SEM. Despite the certain inter-phase tension between the polymer and HNT, the influence on the mechanical and combustion behaviour was observed. Measurement showed a higher content of agglomerates in the sample with 7 wt% HNT fulfilment.

  20. Deciphering the shape and deformation of secondary structures through local conformation analysis

    Directory of Open Access Journals (Sweden)

    Camproux Anne-Claude

    2011-02-01

    Full Text Available Abstract Background Protein deformation has been extensively analysed through global methods based on RMSD, torsion angles and Principal Components Analysis calculations. Here we use a local approach, able to distinguish among the different backbone conformations within loops, α-helices and β-strands, to address the question of secondary structures' shape variation within proteins and deformation at interface upon complexation. Results Using a structural alphabet, we translated the 3 D structures of large sets of protein-protein complexes into sequences of structural letters. The shape of the secondary structures can be assessed by the structural letters that modeled them in the structural sequences. The distribution analysis of the structural letters in the three protein compartments (surface, core and interface reveals that secondary structures tend to adopt preferential conformations that differ among the compartments. The local description of secondary structures highlights that curved conformations are preferred on the surface while straight ones are preferred in the core. Interfaces display a mixture of local conformations either preferred in core or surface. The analysis of the structural letters transition occurring between protein-bound and unbound conformations shows that the deformation of secondary structure is tightly linked to the compartment preference of the local conformations. Conclusion The conformation of secondary structures can be further analysed and detailed thanks to a structural alphabet which allows a better description of protein surface, core and interface in terms of secondary structures' shape and deformation. Induced-fit modification tendencies described here should be valuable information to identify and characterize regions under strong structural constraints for functional reasons.

  1. Deciphering the shape and deformation of secondary structures through local conformation analysis.

    Science.gov (United States)

    Baussand, Julie; Camproux, Anne-Claude

    2011-02-01

    Protein deformation has been extensively analysed through global methods based on RMSD, torsion angles and Principal Components Analysis calculations. Here we use a local approach, able to distinguish among the different backbone conformations within loops, α-helices and β-strands, to address the question of secondary structures' shape variation within proteins and deformation at interface upon complexation. Using a structural alphabet, we translated the 3 D structures of large sets of protein-protein complexes into sequences of structural letters. The shape of the secondary structures can be assessed by the structural letters that modeled them in the structural sequences. The distribution analysis of the structural letters in the three protein compartments (surface, core and interface) reveals that secondary structures tend to adopt preferential conformations that differ among the compartments. The local description of secondary structures highlights that curved conformations are preferred on the surface while straight ones are preferred in the core. Interfaces display a mixture of local conformations either preferred in core or surface. The analysis of the structural letters transition occurring between protein-bound and unbound conformations shows that the deformation of secondary structure is tightly linked to the compartment preference of the local conformations. The conformation of secondary structures can be further analysed and detailed thanks to a structural alphabet which allows a better description of protein surface, core and interface in terms of secondary structures' shape and deformation. Induced-fit modification tendencies described here should be valuable information to identify and characterize regions under strong structural constraints for functional reasons.

  2. Effect of microscopic structure on deformation in nano-sized copper and Cu/Si interfacial cracking

    Energy Technology Data Exchange (ETDEWEB)

    Sumigawa, Takashi, E-mail: sumigawa@cyber.kues.kyoto-u.ac.jp; Nakano, Takuya; Kitamura, Takayuki

    2013-03-01

    The purpose of this work is to examine the effect of microscopic structure on the mechanical properties of nano-sized components (nano-components). We developed a bending specimen with a substructure that can be observed by means of a transmission electron microscope (TEM). We examined the plastic behavior of a Cu bi-crystal and the Cu/Si interfacial cracking in a nano-component. TEM images indicated that an initial plastic deformation takes place near the interface edge (the junction between the Cu/Si interface and the surface) in the Cu film with a high critical resolved shear stress (400–420 MPa). The deformation developed preferentially in a single grain. Interfacial cracking took place at the intersection between the grain boundary and the Cu/Si interface, where a high stress concentration existed due to deformation mismatch. These results indicate that the characteristic mechanical behavior of a nano-component is governed by the microscopic stress field, which takes into account the crystallographic structure. - Highlights: ► A nano-component specimen including a bi-crystal copper layer was prepared. ► A loading test with in-situ transmission electron microscopy was conducted. ► The plastic and cracking behaviors were governed by microscopic stress. ► Stress defined under continuum assumption was still present in nano-components.

  3. Test and analysis of thermal ratcheting deformation for 316L stainless steel cylindrical structure

    International Nuclear Information System (INIS)

    Lee, Hyeong Yeon; Kim, Jong Bum; Lee, Jae Han

    2002-01-01

    In this study, the progressive inelastic deformation, so called, thermal ratchet phenomenon which can occur in high temperature structures of liquid metal simulated with thermal ratchet structural test facility and 316L stainless steel test cylinder. The thermal ratchet deformation at the reactor baffle cylinder of the liquid metal reactor can occur due to the moving temperature distribution along the axial direction as the sodium free surface moves up and down under the cyclic heat-up and cool-down transients. The ratchet deformation was measured with the laser displacement sensor and LVDTs after cooling the structural specimen which is heated up to 550 degree C with steep temperature gradients along the axial direction. The temperature distribution of the test cylinder along the axial direction was measured with 28 channels of thermocouples and was used for the ratchet analysis. The thermal ratchet deformation was analyzed with the constitutive equation of nonlinear combined hardening model which was implemented as ABAQUS user subroutine and the analysis results were compared with those of the test. Thermal ratchet load was applied 9 times and the residual displacement after 9 cycles of thermal load was measured to be 1.79 mm. The ratcheting deformation shapes obtained by the analysis with the combined hardening model were in reasonable agreement with those of the structural tests

  4. Contribution to the study of mechanical properties of nuclear fuel: atomistic modelling of the deformation of uranium dioxide

    International Nuclear Information System (INIS)

    Fossati, P.

    2012-01-01

    Mechanical properties of nuclear fuel are a complex problem, involving many coupled mechanisms occurring at different length scales. We used Molecular Dynamics models to bring some light on some of these mechanisms at the atomic scale. We devised a procedure to calculate transition pathways between some UO 2 polymorphs, and then carried out dynamics simulations of these transitions. We confirmed the stability of the cotunnite structure at high pressure using various empirical potentials, the fluorite structure being the most stable at room pressure. Moreover, we showed a reconstructive phase transition between the fluorite and cotunnite structures. We also showed the importance of the major deformation axis on the kind of transition that occur under tensile conditions. Depending on the loading direction, a scrutinyite or rutile phase can appear. We then calculated the elastic behaviour of UO 2 using different potentials. The relative agreement between them was used to produce a set of parameters to be used as input in mesoscale models. We also simulated crack propagation in UO 2 single crystals. These simulations showed secondary phases nucleation at crack tips, and hinted at the importance thereof on crack propagation at higher length-scales. We then described some properties of edge dislocations in UO 2 . The core structures were compared for various glide planes. The critical resolved shear stress was calculated for temperatures up to 2000 K. These calculations showed a link between lattice disorder at the dislocations core and the dislocations mobility. (author)

  5. 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.

  6. A Nanoindentation Study of the Plastic Deformation and Fracture Mechanisms in Single-Crystalline CaFe2As2

    Science.gov (United States)

    Frawley, Keara G.; Bakst, Ian; Sypek, John T.; Vijayan, Sriram; Weinberger, Christopher R.; Canfield, Paul C.; Aindow, Mark; Lee, Seok-Woo

    2018-04-01

    The plastic deformation and fracture mechanisms in single-crystalline CaFe2As2 has been studied using nanoindentation and density functional theory simulations. CaFe2As2 single crystals were grown in a Sn-flux, resulting in homogeneous and nearly defect-free crystals. Nanoindentation along the [001] direction produces strain bursts, radial cracking, and lateral cracking. Ideal cleavage simulations along the [001] and [100] directions using density functional theory calculations revealed that cleavage along the [001] direction requires a much lower stress than cleavage along the [100] direction. This strong anisotropy of cleavage strength implies that CaFe2As2 has an atomic-scale layered structure, which typically exhibits lateral cracking during nanoindentation. This special layered structure results from weak atomic bonding between the (001) Ca and Fe2As2 layers.

  7. Research on Non-Similarity about Thermal Deformation Error of Mechanical Parts in High-accuracy Measurement

    International Nuclear Information System (INIS)

    Luo, Z; Fei, Y T

    2006-01-01

    Expanding with heat and contracting with cold are common physical phenomenon in the nature. The conventional theories and calculations of thermal deformation are approximate and linear, can only be applied in normal or low precision field. The thermal deformation error of mechanical parts doesn't follow the conventional linear formula, it relates to all physical dimension of the mechanical part, and the deformation can be indicated by a nonlinear formula of physical dimensions. A theory on non-similarity about thermal deformation error of mechanical parts is presented. Studies on some common mechanical parts in precision technology have went on and the mathematical models have been set up, hollow piece, gear and cube are included. The experimental results also make it clear that these models are more logical than traditional models

  8. Tests for development of estimation technology of reactor core deformation. Report No.1: fundamental mechanical properties of wrapper tube (test report)

    International Nuclear Information System (INIS)

    Nishiura, Takeo; Shimazaki, Yuji; Horikiri, Morito

    1998-10-01

    Mechanical properties such as local contact compression stiffness, bending stiffness, deformation properties, material properties, and friction properties of a wrapper tube structure were clarified experimentally, which can be used as the basic data for development of estimation technology of reactor core deformation. Contents of the Tests data as follows: (1) Effects of load supporting boundary conditions, whether or not a contact-proof pad is attached, and length of duct, on cross section deformation of wrapper tube were made clear as the local contact compression stiffness characteristics. (2) Bending stiffness does not depend on the difference of load supporting boundary conditions. The property of cross section deformation under bending load was obtained. (3) The deformation modes and the strain distributions were obtained by the deformation tests of wrapper tube. (4) The stress-strain diagrams including plastic range under various strain variation rates were obtained by the material tests at room temperature. (5) The static and the dynamic friction coefficients by various contact angles and the contact loads between contact-proof pads of two wrapper tubes were obtained by friction property tests. (author)

  9. Bridge Structure Deformation Prediction Based on GNSS Data Using Kalman-ARIMA-GARCH Model.

    Science.gov (United States)

    Xin, Jingzhou; Zhou, Jianting; Yang, Simon X; Li, Xiaoqing; Wang, Yu

    2018-01-19

    Bridges are an essential part of the ground transportation system. Health monitoring is fundamentally important for the safety and service life of bridges. A large amount of structural information is obtained from various sensors using sensing technology, and the data processing has become a challenging issue. To improve the prediction accuracy of bridge structure deformation based on data mining and to accurately evaluate the time-varying characteristics of bridge structure performance evolution, this paper proposes a new method for bridge structure deformation prediction, which integrates the Kalman filter, autoregressive integrated moving average model (ARIMA), and generalized autoregressive conditional heteroskedasticity (GARCH). Firstly, the raw deformation data is directly pre-processed using the Kalman filter to reduce the noise. After that, the linear recursive ARIMA model is established to analyze and predict the structure deformation. Finally, the nonlinear recursive GARCH model is introduced to further improve the accuracy of the prediction. Simulation results based on measured sensor data from the Global Navigation Satellite System (GNSS) deformation monitoring system demonstrated that: (1) the Kalman filter is capable of denoising the bridge deformation monitoring data; (2) the prediction accuracy of the proposed Kalman-ARIMA-GARCH model is satisfactory, where the mean absolute error increases only from 3.402 mm to 5.847 mm with the increment of the prediction step; and (3) in comparision to the Kalman-ARIMA model, the Kalman-ARIMA-GARCH model results in superior prediction accuracy as it includes partial nonlinear characteristics (heteroscedasticity); the mean absolute error of five-step prediction using the proposed model is improved by 10.12%. This paper provides a new way for structural behavior prediction based on data processing, which can lay a foundation for the early warning of bridge health monitoring system based on sensor data using sensing

  10. Bridge Structure Deformation Prediction Based on GNSS Data Using Kalman-ARIMA-GARCH Model

    Directory of Open Access Journals (Sweden)

    Jingzhou Xin

    2018-01-01

    Full Text Available Bridges are an essential part of the ground transportation system. Health monitoring is fundamentally important for the safety and service life of bridges. A large amount of structural information is obtained from various sensors using sensing technology, and the data processing has become a challenging issue. To improve the prediction accuracy of bridge structure deformation based on data mining and to accurately evaluate the time-varying characteristics of bridge structure performance evolution, this paper proposes a new method for bridge structure deformation prediction, which integrates the Kalman filter, autoregressive integrated moving average model (ARIMA, and generalized autoregressive conditional heteroskedasticity (GARCH. Firstly, the raw deformation data is directly pre-processed using the Kalman filter to reduce the noise. After that, the linear recursive ARIMA model is established to analyze and predict the structure deformation. Finally, the nonlinear recursive GARCH model is introduced to further improve the accuracy of the prediction. Simulation results based on measured sensor data from the Global Navigation Satellite System (GNSS deformation monitoring system demonstrated that: (1 the Kalman filter is capable of denoising the bridge deformation monitoring data; (2 the prediction accuracy of the proposed Kalman-ARIMA-GARCH model is satisfactory, where the mean absolute error increases only from 3.402 mm to 5.847 mm with the increment of the prediction step; and (3 in comparision to the Kalman-ARIMA model, the Kalman-ARIMA-GARCH model results in superior prediction accuracy as it includes partial nonlinear characteristics (heteroscedasticity; the mean absolute error of five-step prediction using the proposed model is improved by 10.12%. This paper provides a new way for structural behavior prediction based on data processing, which can lay a foundation for the early warning of bridge health monitoring system based on sensor data

  11. Deformation and damage modes of deep argillaceous rocks under hydro-mechanical stresses

    International Nuclear Information System (INIS)

    Vales, F.

    2008-12-01

    An experimental identification of the hydro-mechanical behaviour of an argillite rock is proposed within a multi-scale approach. In particular, interest is focused on the spatial and temporal localization of strain and damage in a specimen during hydro-mechanical loading. Firstly, we describe the techniques used to follow the rock evolutions under loading, and in particular Digital Images Correlation (DIC), Acoustic Emission, microscopy and mercury intrusion porosimetry. Measurement errors and device limitations are discussed. The studied material is the Callovo-Oxfordian indurated argillaceous rock (or argillite) of the Bure site where ANDRA has built an underground research laboratory to study the radioactive waste storage. Petrophysical characterizations and microstructural observations by optical and scanning electron microscopy provide an identification of the constitutive phase and a characterization of their spatial distribution and typical sizes. Argillite can be described as a composite structure with a continuous clay matrix and embedded mineral particles, essentially quartz and carbonates. The typical size of these particles ranges from a few micrometers to a few hundreds micrometers, with an average close to 50 μ.m. The general experimental procedure combines two steps: in a fist time, imposed suctions bring samples to a given degree of water saturation, and, in a second time, uniaxial mechanical compression tests are performed. To understand the evolutions of the material under hydric and mechanical loading, samples are instrumented with standard measurement techniques, but also with Digital Image Correlation, at both the global scale of the sample and the local scale of the composite microstructure, and with Acoustic Emissions recording. Moisture transfers are imposed by controlled suctions on the range of 150 to 2.8 MPa, corresponding to the relative humidity range of 32 to 98%RH. During pure hydric solicitation, the changes in physical parameters

  12. q-deformed phase-space and its lattice structure

    International Nuclear Information System (INIS)

    Wess, J.

    1998-01-01

    Quantum groups lead to an algebraic structure that can be realized on quantum spaces. These are non-commutative spaces that inherit a well-defined mathematical structure from the quantum group symmetry. In turn, such quantum spaces can be interpreted as non-commutative configuration spaces for physical systems. We study the non-commutative Euclidean space that is based on the quantum group SO q (3)

  13. STUDYING DEFORMATIONS OF AN FLAT TRUSS STRUCTURE STATICALLY INDETERMINATED EXTERNALLY

    Directory of Open Access Journals (Sweden)

    Kirsanov Mikhail Nikolaevich

    2017-08-01

    Full Text Available A flat statically determinate parallel-chord truss structure has a cross-shaped grid and rests upon two rigid pin-bearing supports. Loads in bars are determined in a symbol form using the method of joint isolation by the computer mathematics Maple system. The peculiarity of the considered truss structure is its external static indeterminacy. In fact, all efforts and reactions of supports can be determined from the equilibrium conditions. But the inconvenience is necessary to consider the equilibrium of all the nodes of the truss. The Ritter cross-section method is not applicable to this truss structure. The sections that cut the truss into two parts and pass through the three rods, here exist only for several rods of the extreme panels. The purpose of this paper is to calculate a truss structure with a different number of panels in analytical and numerical form. Finite element calculation method with the use of software LISA 8.0 is applied. It’s noted that a truss structure is kinetically changeable when the number of spans is odd. The corresponding plan of probable velocities is given. In order to receive analytic dependence of deflection on the span number, the induction method and Maxwell-Moor formula has been applied. The operators of the compilation and solution of recurrence equations are involved in determining the general terms of the coefficient sequences. The formulas for calculation of loads in the most compressed bars of a truss structure were received.

  14. Mechanics and Partitioning of Deformation of the Northwestern Okhostk Plate, Northeast Russia

    Science.gov (United States)

    Hindle, D.; Mackey, K.; Fujita, K.

    2007-12-01

    The tectonic evolution and present day deformation of northeastern Russia remains one of the major challenges in plate tectonics. Arguments over the existence of at least a separate Okhotsk plate between North America and Eurasia appear to be resolved on the basis of the latest GPS studies combined with elastic modeling. The question of the mechanical behaviour of the Okhotsk plate, caught between the slowly, obliquely converging North American and Eurasian plates now becomes important. We present an analysis of geological lineaments, micro-seismicity, total seismic moment release and seismic deformation rate and GPS campaign data and global plate tectonic model data (REVEL) to estimate the likelihood of future seismicity and the relative amount of elastic and viscous deformation of the lithosphere of the northwestern Okhotsk plate. We find that it is likely that the Okhotsk plate is cracked into slivers, but that rates of relative motion of these slivers are close to indistinguishable from the behaviour of a single, rigid plate. The analysis also suggests the upper bound for large earthquakes in the region to be Mw 7-7.5 which we expect to occur only on the plate boundary fault itself. This fits geological evidence for a long term offset rate 5-10 times higher on the major plate boundary fault than other lineaments cutting the Okhotsk plate itself.

  15. The effect of mechanical restraint on the deformation of Zircaloy cladding

    International Nuclear Information System (INIS)

    Jones, P.M.; Haste, T.J.

    1980-10-01

    Zircaloy cladding, deformed at temperatures postulated for loss-of-coolant accidents, can exhibit considerable ductility. The actual circumferential strain is governed by the temperature uniformity around the rod during the time at which the major part of the deformation occurs. If the bulges in neighbouring rods in a multi-rod array touch before rupture, and the array is large enough for the outer rods to restrain bulges rather than be pushed away by them, then the stress in such bulges drops. However the stress in adjacent axial regions of the cladding which have not contacted remains high and these continue to strain until they also interact, thus propagating the bulging axially. Meanwhile the non-contacted portions of the interacting bulges continue to strain slowly into the remaining sub-channels. Illustrative calculations suggest that the mechanical restraint of bulging cladding will only be effective in increasing sub-channel blockage when the failure strains are greater than 60-70%. This may occur with temperature differences between neighbouring rods of 10-25 0 C if the deformation process is thermally stabilised. (author)

  16. Quantitative description of changes in the structure in austenitic steels after hot temperature deformation

    International Nuclear Information System (INIS)

    Kuc, D.; Rodak, K.; Niewielski, G.; Hetmanczyk, M.

    1998-01-01

    An investigation on the structural changes in austenitic hard deformable Cr-Mn and Cr-Ni steels during dynamic recrystallization has been presented in the paper. The influence of the factors (strain rate, deformation, temperature) on the geometric characteristic of grains has been taken into consideration. Investigation of the structure were performed using metallographic microscope and transmission electron microscope. The results of researched should widen the theoretical background in order to the model of phenomena, which accompany the dynamic recovery and dynamic recrystallization. (author)

  17. Deformation mechanism maps for pure iron, corrosion resistant austenitic steels and a low-alloy carbon steel

    International Nuclear Information System (INIS)

    Frost, H.Y.; Ashby, M.F.

    1980-01-01

    Principles of construction of deformation mechanisms charts for iron base alloys are presented. Deformation mechanisms charts for pure iron, 316 and 314 stainless steels, a ferritic steel with 1% Cr, Mo, V are given, examples of the charts application being provided. The charts construction is based, when it is possible, on the state equations, deduced from theoretical models and satisfying experimental data. The charts presented should be considered as an attempt to unite the main regularities of the theory of dislocations and diffusion with the observed experimental picture of plastic deformation and creep of commercial steels [ru

  18. Mechanisms of Deformation and Fracture of Thin Coatings on Different Substrates in Instrumented Indentation

    Science.gov (United States)

    Eremina, G. M.; Smolin, A. Yu.; Psakhie, S. G.

    2018-04-01

    Mechanical properties of thin surface layers and coatings are commonly studied using instrumented indentation and scratch testing, where the mechanical response of the coating - substrate system essentially depends on the substrate material. It is quite difficult to distinguish this dependence and take it into account in the course of full-scale experiments due to a multivariative and nonlinear character of the influence. In this study the process of instrumented indentation of a hardening coating formed on different substrates is investigated numerically by the method of movable cellular automata. As a result of modeling, we identified the features of the substrate material influence on the derived mechanical characteristics of the coating - substrate systems and the processes of their deformation and fracture.

  19. The deformable secondary mirror of VLT: final electro-mechanical and optical acceptance test results

    Science.gov (United States)

    Briguglio, Runa; Biasi, Roberto; Xompero, Marco; Riccardi, Armando; Andrighettoni, Mario; Pescoller, Dietrich; Angerer, Gerald; Gallieni, Daniele; Vernet, Elise; Kolb, Johann; Arsenault, Robin; Madec, Pierre-Yves

    2014-07-01

    The Deformable Secondary Mirror (DSM) for the VLT ended the stand-alone electro-mechanical and optical acceptance process, entering the test phase as part of the Adaptive Optics Facility (AOF) at the ESO Headquarter (Garching). The VLT-DSM currently represents the most advanced already-built large-format deformable mirror with its 1170 voice-coil actuators and its internal metrology based on co-located capacitive sensors to control the shape of the 1.12m-diameter 2mm-thick convex shell. The present paper reports the final results of the electro-mechanical and optical characterization of the DSM executed in a collaborative effort by the DSM manufacturing companies (Microgate s.r.l. and A.D.S. International s.r.l.), INAF-Osservatorio Astrofisico di Arcetri and ESO. The electro-mechanical acceptance tests have been performed in the company premises and their main purpose was the dynamical characterization of the internal control loop response and the calibration of the system data that are needed for its optimization. The optical acceptance tests have been performed at ESO (Garching) using the ASSIST optical test facility. The main purpose of the tests are the characterization of the optical shell flattening residuals, the corresponding calibration of flattening commands, the optical calibration of the capacitive sensors and the optical calibration of the mirror influence functions.

  20. The Difference of Structural State and Deformation Behavior between Teenage and Mature Human Dentin

    Directory of Open Access Journals (Sweden)

    Peter Panfilov

    2016-01-01

    Full Text Available Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO45OH; Space Group P63/m (176; a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer 200 A is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too.

  1. Using Ground Radar Interferometry for Precise Determining of Deformation and Vertical Deflection of Structures

    Science.gov (United States)

    Talich, Milan

    2017-12-01

    The paper describes possibilities of the relatively new technics - ground based radar interferometry for precise determining of deformation of structures. Special focus on the vertical deflection of bridge structures and on the horizontal movements of high-rise buildings and structural objects is presented. The technology of ground based radar interferometry can be used in practice to the contactless determination of deformations of structures with accuracy up to 0.01 mm in real time. It is also possible in real time to capture oscillations of the object with a frequency up to 50 Hz. Deformations can be determined simultaneously in multiple places of the object, for example a bridge structure at points distributed on the bridge deck at intervals of one or more meters. This allows to obtain both overall and detailed information about the properties of the structure during the dynamic load and monitoring the impact of movements either individual vehicles or groups. In the case of high-rise buildings, it is possible to monitor the horizontal vibration of the whole object at its different height levels. It is possible to detect and determine the compound oscillations that occur in some types of buildings. Then prevent any damage or even disasters in these objects. In addition to the necessary theory basic principles of using radar interferometry for determining of deformation of structures are given. Practical examples of determining deformation of bridge structures, water towers reservoirs, factory chimneys and wind power plants are also given. The IBIS-S interferometric radar of the Italian IDS manufacturer was used for the measurements.

  2. Deformation structure analysis of material at fatigue on the basis of the vector field

    Science.gov (United States)

    Kibitkin, Vladimir V.; Solodushkin, Andrey I.; Pleshanov, Vasily S.

    2017-12-01

    In the paper, spatial distributions of deformation, circulation, and shear amplitudes and shear angles are obtained from the displacement vector field measured by the DIC technique. This vector field and its characteristics of shears and vortices are given as an example of such approach. The basic formulae are also given. The experiment shows that honeycomb deformation structures can arise in the center of a macrovortex at developed plastic flow. The spatial distribution of local circulation and shears is discovered, which coincides with the deformation structure but their amplitudes are different. The analysis proves that the spatial distribution of shear angles is a result of maximum tangential and normal stresses. The anticlockwise circulation of most local vortices obeys the normal Gaussian law in the area of interest.

  3. Elastogranular Mechanics: Buckling, Jamming, and Structure Formation

    Science.gov (United States)

    Schunter, David J.; Brandenbourger, Martin; Perriseau, Sophia; Holmes, Douglas P.

    2018-02-01

    Confinement of a slender body into a granular array induces stress localization in the geometrically nonlinear structure, and jamming, reordering, and vertical dislodging of the surrounding granular medium. By varying the initial packing density of grains and the length of a confined elastica, we identify the critical length necessary to induce jamming, and demonstrate how folds couple with the granular medium to localize along grain boundaries. Above the jamming threshold, the characteristic length of elastica deformation is shown to diverge in a manner that is coupled with the motion and rearrangement of the grains, suggesting the ordering of the granular array governs the deformation of the slender structure. However, overconfinement of the elastica will vertically dislodge grains, a form of stress relaxation in the granular medium that illustrates the intricate coupling in elastogranular interactions.

  4. Elastogranular Mechanics: Buckling, Jamming, and Structure Formation.

    Science.gov (United States)

    Schunter, David J; Brandenbourger, Martin; Perriseau, Sophia; Holmes, Douglas P

    2018-02-16

    Confinement of a slender body into a granular array induces stress localization in the geometrically nonlinear structure, and jamming, reordering, and vertical dislodging of the surrounding granular medium. By varying the initial packing density of grains and the length of a confined elastica, we identify the critical length necessary to induce jamming, and demonstrate how folds couple with the granular medium to localize along grain boundaries. Above the jamming threshold, the characteristic length of elastica deformation is shown to diverge in a manner that is coupled with the motion and rearrangement of the grains, suggesting the ordering of the granular array governs the deformation of the slender structure. However, overconfinement of the elastica will vertically dislodge grains, a form of stress relaxation in the granular medium that illustrates the intricate coupling in elastogranular interactions.

  5. Magnetic structure and lattice deformation in UO/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Aksenov, V L; Frauenheim, T; Sikora, V [Joint Inst. for Nuclear Research, Dubna (USSR)

    1981-12-21

    The magnetic phase transition in UO/sub 2/ is studied by means of a group theoretical analysis and the admitted symmetry groups in the low temperature phase are determined. With the help of the neutron diffraction data of Faber and Lander a three-arm magnetic and crystallographic structure with two types of translational domains is found and a new interpretation of the experiment of Faber and Lander is given.

  6. Lithospheric structure and deformation of the North American continent

    OpenAIRE

    Magdala Tesauro; Mikhail Kaban; S. Cloetingh; W. D. Mooney

    2013-01-01

    We estimate the integrated strength and elastic thickness (Te) of the North American lithosphere based on thermal, density and structural (seismic) models of the crust and upper mantle. The temperature distribution in the lithosphere is estimated considering for the first time the effect of composition as a result of the integrative approach based on a joint analysis of seismic and gravity data. We do this via an iterative adjustment of the model. The upper mantle temperatures are initially e...

  7. 3D EBSD charactyerization of deformation structures in commercial purity aluminum

    DEFF Research Database (Denmark)

    Fengxiang, Lin; Godfrey, A.; Juul Jensen, Dorte

    2010-01-01

    A method to map the microstructure in deformed aluminum in three dimensions is presented. The method employs serial sectioning by mechanical polishing, and electropolishing to obtain a good surface quality, and orientation mapping of individual grains in each section by electron backscattered...... are analyzed in terms of the deformation-induced orientation spread within each grain. In particular the advantage of using three dimensional data, as opposed to two dimensional data, is illustrated, by inclusion of information about the three dimensional morphology of a grain and its neighbors....

  8. Symmetry analysis in the investigation of the order-disorder phase transition and possible structural deformations

    Energy Technology Data Exchange (ETDEWEB)

    Gurin, O V; Syromyatnikov, V N [AN SSSR, Sverdlovsk. Inst. Fiziki Metallov; Sikora, W [Joint Inst. for Nuclear Research, Dubna (USSR)

    1984-08-01

    Order-disorder phase transitions for the Me-X structures in Nb-H(D) hydrides with hydrogen (deuterium) ordering over the 12d tetrahedral interstices of the GAMMAsub(c)sup(v) lattice and for the Me-X and Me-X/sub 2/ oxides in the Ta-O system with oxygen ordering over octahedral 6b interstices are presented. The concentration of interstitial atoms is assumed to be constant. All possible models of ordered structures with a GAMMAsub(o)sup(b) lattice were determined using symmetry analysis. The possible structural deformations consistent with each variant of the ordering of the interstitial atoms were also considered. The structural deformations include the displacements of the metal atoms and of the centres of the interstices which were deduced using symmetry analysis. The results of the analysis of the final structure symmetry raise the question of understanding the nature of superstructure reflections in neutron diffraction patterns.

  9. Review of Mechanics and Applications of Auxetic Structures

    Directory of Open Access Journals (Sweden)

    Mariam Mir

    2014-01-01

    Full Text Available One of the important mechanical properties of materials is Poisson’s ratio, which is positive for most of the materials. However, certain materials exhibit “auxetic” properties; that is, they have a negative Poisson’s ratio. Thus auxetic and non-auxetic materials exhibit different deformation mechanisms. A specific microscopic structure in the auxetic materials is important for maintaining a negative Poisson’s ratio. Based on their distinct nature auxetic materials execute certain unique properties in contrast to other materials, which are reviewed in this paper. Thus auxetic materials have important applications in the biomedical field which are also a part of this review article. Many auxetic materials have been discovered, fabricated, and synthesized which differ on the basis of structure, scale and deformation mechanism. The different types of auxetic materials such as auxetic cellular solids, microscopic auxetic polymers, molecular auxetic materials, and auxetic composites have been reviewed comprehensively in this paper. Modeling of auxetic structures is of considerable importance and needs appropriate stress strain configurations; thus different aspects of auxetic modeling have also been reviewed. Packing parameters and relative densities are of prime importance in this regard. This review would thus help the researchers in determining and deciding the various aspects of auxetic nature for their products.

  10. Structure-based membrane dome mechanism for Piezo mechanosensitivity.

    Science.gov (United States)

    Guo, Yusong R; MacKinnon, Roderick

    2017-12-12

    Mechanosensitive ion channels convert external mechanical stimuli into electrochemical signals for critical processes including touch sensation, balance, and cardiovascular regulation. The best understood mechanosensitive channel, MscL, opens a wide pore, which accounts for mechanosensitive gating due to in-plane area expansion. Eukaryotic Piezo channels have a narrow pore and therefore must capture mechanical forces to control gating in another way. We present a cryo-EM structure of mouse Piezo1 in a closed conformation at 3.7Å-resolution. The channel is a triskelion with arms consisting of repeated arrays of 4-TM structural units surrounding a pore. Its shape deforms the membrane locally into a dome. We present a hypothesis in which the membrane deformation changes upon channel opening. Quantitatively, membrane tension will alter gating energetics in proportion to the change in projected area under the dome. This mechanism can account for highly sensitive mechanical gating in the setting of a narrow, cation-selective pore. © 2017, Guo et al.

  11. System and process for ultrasonic characterization of deformed structures

    Science.gov (United States)

    Panetta, Paul D [Williamsburg, VA; Morra, Marino [Richland, WA; Johnson, Kenneth I [Richland, WA

    2011-11-22

    Generally speaking, the method of the present invention is performed by making various ultrasonic scans at preselected orientations along the length of a material being tested. Data from the scans are then plotted together with various calculated parameters that are calculated from this data. Lines or curves are then fitted to the respective plotted points. Review of these plotted curves allows the location and severity of defects within these sections to be determined and quantified. With this information various other decisions related to how, when or whether repair or replacement of a particular portion of a structure can be made.

  12. Texture, morphology and deformation mechanisms in β-transformed Zircaloy-4

    International Nuclear Information System (INIS)

    Ciurchea, D.; Furtuna, I.; Todica, M.; Roth, M.

    1996-01-01

    The morphology of the β(bcc) transformed Zircaloy-4 may be treated as a lenticular-twinned martensite. The texture is a consequence of the degeneration of the left angle 0001 right angle α , left angle 1010 right angle α and left angle 1011 right angle α directions into left angle 110 right angle β directions. The crystallographic mechanisms implied in the accommodation of the microscopic Bain strain are (1010) left angle 1120 right angle prism slip, (1012) left angle 101 1 right angle twinning and (1011) left angle 1012 right angle twinning. This degeneration explains the 'parallel plate' and 'basketweave' morphologies observed by microscopy and the texture of the β transformed tube. The macroscopic Bain strain was calculated and agrees with the dimensional measurements. The deformation mechanisms of β transformed Zircaloy-4 are identified from the new texture and from deformation experiments as twinning and interplatelet glide. The interplatelet glide induces a fragile character of fracture in the 'parallel plate' morphology. (orig.)

  13. Algebraic structure of the Green's ansatz and its q-deformed analogue

    International Nuclear Information System (INIS)

    Palev, T.D.

    1994-08-01

    The algebraic structure of the Green's ansatz is analyzed in such a way that its generalization to the case of q-deformed para-Bose and para-Fermi operators is becoming evident. To this end the underlying Lie (super) algebraic properties of the parastatistics are essentially used. (author). 41 refs

  14. The general form of the relaxation of a purely interfacial energy for structured deformations

    Czech Academy of Sciences Publication Activity Database

    Šilhavý, Miroslav

    2017-01-01

    Roč. 5, č. 2 (2017), s. 191-215 ISSN 2326-7186 Institutional support: RVO:67985840 Keywords : structured deformations * relaxation * subadditive envelope * interfacial energy Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics http://msp.org/memocs/2017/5-2/p04.xhtml

  15. Understanding the mechanical coupling between magma emplacement and the resulting deformation: the example of saucer-shaped sills

    Science.gov (United States)

    Galland, O.; Neumann, E. R.; Planke, S.

    2009-12-01

    The mechanical coupling between magma intrusions and the surrounding rocks plays a major role in the emplacement of volcanic plumbing systems. The deformation associated with magma emplacement has been widely studied, such as caldera inflation/deflation, volcano deformation during dike intrusion, and doming above laccoliths. However, the feedback processes, i.e. the effect of deformation resulting from intruding magma on the propagation of the intrusion itself, have rarely been studied. Saucer-shaped sills are adequate geological objects to understand such processes. Indeed, observation show that saucer-shaped sills are often associated with dome-like structures affecting the overlying sediments. In addition, there is a clear geometrical relation between the sills and the domes: the dome diameters are almost identical to those of saucers, and the tips of the inclined sheets of saucers are superimposed on the edges of the domes. In this presentation, we report on experimental investigations of the emplacement mechanisms of saucer-shaped sills and associated deformation. The model materials were (1) cohesive fine-grained silica flour, representing brittle crust, and (2) molten low-viscosity oil, representing magma. A weak layer located at the top of the injection inlet simulates strata. The main variable parameter is injection depth. During experiments, the surface of the model is digitalized through a structured light technique based on the moiré projection principle. Such a tool provides topographic maps of the surface of the model and allows a periodic (every 1.5 s) monitoring of the model topography. When the model magma starts intruding, a symmetrical dome rises above the inlet. Subsequently, the dome inflates and widens, and then evolves to a plateau-like feature, with nearly flat upper surface and steep sides. At the end of the experiments, the intruding liquid erupts at the edge of the plateau. The intrusions formed in the experiments are saucer-shaped sills

  16. Evolution of deformation structures under varying loading conditions followed in situ by high angular resolution 3DXRD

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, B.

    2009-01-01

    copper to different loading conditions are presented: during uninterrupted tensile deformation, formation of subgrains can be observed concurrently with broadening of the Bragg reflection shortly after onset of plastic deformation. With continued tensile deformation, the subgrain structure develops...... intermittently. When the traction is terminated, stress relaxation occurs and number, size and orientation of subgrains are found to be constant. The subgrain structure freezes and only a minor clean-up of the dislocation structure is observed. When changing the tensile direction after pre-deformation in tension...

  17. Deformation mechanism in graphene nanoplatelet reinforced tantalum carbide using high load in situ indentation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng; Boesl, Benjamin [Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Silvestroni, Laura; Sciti, Diletta [Institute of Science and Technology for Ceramics (ISTEC), CNR-ISTEC, Via Granarolo 64, 48018 Faenza (Italy); Agarwal, Arvind, E-mail: agarwala@fiu.edu [Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States)

    2016-09-30

    High load in-situ indentation testing with real time SEM imaging was carried out on spark plasma sintered graphene nanoplatelets (GNP) reinforced TaC composites. The prime goal of this study was to understand the deformation behavior and the reinforcing mechanisms of GNPs. The results suggest that addition of GNPs had significant effect on dissipating indentation energy and confining the overall damage area to a localized region of TaC. The average crack length reduced by 26% whereas total damage area shrunk by 85% in TaC-5 vol% GNP sample as compared to pure TaC. TEM analysis concluded that well dispersed GNPs result in a strong and clean interface between TaC and GNP with trace amount of amorphous layer that leads to improved energy dissipation mechanism.

  18. Compressive response and deformation mechanisms of vertically aligned helical carbon nanotube forests

    Science.gov (United States)

    Scheffer, V. C.; Thevamaran, R.; Coluci, V. R.

    2018-01-01

    We study the dynamic compressive response of vertically aligned helical carbon nanotube forests using a mesoscale model. To describe the compressive response, the model includes the helical geometry of the constituent coils, the entanglement between neighboring coils, and the sideway interactions among coils. Coarse-grained simulations show forest densification and stress localization, which are caused by different deformation mechanisms such as coil packing, buckling, and crushing. We find that these mechanisms depend on the initial overlap between coils and lead to a nonlinear stress-strain behavior that agrees with recent impact experiments. The nonlinear stress-strain behavior was shown to be composed of an initial linear increase of stress in strain followed by an exponential growth. These regimes are an outcome of the characteristics of both the individual coils and the entangled morphology of the forests.

  19. Grain boundary sliding mechanism during high temperature deformation of AZ31 Magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Roodposhti, Peiman Shahbeigi, E-mail: pshahbe@ncsu.edu [North Carolina State University (United States); University of Connecticut (United States); Sarkar, Apu; Murty, Korukonda Linga [North Carolina State University (United States); Brody, Harold [University of Connecticut (United States); Scattergood, Ronald [North Carolina State University (United States)

    2016-07-04

    High temperature tensile creep tests were conducted on AZ31 Magnesium alloy at low stress range of 1–13 MPa to clarify the existence of grain boundary sliding (GBS) mechanism during creep deformation. Experimental data within the GBS regime shows the stress exponent is ~2 and the activation energy value is close to that for grain boundary diffusion. Analyses of the fracture surface of the sample revealed that the GBS provides many stress concentrated sites for diffusional cavities formation and leads to premature failure. Scanning electron microscopy images show the appearances of both ductile and brittle type fracture mechanism. X-ray diffraction line profile analysis (based on Williamson-Hall technique) shows a reduction in dislocation density due to dynamic recovery (DRV). A correlation between experimental data and Langdon's model for GBS was also demonstrated.

  20. A three-dimensional coupled thermo-hydro-mechanical model for deformable fractured geothermal systems

    DEFF Research Database (Denmark)

    Salimzadeh, Saeed; Paluszny, Adriana; Nick, Hamidreza M.

    2018-01-01

    A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled to a mec......A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled....... The model has been validated against several analytical solutions, and applied to study the effects of the deformable fractures on the injection of cold water in fractured geothermal systems. Results show that the creation of flow channelling due to the thermal volumetric contraction of the rock matrix...

  1. Corrosion mechanism of a Ni-based alloy in supercritical water: Impact of surface plastic deformation

    International Nuclear Information System (INIS)

    Payet, Mickaël; Marchetti, Loïc; Tabarant, Michel; Chevalier, Jean-Pierre

    2015-01-01

    Highlights: • The dissolution of Ni and Fe cations occurs during corrosion of Ni-based alloys in SCW. • The nature of the oxide layer depends locally on the alloy microstructure. • The corrosion mechanism changes when cold-work increases leading to internal oxidation. - Abstract: Ni–Fe–Cr alloys are expected to be a candidate material for the generation IV nuclear reactors that use supercritical water at temperatures up to 600 °C and pressures of 25 MPa. The corrosion resistance of Alloy 690 in these extreme conditions was studied considering the surface finish of the alloy. The oxide scale could suffer from dissolution or from internal oxidation. The presence of a work-hardened zone reveals the competition between the selective oxidation of chromium with respect to the oxidation of nickel and iron. Finally, corrosion mechanisms for Ni based alloys are proposed considering the effects of plastically deformed surfaces and the dissolution.

  2. Deformations in structure of the scapolites from northeast, Brazil

    International Nuclear Information System (INIS)

    Gouveia, A.H.C.; Villarroel, H.S.

    1979-01-01

    Scapolites are relatively common constituents of calcium-rich metamorphic rocks. They can be considered as members of the solid solution series marialite and meionite. Relationship between the optical properties, chemical composition and X-ray diffraction data shows that scapolites from northern Brazil are mizzonites and meionites. The structures of these minerals are compatible only with a primitive lattice. The d hkl peaks of natural scapolites are outside the range shown by the two pure end-members of the series, and the unit-cell dimensions increase with percentage of (K+SO 4 ). X-ray diffraction powder data for natural tetragonal and orthorhombic calcium-rich scapolites are detailed in five tables. (author) [pt

  3. Structural interpretations of deformation and fracture behavior of polypropylene/multi-walled carbon nanotube composites

    International Nuclear Information System (INIS)

    Ganss, Martin; Satapathy, Bhabani K.; Thunga, Mahendra; Weidisch, Roland; Poetschke, Petra; Jehnichen, Dieter

    2008-01-01

    The deformation and crack resistance behavior of polypropylene (PP) multi-walled carbon nanotube (MWNT) composites have been studied and their interrelation to the structural attributes studied by transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarization light microscopy has been discussed. The composites were produced from industrial available MWNT by extrusion melt-mixing and injection-molding. In stress-strain measurements a strong increase in the yield stress and the Young's modulus at low MWNT contents has been observed, which was attributed to an efficient load transfer between the carbon nanotubes and polypropylene matrix through a good polymer-nanotube adhesion as indicated by SEM. The extent of enhancement in mechanical properties above 1.5 wt.% of MWNT decreased due to an apparently increased tendency of clustering of carbon nanotubes. Several theoretical models have been taken into account to explain the mechanical properties and to demonstrate the applicability of such models to the system under investigation. The crack resistance behavior has been studied with the essential work of fracture (EWF) approach based on post-yield fracture mechanics (PYFM) concept. A maximum in the non-essential work of fracture was observed at 0.5 wt.% MWNT demonstrating enhanced toughness compared to pure PP, followed by a sharp decline as the MWNT content was increased to 1.5 wt.% reveals a ductile-to-semi-ductile transition. Studies on the kinetics of crack propagation aspects have revealed a qualitative picture of the nature of such a transition in the fracture modes

  4. Micro-Structural Evolution and Size-Effects in Plastically Deformed Single Crystals: Strain Gradient Continuum Modeling

    DEFF Research Database (Denmark)

    El-Naaman, Salim Abdallah

    the macroscopic effects related to strain gradients, most predict smooth micro-structures. The evolution of dislocation micro-structures, during plastic straining of ductile crystalline materials, is highly complex and nonuniform. Published experimental measurements on deformed metal crystals show distinct......An extensive amount of research has been devoted to the development of micro-mechanics based gradient plasticity continuum theories, which are necessary for modeling micron-scale plasticity when large spatial gradients of plastic strain appear. While many models have proven successful in capturing...... strain. It is clear that many challenges are associated with modeling dislocation structures, within a framework based on continuum fields, however, since the strain gradient effects are attributed to the dislocation micro-structure, it is a natural step, in the further development of gradient theories...

  5. Deformation stresses and mechanical behaviour of engineered barriers in the repository environment

    International Nuclear Information System (INIS)

    Ipatti, A.; Majamaeki, O.

    1991-12-01

    The report surveys functioning of the engineered barriers in the Loviisa repository under deformation stresses of the solidification product and the concrete filling material. The survey is based on the latest estimates of the waste amounts and the corresponding repository plans, and on solidification product compositions and properties. The IVOFEM and NASTRAN software was used in the structural analyses. The materials were supposed to be homogeneous and linearly elastic and dislocations small. Accordingly, the design loads were chosen conservatively so that the impacts of deformation stresses are sufficiently overestimated. A reinforced concrete container lined with cellular plastic remains a watertight structure, meeting the requirements set in view of expansion of a solidification product. In view of the stresses, the decisive time is the intermediate storage stage. The greatest stresses are found in junctions between the container wall and the bottom and cover. The concrete filling between the waste packages cannot resist the drying shrinkage and wetting expansion stresses without cracking. Concrete walls of the repository can withstand the stress caused by wetting expansion of the waste packages only when strongly reinforced. However, the forces against the walls are so big that if cracks in the concrete walls are desired to be restricted, due to reinforcement steel corrosion or wall tightness, the present type of filling material between the waste packages is not necessarily technically the best alternative

  6. Structural properties, deformation behavior and thermal stability of martensitic Ti-Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boenisch, Matthias

    2016-06-10

    Ti-Nb alloys are characterized by a diverse metallurgy which allows obtaining a wide palette of microstructural configurations and physical properties via careful selection of chemical composition, heat treatment and mechanical processing routes. The present work aims to expand the current state of knowledge about martensite forming Ti-Nb alloys by studying 15 binary Ti-c{sub Nb}Nb (9 wt.% ≤ c{sub Nb} ≤ 44.5 wt.%) alloy formulations in terms of their structural and mechanical properties, as well as their thermal stability. The crystal structures of the martensitic phases, α{sup '} and α'', and the influence of the Nb content on the lattice (Bain) strain and on the volume change related to the β → α{sup '}/α'' martensitic transformations are analyzed on the basis of Rietveld-refinements. The magnitude of the shuffle component of the β → α{sup '}/α'' martensitic transformations is quantified in relation to the chemical composition. The largest transformation lattice strains are operative in Nb-lean alloys. Depending on the composition, both a volume dilatation and contraction are encountered and the volume change may influence whether hexagonal martensite α{sup '} or orthorhombic martensite α'' forms from β upon quenching. The mechanical properties and the deformation behavior of martensitic Ti-Nb alloys are studied by complementary methods including monotonic and cyclic uniaxial compression, nanoindentation, microhardness and impulse excitation technique. The results show that the Nb content strongly influences the mechanical properties of martensitic Ti-Nb alloys. The elastic moduli, hardness and strength are minimal in the vicinity of the limiting compositions bounding the interval in which orthorhombic martensite α'' forms by quenching. Uniaxial cyclic compressive testing demonstrates that the elastic properties of strained samples are different than those of unstrained ones

  7. Further Development of Ko Displacement Theory for Deformed Shape Predictions of Nonuniform Aerospace Structures

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2009-01-01

    The Ko displacement theory previously formulated for deformed shape predictions of nonuniform beam structures is further developed mathematically. The further-developed displacement equations are expressed explicitly in terms of geometrical parameters of the beam and bending strains at equally spaced strain-sensing stations along the multiplexed fiber-optic sensor line installed on the bottom surface of the beam. The bending strain data can then be input into the displacement equations for calculations of local slopes, deflections, and cross-sectional twist angles for generating the overall deformed shapes of the nonuniform beam. The further-developed displacement theory can also be applied to the deformed shape predictions of nonuniform two-point supported beams, nonuniform panels, nonuniform aircraft wings and fuselages, and so forth. The high degree of accuracy of the further-developed displacement theory for nonuniform beams is validated by finite-element analysis of various nonuniform beam structures. Such structures include tapered tubular beams, depth-tapered unswept and swept wing boxes, width-tapered wing boxes, and double-tapered wing boxes, all under combined bending and torsional loads. The Ko displacement theory, combined with the fiber-optic strain-sensing system, provide a powerful tool for in-flight deformed shape monitoring of unmanned aerospace vehicles by ground-based pilots to maintain safe flights.

  8. Extracting a Purely Non-rigid Deformation Field of a Single Structure

    Science.gov (United States)

    Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

    During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and the stent graft. The problem definition of deformable registration of images covering the entire abdominal region, however, is highly ill-posed. We present a new method for extracting the deformation of an aneurysmatic aorta. The outline of the procedure includes initial rigid alignment of two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. Our non-rigid registration procedure then only computes local non-rigid deformation and leaves out all remaining global rigid transformations. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

  9. Deformation behavior of dragonfly-inspired nodus structured wing in gliding flight through experimental visualization approach.

    Science.gov (United States)

    Zhang, Sheng; Sunami, Yuta; Hashimoto, Hiromu

    2018-04-10

    Dragonfly has excellent flight performance and maneuverability due to the complex vein structure of wing. In this research, nodus as an important structural element of the dragonfly wing is investigated through an experimental visualization approach. Three vein structures were fabricated as, open-nodus structure, closed-nodus structure (with a flex-limiter) and rigid wing. The samples were conducted in a wind tunnel with a high speed camera to visualize the deformation of wing structure in order to study the function of nodus structured wing in gliding flight. According to the experimental results, nodus has a great influence on the flexibility of the wing structure. Moreover, the closed-nodus wing (with a flex-limiter) enables the vein structure to be flexible without losing the strength and rigidity of the joint. These findings enhance the knowledge of insect-inspired nodus structured wing and facilitate the application of Micro Air Vehicle (MAV) in gliding flight.

  10. Structural mechanics in nuclear power plant

    International Nuclear Information System (INIS)

    Han Liangbi

    1998-01-01

    The main research works in structural mechanics in reactor technology are emphatically introduced. It is completed by structural mechanics engineers at Shanghai Nuclear Research and Design Institute associated with the design and construction problems for Qinshan NPP Unit 1 and Pakistani CHASNUPP. About structural mechanics problem for the containment, the rock and soft soil two different bases are considered. For the later the interaction between soil and structure is carefully studied. About the structural mechanics problem for the equipment and pipings, the three dimensional stress and fracture analyses are studied. For the structural dynamics problem, including flow induced vibration, the response analyses under earthquake and loss coolant accident loadings are studied. For pipings, the leak before break technique has been emphatically introduced. A lot of mathematical models, the used computer codes, analytical calculations and experimental results are also introduced. This is a comprehensive description about structural mechanics problem in pressurized water reactor nuclear power plant

  11. Problems of structural mechanics in nuclear design

    International Nuclear Information System (INIS)

    Patwardhan, V.M.; Kakodkar, Anil

    1975-01-01

    A very careful and detailed stress analysis of nuclear presure vessels and components is essential for ensuring the safety and integrity of nuclear power plants. The nuclear designer, therefore, relies heavily on structural mechanics for application of the most advanced stress analysis techniques to practical design problems. The paper reviews the inter-relation between structural mechanics and nuclear design and discusses a few of the specific structural mechanics problems faced by the nuclear designers in the Department of Atomic Energy, India. (author)

  12. Deformation bands and dislocation structures of [1-bar 5 5] coplanar double-slip-oriented copper single crystal under cyclic deformation

    International Nuclear Information System (INIS)

    Li, Y.; Li, S.X.; Li, G.Y.

    2004-01-01

    The features of surface morphology and dislocation structure of [1-bar 5 5] coplanar double-slip-oriented copper single crystal under cyclic deformation at a constant plastic shear strain amplitude of 2x10 -3 were studied using optical microscope (OP) and electron channelling contrast imaging (ECCI) in the scanning electron microscope (SEM). Experimental results show that there are two sets of the secondary type of deformation band (DBII) formed in the specimen. The geometry relationship of the two sets of deformation bands (DBs) and slip band (SB) are given. The habit planes of DBIIs are close to (1-bar 0 1) and (1-bar 1 0) plane, respectively. The surface dislocation structures in the specimen including vein, irregular dislocation cells and dislocation walls were also observed. The typical dislocation structure in DBII is the dislocation walls

  13. Deformation analysis and prediction of bank protection structure with river level fluctuations

    Science.gov (United States)

    Hu, Rui; Xing, Yixuan

    2017-04-01

    Bank structure is an important barrier to maintain the safety of the embankment. The deformation of bank protection structure is not only affected by soil pressure caused by the excavation of the riverway, but also by the water pressure caused river water level fluctuations. Thus, it is necessary to establish a coupled soil-water model to analyze the deformation of bank structure. Based on Druck-Prager failure criteria and groundwater seepage theory, a numerical model of bank protection structure with consideration of the pore water pressure of soil mass is established. According to the measured river level data with seasonal fluctuating, numerical analysis of the deformation of bank protection structure is implemented. The simulation results show that the river water level fluctuation has clear influence on the maximum lateral displacement of the pile. Meanwhile, the distribution of plastic zone is related to the depth of groundwater level. Finally, according to the river water level data of the recent ten years, we analyze the deformation of the bank structure under extreme river level. The result shows that, compared with the scenario of extreme high river level, the horizontal displacement of bank protection structure is larger (up to 65mm) under extreme low river level, which is a potential risk to the embankment. Reference Schweiger H F. On the use of drucker-prager failure criteria for earth pressure problems[J]. Computers and Geotechnics, 1994, 16(3): 223-246. DING Yong-chun,CHENG Ze-kun. Numerical study on performance of waterfront excavation[J]. Chinese Journal of Geotechnical Engineering,2013,35(2):515-521. Wu L M, Wang Z Q. Three gorges reservoir water level fluctuation influents on the stability of the slope[J]. Advanced Materials Research. Trans Tech Publications, 2013, 739: 283-286.

  14. 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.

  15. 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.

  16. Investigation of the Deformation Mechanism of a near β Titanium Alloy through Isothermal Compression

    Directory of Open Access Journals (Sweden)

    Jie Wu

    2017-11-01

    Full Text Available This study investigated the hot deformation behavior of Ti-4Al-1Sn-2Zr-5Mo-8V-2.5Cr alloy through isothermal compression tests at temperatures from 780 to 930 °C with strain rates ranging from 0.001 to 1 s−1. The flow stress decreases with a decreased strain rate and an increased temperature. A constitutive equation was established for this alloy and the dependence of activation energy on temperature and strain rate is discussed. We further proposed a processing map using the dynamic materials model. On the processing map various domains of flow stability and flow instability can be identified. The deformation mechanisms associated with flow stability regions are mainly dynamic recrystallization (DRX and dynamic recovery (DRV. The flow instability is manifested in the form of the band of flow localizations. The optimum processing conditions are suggested such that the temperature range is from 780 to 880 °C and the strain rate ranges from 0.001 to 0.01 s−1.

  17. 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

    Subsurface exploitation of the Earth's natural resources removes the natural system from its chemical and physical equilibrium. As such, groundwater extraction and hydrocarbon production from subsurface reservoirs frequently causes surface subsidence and induces (micro)seismicity. These effects are not only a problem in onshore (e.g. Groningen, the Netherlands) and offshore hydrocarbon fields (e.g. Ekofisk, Norway), but also in urban areas with extensive groundwater pumping (e.g. Venice, Italy). It is known that fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation, and causes significant technical, economic and ecological impact. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased. This is most likely due to time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the rock overburden. Given the societal and ecological impact of surface subsidence, as well as the current interest in developing geothermal energy and unconventional gas resources in densely populated areas, there is much need for obtaining better quantitative understanding of creep in sediments to improve the predictability of the impact of geo-energy and groundwater production. The key problem in developing a reliable, quantitative description of the creep behaviour of sediments, such as sands and sandstones, is that the operative deformation mechanisms are poorly known and poorly quantified. While grain-scale brittle fracturing plus intergranular sliding play an important role in the early stages of compaction, these time-independent, brittle-frictional processes give way to compaction creep on longer time-scales. Thermally-activated mass transfer processes, like pressure solution, can cause creep via dissolution of material at stressed grain contacts, grain

  18. Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

    Science.gov (United States)

    Zhao, L. Z.; Deng, X. X.; Yu, H. Y.; Guan, H. J.; Li, X. Q.; Xiao, Z. Y.; Liu, Z. W.; Greneche, J. M.

    2017-12-01

    High-velocity compaction (HVC) has been proposed as an effective approach for the fabrication of nanocrystalline Nd-Fe-B magnets. In this work, the effect of powder size on the density of HVCed magnets has been studied and the anisotropic nanocrystalline Nd-Fe-B magnets were prepared by HVC followed by hot deformation (HD). It is found that a proper particle size range is beneficial to high density. The investigations on the microstructure, magnetic domain structure, and hyperfine structure, indicate that the deformed grain structure and the magnetic domain structure with uniform paramagnetic grain boundary phase give good magnetic properties of HVC + HDed magnets. These magnets also have good mechanical and anti-corrosion properties. The results indicate that HVC is not only a near-net-shape, room temperature and binder-free process but is also able to maintain uniform nanostructure and to achieve good magnetic properties in both isotropic and anisotropic magnets. As a result, HVC can be employed as an ideal alternative process for bonding or hot pressing for the conventional MQI, MQII and MQIII magnets.

  19. Motion and deformation estimation from medical imagery by modeling sub-structure interaction and constraints

    KAUST Repository

    Sundaramoorthi, Ganesh

    2012-09-13

    This paper presents a novel medical image registration algorithm that explicitly models the physical constraints imposed by objects or sub-structures of objects that have differing material composition and border each other, which is the case in most medical registration applications. Typical medical image registration algorithms ignore these constraints and therefore are not physically viable, and to incorporate these constraints would require prior segmentation of the image into regions of differing material composition, which is a difficult problem in itself. We present a mathematical model and algorithm for incorporating these physical constraints into registration / motion and deformation estimation that does not require a segmentation of different material regions. Our algorithm is a joint estimation of different material regions and the motion/deformation within these regions. Therefore, the segmentation of different material regions is automatically provided in addition to the image registration satisfying the physical constraints. The algorithm identifies differing material regions (sub-structures or objects) as regions where the deformation has different characteristics. We demonstrate the effectiveness of our method on the analysis of cardiac MRI which includes the detection of the left ventricle boundary and its deformation. The experimental results indicate the potential of the algorithm as an assistant tool for the quantitative analysis of cardiac functions in the diagnosis of heart disease.

  20. Investigating the Mechanical Behavior and Deformation Mechanisms of Ultrafinegrained Metal Films Using Ex-situ and In-situ TEM Techniques

    Science.gov (United States)

    Izadi, Ehsan

    Nanocrystalline (NC) and Ultrafine-grained (UFG) metal films exhibit a wide range of enhanced mechanical properties compared to their coarse-grained counterparts. These properties, such as very high strength, primarily arise from the change in the underlying deformation mechanisms. Experimental and simulation studies have shown that because of the small grain size, conventional dislocation plasticity is curtailed in these materials and grain boundary mediated mechanisms become more important. Although the deformation behavior and the underlying mechanisms in these materials have been investigated in depth, relatively little attention has been focused on the inhomogeneous nature of their microstructure (particularly originating from the texture of the film) and its influence on their macroscopic response. Furthermore, the rate dependency of mechanical response in NC/UFG metal films with different textures has not been systematically investigated. The objectives of this dissertation are two-fold. The first objective is to carry out a systematic investigation of the mechanical behavior of NC/UFG thin films with different textures under different loading rates. This includes a novel approach to study the effect of texture-induced plastic anisotropy on mechanical behavior of the films. Efforts are made to correlate the behavior of UFG metal films and the underlying deformation mechanisms. The second objective is to understand the deformation mechanisms of UFG aluminum films using in-situ transmission electron microscopy (TEM) experiments with Automated Crystal Orientation Mapping. This technique enables us to investigate grain rotations in UFG Al films and to monitor the microstructural changes in these films during deformation, thereby revealing detailed information about the deformation mechanisms prevalent in UFG metal films.

  1. Superimposed deformation in seconds: breccias from the impact structure at Kentland, Indiana (USA)

    Science.gov (United States)

    Bjørnerud, M. G.

    1998-05-01

    Breccias from the central uplift at the Kentland, Indiana impact structure have outcrop and microscopic characteristics that give insight into events that may occur in a carbonate-dominated sedimentary sequence in the moments following hypervelocity impact. Three distinct types of brecciated rock bodies — fault breccias, breccia lenses, and breccia dikes — suggest multiple mechanisms of fragmentation. The fault breccias occur along steeply dipping faults that coincide with compositional discontinuities in the stratigraphic succession. The breccia lenses and dikes are less localized in occurrence and show no systematic spatial distribution or orientation. The fault breccias and breccia lenses show no consistent cross-cutting relationships, but both are transected by the breccia dikes. Textural analysis reveals significant differences in particle size distributions for the different breccias. The fault breccias are typically monomict, coarsest and least uniform in grain size, and yield the highest power-law exponent (fractal dimension) in plots of particle size vs. frequency. The polymict dike filling is finest and most uniform in grain size, has the lowest power-law exponent, and is locally laminated and size-sorted. SEM images of the dike-filling breccia show that fragmentation occurred to the scale of microns. Material within the breccia lenses has textural characteristics intermediate between the other two types, but the irregular morphology of these bodies suggests a mechanism of formation different from that of either of the other breccia categories. The breccia lenses and dikes both have sub-mm-scale spheroidal vugs that may have been formed by carbon dioxide bubbles released during sudden devolatilization of the carbonate country rock. Collectively, these observations shed light on the processes that occur during the excavation and modification phases of crater formation in carbonate strata — heterogeneous, polyphase, multiscale deformation accomplished

  2. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Rao, D.G.; Neprochnov, Y.P.

    Analyses of bathymetry, gravity and seismic reflection data of the diffusive plate boundary in the central Indian Ocean reveal a new kind of deformed structure besides the well-reported structures of long-wavelength anticlinal basement rises...

  3. Predicting welding distortion in a panel structure with longitudinal stiffeners using inherent deformations obtained by inverse analysis method.

    Science.gov (United States)

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

    Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results.

  4. 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

  5. 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.

  6. Mechanisms of the plastic deformation of uranium alloys at low temperature

    International Nuclear Information System (INIS)

    Le Poac, P.; Nomine, A.M.; Miannay, D.

    1976-01-01

    The mechanical characteristics of the bcc binary alloys U-6Mo, U-8Mo, U-10Mo, U-12Mo and bcc ternary alloys U-8Mo-1Ti, U-10Mo-1Ti, U-10Mo-1Zr, stressed in compression, were determined between -196 deg C and + 450 deg C. The plastic flow shear stress in non-dependent on temperature above 300 deg C. At lower temperature shear stress is highly activated, except for the alloy U-6Mo and U-12Mo. Athermal shear stress above 300 deg C is due to the hardening of the solid solution described by Mott and Nabarro. In the thermal range, the recombination of the dissociated dislocations controls the plastic deformation [fr

  7. Semantic modeling of the structural and process entities during plastic deformation of crystals and rocks

    Science.gov (United States)

    Babaie, Hassan; Davarpanah, Armita

    2016-04-01

    We are semantically modeling the structural and dynamic process components of the plastic deformation of minerals and rocks in the Plastic Deformation Ontology (PDO). Applying the Ontology of Physics in Biology, the PDO classifies the spatial entities that participate in the diverse processes of plastic deformation into the Physical_Plastic_Deformation_Entity and Nonphysical_Plastic_Deformation_Entity classes. The Material_Physical_Plastic_Deformation_Entity class includes things such as microstructures, lattice defects, atoms, liquid, and grain boundaries, and the Immaterial_Physical_Plastic_Deformation_Entity class includes vacancies in crystals and voids along mineral grain boundaries. The objects under the many subclasses of these classes (e.g., crystal, lattice defect, layering) have spatial parts that are related to each other through taxonomic (e.g., Line_Defect isA Lattice_Defect), structural (mereological, e.g., Twin_Plane partOf Twin), spatial-topological (e.g., Vacancy adjacentTo Atom, Fluid locatedAlong Grain_Boundary), and domain specific (e.g., displaces, Fluid crystallizes Dissolved_Ion, Void existsAlong Grain_Boundary) relationships. The dynamic aspect of the plastic deformation is modeled under the dynamical Process_Entity class that subsumes classes such as Recrystallization and Pressure_Solution that define the flow of energy amongst the physical entities. The values of the dynamical state properties of the physical entities (e.g., Chemical_Potential, Temperature, Particle_Velocity) change while they take part in the deformational processes such as Diffusion and Dislocation_Glide. The process entities have temporal parts (phases) that are related to each other through temporal relations such as precedes, isSubprocessOf, and overlaps. The properties of the physical entities, defined under the Physical_Property class, change as they participate in the plastic deformational processes. The properties are categorized into dynamical, constitutive

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

    Science.gov (United States)

    Wimpenny, S. E.; Copley, A.

    2017-12-01

    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. We used models of stress-driven afterslip and visco-elastic relaxation, in conjunction with a dense time series of 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 modelling indicates that the faults at Bam may remain predominantly locked, and 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. Modelling also suggests parts of the fault that experienced post-seismic creep between 2003-2009 overlapped with areas that also slipped co-seismically. Our observations and models also provide an opportunity to probe how aseismic fault slip leads to 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 at Bam 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.

  9. A diffraction based study of the deformation mechanisms in anomalously ductile B2 intermetallics

    Science.gov (United States)

    Mulay, Rupalee Prashant

    For many decades, the brittle nature of most intermetallic compounds (e.g. NiAl) has been the limiting factor in their practical application. Many B2 (CsCl prototypical structure) intermetallics are known to exhibit slip on the {110} slip mode, which provides only 3 independent slip systems and, hence, is unable to satisfy the von Mises (a.k.a. Taylor) criterion for polycrystalline ductility. As a result, inherent polycrystalline ductility is unexpected. Recent discovery of a number of ductile B2 intermetallics has raised questions about possible violation of the von Mises criterion by these alloys. These ductile intermetallic compounds are MR (metal (M) combined with a rare earth metal or group IV refractory metal (R)) alloys and are stoichiometric, ordered compounds. Single crystal slip trace analyses have only identified the presence of {011} or {010} slip systems. More than 100 other B2 MR compounds are known to exist and many of them have already been shown to be ductile (e.g., CuY, AgY, CuDy, CoZr, CoTi, etc.). Furthermore, these alloys exhibit a large Bauschinger effect. The present work uses several diffraction based techniques including electron back scattered diffraction (EBSD), X-ray diffraction (XRD) and in-situ neutron diffraction; in conjunction with scanning electron microscopy (SEM), transmission electron microscopy (TEM), mechanical testing, and crystal plasticity modeling, to elucidate the reason for ductility in select B2 alloys, explore the spread of this ductility over the B2 family, and understand the Bauschinger effect in these alloys. Several possible explanations (e.g., slip of dislocations, strong texture, phase transformations and twinning) for the anomalous ductility were explored. An X-ray diffraction based analysis ruled out texture, phase purity and departure from order as explanations for the anomalous ductility in MR alloys. In-situ neutron diffraction and post deformation SEM, EBSD, and TEM were unable to detect any evidence for

  10. Structural mechanics of nuclear plant components

    International Nuclear Information System (INIS)

    Roche, R.

    1986-10-01

    Sound structural analysis are needed for designing safe and reliable components, hence his play is very important in nuclear industry. This report is a provisional writing on the good practice in structural mechanics. Emphasis is put on non elastic analysis, damage appraisal, fatigue, fracture mechanics and also on elevated temperature behaviour [fr

  11. Role of structural inheritance on present-day deformation in intraplate domains

    Science.gov (United States)

    Tarayoun, A.; Mazzotti, S.; Gueydan, F.

    2017-12-01

    Understanding the role of structural inheritance on present day surface deformation is a key element for better characterizing the dynamism of intraplate earthquakes. Current deformation and seismicity are poorly understood phenomenon in intra-continental domains. A commonly used hypothesis, based on observations, suggests that intraplate deformation is related to the reactivation of large tectonic paleo-structures, which can act as locally weakened domains. The objective of our study is to quantify the impact of these weakened areas on present-day strain localizations and rates. We combine GPS observations and numerical modeling to analyze the role of structural inheritance on strain rates, with specific observations along the St. Lawrence Valley of eastern Canada. We processed 143 GPS stations from five different networks, in particular one dense campaign network situated along a recognized major normal faults system of the Iapetus paleo-rift, in order to accurately determine the GPS velocities and strain rates. Results of strain rates show magnitude varying from 1.5x10-10 to 6.8x10-9 yr-1 in the St Lawrence valley. Weakened area strain rates are up to one order of magnitude higher than surrounding areas. We compare strain rates inferred from GPS and the new postglacial rebound model. We found that GPS signal is one order of magnitude higher in the weakened zone, which is likely due to structural inheritance. The numerical modeling investigates the steady-state deformation of the continental lithosphere with presence of a weak area. Our new approach integrates ductile structural inheritance using a weakening coefficient that decreases the lithosphere strength at different depths. This allows studying crustal strain rates mainly as a function of rheological contrast and geometry of the weakened domains. Comparison between model predictions and observed GPS strain rates will allow us to investigate the respective role of crustal and mantle tectonic inheritance.

  12. Superposed ruptile deformational events revealed by field and VOM structural analysis

    Science.gov (United States)

    Kumaira, Sissa; Guadagnin, Felipe; Keller Lautert, Maiara

    2017-04-01

    Virtual outcrop models (VOM) is becoming an important application in the analysis of geological structures due to the possibility of obtaining the geometry and in some cases kinematic aspects of analyzed structures in a tridimensional photorealistic space. These data are used to gain quantitative information on the deformational features which coupled with numeric models can assist in understands deformational processes. Old basement units commonly register superposed deformational events either ductile or ruptile along its evolution. The Porongos Belt, located at southern Brazil, have a complex deformational history registering at least five ductile and ruptile deformational events. In this study, we presents a structural analysis of a quarry in the Porongos Belt, coupling field and VOM structural information to understand process involved in the last two deformational events. Field information was acquired using traditional structural methods for analysis of ruptile structures, such as the descriptions, drawings, acquisition of orientation vectors and kinematic analysis. VOM was created from the image-based modeling method through photogrammetric data acquisition and orthorectification. Photogrammetric data acquisition was acquired using Sony a3500 camera and a total of 128 photographs were taken from ca. 10-20 m from the outcrop in different orientations. Thirty two control point coordinates were acquired using a combination of RTK dGPS surveying and total station work, providing a precision of few millimeters for x, y and z. Photographs were imported into the Photo Scan software to create a 3D dense point cloud from structure from-motion algorithm, which were triangulated and textured to generate the VOM. VOM was georreferenced (oriented and scaled) using the ground control points, and later analyzed in OpenPlot software to extract structural information. Data was imported in Wintensor software to obtain tensor orientations, and Move software to process and

  13. Research on geometrical model and mechanism for metal deformation based on plastic flow

    International Nuclear Information System (INIS)

    An, H P; Li, X; Rui, Z Y

    2015-01-01

    Starting with general conditions of metal plastic deformation, it analyses the relation between the percentage spread and geometric parameters of a forming body with typical machining process are studied. A geometrical model of deforming metal is set up according to the characteristic of a flowing metal particle. Starting from experimental results, the effect of technological parameters and friction between workpiece and dies on plastic deformation of a material were studied and a slippage deformation model of mass points within the material was proposed. Finally, the computing methods for strain and deformation energy and temperature rise are derived from homogeneous deformation. The results can be used to select technical parameters and compute physical quantities such as strain, deformation energy, and temperature rise. (paper)

  14. PWR thermocouple mechanical sealing structure

    International Nuclear Information System (INIS)

    Shen Qiuping; He Youguang

    1991-08-01

    The PWR in-core temperature detection device, which is one of measures to insure reactor safety operation, is to monitor and diagnose reactor thermal power output and in-core power distribution. The temperature detection device system uses thermocouples as measuring elements with stainless steel protecting sleeves. The thermocouple has a limited service time and should be replaced after its service time has reached. A new sealing device for the thermocouples of reactor in-core temperature detection system has been developed to facilitate replacement. The structure is complete tight under high temperature and pressure without any leakage and seepage, and easy to be assembled or disassembled in radioactive environment. The device is designed to make it possible to replace the thermocouple one by one if necessary. This is a new, simple and practical structure

  15. Creep deformation and rupture behavior of type 304/308 stainless steel structural weldments

    International Nuclear Information System (INIS)

    McAfee, W.J.; Richardson, M.; Sartory, W.K.

    1977-01-01

    The creep deformation and rupture of type 304/308 stainless steel structural weldments at 593 0 C (1100 0 F) was experimentally investigated to study the comparative behavior of the base metal and weld metal constituents. The tests were conducted in support of ORNL's program to develop high-temperature structural design methods applicable to liquid-metal fast breeder reactor (LMFBR) system components that operate in the creep range. The specimens used were thin-walled, right circular cylinders capped with either flat or hemispherical heads and tested under internal gas pressure. Circumferential welds were located in different regions of the cylinder or head and, with one exception, were geometrically duplicated by all base metal regions in companion specimens. Results are presented on the comparative deformation and rupture behavior of selected points in the base metal and weldment regions of the different specimens and on the overall surface strains for selected specimens

  16. A Numerical Analysis on the Local Deformation of a Spacer Grid Structure for Nuclear Fuel Cells

    International Nuclear Information System (INIS)

    Jang, Myung-Geun; Na, Geum Ju; Kim, Jong-Bong; Shin, Hyunho

    2016-01-01

    The result of a preliminary numerical investigation on local deformation characteristics of a multi-layered spacer-grid structure with five guide tubes is reported based on implicit finite element analysis. For the numerical analysis, displacements of top and bottom cross sections of each guide tube in a single-layer model were constrained while a lateral displacement was imposed on the single layer. Unlike the impact hammer test that is generally employed to characterize the deformation characteristics of the space-grid structure, the buckling phenomenon occurs locally in this study; it takes place at the inner grids around each tube and the degree of bucking is more apparent for tubes near the lateral surface where the lateral displacement was imposed. (paper)

  17. Understanding molecular structure from molecular mechanics.

    Science.gov (United States)

    Allinger, Norman L

    2011-04-01

    Molecular mechanics gives us a well known model of molecular structure. It is less widely recognized that valence bond theory gives us structures which offer a direct interpretation of molecular mechanics formulations and parameters. The electronic effects well-known in physical organic chemistry can be directly interpreted in terms of valence bond structures, and hence quantitatively calculated and understood. The basic theory is outlined in this paper, and examples of the effects, and their interpretation in illustrative examples is presented.

  18. A nonlinear deformed su(2) algebra with a two-color quasitriangular Hopf structure

    International Nuclear Information System (INIS)

    Bonatsos, D.; Daskaloyannis, C.; Kolokotronis, P.; Ludu, A.; Quesne, C.

    1997-01-01

    Nonlinear deformations of the enveloping algebra of su(2), involving two arbitrary functions of J 0 and generalizing the Witten algebra, were introduced some time ago by Delbecq and Quesne. In the present paper, the problem of endowing some of them with a Hopf algebraic structure is addressed by studying in detail a specific example, referred to as scr(A) q + (1). This algebra is shown to possess two series of (N+1)-dimensional unitary irreducible representations, where N=0,1,2,hor-ellipsis. To allow the coupling of any two such representations, a generalization of the standard Hopf axioms is proposed by proceeding in two steps. In the first one, a variant and extension of the deforming functional technique is introduced: variant because a map between two deformed algebras, su q (2) and scr(A) q + (1), is considered instead of a map between a Lie algebra and a deformed one, and extension because use is made of a two-valued functional, whose inverse is singular. As a result, the Hopf structure of su q (2) is carried over to scr(A) q + (1), thereby endowing the latter with a double Hopf structure. In the second step, the definition of the coproduct, counit, antipode, and scr(R)-matrix is extended so that the double Hopf algebra is enlarged into a new algebraic structure. The latter is referred to as a two-color quasitriangular Hopf algebra because the corresponding scr(R)-matrix is a solution of the colored Yang endash Baxter equation, where the open-quotes colorclose quotes parameters take two discrete values associated with the two series of finite-dimensional representations. copyright 1997 American Institute of Physics

  19. Local deformation method for measuring element tension in space deployable structures

    Directory of Open Access Journals (Sweden)

    Belov Sergey

    2017-01-01

    Full Text Available The article describes the local deformation method to determine the tension of cord and thin membrane elements in space deployable structure as antenna reflector. Possible measuring instrument model, analytical and numerical solutions and experimental results are presented. The boundary effects on measurement results of metallic mesh reflector surface tension are estimated. The study case depicting non-uniform reflector surface tension is considered.

  20. Strength and Deformation Rate of Plate Boundaries: The Rheological Effects of Grain Size Reduction, Structure, and Serpentinization.

    Science.gov (United States)

    Montesi, L.; Gueydan, F.

    2016-12-01

    Global strain rate maps reveal 1000-fold contrasts between plate interiors, oceanic or continental diffuse plate boundaries and narrow plate boundaries. Here, we show that rheological models based on the concepts of shear zone localization and the evolution of rock structure upon strain can explain these strain rate contrasts. Ductile shear zones constitute a mechanical paradox in the lithosphere. As every plastic deformation mechanism is strain-rate-hardening, ductile rocks are expected to deform at low strain rate and low stress (broad zone of deformation). Localized ductile shear zones require either a localized forcing (locally high stress) or a thermal or structural anomaly in the shear zone; either can be inherited or develop progressively as rocks deform. We previously identified the most effective process at each depth level of the lithosphere. In the upper crust and middle crust, rocks fabric controls localization. Grain size reduction is the most efficient mechanism in the uppermost mantle. This analysis can be generalized to consider a complete lithospheric section. We assume strain rate does not vary with depth and that the depth-integrated strength of the lithospheric does not change over time, as the total force is controlled by external process such as mantle convection and plate and slab buoyancy. Reducing grain size from a coarse value typical of undeformed peridotite to a value in agreement with the stress level (piezometer) while letting that stress vary from depth to depth (the integrated stress remains the same) increases the lithospheric strain rate by about a factor of 1000. This can explain the development of diffuse plate boundaries. The slightly higher strain rate of continental plate boundary may reflect development of a layered rock fabric in the middle crust. Narrow plate boundaries require additional weakening process. The high heat flux near mid-ocean ridge implies a thin lithosphere, which enhances stress (for constant integrated

  1. Structural mechanisms of formation of adiabatic shear bands

    Directory of Open Access Journals (Sweden)

    Mikhail Sokovikov

    2016-10-01

    size of grains is ~300nm. Rotational deformation modes give rise to the high angular disorientations of grains. The development of plastic shear instability regions has been simulated numerically. For this purpose, we use a recently developed theory, in which the influence of microshears on the deformation properties of materials has been studied by the methods of statistical physics and thermodynamics of irreversible processes. The results of theoretical and experimental studies suggest that one of the mechanisms of the plastic shear instability and localization of plastic strain at high-velocity perforation is related to structural and kinetic transitions in microshear ensembles

  2. An introductory review on gravitational-deformation induced structures, fabrics and modeling

    Science.gov (United States)

    Jaboyedoff, Michel; Penna, Ivanna; Pedrazzini, Andrea; Baroň, Ivo; Crosta, Giovanni B.

    2013-10-01

    Recent studies have pointed out a similarity between tectonics and slope tectonic-induced structures. Numerous studies have demonstrated that structures and fabrics previously interpreted as of purely geodynamical origin are instead the result of large slope deformation, and this led in the past to erroneous interpretations. Nevertheless, their limit seems not clearly defined, but it is somehow transitional. Some studies point out continuity between failures developing at surface with upper crust movements. In this contribution, the main studies which examine the link between rock structures and slope movements are reviewed. The aspects regarding model and scale of observation are discussed together with the role of pre-existing weaknesses in the rock mass. As slope failures can develop through progressive failure, structures and their changes in time and space can be recognized. Furthermore, recognition of the origin of these structures can help in avoiding misinterpretations of regional geology. This also suggests the importance of integrating different slope movement classifications based on distribution and pattern of deformation and the application of structural geology techniques. A structural geology approach in the landslide community is a tool that can greatly support the hazard quantification and related risks, because most of the physical parameters, which are used for landslide modeling, are derived from geotechnical tests or the emerging geophysical approaches.

  3. CFD simulations of flow erosion and flow-induced deformation of needle valve: Effects of operation, structure and fluid parameters

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hongjun, E-mail: ticky863@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China); State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, Sichuan (China); Pan, Qian; Zhang, Wenli; Feng, Guang; Li, Xue [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China)

    2014-07-01

    Highlights: • A combined FSI–CFD and DPM computational method is used to investigate flow erosion and deformation of needle valve. • The numerical model is validated with the comparison of measured and predicted erosion rate. • Effects of operation, structure and fluid parameters on flow erosion and flow-induced deformation are discussed. • Particle diameter has the most significant effect on flow erosion. • Inlet rate has the most obvious effect on flow-induced deformation. - Abstract: A three-dimensional fluid–structure interaction (FSI) computational model coupling with a combined continuum and discrete model has been used to predict the flow erosion rate and flow-induced deformation of needle valve. Comparisons with measured data demonstrate good agreement with the predictions of erosion rate. The flow field distribution of gas-particle flow and the erosion rate and deformation of valve core are captured under different operating and structural conditions with different fluid parameters. The effects of inlet velocity, valve opening and inlet valve channel size, particle concentration, particle diameter and particle phase components are discussed in detail. The results indicate that valve tip has the most severe erosion and deformation, and flow field, erosion rate and deformation of valve are all sensitive to inlet condition changes, structural changes and fluid properties changes. The effect of particle diameter on erosion is the most significant, while the influence of inlet rate on deformation is the greatest one.

  4. Deformation and recrystallization mechanisms in actively extruding salt fountain: Microstructural evidence for a switch in deformation mechanisms with increased availability of meteoric water and decreased grain size (Qum Kuh, central Iran)

    Czech Academy of Sciences Publication Activity Database

    Desbois, G.; Závada, Prokop; Schléder, Z.; Urai, J. L.

    2010-01-01

    Roč. 32, č. 4 (2010), s. 580-594 ISSN 0191-8141 Grant - others:Deutsche Forschungsgemeinschaft(DE) UR 64/9-2 Institutional research plan: CEZ:AV0Z30120515 Keywords : rocksalt * salt extrusion * gamma - irradiation * deformation mechanisms * microstructure Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.911, year: 2010

  5. Relaxation Mechanisms, Structure and Properties of Semi-Coherent Interfaces

    Directory of Open Access Journals (Sweden)

    Shuai Shao

    2015-10-01

    Full Text Available In this work, using the Cu–Ni (111 semi-coherent interface as a model system, we combine atomistic simulations and defect theory to reveal the relaxation mechanisms, structure, and properties of semi-coherent interfaces. By calculating the generalized stacking fault energy (GSFE profile of the interface, two stable structures and a high-energy structure are located. During the relaxation, the regions that possess the stable structures expand and develop into coherent regions; the regions with high-energy structure shrink into the intersection of misfit dislocations (nodes. This process reduces the interface excess potential energy but increases the core energy of the misfit dislocations and nodes. The core width is dependent on the GSFE of the interface. The high-energy structure relaxes by relative rotation and dilatation between the crystals. The relative rotation is responsible for the spiral pattern at nodes. The relative dilatation is responsible for the creation of free volume at nodes, which facilitates the nodes’ structural transformation. Several node structures have been observed and analyzed. The various structures have significant impact on the plastic deformation in terms of lattice dislocation nucleation, as well as the point defect formation energies.

  6. Effect of Deformation Temperature on Microstructure Evolution and Mechanical Properties of Low-Carbon High-Mn Steel

    Directory of Open Access Journals (Sweden)

    Adam Grajcar

    2018-01-01

    Full Text Available This work addresses the influence of deformation temperature in a range from −40°C to 200°C on the microstructure evolution and mechanical properties of a low-carbon high-manganese austenitic steel. The temperature range was chosen to cope at the time during sheet processing or car crash events. Experimental results show that yield stress and ultimate tensile strength gradually deteriorate with an increase in the tensile testing temperature. The dominant mechanism responsible for the strain hardening of steel changes as a function of deformation temperature, which is related to stacking fault energy (SFE changes. When the deformation temperature rises, twinning decreases while a role of dislocation slip increases.

  7. Effects of excessive grain growth on the magnetic and mechanical properties of hot-deformed NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Lin, M., E-mail: linm@nimte.ac.c [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, Ningbo 315201 (China); Wang, H.J. [Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081 (China); Yi, P.P.; Yan, A.R. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, Ningbo 315201 (China)

    2010-08-15

    The magnetic and mechanical properties of rare-earth magnets hot-deformed at temperature range 750-950 deg. C have been investigated. The grains tended to grow excessively from dozens of nanometers to several microns at the temperatures above 850 deg. C. The alignment of grains was disrupted by the hot deformation at the high temperatures. The Nd-rich phase was extruded at the temperatures which are higher than 850 deg. C. The Nd-rich phase extrusion resulted in the reduction of density by 1% and the reduction of remanence from 1.42 to 0.72 T. The reduction of grain boundaries caused by flat platelet-shaped grains changing to spherical grains and the weak binding strength among large grains of Nd{sub 2}Fe{sub 14}B phase may be the main reasons for the low mechanical strength of hot-deformed magnets.

  8. Concurrent multiscale modeling of microstructural effects on localization behavior in finite deformation solid mechanics

    Science.gov (United States)

    Alleman, Coleman N.; Foulk, James W.; Mota, Alejandro; Lim, Hojun; Littlewood, David J.

    2018-02-01

    The heterogeneity in mechanical fields introduced by microstructure plays a critical role in the localization of deformation. To resolve this incipient stage of failure, it is therefore necessary to incorporate microstructure with sufficient resolution. On the other hand, computational limitations make it infeasible to represent the microstructure in the entire domain at the component scale. In this study, the authors demonstrate the use of concurrent multiscale modeling to incorporate explicit, finely resolved microstructure in a critical region while resolving the smoother mechanical fields outside this region with a coarser discretization to limit computational cost. The microstructural physics is modeled with a high-fidelity model that incorporates anisotropic crystal elasticity and rate-dependent crystal plasticity to simulate the behavior of a stainless steel alloy. The component-scale material behavior is treated with a lower fidelity model incorporating isotropic linear elasticity and rate-independent J2 plasticity. The microstructural and component scale subdomains are modeled concurrently, with coupling via the Schwarz alternating method, which solves boundary-value problems in each subdomain separately and transfers solution information between subdomains via Dirichlet boundary conditions. In this study, the framework is applied to model incipient localization in tensile specimens during necking.

  9. High-pressure behavior of intermediate scapolite: compressibility, structure deformation and phase transition

    Science.gov (United States)

    Lotti, Paolo; Comboni, Davide; Merlini, Marco; Hanfland, Michael

    2018-05-01

    Scapolites are common volatile-bearing minerals in metamorphic rocks. In this study, the high-pressure behavior of an intermediate member of the scapolite solid solution series (Me47), chemical formula (Na1.86Ca1.86K0.23Fe0.01)(Al4.36Si7.64)O24[Cl0.48(CO3)0.48(SO4)0.01], has been investigated up to 17.79 GPa, by means of in situ single-crystal synchrotron X-ray diffraction. The isothermal elastic behavior of the studied scapolite has been described by a III-order Birch-Murnaghan equation of state, which provided the following refined parameters: V 0 = 1110.6(7) Å3, {K_{{V_0}}} = 70(2) GPa ({β _{{V_0}}} = 0.0143(4) GPa-1) and {K_{{V}}^' = 4.8(7). The refined bulk modulus is intermediate between those previously reported for Me17 and Me68 scapolite samples, confirming that the bulk compressibility among the solid solution increases with the Na content. A discussion on the P-induced structure deformation mechanisms of tetragonal scapolite at the atomic scale is provided, along with the implications of the reported results for the modeling of scapolite stability. In addition, a single-crystal to single-crystal phase transition, which is displacive in character, has been observed toward a triclinic polymorph at 9.87 GPa. The high-pressure triclinic polymorph was found to be stable up to the highest pressure investigated.

  10. Analysis of High Temperature Deformed Structure and Dynamic Precipitation in W9Mo3Cr4V Steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With TEM、SEM, various high-temperature deformed structures inW9Mo3Cr4V steel were investigated. The sub-structures,recrystallized nuclei, as well as the dynamic precipitation were also studied and analyzed. The relationship between recrystallized structures and dynamic precipitation was discussed. The results showed that the deformed structures in W9Mo3Cr4V steel are more complicated than those in low alloy steels. Because W9Mo3Cr4V steel is a high-speed steel, there are a large number of residual carbides on the matrix. Also, much dynamic precipitating carbides will precipitate during deformation at high temperature.

  11. A coupled hydraulic and structure-dynamic model for prediction of RCCA drop time under hypothetical FA deformation

    International Nuclear Information System (INIS)

    Ren, Mingmin; Dressel, Bernd

    2009-01-01

    The ability of the RCCA (Rod Control Cluster Assemblies) in a pressurized water reactor (PWR) to be fully inserted into the core and to reach the dashpot within a required time limit is one of the important safety requirements for quick shutdown. This kind of quick shutdown in a PWR is initiated by allowing the control rod with the drive rod together to fall into the core by gravity. During normal operation, the RCCA drop time is mainly influenced by the weight of control assembly, hydraulic resistance in the CRDM (Control Rod Drive Mechanism), control rod guide assembly and guide thimbles and by the mechanical friction forces between the RCCA and its surroundings. In the case of an accident, e.g. earthquake, an additional influence of horizontal vibrations of the RCCA and its surroundings has to be considered [1]. A coupled hydraulic and structure-dynamic model is presented in this paper for prediction of RCCA drop time down to dashpot under hypothetical fuel assembly (FA) deformations. This coupled model was verified by RCCA static and dynamic drop tests with a deformed FA and by RCCA drop tests under operational conditions. (orig.)

  12. Field Investigation of Surface Deformation Induced by the 2016 Meinong Earthquake and its Implications to Regional Geological Structures

    Science.gov (United States)

    Yi, De-Cheng; Chuang, Ray Y.; Lin, Ching-Weei

    2017-04-01

    We demonstrate mapping results of a newly-identified active folding-associated fault in southwestern Taiwan, which was triggered by the distant ML 6.6 Meinong earthquake in 2016. The 14.6-km-deep main shock occurred in Meinong at 3:57 (GMT +08) on February 6th while a series of 21-27 km deep aftershocks were induced after 160 seconds in Guanmiao, where is 25km NW away from the epicenter of the main shock. The focal mechanism of the Meinong main shock shows a westward oblique thrust with the fault plane of 275°/42°/17° (strike/dip/rake) but Guanmiao aftershocks show the N-S striking eastward normal movement. The study area locates at an on-going fold-and-thrust belt close to the deformation front of Taiwan orogeny with high rates of convergence, uplift and erosion. The geology of SW Taiwan is characterized by the 3-km-thick mudstones with high fluid pressure underlying the loose sedimentary rocks forming mud diapirs or mud-core anticlines. The significance of the Meinong earthquake is (1) aftershocks are far away from the main shock, and (2) the surface cracks partially distributed systematically along lineaments observed from InSAR, which has never been recognized as geological structures before. This study aims to establish possible kinematic processes of shallow deformation induced by the Meinong earthquake. We mapped surface cracks around the lineaments by using hand-held GPS and measured surface cracks by the compass and vernier. Among 249 kinematic data measured from 244 observed surface cracks and ruptures, the type of deformation was mostly identified as dilation or lateral translation and only 4 data were compressional deformation. The overall surface displacement moved to the northwest and west, consistent with the regional coseismic movement. The opening of the surface cracks range from 0.5 to 105 mm and 85% of them are less than 10 mm. Preseismic deformed features such as failure of the retaining wall were also observed along the western and eastern

  13. Multi-trace deformations in AdS/CFT. Exploring the vacuum structure of the deformed CFT

    Energy Technology Data Exchange (ETDEWEB)

    Papadimitriou, I. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Center for Mathematical Physics, Hamburg (Germany)

    2007-03-15

    We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to 'mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying 'mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of 'mixed' boundary conditions. (orig.)

  14. Multi-trace deformations in AdS/CFT. Exploring the vacuum structure of the deformed CFT

    International Nuclear Information System (INIS)

    Papadimitriou, I.

    2007-03-01

    We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to 'mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying 'mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of 'mixed' boundary conditions. (orig.)

  15. Structure of collective bands and deformations in {sup 74,76}Kr

    Energy Technology Data Exchange (ETDEWEB)

    Tripathy, K.C. [Physics Department, F M College, Balasore, 756 001 (India); Sahu, R. [Physics Department, Berhampur University, Berhampur, 760 007 (India)

    2000-08-01

    The structure of collective bands in {sup 74,76}Kr is studied within the framework of the deformed configuration mixing shell model based on Hartree-Fock states. The active single-particle orbits are 1p{sub 3/2}, 0f{sub 5/2}, 1p{sub 1/2} and 0g{sub 9/2} with {sup 56}Ni as the inert core. A modified Kuo interaction has been used for the above configuration space. The {sup 74}Kr nucleus is found to be the most deformed nucleus among the krypton isotopes which is in agreement with experiment. The deformation is found to decrease for the {sup 76}Kr isotope. The calculated positive- and negative-parity bandsagree quite well with the experiment for both the nuclei. A number of excited bands is also predicted. We have also calculated B(E2) values and compared them with available experimental data. The structure of the strongly coupled band built on K = 4{sup (+)} in {sup 76}Kr is also studied. (author)

  16. Structure of collective bands and deformations in 74,76Kr

    International Nuclear Information System (INIS)

    Tripathy, K.C.; Sahu, R.

    2000-01-01

    The structure of collective bands in 74,76 Kr is studied within the framework of the deformed configuration mixing shell model based on Hartree-Fock states. The active single-particle orbits are 1p 3/2 , 0f 5/2 , 1p 1/2 and 0g 9/2 with 56 Ni as the inert core. A modified Kuo interaction has been used for the above configuration space. The 74 Kr nucleus is found to be the most deformed nucleus among the krypton isotopes which is in agreement with experiment. The deformation is found to decrease for the 76 Kr isotope. The calculated positive- and negative-parity bands agree quite well with the experiment for both the nuclei. A number of excited bands is also predicted. We have also calculated B(E2) values and compared them with available experimental data. The structure of the strongly coupled band built on K = 4 (+) in 76 Kr is also studied. (author)

  17. A study of the deformation and failure mechanisms of protective intermetallic coatings on AZ91 Mg alloys using microcantilever bending

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Mingyuan; Mead, James; Wu, Yueqin; Russell, Hugh; Huang, Han, E-mail: han.huang@uq.edu.au

    2016-10-15

    In this study, a nanoindentation-based microcantilever bending technique was utilized to investigate the interfacial properties of a β-Mg{sub 17}Al{sub 12}/AZ91 Mg alloy film/substrate system under tensile loading conditions. Finite element analysis (FEA) was first undertaken to optimise the design of cantilever structures for inducing high tensile stresses at the interface. Cantilevers consisting of a necked region or notch at the interface were determined to be the most successful designs. Microcantilevers containing the β-Mg{sub 17}Al{sub 12}/AZ91 interface were then made using focused ion beam (FIB) milling technique. Necks were made in the cantilevers to intensify the tension at the interface and notches were used to introduce a stress concentration to the interface. During bending, the cantilevers were deflected to failure. Subsequent analysis of the deformed cantilevers using electron microscopies revealed that plastic deformation, and subsequent ductile rupture, of the AZ91 phase was the dominant failure mechanism. When the β-Mg{sub 17}Al{sub 12}/AZ91 film/substrate system was subjected to tension, the softer AZ91 phase failed prior to interfacial delamination, demonstrating that the strength of the interface exceeded the stresses that caused ductile failure in the substrate material. - Highlights: •Microcantilever bending was used to study the property of film/substrate interface. •FEA was used to optimise cantilever design for achieving high interfacial tension. •The intermetallic coatings on AZ91 substrate have strong interfacial adhesion.

  18. First-principles study of electronic structure of deformed carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Kazuchika Iwami, Hidekazu Goto, Kikuji Hirose and Tomoya Ono

    2007-01-01

    Full Text Available On the basis of density functional theory, we study the electronic structures of five types of carbon nanotubes: the non-deformed (6,6 tube, the uniformly stretched tube along the tube axis, the uniformly compressed tube, the partially stretched tube and the partially compressed tube. The electron charge density increases at the compressed C–C bond of the partially stretched tube, while the density decreases at the stretched C–C bond of the partially stretched tube. In addition, the a1 and e1 states of the (6,6 tube contribute to the bonding along the tube axis and the a2 and e2 states are the bonds connecting the atoms in the same layers. Thus, the energy bands of the a1 and e1 states are sensitively affected by the deformation of the tubes along the tube axis.

  19. The mechanism study between 3D Space-time deformation and injection or extraction of gas pressure change, the Hutubi Underground gas storage

    Science.gov (United States)

    Xiaoqiang, W.; Li, J.; Daiqing, L.; Li, C.

    2017-12-01

    The surface deformation of underground gas reservoir with the change of injection pressure is an excellent opportunity to study the load response under the action of tectonic movement and controlled load. This paper mainly focuses on the elastic deformation of underground structure caused by the change of the pressure state of reservoir rock under the condition of the irregular change of pressure in the underground gas storage of Hutubi, the largest underground gas storage in Xinjiang, at the same time, it makes a fine study on the fault activities of reservoir and induced earthquakes along with the equilibrium instability caused by the reservoir. Based on the 34 deformation integrated observation points and 3 GPS continuous observation stations constructed in the underground gas storage area of Hutubi, using modern measurement techniques such as GPS observation, precise leveling survey, flow gravity observation and so on, combined with remote sensing technology such as InSAR, the 3d space-time sequence images of the surface of reservoir area under pressure change were obtained. Combined with gas well pressure, physical parameters and regional seismic geology and geophysical data, the numerical simulation and analysis of internal changes of reservoir were carried out by using elastic and viscoelastic model, the deformation mechanical relationship of reservoir was determined and the storage layer under controlled load was basically determined. This research is financially supported by National Natural Science Foundation of China (Grant No.41474016, 41474051, 41474097)

  20. Change of structure and some mechanical properties during processing of AlMn(Fe,Si) alloys

    International Nuclear Information System (INIS)

    Kovacs-Csetenyi, E.; Griger, A.; Turmezey, T.; Suchanek, V.

    1990-01-01

    The aim of this work was to study the change of structure and some mechanical properties during processing of AlMn(Fe,Si) alloys. An emphasis was given to the effect of Fe and Si on the properties measured in deformed and annealed states, because of its technological importance

  1. Analysis of the thermo-mechanical deformations in a hot forging tool by numerical simulation

    International Nuclear Information System (INIS)

    L-Cancelos, R.; Varas, F.; Viéitez, I.; Martín, E.

    2016-01-01

    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. (paper)

  2. 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.

  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. Deformation analysis of a film-overlapped micro-pump membrane structure

    International Nuclear Information System (INIS)

    Lee, Fu-Shin; Wang, Pi-Wen; Chen, Chih-Hsiung

    2008-01-01

    A novel approach is developed to study a film-overlapped membrane structure. Meanwhile, the established model is employed to design the micro-pump membrane structure and to evaluate its pumping efficiency. Two-dimensional coupling effects between the overlapping actuator films and the deformable membrane are thoroughly investigated, including the influences on the membrane from the overlapping films' elongation effects, Poisson's ratio effects and shear strain effects. Overall deformations and interactions for the three-layer membrane structures are accurately calculated through exercising the developed model, in contrast to what difficulties are usually encountered in carrying out FEM methods with very thin elements meshed for the actuator films. Furthermore, this study demonstrates that the high stiffness of the actuating metal films needs to be reflected in the equivalent stiffness of the membrane structures, especially when the sizes of the actuator films become compatible with the sizes of the membranes. Hence, the optimal micro-pumping efficiency of a membrane structure is acquired upon exercising the developed model, and larger sizes of the actuating films do not definitely obtain larger pumping efficiencies for the electromagnetically actuated micro-pumps

  5. Dislocation structure evolution in 304L stainless steel and weld joint during cyclic plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Jing, Hongyang; Zhao, Lei; Han, Yongdian; Lv, Xiaoqing [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072 (China); Xu, Lianyong, E-mail: xulianyong@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072 (China)

    2017-04-06

    Dislocation structures and their evolution of 304L stainless steel and weld metal made with ER308L stainless steel welding wire subjected to uniaxial symmetric strain-controlled loading and stress-controlled ratcheting loading were observed by transmission electron microscopy (TEM). The correlation between the cyclic response and the dislocation structure has been studied. The experiment results show that the cyclic behaviour of base metal and weld metal are different. The cyclic behaviour of the base metal consists of primary hardening, slight softening and secondary hardening, while the weld metal shows a short hardening within several cycles followed by the cyclic softening behaviour. The microscopic observations indicate that in base metal, the dislocation structures evolve from low density patterns to those with higher dislocation density during both strain cycling and ratcheting deformation. However, the dislocation structures of weld metal change oppositely form initial complicated structures to simple patterns and the dislocation density gradually decrease. The dislocation evolution presented during the strain cycling and ratcheting deformation is summarized, which can qualitatively explain the cyclic behaviour and the uniaxial ratcheting behaviour of two materials. Moreover, the dislocation evolution in the two types of tests is compared, which shows that the mean stress has an effect on the rate of dislocation evolution during the cyclic loading.

  6. Seismically-induced soft-sediment deformation structures associated with the Magallanes-Fagnano Fault System (Isla Grande de Tierra del Fuego, Argentina)

    Science.gov (United States)

    Onorato, M. Romina; Perucca, Laura; Coronato, Andrea; Rabassa, Jorge; López, Ramiro

    2016-10-01

    In this paper, evidence of paleoearthquake-induced soft-sediment deformation structures associated with the Magallanes-Fagnano Fault System in the Isla Grande de Tierra del Fuego, southern Argentina, has been identified. Well-preserved soft-sediment deformation structures were found in a Holocene sequence of the Udaeta pond. These structures were analyzed in terms of their geometrical characteristics, deformation mechanism, driving force system and possible trigger agent. They were also grouped in different morphological types: sand dykes, convolute lamination, load structures and faulted soft-sediment deformation features. Udaeta, a small pond in Argentina Tierra del Fuego, is considered a Quaternary pull-apart basin related to the Magallanes-Fagnano Fault System. The recognition of these seismically-induced features is an essential tool for paleoseismic studies. Since the three main urban centers in the Tierra del Fuego province of Argentina (Ushuaia, Río Grande and Tolhuin) have undergone an explosive growth in recent years, the results of this study will hopefully contribute to future analyses of the seismic risk of the region.

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

    NARCIS (Netherlands)

    Kurniawan, N.A.; Wong, Long Hui; Rajagopalan, Raj

    2012-01-01

    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

  8. PSP SAR interferometry monitoring of ground and structure deformations in the archeological site of Pompeii

    Science.gov (United States)

    Costantini, Mario; Francioni, Elena; Paglia, Luca; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla; De Nigris, Bruno

    2016-04-01

    The "Major Project Pompeii" (MPP) is a great collective commitment of different institututions and people to set about solving the serious problem of conservation of the largest archeological sites in the world. The ancient city of Pompeii with its 66 hectares, 44 of which are excaveted, is divided into 9 regiones (district), subdivided in 118 insulae (blocks) and almost 1500 domus (houses), and is Unesco site since 1996. The Italian Ministry for Heritage and Cultural Activities and Tourism (MiBACT) and Finmeccanica Group have sealed an agreement whereby the Finmeccanica Group will donate innovative technologies and services for monitoring and protecting the archaeological site of Pompeii. Moreover, the Italian Institute for Environment Protection and Research (ISPRA) - Geological Survey of Italy, was also involved to support the ground based analysis and interpretation of the measurements provided by the industrial team, in order to promote an interdisciplinary approach. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on their interpretation. The satellite monitoring service is based on the processing of COSMO-SkyMed Himage data by the e-Geos proprietary Persistent Scatterer Pair (PSP) SAR interferometry technology. The PSP technique is a proven SAR interferometry method characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artifacts (which are one of the main problems of SAR interferometry). Validations analyses showed that this technique applied to COSMO-SkyMed Himage data is able to retrieve very dense (except of course on vegetated or cultivated areas) millimetric deformation measurements with sub-metric localization. By means of the COSMO-SkyMed PSP SAR interferometry processing, a historical analysis of the ground and structure deformations occurred over the entire archaeological site of Pompeii in the

  9. Mechanics, microstructure and AMS evolution of a synthetic porphyritic calcite aggregate deformed in torsion

    Czech Academy of Sciences Publication Activity Database

    Marques, F. O.; Machek, Matěj; Roxerová, Zuzana; Burg, J.-P.; Almqvist, B. S. G.

    2015-01-01

    Roč. 655, August (2015), s. 41-57 ISSN 0040-1951 Institutional support: RVO:67985530 Keywords : experimental rock deformation * porphyritic calcite aggregate * EBSD and plastic deformation Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.650, year: 2015

  10. Change of mechanical properties of irradiated silicon iron in dependence of preliminary deformation

    International Nuclear Information System (INIS)

    Chirkina, L.A.; Okovit, V.S.; Khinkis, B.A.

    1979-01-01

    Presented are the data on the influence of the 225 MeV electron irradiation on flow limit and specific elongation of silicon iron specimens preliminary deformed by slipping and twinning. The irradiaton was carried out at