WorldWideScience

Sample records for permanently deform metal

  1. Low temperature uniform plastic deformation of metallic glasses during elastic iteration

    International Nuclear Information System (INIS)

    Fujita, Takeshi; Wang Zheng; Liu Yanhui; Sheng, Howard; Wang Weihua; Chen Mingwei

    2012-01-01

    Molecular dynamics simulations and dynamic mechanical analysis experiments were employed to investigate the mechanical behavior of metallic glasses subjected to iteration deformation in a nominally elastic region. It was found that cyclic deformation leads to the formation of irreversible shear transformation zones (STZs) and a permanent uniform strain. The initiation of STZs is directly correlated with the atomic heterogeneity of the metallic glass and the accumulated permanent strain has a linear relation with the number of STZs. This study reveals a new deformation mode and offers insights into the atomic mechanisms of STZ formation and low temperature uniform plastic deformation of metallic glasses.

  2. Permanent deformation and deflection relationship from pavement condition assessment

    Directory of Open Access Journals (Sweden)

    Fabricio Leiva-Villacorta

    2017-07-01

    Full Text Available The development of permanent deformation in flexible pavements has been a research topic for several decades. Currently there are models included in the structural design of pavements that can predict this type of failure. However, the variables required for the prediction of this distress are complex or difficult to obtain in the field, making its application in pavement evaluation also difficult. Measurement of the deflection of pavement structures by means of non-destructive testing is a technique used to assess the condition of the pavement. This research study seeks to correlate data from deflections of the pavement surface with probable permanent deformation in time. In addition, prediction of the remaining life of the pavement structure using a specified criterion is also analyzed. In order to accomplish these objectives, data acquired from 4 different full scale accelerated pavement test tracks was used to develop a permanent deformation model as a function of deflection, load repetitions and pavement layer thickness. The developed model considered a time series model that incorporates an Auto-regressive parameter of order 1. The proposed model presents an advantage over currently available models because it reduces the required parameters to predict the permanent deformation and/or remaining life in the structure and because these variables can be easily found and updated in a pavement management system. Keywords: HVS, Permanent deformation, Deflections, APT, Time series, Instrumentation

  3. Contributory Factors Related to Permanent Deformation of Hot Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Alaa Husein Abd

    2017-03-01

    Full Text Available Permanent deformation (Rutting of asphalt pavements which appears in many roads in Iraq, have caused a major impact on pavement performance by reducing the useful service life of pavement and creating services hazards for highway users. The main objective of this research is investigating the effect of some contributory factors related to permanent deformation of asphalt concrete mixture. To meet the objectives of this research, available local materials are used including asphalt binder, aggregates, mineral filler and modified asphalt binder. The Superpave mix design system was adopted with varying volumetric compositions. The Superpave Gyratory Compactor was used to compact 24 asphalt concrete cylindrical specimens. To collect the required data and investigate the development of permanent deformation in asphalt concrete under repeated loadings, Wheel-Tracking apparatus has been used in a factorial testing program during which 44 slab samples; with dimensions of 400×300×50 mm; were tested to simulate . actual pavement. Based on wheel-tracking test results, it has been concluded that increasing the compaction temperature from 110 to 150ºC caused a decreasing in permanent deformation by 20.5 and 15.6 percent for coarse and fine gradation control asphalt mixtures respectively. While the permanent deformation decreased about 21.3 percent when the compaction temperature is increased from 110 to 150ºC for coarse gradation asphalt mixtures modified with styrene butadiene styrene SBS with 3 percent by asphalt binder weight.

  4. 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...

  5. Deformation of ferrofluid marbles in the presence of a permanent magnet.

    Science.gov (United States)

    Nguyen, Nam-Trung

    2013-11-12

    This paper investigates the deformation of ferrofluid marbles in the presence of a permanent magnet. Ferrofluid marbles are formed using a water-based ferrofluid and 1 μm hydrophobic polytetrafluoride particles. A marble placed on a Teflon coated glass plate deforms under gravity. In the presence of a permanent magnet, the marble is further deformed with a larger contact area. The geometric parameters are normalized by the radius of an undistorted spherical marble. The paper first discusses a scaling relationship between the dimensionless radius of the contact area as well as the dimensionless height and the magnetic Bond number. The dimensionless contact radius is proportional to the fourth root of the magnetic bond number. The dimensionless height scales with the inverse square root of the magnetic Bond number. In the case of a moving marble dragged by a permanent magnet, the deformation is evaluated as the difference between advancing and receding curvatures of the top view. The dimensionless height and the contact diameter of the marble do not significantly depend on the speed or the capillary number. The scaling analysis and experimental data show that the deformation is proportional to the capillary number.

  6. Evaluation of Permanent Deformation of Unmodified and Rubber-Reinforced SMA Asphalt Mixtures Using Dynamic Creep Test

    Directory of Open Access Journals (Sweden)

    Herda Yati Katman

    2015-01-01

    Full Text Available This paper presents the evaluation of permanent deformation of rubber-reinforced SMA asphalt mixtures by using dynamic creep test. The effect of trans-polyoctenamer as a cross-linking agent in permanent deformation of rubberized mixtures was also evaluated. Dynamic creep test was conducted at different stress levels (200 kPa, 400 kPa and temperatures (40°C, 50°C. Permanent deformation parameters such as dynamic creep curve, ultimate strain, and creep strain slope (CSS were used to analyse the results. Finally, the creep behaviour of the specimens was estimated by the Zhou three-stage creep model. The results show that crumb rubber and trans-polyoctenamer significantly affected the parameters especially at high stress and temperatures. Consistent findings were observed for all permanent deformation parameters. Moreover, based on Zhou model, it was concluded that resistance to permanent deformation was improved by application of crumb rubber and trans-polyoctenamer.

  7. Permanent deformation testing for a new South African mechanistic pavement design method

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2012-01-01

    Full Text Available is to develop test protocols for hot-mix asphalt materials. To date, no permanent deformation test is incorporated into South African pavement design guides. The objective of this paper is to present the development process of a repeated load axial permanent...

  8. Effect of accelerated ageing and surface sealing on the permanent deformation of auto-polymerising soft linings.

    Science.gov (United States)

    da Silva, Joaquim; Takahashi, Jessica; Nuňez, Juliana; Consani, Rafael; Mesquita, Marcelo

    2012-09-01

    To compare the effects of different ageing methods on the permanent deformation of two permanent soft liners. The materials selected were auto-polymerising acrylic resin and silicone-based reliners. Sealer coating was also evaluated. Sixty specimens of each reliner were manufactured (12.7 mm diameter and 19 mm length). Specimens were randomly distributed into 12 groups (n = 10) and submitted to one of the accelerated ageing processes. Permanent deformation tests were conducted with a mechanical device described within the American Dental Association specification number 18 with a compressive load of 750 gf applied for 30 s. All data were submitted for statistical analysis. Mann-Whitney test compared the effect of the surface sealer on each material and the permanent deformation of the materials in the same ageing group (p = 0.05). Kruskal-Wallis and Dunn tests compared all ageing groups of each material (p = 0.05). The silicone-based reliner presented a lower permanent deformation than the acrylic resin-based reliner, regardless of the ageing procedure. The surface sealer coating was effective only for the thermocycled silicone group and the accelerated ageing processes affected only the permanent deformation of the acrylic resin-based material. The silicone-based reliner presented superior elastic properties and the thermocycling was more effective in ageing the materials. © 2010 The Gerodontology Society and John Wiley & Sons A/S.

  9. Characteristics of permanent deformation rate of warm mix asphalt with additives variation (BNA-R and zeolite)

    Science.gov (United States)

    Wahjuningsih, Nurul; Hadiwardoyo, Sigit Pranowo; Sumabrata, R. Jachrizal

    2017-06-01

    Permanent deformation is one of the criteria of failure on asphalt concrete mixture. The nature of the bitumen melt at high temperatures, this condition causes the asphalt concrete mixture tends to soften due to an increase in temperature of the road surface. The increase in surface temperature and the load wheel that has repeated itself on the same trajectory causes deformation groove has formed. Conditions rutting due to permanent deformation has resulted in inconvenience to the passengers and can lead to high costs of road maintenance. On the road planning process required a prediction of the rate of the permanent deformation of asphalt concrete mixtures. It is important to know early on the road surface damage due to vehicle load and surface temperature during service life. Asphalt has been mixed with the additive BNA-R and Zeolite intended to make variations in the characteristics of bitumen in this study. This variation is further combined with variations in the composition of aggregate in order to obtain a combination of asphalt-aggregate mixture. This mixture using warm mix, and to determine the permanent deformation of asphalt mix with material combinations was performed through the wheel tracking test machine with 3,780 cycles or 7,560 tracks for 3 hours. Another analysis to determine the characteristics of asphalt concrete mixtures have also been carried out changes in the surface temperature at the time of the test track. From the results of the test track to nearly 8 thousand passes has seen permanent deformation characteristics of asphalt concrete mixture with a variation of the characteristics of bitumen and aggregate variation. Groove of deformation due to a wheel load from the initial until the last passes shows that there are influence of compaction temperature on the variation of bitumen and aggregate composition to the relationship of permanent deformation of the wheel groove, especially on the road surface temperature changes.

  10. Characterization of Failure and Permanent Deformation Behaviour of Asphalt Concrete

    NARCIS (Netherlands)

    Wang, J.G.

    2015-01-01

    Asphalt concrete is a viscoelastic material consisting of aggregates, filler and bitumen. The response of asphalt concrete is highly dependent on temperature, loading rate and confining pressure. Permanent deformation is one of the most important distresses developing during the flexible pavement

  11. The effect of sealer and water storage on permanent deformation of a tissue conditioner

    Directory of Open Access Journals (Sweden)

    Rafael Leonardo Xediek Consani

    2008-01-01

    Full Text Available When they are used to treat inflamed, irritated, or distorted tissues or in implant therapy, tissue conditioners are required to function over relatively long time periods. Purpose: This in vitro study evaluated the effect of sealer and water storage on permanent deformation one tissue conditioner. Material and methods: Sixty cylindrically-shaped specimens (12.7-mm diameter 3 19.0-mm height were used for the deformation tests. Specimens were divided into 6 test groups (n=10, according to surface treatment (sealer application and water storage (1 hour, 1 week and 2 weeks. Permanent deformation, expressed as a percent (%, was determined using ADA specification no. 18. Data were examined a analysis of variance and a Mann-Whitney test (a= 0.05. Results: Significant differences were observed only after 1 week of water storage, for both groups. The surface treated group presented the highest permanent deformation percentage. Conclusions: This in vitro study indicated that the tissue conditioner evaluated is only useful for 1 week. After this period, the material must be replaced.

  12. Deformation limits of polymer coated metal sheets

    NARCIS (Netherlands)

    Van Den Bosch, M.J.W.J.P.; Schreurs, P.J.G; Geers, M.G.D.

    2005-01-01

    Polymer coated metals are increasingly used by the packaging and automotive industry. During industrial deformation processes (drawing, roll-forming, bending etc.) the polymer-metal laminate is highly deformed at high deformation rates. These forming conditions can affect the mechanical integrity

  13. Deformation of the Japanese Islands and seismic coupling: an interpretation based on GSI permanent GPS observations

    Science.gov (United States)

    Le Pichon, Xavier; Mazzotti, Stéphane; Henry, Pierre; Hashimoto, Manabu

    1998-08-01

    The entire area of the Japanese Islands has been covered by the permanent GPS observation network of the Geographical Survey Institute since 1994. In this paper we use a solution for the vectors of motion during 1995 for a selection of 116 stations to discuss the origin of the observed deformation field. We refer the displacement field to Eurasia using the VLBI-determined motion of Kashima and demonstrate that other choices such as the Okhotsk or North American plates for north Japan are not compatible with the data. 1 yr GPS velocities are much higher than geological constraints would allow because these short-term measurements include transient elastic deformation. However, the good qualitative agreement between the observed geodetic deformation tensors and those inferred from active faults and earthquakes suggests that the Quaternary permanent deformation is essentially the result of the transfer of part of the subduction-induced elastic deformation into permanent plastic deformation. We then compute the elastic deformation of the Japanese Islands caused by interseismic loading of the Pacific and Philippine subduction planes. The geometry of the coupled zone and its downward extension are determined from the distribution of earthquakes for the Pacific slab. For the Philippine slab we use the geometry proposed by Hyndman et al. (1995). These elastic models account for most of the observed velocity field if the subduction movement of the Philippine Sea Plate is 100 per cent locked and if that of the Pacific Plate is 75-85 per cent locked. We note that the boundaries of the areas where significant elastic deformation is predicted (more than 10 mm yr-1 of motion with respect to Eurasia) coincide with the main zones of permanent deformation: the Eastern Japan Sea deformation zone for the Pacific subduction elastic deformation field and the Setouchi/MTL deformation zone for the Nankai field. Each zone probably accommodates 10-15 mm yr-1 of motion in the long term

  14. Impact of the Superpave hot mix asphalt properties on its permanent deformation behavior

    Directory of Open Access Journals (Sweden)

    Qasim Zahra

    2018-01-01

    Full Text Available In Iraq, the severity of rutting has increased in asphalt pavements possibly due to the increase in truck axle loads, tyre pressure, and high pavement temperature in summer. As of late, Superpave has been accounted as an enhanced system for performance based design, analysis of asphalt pavement performance prediction for asphalt concrete mixes. In this research the development of permanent deformation in asphalt concrete under repeated loadings was investigated, Wheel-Tracking apparatus has been used in a factorial testing program during which 44 slab samples were tested to simulate actual pavement. The objectives of the present research include; investigating the main factors affecting rutting in asphalt concrete mixture, quantifying the effect of SBS polymer and steel reinforcement on asphalt concrete mixtures in addition to studying the effect of variables on the asphalt concrete mixes against moisture sensitivity. It has been determined that that increasing of compaction temperature from 110 to 150°C will decrease the permanent deformation by 20.5 and 15.6 percent for coarse and fine gradation control asphalt mixtures, respectively. While the permanent deformation decreases by 21.3 percent when the compaction temperature is increased from 110 to 150°C for coarse gradation SBS modified asphalt mixtures.

  15. Nanodisturbances in deformed Gum Metal

    International Nuclear Information System (INIS)

    Gutkin, Mikhail Yu.; Ishizaki, Toshitaka; Kuramoto, Shigeru; Ovid'ko, Ilya A.

    2006-01-01

    Systematic experiments have been performed to characterize defect structures in deformed Gum Metal, a special titanium alloy with high strength, low Young's modulus, excellent cold workability and low resistance to shear in certain crystallographic planes. Results from high-resolution transmission electron microscopy characterization reveal nanodisturbances (planar nanoscopic areas of local shear) as typical elements of defect structures in deformed Gum Metal. A theoretical model is suggested describing nanodisturbances as nanoscale dipoles of non-conventional partial dislocations with arbitrary, non-quantized Burgers vectors. It is shown theoretically that the homogeneous generation of nanodisturbances is energetically favorable in Gum Metal, where they effectively carry plastic flow

  16. Two cylinder permanent magnet stirrer for liquid metals

    Science.gov (United States)

    Bojarevičs, A.; Baranovskis, R.; Kaldre, I.; Milgrāvis, M.; Beinerts, T.

    2017-07-01

    To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

  17. Influence of Temperature Upon Permanent Deformation Parameters of Asphalt Concrete Mixes

    Directory of Open Access Journals (Sweden)

    Amjad Hamad Albayati

    2017-07-01

    Full Text Available The performance of asphalt concrete pavement has affected by many factors, the temperature is the most important environmental one which has a large effect on the structural behavior of flexible pavement materials. The main cause of premature failure of pavement is the rutting, Due to the viscoelastic nature of the asphalt cement, rutting is more pronounced in hot climate areas because the viscosity of the asphalt binder which is inversely related to rutting is significantly reduced with the increase in temperature resulting in a more rut susceptible paving mixtures. The objective of this study is to determine the effect of temperatures variations on the permanent deformation parameters (permanent strain (p, intercept (a, slope (b, Alpha and Mu as well as resilient strain (r and resilient modulus (Mr. To achieve this objective, one aggregate gradation with 12.5mm nominal maximum size, two grades of asphalt cements (40-50 and 60-70 brought form Al- Daurah refinery, limestone dust filler has been used to prepare the asphalt concrete mixtures. 30 Marshall specimens were prepared to determine the optimum asphalt cement content. Thereafter, 30 cylindrical asphalt concrete specimens (102mm in diameter and 203 mm in height are prepared in optimum asphalt cement and optimum ±0.5 percent. The prepared specimens were used in uniaxial repeated load test to evaluate the permanent deformation parameters of asphalt concrete mixes under the following testing temperature (5, 15, 25, 40 and 60c. The test result analyses appeared that Mr is decrease 51 percent when temperature increased from 5 c to 25 c and then decrease 22 percent with further increase in temperature from 25 c to 60 c. Also, the Alpha value decreases by a factor of 1.25 and 1.13 when temperature increases from 5 c to 25 c and 25 c to 60 c, espectively. Finally, statistical models were developed to predict the Alpha and Mu parameters of permanent deformation.

  18. Characterizing Cracking and Permanent Deformation; An Attempt for Predicting the End of the Structural Pavement Life

    NARCIS (Netherlands)

    Pramesti, F.P.; Molenaar, A.A.A.; van de Ven, M.F.C.

    2017-01-01

    Durable, therefore sustainable, road needs to attain specific characteristics, among others, resistance to permanent deformation and cracking. Determining the development of both characteristics are important to be able to predict pavement life and performance. In this research, permanent

  19. 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

  20. Repeated Load Permanent Deformation Behavior of Mixes With and Wihtout Modified Bituments

    Directory of Open Access Journals (Sweden)

    Imran Hafeez

    2011-01-01

    Full Text Available Premature rutting in flexible pavement structure is being observed on most of the road network of Pakistan. It initiates primarily due to uncontrolled axle loading and high ambient temperatures. NHA (National Highway Authority, Pakistan has continuously been modifying aggregate gradations and penetration grade of bitumen, without any prior investigation of the mix behaviour under the prevailing axle load and environmental conditions of the country. A comprehensive laboratory investigation was carried out on six mixes ranging from finer to coarser. Specimens were subjected to cyclic loading on UTM-5P (Universal Testing Machine to study the resistance against permanent deformation of the mixes at 25, 40 and 550C. At low temperatures and stress levels, both coarse and fine graded mixes showed less accumulated strain, whereas at higher temperatures and stress levels, coarse graded mix with PMB (Polymer Modified Bitumen showed good resistance to permanent deformation.

  1. Plastic Deformation of Metal Surfaces

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2013-01-01

    of metal components. An optimization of processes and material parameters must be based on a quantification of stress and strain gradients at the surface and in near surface layer where the structural scale can reach few tens of nanometers. For such fine structures it is suggested to quantify structural...... parameters by TEM and EBSD and apply strength-structural relationships established for the bulk metal deformed to high strains. This technique has been applied to steel deformed by high energy shot peening and a calculated stress gradient at or near the surface has been successfully validated by hardness...

  2. Studies on the optimization of deformation processed metal metal matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, Tim W. [Iowa State Univ., Ames, IA (United States)

    1994-01-04

    A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.

  3. Treatment of Rigid Hammer-Toe Deformity: Permanent Versus Removable Implant Selection.

    Science.gov (United States)

    Doty, Jesse F; Fogleman, Jason A

    2018-03-01

    Hammer-toe deformities that fail nonoperative treatment can be successfully addressed with proximal interphalangeal joint resection arthroplasty or fusion. The goal of surgery is to eliminate the deformity and rigidly fix the toe in a well-aligned position. Hammer-toe correction procedures can be performed with temporary Kirschner wire (K-wire) fixation for 3 to 6 weeks with high success rates. Pain relief with successful hammer-toe correction approaches 90%; patient satisfaction rates approximate 84%. Although complication rates are rare in most series, there remains a concern regarding exposed temporary K-wire fixation, which has led to the development of multiple permanent internal fixation options. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. 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...

  5. 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.

  6. Plastic Deformation of Pressured Metallic Glass

    Directory of Open Access Journals (Sweden)

    Yun Cheng

    2017-11-01

    Full Text Available Although pressured metallic glass (MG has been reported in the literature; there are few studies focusing on pressure effects on the structure; dynamics and its plastic deformation. In this paper; we report on and characterize; via molecular dynamics simulation, the structure and dynamics heterogeneity of pressured MGs, and explore a causal link between local structures and plastic deformation mechanism of pressured glass. The results exhibit that the dynamical heterogeneity of metallic liquid is more pronounced at high pressure, while the MGs were less fragile after the release of external pressure, reflected by the non-Gaussian parameter (NGP. High pressure glass shows better plastic deformation; and the local strain zone distributed more uniformly than of in normal glass. Further research indicates that although the number of icosahedrons in pressured glass was much larger than that in normal glass, while the interpenetrating connections of icosahedra (ICOI exhibited spatial correlations were rather poor; In addition, the number of ‘fast’ atoms indexed by the atoms’ moving distance is larger than that in normal glass; leading to the sharp decreasing in number of icosahedrons during deformation. An uniform distribution of ‘fast’ atoms also contributed to better plastic deformation ability in the pressured glass. These findings may suggest a link between the deformation and destruction of icosahedra with short-range order.

  7. Correlations between deformations, surface state and leak rate in metal to metal contact; Correlations entre deformations, etat de surface et debit de fuite au contact metal-metal

    Energy Technology Data Exchange (ETDEWEB)

    Armand, G; Lapujoulade, J; Paigne, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The study of metal to metal contact from the stand-point of the leak rate has been carried on a copper ring located between two hard-steel flanges. The analysis of the results confirms the hysteresis phenomenon already seen. Some curves (leak rate versus force and leak rate versus true deformation) in semi-logarithmic coordinates are straight lines. Likewise some curves (electrical contact resistance versus force) in bi-logarithmic coordinates are straight lines. All these results can be understood by looking at the conductance introduced by the deformations of the micro-geometry of the surfaces in contact. Some tests carried out in rising the temperature confirm these hypothesis. (authors) [French] L'etude du contact metal-metal du point de vue debit de fuite a ete poursuivie en utilisant un anneau de cuivre place entre brides d'acier dur. L'analyse des resultats confirme le phenomene d'hysteresis deja constate, montre l'influence de l'etat de surface des brides et du joint. Certaines courbes (debit de fuite/force et debit de fuite/deformation rationnelle), en coordonnees semi-logarithmiques, sont des droites. De meme, certaines courbes (resistance de contact/force) en coordonnees bi-logarithmiques, sont des droites. Ces resultats s'interpretent en considerant la conductance produite par la deformation des microgeometries des surfaces en contact. Quelques essais d'elevation de temperature confirment ces resultats. (auteurs)

  8. Does permanent extensional deformation in lower forearc slopes indicate shallow plate-boundary rupture?

    Science.gov (United States)

    Geersen, J.; Ranero, C. R.; Kopp, H.; Behrmann, J. H.; Lange, D.; Klaucke, I.; Barrientos, S.; Diaz-Naveas, J.; Barckhausen, U.; Reichert, C.

    2018-05-01

    Seismic rupture of the shallow plate-boundary can result in large tsunamis with tragic socio-economic consequences, as exemplified by the 2011 Tohoku-Oki earthquake. To better understand the processes involved in shallow earthquake rupture in seismic gaps (where megathrust earthquakes are expected), and investigate the tsunami hazard, it is important to assess whether the region experienced shallow earthquake rupture in the past. However, there are currently no established methods to elucidate whether a margin segment has repeatedly experienced shallow earthquake rupture, with the exception of mechanical studies on subducted fault-rocks. Here we combine new swath bathymetric data, unpublished seismic reflection images, and inter-seismic seismicity to evaluate if the pattern of permanent deformation in the marine forearc of the Northern Chile seismic gap allows inferences on past earthquake behavior. While the tectonic configuration of the middle and upper slope remains similar over hundreds of kilometers along the North Chilean margin, we document permanent extensional deformation of the lower slope localized to the region 20.8°S-22°S. Critical taper analyses, the comparison of permanent deformation to inter-seismic seismicity and plate-coupling models, as well as recent observations from other subduction-zones, including the area that ruptured during the 2011 Tohoku-Oki earthquake, suggest that the normal faults at the lower slope may have resulted from shallow, possibly near-trench breaking earthquake ruptures in the past. In the adjacent margin segments, the 1995 Antofagasta, 2007 Tocopilla, and 2014 Iquique earthquakes were limited to the middle and upper-slope and the terrestrial forearc, and so are upper-plate normal faults. Our findings suggest a seismo-tectonic segmentation of the North Chilean margin that seems to be stable over multiple earthquake cycles. If our interpretations are correct, they indicate a high tsunami hazard posed by the yet un

  9. Collective excitations in deformed alkali metal clusters

    International Nuclear Information System (INIS)

    Lipparini, E.; Stringari, S.; Istituto Nazionale di Fisica Nucleare, Povo

    1991-01-01

    A theoretical study of collective excitations in deformed metal clusters is presented. Sum rules are used to study the splittings of the dipole surface plasma resonance originating from the cluster deformation. The vibrating potential model is developed and used to predict the occurrence of a low lying collective mode of orbital magnetic nature. (orig.)

  10. Evaluation of permanent deformation and durability of epoxidized natural rubber modified asphalt mix

    Science.gov (United States)

    Al-Mansob, Ramez A.; Ismail, Amiruddin; Rahmat, Riza Atiq O. K.; Nazri Borhan, Muhamad; Alsharef, Jamal M. A.; Albrka, Shaban Ismael; Rehan Karim, Mohamed

    2017-09-01

    The road distresses have caused too much in maintenance cost. However, better understandings of the behaviours and properties of asphalt, couples with greater development in technology, have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, modifiers such as polymers are the most popular modifiers used to improve the performance of asphalt mix. This study was conducted to investigate the use of epoxidized natural rubber (ENR) to be mixed with asphalt mix. Tests were conducted to investigate the performance characteristics of ENR-asphalt mixes, where the mixes were prepared according to the wet process. Mechanical testing on the ENR-asphalt mixes have demonstrated that the asphalt mix permanent deformation performance at high temperature was found to be improved compared to the base mixes. However, the durability studies have indicated that ENR-asphalt mixes are slightly susceptible with the presence of moisture. The durability of the ENR-asphalt mixes were found to be enhanced in term of permanent deformation at high and intermediate temperatures compared to the base asphalt mixes. As conclusion, asphalt pavement performance can be enhanced by using ENR as modifier to face the major road distresses.

  11. Hardening by annealing and softening by deformation in nanostructured metals

    DEFF Research Database (Denmark)

    Huang, X.; Hansen, N.; Tsuji, N.

    2006-01-01

    We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation-dislocation and ......We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation....... As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing....

  12. Basic investigation of the laminated alginate impression technique: Setting time, permanent deformation, elastic deformation, consistency, and tensile bond strength tests.

    Science.gov (United States)

    Kitamura, Aya; Kawai, Yasuhiko

    2015-01-01

    Laminated alginate impression for edentulous is simple and time efficient compared to border molding technique. The purpose of this study was to examine clinical applicability of the laminated alginate impression, by measuring the effects of different Water/Powder (W/P) and mixing methods, and different bonding methods in the secondary impression of alginate impression. Three W/P: manufacturer-designated mixing water amount (standard), 1.5-fold (1.5×) and 1.75-fold (1.75×) water amount were mixed by manual and automatic mixing methods. Initial and complete setting time, permanent and elastic deformation, and consistency of the secondary impression were investigated (n=10). Additionally, tensile bond strength between the primary and secondary impression were measured in the following surface treatment; air blow only (A), surface baking (B), and alginate impression material bonding agent (ALGI-BOND: AB) (n=12). Initial setting times significantly shortened with automatic mixing for all W/P (p<0.05). The permanent deformation decreased and elastic deformation increased as high W/P, regardless of the mixing method. Elastic deformation significantly reduced in 1.5× and 1.75× with automatic mixing (p<0.05). All of these properties resulted within JIS standards. For all W/P, AB showed a significantly high bonding strength as compared to A and B (p<0.01). The increase of mixing water, 1.5× and 1.75×, resulted within JIS standards in setting time, suggesting its applicability in clinical setting. The use of automatic mixing device decreased elastic strain and shortening of the curing time. For the secondary impression application of adhesives on the primary impression gives secure adhesion. Copyright © 2014 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  13. Texture-geometric deformational effects in some metal-hydrogen systems

    International Nuclear Information System (INIS)

    Spivak, L.V.; Kats, M.Ya.

    1992-01-01

    Possible deformation effects were studied in vanadium, tantalum, niobium, palladium and iron which occurred during electrolytic hydrogenation of specimens preliminarily deformed by torsion and then annealed. Noticeable texture-geometric effects were observed and related to the system tendency to enhance the degree of specimen form symmetry during hydrogenation. The latter was an off-beat realization of Le-Chatelier principle. It was assumed that the nature of deformation effects was connected with one of minimization channels for overall elastic stress fields in metals being hydrogenated. Some distinction was revealed in behaviour of 5a group metal, palladium and iron

  14. 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

  15. Evaluation of permanent deformation characteristics of unmodified and Polyethylene Terephthalate modified asphalt mixtures using dynamic creep test

    International Nuclear Information System (INIS)

    Baghaee Moghaddam, Taher; Soltani, Mehrtash; Karim, Mohamed Rehan

    2014-01-01

    Highlights: • Waste PET was utilized as modifier in asphalt mixture. • Deformation characteristics of asphalt mixtures were assessed. • Dynamic creep test was conducted at different temperatures and stress levels. • Permanent deformation models were introduced. - Abstract: One of the major types of plastics that can be found in Municipal Solid Waste (MSW) is Polyethylene Terephthalate (PET) which is a non-biodegradable semi-crystalline thermoplastic polymer, and is considered as polyester material. Generating large amount of waste PET, mainly as bottles, would cause environmental hazards by disposing in landfills. This paper aims to evaluate effects of utilizing waste PET flakes as modifier in asphalt mixture as an alternative solution to overcome the potential risks arise from producing large amount of waste PET as well as evaluating the deformation characteristics of unmodified and PET modified asphalt mixtures. To achieve this aim, different percentages of PET were designated for this investigation, namely: 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1% by weight of aggregate particles, and dynamic creep test was performed at different stress levels (300 kPa and 400 kPa) and temperatures (10 °C, 25 °C and 40 °C). Consequently, Zhou three-stage model was developed. The results showed that permanent deformation characteristics of asphalt mixture were considerably improved by utilization of PET modification, when the permanent strain was remarkably decreased in PET modified mixture compared to the conventional mixture at all stress levels and temperatures. Besides, based on Zhou model, it was concluded that elastic and visco-elastic properties of asphalt mixture were improved by application of PET modification

  16. Slip systems, dislocation boundaries and lattice rotations in deformed metals

    DEFF Research Database (Denmark)

    Winther, Grethe

    2009-01-01

    Metals are polycrystals and consist of grains, which are subdivided on a finer scale upon plastic deformation due to formation of dislocation boundaries. The crystallographic alignment of planar dislocation boundaries in face centred cubic metals, like aluminium and copper, deformed to moderate...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...

  17. Local microstructure and flow stress in deformed metals

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Hansen, Niels; Nielsen, Chris Valentin

    2017-01-01

    The microstructure and flow stress of metals are related through many well-known strength-structure relationships based on structural parameters, where grain size and dislocation density are examples. In heterogeneous structures, the local stress and strain are important as they will affect...... the bulk properties. A microstructural method is presented which allows the local stress in a deformed metal to be estimated based on microstructural parameters determined by an EBSD analysis. These parameters are the average spacing of deformation introduced boundaries and the fraction of high angle...... boundaries. The method is demonstrated for two heterogeneous structures: (i) a gradient (sub)surface structure in steel deformed by shot peening; (ii) a heterogeneous structure introduced by friction between a tool and a workpiece of aluminum. Flow stress data are calculated based on the microstructural...

  18. 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)

  19. Electromigration-induced plastic deformation in passivated metal lines

    Science.gov (United States)

    Valek, B. C.; Bravman, J. C.; Tamura, N.; MacDowell, A. A.; Celestre, R. S.; Padmore, H. A.; Spolenak, R.; Brown, W. L.; Batterman, B. W.; Patel, J. R.

    2002-11-01

    We have used scanning white beam x-ray microdiffraction to study microstructural evolution during an in situ electromigration experiment on a passivated Al(Cu) test line. The data show plastic deformation and grain rotations occurring under the influence of electromigration, seen as broadening, movement, and splitting of reflections diffracted from individual metal grains. We believe this deformation is due to localized shear stresses that arise due to the inhomogeneous transfer of metal along the line. Deviatoric stress measurements show changes in the components of stress within the line, including relaxation of stress when current is removed.

  20. Three-dimensional phase-field simulation on the deformation of metallic glass nanowires

    International Nuclear Information System (INIS)

    Zhang, H.Y.; Zheng, G.P.

    2014-01-01

    Highlights: • 3D phase-field modeling is developed to investigate the deformation of MG nanowires. • The surface defects significantly affect the mechanical properties of nanowires. • Multiple shear bands are initiated from the surfaces of nanowires with D < 50 nm. - Abstract: It is very challenging to investigate the deformation mechanisms in micro- and nano-scale metallic glasses with diameters below several hundred nanometers using the atomistic simulation or the experimental approaches. In this work, we develop the fully three-dimensional phase-field model to bridge this gap and investigate the sample size effects on the deformation behaviors of metallic glass nanowires. The initial deformation defects on the surface are found to significantly affect the mechanical strength and deformation mode of nanowires. The improved ductility of metallic glass nanowires could be related with the multiple shear bands initiated from the nanowire surfaces

  1. Determination of parameters of microstructural inhomogeneity of metal deformation by the method of modelling

    International Nuclear Information System (INIS)

    Kornienko, V.T.

    1991-01-01

    A method is suggested to estimate microstructural non-uniformity of deformation in metals by means of modelling. This method includes measurement of deformation in metals by small-dimensioned dividing grid cells as well as calculation of parameters by means of model representation of microdeformation distribution. It is shown that the method of modelling gives an opportunity to objectively estimate deformation non-uniformity in metals irrespective of the selected dimension of a dividing grid cells. New structural characteristics: base and wave of variations, reflecting a degree of dividing or uniting grains in metals according to the non-uniformity of deformation are introduced

  2. Micromagnetic simulation for the magnetization reversal process of Nd-Fe-B hot-deformed nanocrystalline permanent magnets

    Directory of Open Access Journals (Sweden)

    Hiroshi Tsukahara

    2017-05-01

    Full Text Available We numerically demonstrated the magnetization reversal process inside a hot-deformed nanocrystalline permanent magnet. We performed large-scale micromagnetics simulation based on the Landau–Lifshitz–Gilbert equation with 0.1 billion calculation cells. The simulation model for the hot-deformed nanocrystalline permanent magnet consists of 2622 tabular grains that interact with each other by inter-grain exchange and dipole interactions. When the strength of the external field approached a coercive force, nucleation cores were created at the grain surface. The magnetization reversal was propagated by the inter-grain and dipole interactions. When the grains had overlapping regions parallel to the external field, the magnetization reversal propagated quickly between the grains due to the dipole interaction. In contrast, the motion of the magnetic domain wall was inhibited at interfaces between the grains perpendicular to the external field. Reversal magnetic domains had a pillar-shaped structure that is parallel to the external field. In the perpendicular direction, the reversal magnetic domain expanded gradually because of the inhibition of the domain wall motion.

  3. ACCUMULATED DEFORMATION MODELING OF PERMANENT WAY BASED ON ENTROPY SYSTEM

    Directory of Open Access Journals (Sweden)

    D. M. Kurhan

    2015-07-01

    Full Text Available Purpose. The work provides a theoretical research about the possibility of using methods that determine the lifetime of a railway track not only in terms of total stresses, and accounting its structure and dynamic characteristics. The aim of these studies is creation the model of deformations accumulation for assessment of service life of a railway track taking into account these features. Methodology. To simulate a gradual change state during the operation (accumulation of deformations the railway track is presented as a system that consists of many particles of different materials collected in a coherent design. It is appropriate to speak not about the appearance of deformations of a certain size in a certain section of the track, and the probability of such event on the site. If to operate the probability of occurrence of deviations, comfortable state of the system is characterized by the number of breaks of the conditional internal connections. The same state of the system may correspond to different combinations of breaks. The more breaks, the more the number of options changes in the structure of the system appropriate to its current state. Such a process can be represented as a gradual transition from an ordered state to a chaotic one. To describe the characteristics of the system used the numerical value of the entropy. Findings. Its entropy is constantly increasing at system aging. The growth of entropy is expressed by changes in the internal energy of the system, which can be determined using mechanical work forces, which leads to deformation. This gives the opportunity to show quantitative indication of breaking the bonds in the system as a consequence of performing mechanical work. According to the results of theoretical research methods for estimation of the timing of life cycles of railway operation considering such factors as the structure of the flow of trains, construction of the permanent way, the movement of trains at high

  4. 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

  5. Measuring time-dependent deformations in metallic MEMS

    NARCIS (Netherlands)

    Bergers, L.I.J.C.; Hoefnagels, J.P.M.; Delhey, N.K.R.; Geers, M.G.D.

    2011-01-01

    The reliability of metallic microelectromechanical systems (MEMS) depends on time-dependent deformation such as creep. Key to this process is the interaction between microstructural length scales and dimensional length scales, so-called size-effects. As a first critical step towards studying these

  6. Order and chaos in nuclear and metal cluster deformation

    International Nuclear Information System (INIS)

    Radu, S.

    1995-08-01

    The vast amount of nuclear and metal cluster data indicates that shell structure and deformation are two simultaneous properties. A conflicting situation is therefore encountered as the shell structure, a firm expression of order, is apparently not compatible with the non-integrable nature of the models incorporating deformation. The main issue covered in this thesis is the intricate connection between deformation and chaotic behaviour in deformation models pertinent to nuclear structure and metal cluster physics. It is shown that, at least in some cases, it is possible to reconcile the occurrence of shell structure with non-integrability. The coupling of an axially deformed harmonic oscillator to an axially symmetric octupole term renders the problem non-integrable. The chaotic character of the motion is strongly dependent on the type of deformation, in that a prolate shape shows virtually no chaos, while in an oblate case the motion exhibits fully developed chaos when the octupole term is switched on. Whereas the problem is non-integrable, the quantum mechanical spectrum nevertheless shows some shell structure in the prolate case for particular, yet fairly large octupole strengths; for spherical or oblate deformation the shell structure disappears. This result is explained in terms of classical periodic orbits which are found by employing the 'removal of resonances method'. Particular emphasis is put on the effect of the hexadecapole deformation which is important in fission processes. The combined effect of octupole and hexadecapole deformation leads to important conclusions for the experimental work as a high degree of ambiguity is signaled for the interpretation of data. The ambiguity results from the discovery of a mutual cancellation of the octupole and hexadecapole deformation in prolate superdeformed systems. The phenomenological Nilsson model is treated in a similar way. It is argued that while in nuclei it produces good results for the low-lying levels

  7. Influence of Hydrated Lime on the Properties and Permanent Deformation of the Asphalt Concrete Layers in Pavement

    Directory of Open Access Journals (Sweden)

    Al-Tameemi Ahmed F.

    2015-07-01

    Full Text Available Flexible or asphalt concrete pavement is the paving system most widely adopted all over the world. It has been recognized that there are many different types of the factors affecting the performance and durability of asphalt concrete pavement, including the service conditions, such as: the variation of temperature from mild to extremes and the repeated excessive axle loading as well as the inadequate quality of the raw materials. All of these when combined together are going to accelerate the occurrence of distresses in flexible pavement such as permanent deformation and fatigue cracking. As the result, there has an urgent need to enhance the ability of asphalt concrete mixture to resist distresses happened in pavement. Use of additives is one of the techniques adopted to improve pavement properties. It has been found that hydrated lime might be one of the effective additives because it is widely available and relatively cheap compared to other modifiers like polymers. This paper presents an experimental study of the hydrated-lime modified asphalt concrete mixtures. Five different percentages of the hydrated lime additive were investigated, namely (1, 1.5, 2, 2.5 and 3 percent. The hydrated lime additive was used as partial replacement of limestone filler by total weight of the aggregate. The designed Hot Mix Asphalt (HMA concretes are for the application of three pavement courses, i.e. Surface, Leveling and Base. These mixtures are designed and tested following Marshall procedure and uniaxial repeated loading to evaluate permanent deformation at different temperatures of 20°C, 40°C and 60°C. The experimental results show that the addition of hydrated lime as a partial replacement of ordinary limestone mineral filler results a significant improvement on mechanical properties and the resistant to permanent deformation of the designed asphalt concrete mixtures.

  8. Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

    DEFF Research Database (Denmark)

    Schiøtz, Jakob; Vegge, Tejs; Di Tolla, Francesco

    1999-01-01

    that the main deformation mode is sliding in the grain boundaries through a large number of uncorrelated events, where a few atoms (or a few tens of atoms) slide with respect to each other. Little dislocation activity is seen in the grain interiors. The localization of the deformation to the grain boundaries......Nanocrystalline metals, i.e., metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength. We present atomic-scale simulations of the plastic behavior of nanocrystalline copper. The simulations show...

  9. Stability of surface plastic flow in large strain deformation of metals

    Science.gov (United States)

    Viswanathan, Koushik; Udapa, Anirduh; Sagapuram, Dinakar; Mann, James; Chandrasekar, Srinivasan

    We examine large-strain unconstrained simple shear deformation in metals using a model two-dimensional cutting system and high-speed in situ imaging. The nature of the deformation mode is shown to be a function of the initial microstructure state of the metal and the deformation geometry. For annealed metals, which exhibit large ductility and strain hardening capacity, the commonly assumed laminar flow mode is inherently unstable. Instead, the imposed shear is accommodated by a highly rotational flow-sinuous flow-with vortex-like components and large-amplitude folding on the mesoscale. Sinuous flow is triggered by a plastic instability on the material surface ahead of the primary region of shear. On the other hand, when the material is extensively strain-hardened prior to shear, laminar flow again becomes unstable giving way to shear banding. The existence of these flow modes is established by stability analysis of laminar flow. The role of the initial microstructure state in determining the change in stability from laminar to sinuous / shear-banded flows in metals is elucidated. The implications for cutting, forming and wear processes for metals, and to surface plasticity phenomena such as mechanochemical Rehbinder effects are discussed.

  10. 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...

  11. Anelastic deformation processes in metallic glasses and activation energy spectrum model

    NARCIS (Netherlands)

    Ocelik, [No Value; Csach, K; Kasardova, A; Bengus, VZ; Ocelik, Vaclav

    1997-01-01

    The isothermal kinetics of anelastic deformation below the glass transition temperature (so-called 'stress induced ordering' or 'creep recovery' deformation) was investigated in Ni-Si-B metallic glass. The relaxation time spectrum model and two recently developed methods for its calculation from the

  12. Expanding hollow metal rings

    Science.gov (United States)

    Peacock, Harold B [Evans, GA; Imrich, Kenneth J [Grovetown, GA

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  13. Micromechanical modeling of the deformation of HCP metals

    Energy Technology Data Exchange (ETDEWEB)

    Graff, S. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2008-12-04

    Nowadays, intense research is conducted to understand the relation between microstructural features and mechanical properties of hexagonal close-packed (hcp) metals. Due to their hexagonal structure, hcp metals exhibit mechanical properties such as strong anisotropy, which is more pronounced than for construction metals with cubic crystal structure, and tension/compression asymmetry. Deformation mechanisms in hcp metals, dislocation motion on specific slip systems and activation of twinning, are not yet completely understood. The purpose of this work is to link the physical mechanisms developing during deformation of magnesium (Mg) on the microscale with the macroscopic yielding properties of texture Mg samples. It will be shown that the mechanical behavior of hcp metals may be understood and reproduced with the help of a visco-plastic model for crystal plasticity and a phenomenological yield criterion with appropriate hardening behavior. The study of single crystal specimens subjected to channel die compression tests reveals the active slip systems and twinning systems of the material considered. The material anisotropy at mesoscale is reproduced by using adequate critical resolved shear stresses (CRSS) for the considered deformation mechanisms. In order to describe the macroscopic behavior, texture is incorporated into polycrystalline Representative Volume Elements (RVEs) and various mechanical properties of extruded bars and rolled plates can be predicted. For RVEs exhibiting the texture of rolled plates the numerical results reveal the plate's anisotropic yielding and hardening behavior on a mesoscale. In order to extend the modeling possibilities to process simulations and to allow for time-saving simulations of structural behavior, a phenomenological yield surface accounting for anisotropy and tension/compression asymmetry has been established and implemented in a finite element code. Its numerous model parameters are calibrated by an optimization

  14. New deformation model of grain boundary strengthening in polycrystalline metals

    International Nuclear Information System (INIS)

    Trefilov, V.I.; Moiseev, V.F.; Pechkovskij, Eh.P.

    1988-01-01

    A new model explaining grain boundary strengthening in polycrystalline metals and alloys by strain hardening due to localization of plastic deformation in narrow bands near grain boundaries is suggested. Occurrence of localized deformation is caused by different flow stresses in grains of different orientation. A new model takes into account the active role of stress concentrator, independence of the strengthening coefficient on deformation, influence of segregations. Successful use of the model suggested for explanation of rhenium effect in molybdenum and tungsten is alloys pointed out

  15. Microstructure, Properties and Atomic Level Strain in Severely Deformed Rare Metal Niobium

    Directory of Open Access Journals (Sweden)

    Lembit KOMMEL

    2012-12-01

    Full Text Available The mechanical and physical properties relationship from atomic level strain/stress causes dislocation density and electrical conductivity relationship, as well as crystallites deformation and hkl-parameter change in the severely deformed pure refractory rare metal Nb at ambient temperature and during short processing times. The above mentioned issues are discussed in this study. For ultrafine-grained and nanocrystalline microstructure forming in metal the equal-channel angular pressing and hard cyclic viscoplastic deformation were used. The flat deformation and heat treatment at different parameters were conducted as follows. The focused ion beam method was used for micrometric measures samples manufacturied under nanocrystalline microstructure study by transmission electron microscope. The microstructure features of metal were studied under different orientations by X-ray diffraction scattering method, and according to the atomic level strains, dislocation density, hkl-parameters and crystallite sizes were calculated by different computation methods. According to results the evolutions of atomic level strains/stresses, induced by processing features have great influence on the microstructure and advanced properties forming in pure Nb. Due to cumulative strain increase the tensile stress and hardness were increased significantly. In this case the dislocation density of Nb varies from 5.0E+10 cm–2 to 2.0E+11 cm–2. The samples from Nb at maximal atomic level strain in the (110 and (211 directions have the maximal values of hkl-parameters, highest tensile strength and hardness but minimal electrical conductivity. The crystallite size was minimal and relative atomic level strain maximal in (211 orientation of crystal. Next, flat deformation and heat treatment increase the atomic level parameters of severely deformed metal.DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3091

  16. Even-Odd Differences and Shape Deformation of Metal Clusters

    OpenAIRE

    Hidetoshi, Nishioka; Yoshio, Takahashi; Department of Physics, Konan University; Faculty of General Education, Yamagata University

    1994-01-01

    The relation between even-odd difference of metal cluster and the deformation of equilibrium shape is studied in terms of two different models; (i) tri-axially deformed harmonic oscillator model, (ii) rectangular box model. Having assumed the matter density ρ kept constant for different shapes of a cluster, we can determine the equilibrium shape both for the two models. The enhancement of HOMO-LUMO gap is obtained and it is ascribed to Jahn-Teller effect. Good agreement of the calculated resu...

  17. High Strain Rate and Shock-Induced Deformation in Metals

    Science.gov (United States)

    Ravelo, Ramon

    2012-02-01

    Large-scale non-equilibrium molecular Dynamics (MD) simulations are now commonly used to study material deformation at high strain rates (10^9-10^12 s-1). They can provide detailed information-- such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in fcc and bcc single, mono-crystal metals, exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. These generic features in the response of single crystals subjected to high strain rates of deformation can be explained from the changes in the energy landscape of the uniaxially compressed crystal lattice. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic-wave propagation velocities. The elastic-plastic transition threshold can accurately be predicted by a wave-propagation stability analysis. These strain-induced instabilities create incipient defect structures, which can be quite different from the ones, which characterize the long-time, asymptotic state of the compressed solid. With increase compression and strain rate, plastic deformation via extended defects gives way to amorphization associated with the loss in shear rigidity along specific deformation paths. The hot amorphous or (super-cooled liquid) metal re-crystallizes at rates, which depend on the temperature difference between the amorphous solid and the equilibrium melt line. This plastic-amorphous transition threshold can be computed from shear-waves stability analyses. Examples from selected fcc and bcc metals will be presented employing semi-empirical potentials of the embedded atom method (EAM) type as well as

  18. Boundary-integral equation formulation for time-dependent inelastic deformation in metals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, V; Mukherjee, S

    1977-01-01

    The mathematical structure of various constitutive relations proposed in recent years for representing time-dependent inelastic deformation behavior of metals at elevated temperatues has certain features which permit a simple formulation of the three-dimensional inelasticity problem in terms of real time rates. A direct formulation of the boundary-integral equation method in terms of rates is discussed for the analysis of time-dependent inelastic deformation of arbitrarily shaped three-dimensional metallic bodies subjected to arbitrary mechanical and thermal loading histories and obeying constitutive relations of the kind mentioned above. The formulation is based on the assumption of infinitesimal deformations. Several illustrative examples involving creep of thick-walled spheres, long thick-walled cylinders, and rotating discs are discussed. The implementation of the method appears to be far easier than analogous BIE formulations that have been suggested for elastoplastic problems.

  19. The Micromechanics of Deformation and Failure in Metal-Matrix Composites

    National Research Council Canada - National Science Library

    Needleman, Alan

    1997-01-01

    .... However, metal-matrix composites often have low ductility and low fracture toughness. An improved understanding of the basic deformation and failure mechanisms is needed to overcome these problems...

  20. High Rate Plastic Deformation and Failure of Tungsten-Sintered Metals

    National Research Council Canada - National Science Library

    Bjerke, Todd

    2004-01-01

    The competition between plastic deformation and brittle fracture during high rate loading of a tungsten-sintered metal is examined through impact experiments, post-experiment microscopy, and numerical simulation...

  1. High rate deformation of metallic liner and its dislocation description

    International Nuclear Information System (INIS)

    Prut, V.V.; Shybaev, S.A.

    1996-01-01

    The dynamics of deformation in cylindrical liners are studied experimentally and theoretically in Z-pinch geometry, where the cylinders are deformed by a magnetic field created by a current flowing along the axis. This method allows one to obtain one-dimensional deformation and a reliable recording of magnetic field and cylinder deformation. The experiments are performed with a current amplitude of 0.8-3 MA and a current rise time of 2.5-4 μs. Aluminium and copper tubes, from 4 to 6 mm in diameter and 0.25-1 mm wall thick, are compressed. The deformation rates under study are in the range of 10 5 -10 6 s -1 . The time dependence of the radii of the copper and aluminium tubes are measured with a streak camera and by the pulsed x-ray technique. The time resolution of the streak and x-ray photographs is 10-15 ns, their spatial resolution is 10-15 μm. A rheological model describing the dynamics of compression is developed. The model includes the description of the metal as a plastic medium with moving dislocations in the solid state, and as a viscous medium in the liquid state. The one-dimensional solution to magneto-hydrodynamical equations of the liner dynamics is compared with the experimental results and thus the following rheological parameters of the metal are obtained: β, the probability of dislocation generation in plastic deformation; and σ d , the drag stress, the parameter which characterizes a drag force acting on the dislocation. (Author)

  2. Adhesion along metal-polymer interfaces during plastic deformation

    NARCIS (Netherlands)

    van Tijum, R.; Vellinga, W. P.; De Hosson, J. Th. M.

    In this paper a numerical study is presented that concentrates on the influence of the interface roughness that develops during plastic deformation of a metal, on the work of adhesion and on the change of interface energy upon contact with a glassy polymer. The polymer coating is described with a

  3. Computer simulation of plastic deformation in irradiated metals

    International Nuclear Information System (INIS)

    Colak, U.

    1989-01-01

    A computer-based model is developed for the localized plastic deformation in irradiated metals by dislocation channeling, and it is applied to irradiated single crystals of niobium. In the model, the concentrated plastic deformation in the dislocation channels is postulated to occur by virtue of the motion of dislocations in a series of pile-tips on closely spaced parallel slip planes. The dynamics of this dislocation motion is governed by an experimentally determined dependence of dislocation velocity on shear stress. This leads to a set of coupled differential equations for the positions of the individual dislocations in the pile-up as a function of time. Shear displacement in the channel region is calculated from the total distance traveled by the dislocations. The macroscopic shape change in single crystal metal sheet samples is determined by the axial displacement produced by the shear displacements in the dislocation channels. Computer simulations are performed for the plastic deformation up to 20% engineering strain at a constant strain rate. Results of the computer calculations are compared with experimental observations of the shear stress-engineering strain curve obtained in tensile tests described in the literature. Agreement between the calculated and experimental stress-strain curves is obtained for shear displacement of 1.20-1.25 μm and 1000 active slip planes per channel, which is reasonable in the view of experimental observations

  4. Optimization of film synthesized rare earth transition metal permanent magnet systems

    International Nuclear Information System (INIS)

    Cadieu, F.J.

    1990-01-01

    This report reviews work on the optimization of film synthesized rare earth transition metal permanent magnet systems. Topics include: high coercivity in Sm-Fe-Ti-V, Sm-Fe-V, and two element systems; ThMn 12 type pseudobinary SmFe 12 - X T X ; and sputter process control for the synthesis of precisely textured RE-TM magnetic films. (JL)

  5. Prediction of contact mechanics in metal-on-metal Total Hip Replacement for parametrically comprehensive designs and loads.

    Science.gov (United States)

    Donaldson, Finn E; Nyman, Edward; Coburn, James C

    2015-07-16

    Manufacturers and investigators of Total Hip Replacement (THR) bearings require tools to predict the contact mechanics resulting from diverse design and loading parameters. This study provides contact mechanics solutions for metal-on-metal (MoM) bearings that encompass the current design space and could aid pre-clinical design optimization and evaluation. Stochastic finite element (FE) simulation was used to calculate the head-on-cup contact mechanics for five thousand combinations of design and loading parameters. FE results were used to train a Random Forest (RF) surrogate model to rapidly predict the contact patch dimensions, contact area, pressures and plastic deformations for arbitrary designs and loading. In addition to widely observed polar and edge contact, FE results included ring-polar, asymmetric-polar, and transitional categories which have previously received limited attention. Combinations of design and load parameters associated with each contact category were identified. Polar contact pressures were predicted in the range of 0-200 MPa with no permanent deformation. Edge loading (with subluxation) was associated with pressures greater than 500 MPa and induced permanent deformation in 83% of cases. Transitional-edge contact (with little subluxation) was associated with intermediate pressures and permanent deformation in most cases, indicating that, even with ideal anatomical alignment, bearings may face extreme wear challenges. Surrogate models were able to accurately predict contact mechanics 18,000 times faster than FE analyses. The developed surrogate models enable rapid prediction of MoM bearing contact mechanics across the most comprehensive range of loading and designs to date, and may be useful to those performing bearing design optimization or evaluation. Published by Elsevier Ltd.

  6. Numerical Simulation of Multiphase Magnetohydrodynamic Flow and Deformation of Electrolyte-Metal Interface in Aluminum Electrolysis Cells

    Science.gov (United States)

    Hua, Jinsong; Rudshaug, Magne; Droste, Christian; Jorgensen, Robert; Giskeodegard, Nils-Haavard

    2018-06-01

    A computational fluid dynamics based multiphase magnetohydrodynamic (MHD) flow model for simulating the melt flow and bath-metal interface deformation in realistic aluminum reduction cells is presented. The model accounts for the complex physics of the MHD problem in aluminum reduction cells by coupling two immiscible fluids, electromagnetic field, Lorentz force, flow turbulence, and complex cell geometry with large length scale. Especially, the deformation of bath-metal interface is tracked directly in the simulation, and the condition of constant anode-cathode distance (ACD) is maintained by moving anode bottom dynamically with the deforming bath-metal interface. The metal pad deformation and melt flow predicted by the current model are compared to the predictions using a simplified model where the bath-metal interface is assumed flat. The effects of the induced electric current due to fluid flow and the magnetic field due to the interior cell current on the metal pad deformation and melt flow are investigated. The presented model extends the conventional simplified box model by including detailed cell geometry such as the ledge profile and all channels (side, central, and cross-channels). The simulations show the model sensitivity to different side ledge profiles and the cross-channel width by comparing the predicted melt flow and metal pad heaving. In addition, the model dependencies upon the reduction cell operation conditions such as ACD, current distribution on cathode surface and open/closed channel top, are discussed.

  7. Creep of crystals: High-temperature deformation processes in metals, ceramics and minerals

    Science.gov (United States)

    Poirier, J. P.

    An introductory text describing high-temperature deformation processes in metals, ceramics, and minerals is presented. Among the specific topics discussed are: the mechanical aspects of crystal deformation; lattice defects; and phenomenological and thermodynamical analysis of quasi-steady-state creep. Consideration is also given to: dislocation creep models; the effect of hydrostatic pressure on deformation; creep polygonization; and dynamic recrystallization. The status of experimental techniques for the study of transformation plasticity in crystals is also discussed.

  8. Compression deformation behaviors of sheet metals at various clearances and side forces

    Directory of Open Access Journals (Sweden)

    Zhan Mei

    2015-01-01

    Full Text Available Modeling sheet metal forming operations requires understanding of plastic behaviors of sheet metals along non-proportional strain paths. The plastic behavior under reversed uniaxial loading is of particular interest because of its simplicity of interpretation and its application to material elements drawn over a die radius and underwent repeated bending. However, the attainable strain is limited by failures, such as buckling and in-plane deformation, dependent on clearances and side forces. In this study, a finite element (FE model was established for the compression process of sheet specimens, to probe the deformation behavior. The results show that: With the decrease of the clearance from a very large value to a very small value, four defects modes, including plastic t-buckling, micro-bending, w-buckling, and in-plane compression deformation will occur. With the increase of the side force from a very small value to a very large value, plastic t-buckling, w-buckling, uniform deformation, and in-plane compression will occur. The difference in deformation behaviors under these two parameters indicates that the successful compression process without failures for sheet specimens only can be carried out under a reasonable side force.

  9. Crustal deformations at permanent GPS sites in Denmark

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Knudsen, Per; Tscherning, Carl Christian

    2005-01-01

    The National Survey and Cadastre (KMS) is responsible for the geodetic definition of the reference network in Denmark. Permanent GPS stations play an important role in the monitoring and maintenance of the geodetic network. During 1998 and 1999 KMS established three permanent GPS station in Denma...

  10. Deformations in micro extrusion of metals

    Directory of Open Access Journals (Sweden)

    J. Piwnik

    2010-07-01

    Full Text Available Production technologies of small dimensions metallic elements are known for a long time. They are produced by machining methods:turning, milling, polishing. Recently, methods for manufacturing small details by forming are developed – microforming. This process ischaracterized by the high dimensions accuracy and the surface smoothness of received items and the high production rate. When a forming process is scaled down to micro dimensions, the microstructure of the workpiece, the surface topology of the workpiece and that of the tooling remain unchanged. Size effect is appearing. This paper analyses specifications of a metal extrusion in micro scale. To determine the impact of the tool surface roughness on deformation process the numerical model of roughness as triangle wave were developed. In paper the influence of the wave presence on the material flow is described. Impact of the forming conditions on extrusion forces there is also characterized.

  11. Stress analysis and deformation prediction of sheet metal workpieces based on finite element simulation

    OpenAIRE

    Ren Penghao; Wang Aimin; Wang Xiaolong; Zhang Yanlin

    2017-01-01

    After aluminum alloy sheet metal parts machining, the residual stress release will cause a large deformation. To solve this problem, this paper takes a aluminum alloy sheet aerospace workpiece as an example, establishes the theoretical model of elastic deformation and the finite element model, and places quantitative initial stress in each element of machining area, analyses stress release simulation and deformation. Through different initial stress release simulative analysis of deformation ...

  12. Modeling of dislocation generation and interaction during high-speed deformation of metals

    DEFF Research Database (Denmark)

    Schiøtz, J.; Leffers, T.; Singh, B.N.

    2002-01-01

    Recent experiments by Kiritani et al. [1] have revealed a surprisingly high rate of vacancy production during highspeed deformation of thin foils of fcc metals. Virtually no dislocations are seen after the deformation. This is interpreted as evidence for a dislocation-free deformation mechanism...... at very high strain rates. We have used molecular-dynamics simulations to investigate high-speed deformation of copper crystals. Even though no pre-existing dislocation sources are present in the initial system, dislocations are quickly nucleated and a very high dislocation density is reached during...... the deformation. Due to the high density of dislocations, many inelastic interactions occur between dislocations, resulting in the generation of vacancies. After the deformation, a very high density of vacancies is observed, in agreement with the experimental observations. The processes responsible...

  13. Modeling the Mechanical Behavior of Aluminum Laminated Metal Composites During High Temperature Deformation

    National Research Council Canada - National Science Library

    Grishber, R

    1997-01-01

    A constitutive model for deformation of a novel laminated metal composite (LMC) which is comprised of 21 alternating layers of Al 5182 alloy and Al 6090/SiC/25p metal matrix composite (MMC) has been proposed...

  14. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

    Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

    2017-12-01

    Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

  15. The role of edge dislocations in the deformation of BCC metals

    International Nuclear Information System (INIS)

    Lung, C.W.

    1994-08-01

    It was widely accepted that the screw dislocation is responsible for the strong temperature dependence of the yield stresses observed in bcc metals. In this paper, we show the role of edge dislocations in the deformation of bcc metals and point out that in some cases, its main contribution to the yield stress cannot be ignored. (author). 15 refs, 2 figs, 1 tab

  16. INVESTIGATION OF MATERIAL RESISTANCE TO PLASTIC DEFORMATION AT PROCESSING METALS BY PRESSURE WITH IMPOSING ULTRASONIC OSCILLATIONS

    Directory of Open Access Journals (Sweden)

    V. V. Klubovich

    2007-01-01

    Full Text Available The paper contains substantiation for application of experimental technique in order to investigate material resistance to plastic deformation at processing metals by pressure with imposing ultrasonic oscillations while proceeding from laws of similarity. It is shown that at modeling any metal processing by pressure with imposing ultrasonic oscillations it is possible to consider that actual elastic and plastic metal properties remain constant during processing under ultrasound action. The second aspect that requires a special attention at modeling is pulse or vibration-shock deformation at processing metals by pressure with imposing ultrasonic oscillations.

  17. Deformation of extreme viscoelastic metals and composites

    International Nuclear Information System (INIS)

    Wang, Y.C.; Ludwigson, M.; Lakes, R.S.

    2004-01-01

    The figure of merit for structural damping and damping layer applications is the product of stiffness E and damping tan δ. For most materials, even practical polymer damping layers, E tan δ is less than 0.6 GPa. We consider several methods to achieve high values of this figure of merit: high damping metals, metal matrix composites and composites containing constituents of negative stiffness. As for high damping metals, damping of polycrystalline zinc was determined and compared with InSn studied earlier. Damping of Zn is less dependent on frequency than that of InSn, so Zn is superior at high frequency. High damping and large stiffness anomalies are possible in viscoelastic composites with inclusions of negative stiffness. Negative stiffness entails a reversal of the usual directional relationship between force and displacement in deformed objects. An isolated object with negative stiffness is unstable, but an inclusion embedded in a composite matrix can be stabilized under some circumstances. Ferroelastic domains in the vicinity of a phase transition can exhibit a region of negative stiffness. Metal matrix composites containing vanadium dioxide were prepared and studied. The concentration of embedded particles was sensitive to the processing method

  18. Nucleation of recrystallization at selected sites in deformed fcc metals

    DEFF Research Database (Denmark)

    Xu, Chaoling

    The objective of this thesis is to explore nucleation of recrystallization at selected sites in selected face-centered-cubic (FCC) metals, namely cold rolled columnar-grained nickel and high purity aluminum further deformed by indenting. Various techniques, including, optical microscopy, electron...... backscattered diffraction (EBSD), electron channeling contrast (ECC) and synchrotron X-ray technique, differential-aperture X-ray microscopy (DAXM), were used to characterize the microstructures, to explore nucleation sites, orientation relationships between nuclei and deformed microstructures, and nucleation...... mechanisms. In the cold rolled nickel samples, the preference of triple junctions (TJs) and grain boundaries (GBs) as nucleation sites is observed. The majorities of the nuclei have the same orientations as the surrounding matrix or are twin-related to a surrounding deformed grain. Only a few nuclei...

  19. Residual strain evolution during the deformation of single fiber metal matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Hanan, J.C.; Uestuendag, E.; Clausen, B. [Dept. of Materials Science, California Inst. of Tech., Pasadena, CA (United States); Sivasambu, M.; Beyerlein, I.J. [Theoretical Div., Los Alamos National Lab., Los Alamos, NM (United States); Brown, D.W.; Bourke, M.A.M. [Materials Science and Technology Div., Los Alamos National Lab., Los Alamos, NM (United States)

    2002-07-01

    Successful application of metal matrix composites often requires strength and lifetime predictions that account for the deformation of each phase. Yet, the deformation of individual phases in composites usually differs significantly from their respective monolithic behaviors. An approach is presented that quantifies the deformation parameters of each phase using neutron diffraction measurements before, during, and after failure under tensile loading in model composites consisting of a single alumina fiber embedded in an aluminum matrix. The evolution of residual strains after loading was examined including the effects of fiber failure. (orig.)

  20. Cyclic deformation behavior of steels and light-metal alloys

    International Nuclear Information System (INIS)

    Walther, Frank; Eifler, Dietmar

    2007-01-01

    The detailed knowledge of the cyclic deformation behavior of metallic materials is an essential condition for the comprehensive understanding of fatigue mechanisms and a reliable lifetime calculation of cyclically loaded specimens and components. Various steels and light-metal alloys were investigated under stress and strain control on servohydraulic testing systems. In addition to mechanical stress-strain hysteresis measurements, the changes of the specimen temperature and the electrical resistance due to plastic deformation processes were measured. The plasticity-induced martensite formation in metastable austenitic steels was detected in situ with a ferritescope sensor. As advanced magnetic measuring technique giant-magneto-resistance sensors in combination with an universal eddy-current equipment were used for the on-line monitoring of fatigue processes. Due to their direct dependence on microstructural changes, all physical values show a clear interaction with the actual fatigue state. The results of the plastic strain, thermometric, electric and magnetic measuring techniques were presented versus the number of cycles as well as in Morrow and Coffin-Manson plots. The microstructures were characterized by scanning electron microscopy

  1. Cyclic deformation behavior of steels and light-metal alloys

    Energy Technology Data Exchange (ETDEWEB)

    Walther, Frank [University of Kaiserslautern, Institute of Materials Science and Engineering, P.O. Box 3049, D-67653 Kaiserslautern (Germany)], E-mail: walther@mv.uni-kl.de; Eifler, Dietmar [University of Kaiserslautern, Institute of Materials Science and Engineering, P.O. Box 3049, D-67653 Kaiserslautern (Germany)

    2007-11-15

    The detailed knowledge of the cyclic deformation behavior of metallic materials is an essential condition for the comprehensive understanding of fatigue mechanisms and a reliable lifetime calculation of cyclically loaded specimens and components. Various steels and light-metal alloys were investigated under stress and strain control on servohydraulic testing systems. In addition to mechanical stress-strain hysteresis measurements, the changes of the specimen temperature and the electrical resistance due to plastic deformation processes were measured. The plasticity-induced martensite formation in metastable austenitic steels was detected in situ with a ferritescope sensor. As advanced magnetic measuring technique giant-magneto-resistance sensors in combination with an universal eddy-current equipment were used for the on-line monitoring of fatigue processes. Due to their direct dependence on microstructural changes, all physical values show a clear interaction with the actual fatigue state. The results of the plastic strain, thermometric, electric and magnetic measuring techniques were presented versus the number of cycles as well as in Morrow and Coffin-Manson plots. The microstructures were characterized by scanning electron microscopy.

  2. Microscopic study of gum-metal alloys: A role of trace oxygen for dislocation-free deformation

    International Nuclear Information System (INIS)

    Nagasako, Naoyuki; Asahi, Ryoji; Isheim, Dieter; Seidman, David N.; Kuramoto, Shigeru; Furuta, Tadahiko

    2016-01-01

    A class of Ti–Nb–Ta–Zr–O alloys called gum metal are known to display high strength, low Young's modulus and high elastic deformability up to 2.5%, simultaneously, and considered to deform by a dislocation-free deformation mechanism. A trace of oxygen (∼1%) in gum metal is indispensable to realize such significant properties; however, the detailed mechanism and the role of the oxygen has not been understood. To investigate an effect of trace oxygen included in gum metal, first-principles calculations for gum-metal approximants including zirconium and oxygen are performed. Calculated results clearly indicate that oxygen site with less neighboring Nb atom is energetically favorable, and that Zr–O bonding has an important role to stabilize the bcc structure of gum metal. The three-dimensional atom-probe tomography (3-D APT) measurements for gum metal were also performed to identify compositional inhomogeneity attributed to the trace elements. From the 3-D APT measurements, Zr ions bonding with oxygen ions are observed, which indicates existence of Zr–O nano-clusters in gum metal. Consequently, it is found that (a) coexistence of Zr atom and oxygen atom improves elastical stability of gum metal, (b) inhomogeneous distribution of the compositions induced by the trace elements causes anisotropical change of shear moduli, and (c) Zr–O nano-clusters existing in gum metal are expected to be obstacles to suppress movemen of dislocations.

  3. Direct observation of radial distribution change during tensile deformation of metallic glass by high energy X-ray diffraction method

    Energy Technology Data Exchange (ETDEWEB)

    Nasu, Toshio, E-mail: nasu@kekexafs.kj.yamagata-u.ac.j [Faculty of Education, Arts and Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata, Yamagata, 990-8560 (Japan); Sasaki, Motokatsu [Faculty of Education, Arts and Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata, Yamagata, 990-8560 (Japan); Usuki, Takeshi; Sekine, Mai [Faculty of Science, Yamagata University, Yamagata 990-8560 (Japan); Takigawa, Yorinobu; Higashi, Kenji [Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8531 (Japan); Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Harima Science Garden City, Sayo town, Hyogo 679-5198 (Japan); Sakurai, Masaki; Wei Zhang; Inoue, Akihisa [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2009-08-26

    The purpose of this research is to investigate the micro-mechanism of deformation behavior of metallic glasses. We report the results of direct observations of short-range and medium-range structural change during tensile deformation of metallic glasses by high energy X-ray diffraction method. Cu{sub 50}Zr{sub 50} and Ni{sub 30}Zr{sub 70} metallic glass samples in the ribbon shape (1.5 mm width and 25 mum) were made by using rapid quenching method. Tensile deformation added to the sample was made by using special equipment adopted for measuring the high energy X-ray diffraction. The peaks in pair distribution function g(r) for Cu{sub 50}Zr{sub 50} and N{sub 30}iZr{sub 70} metallic glasses move zigzag into front and into rear during tensile deformation. These results of direct observation on atomic distribution change for Cu{sub 50}Zr{sub 50} and Ni{sub 30}Zr{sub 70} metallic glass ribbons during tensile deformation suggest that the micro-relaxations occur.

  4. Effect of pass schedule and groove design on the metal deformation ...

    Indian Academy of Sciences (India)

    c Indian Academy of Sciences. Effect of pass schedule and ... metal flow behaviour in a hot rolling process is a complex phenomenon, which is ... Computer based FEM simulations incorporating deformation mod- els can be used to develop ...

  5. Prediction of pavement remaining service life based on repetition of load and permanent deformation

    Science.gov (United States)

    Usman, R. S.; Setyawan, A.; Suprapto, M.

    2018-03-01

    One of the methods which was applied in the assessment of flexible pavement performance was mechanistic method assuming structures of road pavement to become multi-layer structure for flexible pavement, that the vehicle load working on the pavement layer under repetition with power failure worth 1 (one) unit which was assumed as evenly distributed static load, and therefore the pavement material would provide response in the form of stress, strain, and deflection. This is closely related in order to assess the structure of flexible pavement and to predict the remaining service life on the roads of Pulau Indah sta 0 + 000 to sta. 0 + 845 in Kota Kupang, Nusa Tenggara Timur. The performance appraisal indicator which was used was fatigue cracking happening bottom of the asphalt layer and permanent deformation (rutting) on the surface of subgrade. The strain estimate on the flexible pavement layer structure needs carefulness and high accuracy and therefore a software like KENPAVE which produces horizontal tensile strain of 8,802E-05 and vertical compressive strain of 2,642E-04 was used. By applying equation of The Asphalt Instituteit was obtained repetition of permit load when reaching fatigue cracking (Nf) was 16.071.516 ESAL and permanent deformation (rutting) was 14.703.867 ESAL and also it was predicted the remaining service life of pavement applied the equation of AASTHO 1993 by considering Traffic Multiplier factor (TM 1.8, TM 1.9 and TM 2.0) obtained the remaining life service due to fatigue of 5.51% in the year of 13th (TM 1.8), 7.95% in the year of12th (TM 1.9) and 3.11% (TM 2.0) in the year of 12th, also the remaining service life due to rutting of 4.69% in the year of 12th(TM 1.8), 7.79% in the year of 11th (TM 1.9), and 2.94 in the year of 11th (TM 2.0).

  6. Inelastic deformations of fault and shear zones in granitic rock

    International Nuclear Information System (INIS)

    Wilder, D.G.

    1986-02-01

    Deformations during heating and cooling of three drifts in granitic rock were influenced by the presence of faults and shear zones. Thermal deformations were significantly larger in sheared and faulted zones than where the rock was jointed, but neither sheared nor faulted. Furthermore, thermal deformations in faulted or sheared rock were not significantly recovered during subsequent cooling, thus a permanent deformation remained. This inelastic response is in contrast with elastic behavior identified in unfaulted and unsheared rock segments. A companion paper indicates that deformations in unsheared or unfaulted rock were effectively modeled as an elastic response. We conclude that permanent deformations occurred in fractures with crushed minerals and fracture filling or gouge materials. Potential mechanisms for this permanent deformation are asperity readjustments during thermal deformations, micro-shearing, asperity crushing and crushing of the secondary fracture filling minerals. Additionally, modulus differences in sheared or faulted rock as compared to more intact rock would result in greater deformations in response to the same thermal loads

  7. Recent improvements in modelling fission gas release and rod deformation on metallic fuel in LMR

    International Nuclear Information System (INIS)

    Hwang, Woan; Lee, Byoung-Oon; Kim, Young Jin

    2000-01-01

    Metallic fuel design is a key feature to assure LMR core safety goals. To date, a large effort has been devoted to the development of the MACSIS code for metallic fuel rod design and the evaluation of operational limits under irradiation conditions. The updated models of fission gas release, fuel core swelling, and rod deformation are incorporated into the correspondence routines in MACSIS MOD1. The MACSIS MOD1 which is a new version of MACSIS, has been partly benchmarked on FGR, fuel swelling and rod deformation comparing with the results of U-Zr and U-Pu-Zr metal fuels irradiated in LMRs. The MACSIS MOD1 predicts, relatively well, the absolute magnitudes and trends of the gas release and rod deformations depending on burn-up, and it gives better agreement with the experimental data than the previous predictions of MACSIS and the results of the empirical model

  8. 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

  9. Investigation of peculiarities of metal deformability during multi-operation cold working with intermediate annealings

    International Nuclear Information System (INIS)

    Bogatov, A.A.; Smirnov, S.V.; Kolmogorov, V.L.

    1979-01-01

    Deformation defects in ready products considerably deteriorate their exploitation characteristics. Recovery of plasticity reserve PSI of the cold deformed 12Kh18N10T steel during electroannealing has been investigated. Moments of micropore (PSIsub(*) approximately O.33) and microcrack (PSIsub(*) approximately 0.55) formation in a deformed metal have been found. The conclusion has been made that PSI value before annealing on a ready size in technological processes of metal treatment with pressure should be restricted by the following conditions: PSI<1 - for products suffering no considerable loadings, PSI< PSIsub(**-0.5) - for most of the products, which have restrictions over the lower strength limit, toughness, durability, and for products which operate in agressive media; PSI< PSIsub(*)=0.33 - for products intended for exploitation under ''rigid'' conditions (low temperatures, shock loadings)

  10. ''Heat Transfer at the Mold-Metal Interface in Permanent Mold Casting of Aluminum Alloys'' Final Project Report; FINAL

    International Nuclear Information System (INIS)

    Pehlke, R. D.; Cookson, John M.; Shouwei Hao; Prasad Krishna; Bilkey, Kevin T.

    2001-01-01

    This project on heat transfer coefficients in metal permanent mold casting has been conducted in three areas. They are the theoretical study at the University of Michigan, the experimental investigation of squeeze casting at CMI-Tech Center (Now Hayes-Lemmerz Technical Center) and the experimental investigation of low pressure permanent mold casting at Amcast Automotive

  11. The deformation of Gum Metal through in situ compression of nanopillars

    International Nuclear Information System (INIS)

    Withey, E.A.; Minor, A.M.; Chrzan, D.C.; Morris, J.W.; Kuramoto, S.

    2010-01-01

    The name 'Gum Metal' has been given to a set of β-Ti alloys that achieve exceptional elastic elongation and, with appropriate preparation, appear to deform by a dislocation-free mechanism triggered by elastic instability at the limit of strength. We have studied the compressive deformation of these materials with in situ nanocompression in a quantitative stage in a transmission electron microscope. The samples studied are cylindrical nanopillars 80-250 nm in diameter. The deformation pattern is monitored in real time using bright-field microscopy, dark-field microscopy or electron diffraction. Interesting results include the following: (i) nanopillars approach, and in several examples appear to reach, ideal strength; (ii) in contrast to conventional crystalline materials, there is no substantial 'size effect' in pillar strength; (iii) the deformation mode is fine-scale with respect to the sample dimension, even in pillars of 100 nm size; (iv) shear bands ('giant faults') do form in some tests, but only after yield and plastic deformation; and (v) a martensitic transformation to the base-centered orthorhombic α'' phase is sometimes observed, but is an incidental feature of the deformation rather than a significant cause of it.

  12. NRC Information No. 89-43: Permanent deformation of torque switch helical springs in Limitorque SMA-type motor operators

    International Nuclear Information System (INIS)

    Rossi, C.E.

    1992-01-01

    Problems with the helical springs were discovered during a series of dynamic tests that were conducted with a motor-operated wedge-gate valve from the decommissioned Shippingport Atomic Power Station (Shippingport). The valve was installed in a portion of the piping system that had been modified to simulate the stiffness of a typical US piping system. The valve was 30 years old and had its original Limitorque SMA-type motor operator. One of the main objectives of these tests was to determine the operating capability of the valve when subjected to simultaneous internal hydraulic and seismic loadings. This was typically accomplished by operating the valve to achieve maximum hydraulic loading during maximum seismic loading. During testing, an operability problem with the valve motor operator occurred. The design of the SMA-type motor operator is such that the torque switch helical spring is in its most compressed condition when the valve is closed. Thus, a normally closed valve is more likely to experience permanent deformation of the helical torque spring. A review of the Shippingport records indicated that both of these valves had been used as normally closed valves at Shippingport. Thus, normally closed, safety-related valves with Limitorque SMA-type motor operators may not accomplish their intended safety-related function because the original torque switch setting may result in lower output torque caused by the permanent deformation of their torque switch helical springs

  13. Multi Scale Models for Flexure Deformation in Sheet Metal Forming

    Directory of Open Access Journals (Sweden)

    Di Pasquale Edmondo

    2016-01-01

    Full Text Available This paper presents the application of multi scale techniques to the simulation of sheet metal forming using the one-step method. When a blank flows over the die radius, it undergoes a complex cycle of bending and unbending. First, we describe an original model for the prediction of residual plastic deformation and stresses in the blank section. This model, working on a scale about one hundred times smaller than the element size, has been implemented in SIMEX, one-step sheet metal forming simulation code. The utilisation of this multi-scale modeling technique improves greatly the accuracy of the solution. Finally, we discuss the implications of this analysis on the prediction of springback in metal forming.

  14. Stress analysis and deformation prediction of sheet metal workpieces based on finite element simulation

    Directory of Open Access Journals (Sweden)

    Ren Penghao

    2017-01-01

    Full Text Available After aluminum alloy sheet metal parts machining, the residual stress release will cause a large deformation. To solve this problem, this paper takes a aluminum alloy sheet aerospace workpiece as an example, establishes the theoretical model of elastic deformation and the finite element model, and places quantitative initial stress in each element of machining area, analyses stress release simulation and deformation. Through different initial stress release simulative analysis of deformation of the workpiece, a linear relationship between initial stress and deformation is found; Through simulative analysis of coupling direction-stress release, the superposing relationship between the deformation caused by coupling direction-stress and the deformation caused by single direction stress is found. The research results provide important theoretical support for the stress threshold setting and deformation controlling of the workpieces in the production practice.

  15. 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

  16. A finite element study on the effects of toughness and permanent out-of-plane deformation on post-impact compressive strength

    OpenAIRE

    Bull, Daniel; Spearing, Simon; Sinclair, Ian

    2015-01-01

    This study applies mechanisms observed from previous work (the undamaged cone, toughness and extent of permanent out-of-plane deformation) to parametrically study their effects on residual compression after impact (CAI) strength using finite element models. Based on previous experimental work, tougher material systems exhibited up to 30% greater CAI strength for a given damage area. Based on this, it is necessary to understand what other parameters, beyond damage area, contribute to a loss in...

  17. Void growth and coalescence in metals deformed at elevated temperature

    DEFF Research Database (Denmark)

    Klöcker, H.; Tvergaard, Viggo

    2000-01-01

    For metals deformed at elevated temperatures the growth of voids to coalescence is studied numerically. The voids are assumed to be present from the beginning of deformation, and the rate of deformation considered is so high that void growth is dominated by power law creep of the material, without...... any noticeable effect of surface diffusion. Axisymmetric unit cell model computations are used to study void growth in a material containing a periodic array of voids, and the onset of the coalescence process is defined as the stage where plastic flow localizes in the ligaments between neighbouring...... voids. The focus of the study is on various relatively high stress triaxialties. In order to represent the results in terms of a porous ductile material model a set of constitutive relations are used, which have been proposed for void growth in a material undergoing power law creep....

  18. Removing metal debris from thermosetting EMC powders by Nd-Fe-B permanent magnets

    Directory of Open Access Journals (Sweden)

    Liaw Yowching

    2017-01-01

    Full Text Available During the preparation of thermosetting encapsulation molding compounds (EMCs for semiconductor packaging, metal debris are always present in the EMC powders due to the hard silica fillers in the compound. These metal debris in the EMC powders will cause circuit shortage and therefore have to be removed before molding. In this study, Nd-Fe-B permanent magnets are used to remove these debris. The results show that the metal debris can be removed effectively as the rate of accumulation of the metal debris increases as time proceeds in the removing operation. The removal effectiveness of the debris is affected by both the magnetic flux density and the flow around the magnet. The wake flow behind the magnet is a relatively low speed recirculation region which facilities the attraction of metal debris in the powders. Thus, the largest amount of the accumulated EMC powders occurs downstream of the magnet. Hence, this low speed recirculation region should be better utilized to enhance the removal efficiency of the metal debris.

  19. Cyclic Deformation and Fatigue Behaviors of Alloy 617 Base Metal and Weldments at 900℃ for VHTR Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seon Jin; Kim, Byung Tak; Dewa, Rando T.; Hwang, Jeong Jun; Kim, Tae Su [Pukyong National Univ., Busan (Korea, Republic of); Kim, Woo Gon; Kim, Eung Seon [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    An analysis of cyclic deformation can contribute to a deeper understanding of the fatigue fracture mechanisms as well as to improvements in the design and application of VHTR system. However, the studies associated with cyclic deformation and low cycle fatigue (LCF) properties of Alloy 617 have focused mainly on the base metal, with little attention given to the weldments. Totemeier studied on high-temperature creep-fatigue of Alloy 617 base metal and weldments. Current research activities at PKNU and KAERI focus on the study of cyclic deformation and LCF behaviors of Alloy 617 base metal (BM) and weldments (WM) specimens were machined from GTAW buttwelded plates at very high-temperature of 900℃. In this work, the cyclic deformation characteristics and fatigue behaviors of Alloy 617 BM and WM are studied and discussed with respect to LCF. In this paper, cyclic deformation and low cycle fatigue behaviors of Alloy 617 base metal and weldments was evaluated using strain-controlled LCF tests at 900℃for 0.6% total strain range. Results of the current experiments can be concluded; The WM specimen has shown a higher cyclic stress response than the BM specimen. The fatigue life of WM specimen was reduced relative to that of BM specimen.

  20. Ground state of the polar alkali-metal-atom-strontium molecules: Potential energy curve and permanent dipole moment

    International Nuclear Information System (INIS)

    Guerout, R.; Aymar, M.; Dulieu, O.

    2010-01-01

    In this study, we investigate the structure of the polar alkali-metal-atom-strontium diatomic molecules as possible candidates for the realization of samples of ultracold polar molecular species not yet investigated experimentally. Using a quantum chemistry approach based on effective core potentials and core polarization potentials, we model these systems as effective three-valence-electron systems, allowing for calculation of electronic properties with full configuration interaction. The potential curve and the permanent dipole moment of the 2 Σ + ground state are determined as functions of the internuclear distance for LiSr, NaSr, KSr, RbSr, and CsSr molecules. These molecules are found to exhibit a significant permanent dipole moment, though smaller than those of the alkali-metal-atom-Rb molecules.

  1. Molecular Dynamics Simulation of Structural Characterization of Elastic and Inelastic Deformation in ZrCu Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Shidong Feng

    2014-01-01

    Full Text Available The nanoscopic deformation behaviors in a ZrCu metallic glass model during loading-unloading process under uniaxial compression have been analyzed on the basis of the molecular dynamics (MD. The reversible degree of shear origin zones (SOZs is used as the structural indicator to distinguish the elastic deformation and inelastic deformation of ZrCu metallic glass at the atomic level. We find that the formation of SOZs is reversible at the elastic stage but irreversible at the inelastic stage during the loading and unloading processes. At the inelastic stage, the full-icosahedra fraction in SOZs is quickly reduced with increased strain and the decreasing process is also irreversible during the unloading processes.

  2. Two-scale characterization of deformation-induced anisotropy of polycrystalline metals

    International Nuclear Information System (INIS)

    Watanabe, Ikumu; Terada, Kenjiro

    2004-01-01

    The anisotropic macro-scale mechanical behavior of polycrystalline metals is characterized by incorporating the micro-scale constitutive model of single crystal plasticity into the two-scale modeling based on the mathematical homogenization theory. The two-scale simulations are conducted to analyze the macro-scale anisotropy induced by micro-scale plastic deformation of the polycrystalline aggregate. In the simulations, the micro-scale representative volume element (RVE) of a polycrystalline aggregate is uniformly loaded in one direction, unloaded to macroscopically zero stress in a certain stage of deformation and then re-loaded in the different directions. The last re-loading calculations provide different macro-scale responses of the RVE, which can be the appearance of material anisotropy. We then try to examine the effects of the intergranular and intragranular behaviors on the anisotropy by means of various illustrations of plastic deformation process in stead of the use of pole figures for the change of crystallographic orientations

  3. Compression deformation behaviors of sheet metals at various clearances and side forces

    OpenAIRE

    Zhan Mei; Wang Xianxian; Cao Jian; Yang He

    2015-01-01

    Modeling sheet metal forming operations requires understanding of plastic behaviors of sheet metals along non-proportional strain paths. The plastic behavior under reversed uniaxial loading is of particular interest because of its simplicity of interpretation and its application to material elements drawn over a die radius and underwent repeated bending. However, the attainable strain is limited by failures, such as buckling and in-plane deformation, dependent on clearances and side forces. I...

  4. Multi-Axial Deformation Setup for Microscopic Testing of Sheet Metal to Fracture

    NARCIS (Netherlands)

    Tasan, C.C.; Hoefnagels, J.P.M.; Dekkers, E.C.A.; Geers, M.G.D.

    2012-01-01

    While the industrial interest in sheet metal with improved specific-properties led to the design of new alloys with complex microstructures, predicting their safe forming limits and understanding their microstructural deformation mechanisms remain as significant challenges largely due to the

  5. Energy Saving Melting and Revert Reduction Technology (Energy-SMARRT): Light Metals Permanent Mold Casting

    Energy Technology Data Exchange (ETDEWEB)

    Fasoyinu, Yemi [CanmetMATERIALS

    2014-03-31

    Current vehicles use mostly ferrous components for structural applications. It is possible to reduce the weight of the vehicle by substituting these parts with those made from light metals such as aluminum and magnesium. Many alloys and manufacturing processes can be used to produce these light metal components and casting is known to be most economical. One of the high integrity casting processes is permanent mold casting which is the focus of this research report. Many aluminum alloy castings used in automotive applications are produced by the sand casting process. Also, aluminum-silicon (Al-Si) alloys are the most widely used alloy systems for automotive applications. It is possible that by using high strength aluminum alloys based on an aluminum-copper (Al-Cu) system and permanent mold casting, the performance of these components can be enhanced significantly. This will also help to further reduce the weight. However, many technological obstacles need to be overcome before using these alloys in automotive applications in an economical way. There is very limited information in the open literature on gravity and low-pressure permanent mold casting of high strength aluminum alloys. This report summarizes the results and issues encountered during the casting trials of high strength aluminum alloy 206.0 (Al-Cu alloy) and moderate strength alloy 535.0 (Al-Mg alloy). Five engineering components were cast by gravity tilt-pour or low pressure permanent mold casting processes at CanmetMATERIALS (CMAT) and two production foundries. The results of the casting trials show that high integrity engineering components can be produced successfully from both alloys if specific processing parameters are used. It was shown that a combination of melt processing and mold temperature is necessary for the elimination of hot tears in both alloys.

  6. Use of state variables in the description of irradiation creep and deformation of metals

    International Nuclear Information System (INIS)

    Hart, E.W.; Li, C.Y.

    1976-01-01

    The understanding of the effects of irradiation on metal creep and deformation are not yet satisfactory, owing in part to the limitations on experimentation in radiation environment. Because of such limitations, theoretical considerations must play a strong role. Virtually all of the theoretical considerations currently employed are based on micro-mechanical models for the deformation behavior. The recent theoretical and experimental development of a plastic equation of state for metal deformation has led to the identification of some of the principal micro-mechanisms in phenomenological terms. The role of the individual mechanisms can be related to the state variables of the description, and those variables are directly accessible measurable quantities. This paper explores how irradiation might affect this description. It is shown that the radiation flux and the radiation fluence are expected to affect different components of the equation of state. The resultant description makes considerable use of the information developed in radiation-free environment. 5 fig

  7. Surface flow in severe plastic deformation of metals by sliding

    International Nuclear Information System (INIS)

    Mahato, A; Yeung, H; Chandrasekar, S; Guo, Y

    2014-01-01

    An in situ study of flow in severe plastic deformation (SPD) of surfaces by sliding is described. The model system – a hard wedge sliding against a metal surface – is representative of surface conditioning processes typical of manufacturing, and sliding wear. By combining high speed imaging and image analysis, important characteristics of unconstrained plastic flow inherent to this system are highlighted. These characteristics include development of large plastic strains on the surface and in the subsurface by laminar type flow, unusual fluid-like flow with vortex formation and surface folding, and defect and particle generation. Preferred conditions, as well as undesirable regimes, for surface SPD are demarcated. Implications for surface conditioning in manufacturing, modeling of surface deformation and wear are discussed

  8. Plastic deformation and failure mechanisms in nano-scale notched metallic glass specimens under tensile loading

    Science.gov (United States)

    Dutta, Tanmay; Chauniyal, Ashish; Singh, I.; Narasimhan, R.; Thamburaja, P.; Ramamurty, U.

    2018-02-01

    In this work, numerical simulations using molecular dynamics and non-local plasticity based finite element analysis are carried out on tensile loading of nano-scale double edge notched metallic glass specimens. The effect of acuteness of notches as well as the metallic glass chemical composition or internal material length scale on the plastic deformation response of the specimens are studied. Both MD and FE simulations, in spite of the fundamental differences in their nature, indicate near-identical deformation features. Results show two distinct transitions in the notch tip deformation behavior as the acuity is increased, first from single shear band dominant plastic flow localization to ligament necking, and then to double shear banding in notches that are very sharp. Specimens with moderately blunt notches and composition showing wider shear bands or higher material length scale characterizing the interaction stress associated with flow defects display profuse plastic deformation and failure by ligament necking. These results are rationalized from the role of the interaction stress and development of the notch root plastic zones.

  9. The effect of tooling deformation on process control in multistage metal forming

    NARCIS (Netherlands)

    Havinga, Gosse Tjipke; van den Boogaard, Antonius H.; Chinesta, F; Cueto, E; Abisset-Chavanne, E.

    2016-01-01

    Forming of high-strength steels leads to high loads within the production process. In multistage metal forming, the loads in different process stages are transferred to the other stages through elastic deformation of the stamping press. This leads to interactions between process steps, affecting the

  10. Modelling of the plastic deformation and primary creep of metals coupled with DC in terms of the synthetic theory of irrecoverable deformation

    Science.gov (United States)

    Rusinko, Andrew; Varga, Peter

    2018-04-01

    The paper deals with modelling of the plastic and creep deformation of metals coupled with current. The passage of DC manifests itself in the increase in creep deformation and leads to primary creep time shortening. With plastic deformation, a short electric impulse results in the step-wise decrease of stress (stress-drop) on the stress-strain diagram. To catch these phenomena, we utilize the synthetic theory of recoverable deformation. The constitutive equation of this theory is supplemented by a term taking into account the intensity of DC. Further, we introduce DC intensity into the function governing transient creep. As a result, we predict the parameters of transient creep and calculate the stress-drop as a function of current intensity. The model results show good agreement with experimental data.

  11. 21 CFR 886.4445 - Permanent magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove metallic...

  12. 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...

  13. Research of state of metal welded joint by deformation and corrosion surface projection parameters

    Directory of Open Access Journals (Sweden)

    Demchenko Maria Vyacheslavovna

    2017-10-01

    Full Text Available At industrial enterprises in building structures and equipment one can see corrosion damage, as well as damage accumulated during operation period. The areas of stress concentration are welded joints as their structure is heterogeneous. From the point of view of the scale hierarchy, the welded joint represents the welded and base metal zones at the meso-macrolevel, the weld zone, the thermal zone, the base metal at the micro-mesolevel, the grain constituents at the nano-microlevel. Borders are the stress concentrators at different scale levels, thus they becomes the most dangerous places of metal structure. Modeling by the molecular dynamics method at the atomic level has shown nanocracks initiation in triple junctions of grain boundaries and on the ledges of the grain boundaries. Due to active development of nanotechnology, it became possible to evaluate the state of the weld metal at the nanoscale, where irreversible changes take place from the very beginning. Existing methods of nondestructive testing can detect damage only at the meso- and macrolevel. Modern equipment makes it possible to use other methods of control and approaches. For example, according to GOST R55046-2012 and R57223-2016, the analysis of the parameters of the surface projection deformation performed by confocal laser scanning microscopy should be taken into account when the evaluation of state of metal pipelines is carried out. However, there is a problem to monitore it due to various factors affecting the surface during operation. The paper proposes an additional method to estimate the state of weld metal at any stage of deformation that uses 3D analysis of the parameters of the «artificial» corrosion relief of surface. During the operation period changes in the stress-strain state and structure of the metal take place, as the result the character and depth of etching of the grains of the structural components and their boundaries change too. Evaluation of the

  14. 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

  15. Computer Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    Science.gov (United States)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2004-01-01

    In friction stir welding, a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. This solid-state technique has been successfully used in the joining of materials that are difficult to fusion weld such as aluminum alloys. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and thus tracks the aluminum deformation flow paths in a unique 3-dimensional manner. CT scanning is a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  16. Permanent deformation behavior of naturally occurring bituminous sands

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2008-01-01

    Full Text Available and mining equipment at two different load pulse durations or loading frequencies (related to field-trafficking speeds). Both the test data and axial permanent strain models developed in the form of power functions of the number of repeated load applications...

  17. Atomistic simulation study of the shear-band deformation mechanism in Mg-Cu metallic glasses

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2006-01-01

    We have simulated plastic deformation of a model Mg-Cu metallic glass in order to study shear banding. In uniaxial tension, we find a necking instability occurs rather than shear banding. We can force the latter to occur by deforming in plane strain, forbidding the change of length in one...... of the transverse directions. Furthermore, in most of the simulations a notch is used to initiate shear bands, which lie at a 45 degrees angle to the tensile loading direction. The shear bands are characterized by the Falk and Langer local measure of plastic deformation D-min(2), averaged here over volumes...... observe a slight decrease in density, up to 1%, within the shear band, which is consistent with notions of increased free volume or disorder within a plastically deforming amorphous material....

  18. Bending and tensile deformation of metallic nanowires

    International Nuclear Information System (INIS)

    McDowell, Matthew T; Leach, Austin M; Gall, Ken

    2008-01-01

    Using molecular statics simulations and the embedded atom method, a technique for bending silver nanowires and calculating Young's modulus via continuum mechanics has been developed. The measured Young's modulus values extracted from bending simulations were compared with modulus values calculated from uniaxial tension simulations for a range of nanowire sizes, orientations and geometries. Depending on axial orientation, the nanowires exhibit stiffening or softening under tension and bending as size decreases. Bending simulations typically result in a greater variation of Young's modulus values with nanowire size compared with tensile deformation, which indicates a loading-method-dependent size effect on elastic properties at sub-5 nm wire diameters. Since the axial stress is maximized at the lateral surfaces in bending, the loading-method-dependent size effect is postulated to be primarily a result of differences in nanowire surface and core elastic modulus. The divergence of Young's modulus from the bulk modulus in these simulations occurs at sizes below the range in which experiments have demonstrated a size scale effect on elastic properties of metallic nanowires. This difference indicates that other factors beyond native metallic surface properties play a role in experimentally observed nanowire elastic modulus size effects

  19. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  20. Numerical Modelling of Metal-Elastomer Spring Nonlinear Response for Low-Rate Deformations

    Directory of Open Access Journals (Sweden)

    Sikora Wojciech

    2018-03-01

    Full Text Available Advanced knowledge of mechanical characteristics of metal-elastomer springs is useful in their design process and selection. It can also be used in simulating dynamics of machine where such elements are utilized. Therefore this paper presents a procedure for preparing and executing FEM modelling of a single metal-elastomer spring, also called Neidhart’s spring, for low-rate deformations. Elastomer elements were made of SBR rubber of two hardness values: 50°Sh and 70°Sh. For the description of material behaviour the Bergström-Boyce model has been used.

  1. Free volume model: High-temperature deformation of a Zr-based bulk metallic glass

    International Nuclear Information System (INIS)

    Bletry, M.; Guyot, P.; Blandin, J.J.; Soubeyroux, J.L.

    2006-01-01

    The homogeneous deformation of a zirconium-based bulk metallic glass is investigated in the glass transition region. Compression tests at different temperatures and strain rates have been conducted. The mechanical behavior is analyzed in the framework of the free volume model, taking into account the dependence of the flow defect concentration on deformation. The activation volume is evaluated and allows one to gather the viscosity data (for the different strain rates and temperatures) on a unique master curve. It is also shown that, due to the relation between flow defect concentration and free volume, it is not possible to deduce the equilibrium flow defect concentration directly from mechanical measurements. However, if this parameter is arbitrarily chosen, mechanical measurements give access to the other parameters of the model, these parameters for the alloy under investigation being of the same order of magnitude as those for other metallic glasses

  2. Plastic Deformation of Metal Tubes Subjected to Lateral Blast Loads

    Directory of Open Access Journals (Sweden)

    Kejian Song

    2014-01-01

    Full Text Available When subjected to the dynamic load, the behavior of the structures is complex and makes it difficult to describe the process of the deformation. In the paper, an analytical model is presented to analyze the plastic deformation of the steel circular tubes. The aim of the research is to calculate the deflection and the deformation angle of the tubes. A series of assumptions are made to achieve the objective. During the research, we build a mathematical model for simply supported thin-walled metal tubes with finite length. At a specified distance above the tube, a TNT charge explodes and generates a plastic shock wave. The wave can be seen as uniformly distributed over the upper semicircle of the cross-section. The simplified Tresca yield domain can be used to describe the plastic flow of the circular tube. The yield domain together with the plastic flow law and other assumptions can finally lead to the solving of the deflection. In the end, tubes with different dimensions subjected to blast wave induced by the TNT charge are observed in experiments. Comparison shows that the numerical results agree well with experiment observations.

  3. Discontinuities of Plastic Deformation in Metallic Glasses with Different Glass Forming Ability

    Science.gov (United States)

    Hurakova, Maria; Csach, Kornel; Miskuf, Jozef; Jurikova, Alena; Demcak, Stefan; Ocelik, Vaclav; Hosson, Jeff Th. M. De

    The metallic ribbons Fe40Ni40B20, Cu47Ti35Zr11Ni6Si1 and Zr65Cu17.5Ni10Al7.5 with different microhardness and glass forming ability were studied at different loading rates from 0.05 to 100 mN/s. We describe in details the differences in elemental discontinuities on the loading curves for the studied alloys. It was found that the discontinuities began at a certain local deformation independently on the macroscopic mechanical properties of a ribbon. More developed discontinuities at higher deformations are created for the materials with lower microhardness and so lower strength.

  4. Evaluation of permanent deformation of CRM-reinforced SMA and its correlation with dynamic stiffness and dynamic creep.

    Science.gov (United States)

    Mashaan, Nuha Salim; Karim, Mohamed Rehan

    2013-01-01

    Today, rapid economic and industrial growth generates increasing amounts of waste materials such as waste tyre rubber. Attempts to inspire a green technology which is more environmentally friendly that can produce economic value are a major consideration in the utilization of waste materials. The aim of this study is to evaluate the effect of waste tyre rubber (crumb rubber modifier (CRM)), in stone mastic asphalt (SMA 20) performance. The virgin bitumen (80/100) penetration grade was used, modified with crumb rubber at four different modification levels, namely, 6%, 12%, 16%, and 20% by weight of the bitumen. The testing undertaken on the asphalt mix comprises the indirect tensile (dynamic stiffness), dynamic creep, and wheel tracking tests. By the experimentation, the appropriate amount of CRM was found to be 16% by weight of bitumen. The results show that the addition of CRM into the mixture has an obvious significant effect on the performance properties of SMA which could improve the mixture's resistance against permanent deformation. Further, higher correlation coefficient was obtained between the rut depth and permanent strain as compared to resilient modulus; thus dynamic creep test might be a more reliable test in evaluating the rut resistance of asphalt mixture.

  5. Evaluation of Permanent Deformation of CRM-Reinforced SMA and Its Correlation with Dynamic Stiffness and Dynamic Creep

    Directory of Open Access Journals (Sweden)

    Nuha Salim Mashaan

    2013-01-01

    Full Text Available Today, rapid economic and industrial growth generates increasing amounts of waste materials such as waste tyre rubber. Attempts to inspire a green technology which is more environmentally friendly that can produce economic value are a major consideration in the utilization of waste materials. The aim of this study is to evaluate the effect of waste tyre rubber (crumb rubber modifier (CRM, in stone mastic asphalt (SMA 20 performance. The virgin bitumen (80/100 penetration grade was used, modified with crumb rubber at four different modification levels, namely, 6%, 12%, 16%, and 20% by weight of the bitumen. The testing undertaken on the asphalt mix comprises the indirect tensile (dynamic stiffness, dynamic creep, and wheel tracking tests. By the experimentation, the appropriate amount of CRM was found to be 16% by weight of bitumen. The results show that the addition of CRM into the mixture has an obvious significant effect on the performance properties of SMA which could improve the mixture's resistance against permanent deformation. Further, higher correlation coefficient was obtained between the rut depth and permanent strain as compared to resilient modulus; thus dynamic creep test might be a more reliable test in evaluating the rut resistance of asphalt mixture.

  6. Ra and the average effective strain of surface asperities deformed in metal-working processes

    DEFF Research Database (Denmark)

    Bay, Niels; Wanheim, Tarras; Petersen, A. S

    1975-01-01

    Based upon a slip-line analysis of the plastic deformation of surface asperities, a theory is developed determining the Ra-value (c.l.a.) and the average effective strain in the surface layer when deforming asperities in metal-working processes. The ratio between Ra and Ra0, the Ra-value after...... and before deformation, is a function of the nominal normal pressure and the initial slope γ0 of the surface asperities. The last parameter does not influence Ra significantly. The average effective strain View the MathML sourcege in the deformed surface layer is a function of the nominal normal pressure...... and γ0. View the MathML sourcege is highly dependent on γ0, View the MathML sourcege increasing with increasing γ0. It is shown that the Ra-value and the strain are hardly affected by the normal pressure until interacting deformation of the asperities begins, that is until the limit of Amonton's law...

  7. The role of deformation microstructure in recovery and recrystallization of heavily strained metals

    DEFF Research Database (Denmark)

    Hansen, Niels

    2012-01-01

    Metals deformed to high and ultrahigh strains are characterized by a nanoscale microstructure, a large fraction of high angle boundaries and a high dislocation density. Another characteristic of such a microstructure is a large stored energy that combines elastic energy due to dislocations and bo...

  8. 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.

  9. Inspection and Reconstruction of Metal-Roof Deformation under Wind Pressure Based on Bend Sensors

    OpenAIRE

    Yang, Liman; Cui, Langfu; Li, Yunhua; An, Chao

    2017-01-01

    Metal roof sheathings are widely employed in large-span buildings because of their light weight, high strength and corrosion resistance. However, their severe working environment may lead to deformation, leakage and wind-lift, etc. Thus, predicting these damages in advance and taking maintenance measures accordingly has become important to avoid economic losses and personal injuries. Conventionally, the health monitoring of metal roofs mainly relies on manual inspection, which unavoidably com...

  10. Computed Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    Science.gov (United States)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2005-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and is carried with the macro-flow of the weld metal. By using CT images, a 3-dimensional (3D) image of the lead flow pattern can be reconstructed. CT imaging was found to be a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  11. An Evaluation of the Resilient Modulus and Permanent Deformation of Unbound Mixtures of Granular Materials and Rubber Particles from Scrap Tyres to Be Used in Subballast Layers

    Energy Technology Data Exchange (ETDEWEB)

    Hidalgo Sgnes, C.

    2016-07-01

    Over the last years rubber from scrap tyres has been reused in different civil works such as road embankments and railway platforms due to its resilient properties, low degradation and vibration attenuation. Unfortunately, this issue is still scarce. For instance, in Spain about 175.000 tonnes of scrap tyres were collected in 2014, of which only 0.6% were reused in civil works. Aiming to contribute to the reutilisation of large quantities of this waste material, this paper focuses on the analysis of unbound mixtures of granular materials with different percentages of rubber particles to be used as subballast layers. Mixtures are tested under cyclic triaxial tests so as to obtain their resilient modulus and evaluate their permanent deformations. It is found that as the rubber content increases, the resilient modulus decreases and the permanent deformation increases. Taking into account the usual loads transmitted to the subballast layer, the optimum rubber content that does not compromise the behaviour of the mixture is set in a range between 2.5% and 5% in terms of weight. (Author)

  12. 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.

  13. Two-dimensional discrete dislocation models of deformation in polycrystalline thin metal films on substrates

    International Nuclear Information System (INIS)

    Hartmaier, Alexander; Buehler, Markus J.; Gao, Huajian

    2005-01-01

    The time-dependent irreversible deformation of polycrystalline thin metal films on substrates is investigated using two-dimensional discrete dislocation dynamics models incorporating essential parameters determined from atomistic studies. The work is focused on the mechanical properties of uncapped films, where diffusive processes play an important role. The simulations incorporate dislocation climb along the grain boundary as well as conservative glide. Despite of severe limitations of the two-dimensional dislocation models, the simulation results are found to largely corroborate experimental findings on different dominant deformation mechanisms at different film thicknesses

  14. On the fast amorphous phase growth in plastically deformed metallic couples

    International Nuclear Information System (INIS)

    Mazzone, G.; Montone, A.; Antisari, M.V.

    1993-01-01

    The authors have modeled the kinetics of glass formation at the Ni-Zr interface of plastically deformed diffusion couples on the basis of a free volume description of glass structure, taking also into account the structural effects of an externally applied stress. Owing to the complexity of the problem several approximations have necessarily been introduced, the main ones being probably the simplified description of the structure and of the tensile behavior of a metallic glass and the use of the Spaepen Eqs. in an alloy system. However, these approximations do not seem to significantly affect the main trends displayed by the computations, that is the high value of D, the exponential dependence of x on var-epsilon and the low value of the activation energy, in agreement with experimental trends (3) not easily attributable to other causes. Of course, the numerical values of the free parameters have to be considered an approximate evaluation of the corresponding physical quantities. However, despite of the above limitations, their values are physically plausible. In conclusion the authors have shown that the present model describes in a quantitative way the kinetics of solid state amorphization at the interface of a diffusion couple plastically deformed during the reaction. The effective diffusion coefficient increases by several orders of magnitude as a consequence of a small increase in vf driven by the stress required to deform the growing film. The effects of strain rate and deformation time balance each other almost exactly so that the film thickness increases exponentially with the total deformation of the diffusion couple

  15. 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.

  16. Deformation in Metallic Glass: Connecting Atoms to Continua

    Science.gov (United States)

    Hinkle, Adam R.; Falk, Michael L.; Rycroft, Chris H.; Shields, Michael D.

    Metallic glasses like other amorphous solids experience strain localization as the primary mode of failure. However, the development of continuum constitutive laws which provide a quantitative description of disorder and mechanical deformation remains an open challenge. Recent progress has shown the necessity of accurately capturing fluctuations in material structure, in particular the statistical changes in potential energy of the atomic constituents during the non-equilibrium process of applied shear. Here we directly cross-compare molecular dynamics shear simulations of a ZrCu glass with continuum shear transformation zone (STZ) theory representations. We present preliminary results for a methodology to coarse-grain detailed molecular dynamics data with the goal of initializing a continuum representation in the STZ theory. NSF Grants Awards 1107838, 1408685, and 0801471.

  17. Effect of cooling rate on microstructure and deformation behavior of Ti-based metallic glassy/crystalline powders

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.J. [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Huang, Y.J. [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); Shen, J., E-mail: junshen@hit.edu.cn [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); Wu, Y.Q.; Huang, H. [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Zou, J., E-mail: j.zou@uq.edu.au [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, QLD 4072 (Australia)

    2010-08-20

    The microstructures and deformation behavior of Ti-based metallic powders were comprehensively investigated. It has been found that, with increasing the powder size, the phase constituent alters from pure glassy to glassy with crystalline phases (face centered cubic structured NiSnZr and hexagonal structured Ti{sub 3}Sn phases). Our results suggest that the synergetic effect of the thermodynamics and kinetics determines the subsequent characteristics of the crystalline precipitations. Through comparative nanoindentation tests, it was found that the small powders exhibit more pop-in events and a larger pile-up ratio, suggesting that the plastic deformation of the metallic powders is governed by the combined effects of the free volume and the crystallization, which are determined by the cooling rate.

  18. In-situ deformation studies of an aluminum metal-matrix composite in a scanning electron microscope

    Science.gov (United States)

    Manoharan, M.; Lewandowski, J. J.

    1989-01-01

    Tensile specimens made of a metal-matrix composite (cast and extruded aluminum alloy-based matrix reinforced with Al2O3 particulate) were tested in situ in a scanning electron microscope equipped with a deformation stage, to directly monitor the crack propagation phenomenon. The in situ SEM observations revealed the presence of microcracks both ahead of and near the crack-tip region. The microcracks were primarily associated with cracks in the alumina particles. The results suggest that a region of intense deformation exists ahead of the crack and corresponds to the region of microcracking. As the crack progresses, a region of plastically deformed material and associated microcracks remains in the wake of the crack.

  19. Investigation of crystallization kinetics and deformation behavior in supercooled liquid region of CuZr-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ke; Fan, Xinhui; Li, Bing; Li, Yanhong; Wang, Xin; Xu, Xuanxuan [Xi' an Technological Univ. (China). School of Material and Chemical Engineering

    2017-08-15

    In this paper, a systematic study of crystallization kinetics and deformation behavior is presented for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} bulk metallic glass in the supercooled liquid region. Crystallization results showed that the activation energy for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} was calculated using the Arrhenius equation in isothermal mode and the Kissinger-Akahira-Sunose method in non-isothermal mode. The activation energy was quite high compared with other bulk metallic glasses. Based on isothermal transformation kinetics described by the Johson-Mehl-Avrami model, the average Avrami exponent of about 3.05 implies a mainly diffusion controlled three-dimensional growth with an increasing nucleation rate during the crystallization. For warm deformation, the results showed that deformation behavior, composed of homogeneous and inhomogeneous deformation, is strongly dependent on strain rate and temperature. The homogeneous deformation transformed from non-Newtonian flow to Newtonian flow with a decrease in strain rate and an increase in temperature. It was found that the crystallization during high temperature deformation is induced by heating. The appropriate working temperature/strain rate combination for the alloy forming, without in-situ crystallization, was deduced by constructing an empirical deformation map. The optimum process condition for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} can be expressed as T∝733 K and ∝ ε 10{sup -3} s{sup -1}.

  20. Evaluation of Package Stress during Temperature Cycling using Metal Deformation Measurement and FEM Simulation

    International Nuclear Information System (INIS)

    Hoeglauer, J.; Bohm, C.; Otremba, R.; Maerz, J.; Nelle, P.; Stecher, M.; Alpern, P.

    2006-01-01

    Plastic encapsulated devices that are exposed to Temperature Cycling (TC) tests undergo an excessive mechanical stress due to different Coefficients of Thermal Expansion (CTE) of the various materials used in the system. Especially in the corners of the die, passivation cracks and shifted metal lines can be observed, which demonstrates an increasing mechanical stress from chip center to the corners of the die. This effect has been known for a long time. This paper presents a simple measurement technique to quantify the mechanical shear stress at the chip-Mold Compound (MC) interface by measuring the deformation of a periodical metal structure. Based on this deformation measurement, we evaluated the stress distribution within the package, and the influence of different parameters such as number of cycles and chip size. Furthermore, these experimental results were compared with FEM simulation, and showed good agreement but could not account in all cases for the total amount of observed shift

  1. Deformation processes in refractory metals. Progress report, 1 December 1974--30 November 1975

    International Nuclear Information System (INIS)

    Donoso, J.R.; Reed-Hill, R.E.

    1975-01-01

    Work in progress is mostly concerned with the stress-strain behavior of niobium, as affected by dynamic strain aging. An investigation of the aging phenomena in nickel containing carbon as the major interstitial impurity was also conducted. Some aspects of the deformation behavior of the hexagonal metals titanium and zirconium still warrant investigation and are also being considered. (auth)

  2. Slot deformation of various stainless steel bracket due to the torque force of the beta-titanium wire

    Science.gov (United States)

    Huda, M. M.; Siregar, E.; Ismah, N.

    2017-08-01

    Stainless steel bracket slot deformation ffects the force applied to teeth and it can impede tooth movement and prolong orthodontic treatment time. The aim of this study is to determine the slot deformation due to torque of a 0.021 × 0.025 inch Beta Titanium wire with a torsional angle of 30° and 45° for five different bracket brands: y, 3M, Biom, Versadent, Ormco, and Shinye. The research also aims to compare the deformation and amount of torque among all five bracket brands at torsional angles of 30° and 45°. Fifty stainless steel edgewise brackets from the five bracket group brands (n=10) were attached to acrylic plates. The bracket slot measurements were carried out in two stages. In the first stage, the, deformation was measured by calculating the average bracket slot height using a stereoscopy microscope before and after application of torque. In the second stage, the torque was measured using a torque measurement apparatus. The statistical analysis shows that slot deformations were found on all five bracket brands with a clinical permanent deformation on the Biom (2.79 μm) and Shinye (2.29 μm) brackets. The most torque was observed on the 3M bracket, followed by the Ormco, Versadent, Shinye, and Biom brackets. When the brands were compared, a correlation between bracket slot deformation and the amount of torque was found, but the correlation was not statistically significant for the 3M and Ormco brackets and the Biom and Shinye brackets. There is a difference in the amount of torque between the five brands with a torsional angle of 30° (except the 3M and Ormco brackets) and those with a torsional angle of 45°. The composition of the metal and the manufacturing process are the factors that influence the occurrence of bracket slot deformation and the amount of torque. A manufacturing process using metal injection molding (MIM) and metal compositions of AISI 303 and 17-4 PH stainless steel reduce the risk of deformation.

  3. A Deformation Model of TRU Metal Dispersion Fuel Rod for HYPER

    International Nuclear Information System (INIS)

    Lee, Byoung Oon; Hwang, Woan; Park, Won S.

    2002-01-01

    Deformation analysis in fuel rod design is essential to assure adequate fuel performance and integrity under irradiation conditions. An in-reactor performance computer code for a dispersion fuel rod is being developed in the conceptual design stage of blanket fuel for HYPER. In this paper, a mechanistic deformation model was developed and the model was installed into the DIMAC program. The model was based on the elasto-plasticity theory and power-law creep theory. The preliminary deformation calculation results for (TRU-Zr)-Zr dispersion fuel predicted by DIMAC were compared with those of silicide dispersion fuel predicted by DIFAIR. It appeared that the deformation levels for (TRU-Zr)-Zr dispersion fuel were relatively higher than those of silicide fuel. Some experimental tests including in-pile and out-pile experiments are needed for verifying the predictive capability of the DIMAC code. An in-reactor performance analysis computer code for blanket fuel is being developed at the conceptual design stage of blanket fuel for HYPER. In this paper, a mechanistic deformation model was developed and the model was installed into the DIMAC program. The model was based on the elasto-plasticity theory and power-law creep theory. The preliminary deformation calculation results for (TRUZr)- Zr dispersion fuel predicted by DIMAC were compared with those of silicide dispersion fuel predicted by DIFAIR. It appears that the deformation by swelling within fuel meat is very large for both fuels, and the major deformation mechanism at cladding is creep. The swelling strain is almost constant within the fuel meat, and is assumed to be zero in the cladding made of HT9. It is estimated that the deformation levels for (TRU-Zr)-Zr dispersion fuel were relatively higher than those of silicide fuel, and the dispersion fuel performance may be limited by swelling. But the predicted volume change of the (TRU-Zr)-Zr dispersion fuel models is about 6.1% at 30 at.% burnup. The value of cladding

  4. Phase engineering of monolayer transition-metal dichalcogenide through coupled electron doping and lattice deformation

    International Nuclear Information System (INIS)

    Ouyang, Bin; Lan, Guoqiang; Song, Jun; Guo, Yinsheng; Mi, Zetian

    2015-01-01

    First-principles calculations were performed to investigate the phase stability and transition within four monolayer transition-metal dichalcogenide (TMD) systems, i.e., MX 2 (M = Mo or W and X = S or Se) under coupled electron doping and lattice deformation. With the lattice distortion and electron doping density treated as state variables, the energy surfaces of different phases were computed, and the diagrams of energetically preferred phases were constructed. These diagrams assess the competition between different phases and predict conditions of phase transitions for the TMDs considered. The interplay between lattice deformation and electron doping was identified as originating from the deformation induced band shifting and band bending. Based on our findings, a potential design strategy combining an efficient electrolytic gating and a lattice straining to achieve controllable phase engineering in TMD monolayers was demonstrated

  5. Thermoplastic deformation of ferromagnetic CoFe-based bulk metallic glasses

    Science.gov (United States)

    Wu, Chenguang; Hu, Renchao; Man, Qikui; Chang, Chuntao; Wang, Xinmin

    2017-12-01

    The superplastic deformation behavior of the ferromagnetic Co31Fe31Nb8B30 bulk metallic glass (BMG) in the supercooled liquid region was investigated. At a given temperature, the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at high strain rates. The high thermal stability of this glassy alloy system offers an enough processing window to thermoplastic forming (TPF), and the strong processing ability was examined by simple micro-replication experiments. It is demonstrated that the TPF formability on length scales ranging down to nanometers can be achieved in the selected experimental condition. Based on the analysis of deformation behavior, the nearly full density sample (i.e. nearly 100%), was produced from water-atomized glassy powders and consolidated by the hot-pressing technique. The sample exhibits good soft-magnetic and mechanical properties, i.e., low coercive force of 0.43 Oe, high initial permeability of 4100 and high Vickers hardness 1398. These results suggest that the hot-pressing process opens up possibilities for the commercial exploitation of BMGs in engineering applications.

  6. A work-hardening rule for finite elastic-plastic deformation of metals at elevated temperatures

    International Nuclear Information System (INIS)

    Lee, L.H.N.; Horng, J.T.

    1975-01-01

    The paper is concerned with an extension of Prager-Ziegler's kinematic work-hardening rule for infinitesimal elastic-plastic deformation to a work-hardening rule for finite elastic-plastic deformation of a polycrystalline metal. It is shown that the finite work-hardening rule, which accounts for the Bauschinger and temperature effects within certain pressure and temperature ranges, satisfies certain invariant, continuity and thermodynamic requirements. A description of the kinematics of an elastic-plastic body is employed with reference to three separate configurations: initial, current and an intermediate configuration. The intermediate configuration is a conceptual, local configuration obtained by removing the stress and temperature changes in the neighborhood of an element. A rigid body rotation of the intermediate configuration is allowed. Piola-Kirchhoff stresses and Green deformation tensors referred to the initial and intermediate configurations are employed as stress and strain measures. The plastic deformation has been associated with the motion and production of dislocations. It has been observed that the motion of mobile dislocations usually occur in the narrow slip bands in each grain, leaving the basic lattice structure practically intact, so that the macroscopic elastic properties of the material are essentially independent of plastic deformation. Employing this fact and the thermodynamic laws, a simplified elastic stress-strain relationship of the plastically deformed material, which agrees with the results of Naghdi and Trapp, is obtained

  7. 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

  8. Generalized vibrating potential model for collective excitations in spherical, deformed and superdeformed systems: (1) atomic nuclei, (2) metal clusters

    International Nuclear Information System (INIS)

    Nesterenko, V.O.; Kleinig, W.

    1995-01-01

    The self-consistent vibrating potential model (VPM) is extended for description of Eλ collective excitations in atomic nuclei and metal clusters with practically any kind of static deformation. The model is convenient for a qualitative analysis and provides the RPA accuracy of numerical calculations. The VPM is applied to study Eλ giant resonances in spherical metal clusters and deformed and superdeformed nuclei. It is shown that the deformation splitting of superdeformed nuclei results in a very complicated (''jungle-like'') structure of the resonances, which makes the experimental observation of E2 and E3 giant resonances in superdeformed nuclei quite problematic. Calculations of E1 giant resonance in spherical sodium clusters Na 8 , Na 20 and Na 40 are presented, as a test of the VPM in this field. The results are in qualitative agreement with the experimental data. (orig.)

  9. Induction of mouthpart deformities in chironomid larvae exposed to contaminated sediments

    Energy Technology Data Exchange (ETDEWEB)

    Di Veroli, Alessandra [Dipartimento di Biologia Cellulare e Ambientale, Universita degli Studi di Perugia, Via Elce Di Sotto, 06123 Perugia (Italy); Goretti, Enzo [Dipartimento di Biologia Cellulare e Ambientale, Universita degli Studi di Perugia, Via Elce Di Sotto, 06123 Perugia (Italy); Paumen, Miriam Leon; Kraak, Michiel H.S.; Admiraal, Wim [Department of Aquatic Ecology and Ecotoxicology, Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Sciencepark 904, 1098 XH Amsterdam (Netherlands)

    2012-07-15

    The aim of the present study was to improve the cause-effect relationship between toxicant exposure and chironomid mouthpart deformities, by linking induction of mouthpart deformities to contaminated field sediments, metal mixtures and a mutagenic polycyclic aromatic compound metabolite (acridone). Mouthpart deformities in Chironomus riparius larvae were induced by both the heavy metal mixture and by acridone. A clear correlation between metal concentrations in the sediment and deformities incidence was only observed when the contaminated field sediments were left out of the analysis, probably because these natural sediments contained other toxic compounds, which could be responsible for a higher incidence of deformities than predicted by the measured metal concentrations only. The present study clearly improved the cause-effect relationship between toxicant exposure and the induction of mouthpart deformities. It is concluded that the incidence of mouthpart deformities may better reflect the potential toxicity of contaminated sediments than chemical analysis. - Highlights: Black-Right-Pointing-Pointer We tested the induction of deformities in C. riparius in laboratory toxicity experiments. Black-Right-Pointing-Pointer We used field sediments and spiked sediments with heavy metals and mutagenic PAC. Black-Right-Pointing-Pointer Mouthpart deformities were induced both by heavy metal mixtures and by acridone. Black-Right-Pointing-Pointer A correlation between metal concentrations in the sediment and deformities was found. Black-Right-Pointing-Pointer Mouthpart deformities better reflect the toxicity of sediments than chemical analysis. - Mouthpart deformities of Chironomus riparius larvae better reflect the toxicity of sediments than chemical analysis.

  10. Modelling plastic deformation of metals over a wide range of strain rates using irreversible thermodynamics

    International Nuclear Information System (INIS)

    Huang Mingxin; Rivera-Diaz-del-Castillo, Pedro E J; Zwaag, Sybrand van der; Bouaziz, Olivier

    2009-01-01

    Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that there is a transitional strain rate (∼ 10 4 s -1 ) over which the phonon drag effects appear, resulting in a significant increase in the flow stress and the average dislocation density. The model is applied to pure Cu deformed at room temperature and at strain rates ranging from 10 -5 to 10 6 s -1 showing good agreement with experimental results.

  11. Experimental studies on the deformation and rupture of thin metal plates subject to underwater shock wave loading

    Directory of Open Access Journals (Sweden)

    Chen Pengwan

    2015-01-01

    Full Text Available In this paper, the dynamic deformation and rupture of thin metal plates subject to underwater shock wave loading are studied by using high-speed 3D digital image correlation (3D-DIC. An equivalent device consist of a gas gun and a water anvil tube was used to supplying an exponentially decaying pressure in lieu of explosive detonation which acted on the panel specimen. The thin metal plate is clamped on the end of the shock tube by a flange. The deformation and rupture process of the metal plates subject to underwater shock waves are recorded by two high-speed cameras. The shape, displacement fields and strain fields of the metal plates under dynamic loading are obtained by using VIC-3D digital image correlation software. The strain gauges also were used to monitor the structural response on the selected position for comparison. The DIC data and the strain gauges results show a high level of correlation, and 3D-DIC is proven to be an effective method to measure 3D full-field dynamic response of structures under underwater impact loading. The effects of pre-notches on the failure modes of thin circular plate were also discussed.

  12. Compressive deformation of in situ formed bulk metallic glass composites

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, B. [Lujan Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lee, S.Y. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Ustuendag, E. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States)]. E-mail: ustundag@iastate.edu; Kim, C.P. [Liquidmetal Technologies, Lake Forest, CA 92630 (United States); Brown, D.W. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2006-02-15

    A bulk metallic glass matrix composite with dendc second phase precipitates was investigated using neutron diffraction and self-consistent modeling (SCM) to ascertain its deformation mechanisms. The compressive behavior of both the composite and the second phase (in its monolithic form) were investigated. The diffraction data were compared to the predictions of a new SCM resulting in good agreement. For the first time, this model considered both amorphous and crystalline phases and allowed the calculation of single crystal elastic constants from polycrystalline diffraction data. It was shown that the ductile second phase yielded first upon loading, and this was followed by multiple shear band formation in the matrix, a process which enhanced the ductility of the composite.

  13. Compressive deformation of in situ formed bulk metallic glass composites

    International Nuclear Information System (INIS)

    Clausen, B.; Lee, S.Y.; Ustuendag, E.; Kim, C.P.; Brown, D.W.; Bourke, M.A.M.

    2006-01-01

    A bulk metallic glass matrix composite with dendritic second phase precipitates was investigated using neutron diffraction and self-consistent modeling (SCM) to ascertain its deformation mechanisms. The compressive behavior of both the composite and the second phase (in its monolithic form) were investigated. The diffraction data were compared to the predictions of a new SCM resulting in good agreement. For the first time, this model considered both amorphous and crystalline phases and allowed the calculation of single crystal elastic constants from polycrystalline diffraction data. It was shown that the ductile second phase yielded first upon loading, and this was followed by multiple shear band formation in the matrix, a process which enhanced the ductility of the composite

  14. Plastic deformation, residual stress, and crystalline texture measurements for in-process characterization of FCC metal alloys

    International Nuclear Information System (INIS)

    Ruud, C.O.; Jacobs, M.E.; Weedman, S.D.; Snoha, D.J.

    1989-01-01

    This paper describes the results of several on-going investigations on the measurement of plastic deformation, residual stress, and crystalline texture in nickel, copper, and aluminum base alloys by x-ray diffraction techniques. X-ray diffraction techniques have been shown to be effective in the measurement of plastic deformation, residual stress, and crystalline texture in FCC metals, from the breadth, position, and intensity of the x-ray diffraction peaks. The Ruud-Barrett position-sensitive scintillation detector has been demonstrated to be fast, non-contacting, and tolerant of detector to component distance variation -- necessary requirements for cost-effective in-process inspection of materials

  15. 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...

  16. Mouthpart deformities in Chironomidae (Diptera) as bioindicators of heavy metals pollution in Shiroro Lake, Niger State, Nigeria.

    Science.gov (United States)

    Arimoro, Francis O; Auta, Yohanna I; Odume, Oghenekaro N; Keke, Unique N; Mohammed, Adamu Z

    2018-03-01

    In this study, mouthpart deformities in Chironomid larvae (Diptera) were investigated in relation to sediment contamination in the Shiroro Lake in Nigeria. Metals and chironomids were sampled monthly at three stations (A-C) between August 2013 and January 2014. Across the stations, zinc ranged (3.9-75mg/g), manganese (1.29-1.65mg/g), lead (0.00-0.10mg/g), iron (101-168mg/g) and copper (0.13-0.17mg/g). The metal ions did not differ significantly (P > 0.05) between the sampling stations. However, zinc and iron ions were significantly different between the sampling seasons (P < 0.05). Thirteen chironomid species were recorded, with Chironomus sp., Polypedilum sp. and Ablabesmyia sp. dominating the assemblage structure. Mouthpart deformities were significantly higher at Station A compared with Station C, and seasonally significantly higher during dry season compared with wet season. Elevated incidences of deformity were recorded in Chironomus spp larvae as compared to other genera therefore for further studies in this region assessments should be based solely on Chironomus species and ignoring the rest. Strategies need to be developed to reduce the contaminations and the biological effects. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Deformation of Ordinary Chondrite Under Very Reducing Conditons: Implications for Liquid Metal Compositions, HSE Partitioning and Enstatite Chondrites

    Science.gov (United States)

    Rushmer, T.; Corgne, A.

    2008-12-01

    One important method in which to gain insight into metallic liquid compositions and their ability to control HSE (highly siderophile element) distribution is through experimentation. Deformation experiments can additionally provide information into mechanisms and chemical consequences of dynamic liquid metal segregation under a variety of conditions. We report results on metallic liquid HSE compositions and their distribution from a set of deformation experiments on a natural H6 ordinary chondrite, performed under very reducing conditions and a series of phase equilibria experiments focused on HSE partitioning between Si-rich and S-rich Fe molten alloys. The deformation experiments were conducted at temperatures between 925°C and 950°C, at 1.3 GPa confining pressure with a strain rate of 10-4/s. Major element analyses of both silicate and metal phases show that they are considerably reduced and the typically lithophile elements are behaving like siderophiles. Fe-Ni-Si compositions are found in the shear zones produced during the deformation experiment. Metallic compositions also include (Mg,Fe,Ca)S, Fe-Ni-Si, FeP, and Fe-Ni-S quench metal. Silicate phases include forsterite (Fo92-96) and enstatite (En98). Highly siderophile element (HSE) concentrations have been measured in the sulphide ((Fe,Mg,Ca)S) and metal (Fe- Ni-Si) phases by LA-ICPMS and compared with results from an earlier set of experiments on the same material but which were not performed under reducing conditions. The partitioning of the PGE is modified by the changing conditions with elements such as Ir and Os having higher DMetal/Sulphide values under reducing conditions. Partitioning experiments between molten FeS and Ni-, Si-bearing molten Fe were performed at 1.5-5.0 GPa and 1500-1750° to further investigate this observation. The starting material is synthetic, doped with a range of trace and HSE elements. The results confirm the preference of the HSE for the metallic phase with DMetal

  18. Evaluation of Dynamic Deformation Behaviors in Metallic Materials under High Strain-Rates Using Taylor Bar Impact Test

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Kyung Oh; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of)

    2016-09-15

    To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10{sup 4} s{sup -1}. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

  19. 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...

  20. Effect of rolling deformation on the microstructure of bulk Cu60Zr20Ti20 metallic glass and its crystallization

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.

    2006-01-01

    Bulk Cu60Zr20Ti20 metallic glass has been rolled at room temperature (RT) and cryogenic temperature (CIF) up to 97% in thickness reduction, and the dependences of microstructure on the strain and temperature have been investigated. It is revealed that as the deformation proceeds below a critical...... thickness reduction, which is 87% at RT and 89% at CT, only the shear band density and the free-volume content increase, whereas the thermal stability of the deformed glass remains unchanged. Deformation above the critical thickness reduction results in phase separation plus nanocrystallization at RT...

  1. Scaling laws for dislocation microstructures in monotonic and cyclic deformation of fcc metals

    International Nuclear Information System (INIS)

    Kubin, L.P.; Sauzay, M.

    2011-01-01

    This work reviews and critically discusses the current understanding of two scaling laws, which are ubiquitous in the modeling of monotonic plastic deformation in face-centered cubic metals. A compilation of the available data allows extending the domain of application of these scaling laws to cyclic deformation. The strengthening relation tells that the flow stress is proportional to the square root of the average dislocation density, whereas the similitude relation assumes that the flow stress is inversely proportional to the characteristic wavelength of dislocation patterns. The strengthening relation arises from short-range reactions of non-coplanar segments and applies all through the first three stages of the monotonic stress vs. strain curves. The value of the proportionality coefficient is calculated and simulated in good agreement with the bulk of experimental measurements published since the beginning of the 1960's. The physical origin of what is called similitude is not understood and the related coefficient is not predictable. Its value is determined from a review of the experimental literature. The generalization of these scaling laws to cyclic deformation is carried out on the base of a large collection of experimental results on single and polycrystals of various materials and on different microstructures. Surprisingly, for persistent slip bands (PSBs), both the strengthening and similitude coefficients appear to be more than two times smaller than the corresponding monotonic values, whereas their ratio is the same as in monotonic deformation. The similitude relation is also checked in cell structures and in labyrinth structures. Under low cyclic stresses, the strengthening coefficient is found even lower than in PSBs. A tentative explanation is proposed for the differences observed between cyclic and monotonic deformation. Finally, the influence of cross-slip on the temperature dependence of the saturation stress of PSBs is discussed in some detail

  2. Symmetry-induced deformation and reconstructive phase transformation in metal-oxide interface: the Fe (001) example

    International Nuclear Information System (INIS)

    Lahoche, L.; Universite de Technologie de Compiegne; Lorman, V.; Roelandt, J.M.; Rochal, S.B.

    1996-01-01

    A model is proposed for the structural transformation and corresponding induced deformation in physical three-dimensional interface of the metal-oxide system. The thermodynamical and elastic state of the system is described by the Landau-Ginzbourg free energy. Calculated theoretical phase diagram shows several different types of isothermal growth processes. The model is applied to the case of the oxidation of the (001) Fe surface. (orig.)

  3. High-temperature deformation and processing maps of Zr-4 metal matrix with dispersed coated surrogate nuclear fuel particles

    Science.gov (United States)

    Chen, Jing; Liu, Huiqun; Zhang, Ruiqian; Li, Gang; Yi, Danqing; Lin, Gaoyong; Guo, Zhen; Liu, Shaoqiang

    2018-06-01

    High-temperature compression deformation of a Zr-4 metal matrix with dispersed coated surrogate nuclear fuel particles was investigated at 750 °C-950 °C with a strain rate of 0.01-1.0 s-1 and height reduction of 20%. Scanning electron microscopy was utilized to investigate the influence of the deformation conditions on the microstructure of the composite and damage to the coated surrogate fuel particles. The results indicated that the flow stress of the composite increased with increasing strain rate and decreasing temperature. The true stress-strain curves showed obvious serrated oscillation characteristics. There were stable deformation ranges at the initial deformation stage with low true strain at strain rate 0.01 s-1 for all measured temperatures. Additionally, the coating on the surface of the surrogate nuclear fuel particles was damaged when the Zr-4 matrix was deformed at conditions of high strain rate and low temperature. The deformation stability was obtained from the processing maps and microstructural characterization. The high-temperature deformation activation energy was 354.22, 407.68, and 433.81 kJ/mol at true strains of 0.02, 0.08, and 0.15, respectively. The optimum deformation parameters for the composite were 900-950 °C and 0.01 s-1. These results are expected to provide guidance for subsequent determination of possible hot working processes for this composite.

  4. Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

    Science.gov (United States)

    Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

    2015-01-01

    Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

  5. EBSD-based techniques for characterization of microstructural restoration processes during annealing of metals deformed to large plastic strains

    DEFF Research Database (Denmark)

    Godfrey, A.; Mishin, Oleg; Yu, Tianbo

    2012-01-01

    Some methods for quantitative characterization of the microstructures deformed to large plastic strains both before and after annealing are discussed and illustrated using examples of samples after equal channel angular extrusion and cold-rolling. It is emphasized that the microstructures...... in such deformed samples exhibit a heterogeneity in the microstructural refinement by high angle boundaries. Based on this, a new parameter describing the fraction of regions containing predominantly low angle boundaries is introduced. This parameter has some advantages over the simpler high angle boundary...... on mode of the distribution of dislocation cell sizes is outlined, and it is demonstrated how this parameter can be used to investigate the uniformity, or otherwise, of the restoration processes occurring during annealing of metals deformed to large plastic strains. © (2012) Trans Tech Publications...

  6. Deformation aspects of time dependent fracture

    International Nuclear Information System (INIS)

    Li, C.Y.; Turner, A.P.L.; Diercks, D.R.; Laird, C.; Langdon, T.G.; Nix, W.D.; Swindeman, R.; Wolfer, W.G.; Woodford, D.A.

    1979-01-01

    For all metallic materials, particularly at elevated temperatures, deformation plays an important role in fracture. On the macro-continuum level, the inelastic deformation behavior of the material determines how stress is distributed in the body and thus determines the driving force for fracture. At the micro-continuum level, inelastic deformation alters the elastic stress singularity at the crack tip and so determines the local environment in which crack advance takes place. At the microscopic and mechanistic level, there are many possibilities for the mechanisms of deformation to be related to those for crack initiation and growth. At elevated temperatures, inelastic deformation in metallic systems is time dependent so that the distribution of stress in a body will vary with time, affecting conditions for crack initiation and propagation. Creep deformation can reduce the tendency for fracture by relaxing the stresses at geometric stress concentrations. It can also, under suitable constraints, cause a concentration of stresses at specific loading points as a result of relaxation elsewhere in the body. A combination of deformation and unequal heating, as in welding, can generate large residual stress which cannot be predicted from the external loads on the body. Acceleration of deformation by raising the temperature can be an effective way to relieve such residual stresses

  7. Status of design code work for metallic high temperature components

    International Nuclear Information System (INIS)

    Bieniussa, K.; Seehafer, H.J.; Over, H.H.; Hughes, P.

    1984-01-01

    The mechanical components of high temperature gas-cooled reactors, HTGR, are exposed to temperatures up to about 1000 deg. C and this in a more or less corrosive gas environment. Under these conditions metallic structural materials show a time-dependent structural behavior. Furthermore changes in the structure of the material and loss of material in the surface can result. The structural material of the components will be stressed originating from load-controlled quantities, for example pressure or dead weight, and/or deformation-controlled quantities, for example thermal expansion or temperature distribution, and thus it can suffer rowing permanent strains and deformations and an exhaustion of the material (damage) both followed by failure. To avoid a failure of the components the design requires the consideration of the following structural failure modes: ductile rupture due to short-term loadings; creep rupture due to long-term loadings; reep-fatigue failure due to cyclic loadings excessive strains due to incremental deformation or creep ratcheting; loss of function due to excessive deformations; loss of stability due to short-term loadings; loss of stability due to long-term loadings; environmentally caused material failure (excessive corrosion); fast fracture due to instable crack growth

  8. Deformation microstructures

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Hughes, D.A.

    2004-01-01

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...... of the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10...

  9. Acoustic softening in metals during ultrasonic assisted deformation via CP-FEM

    KAUST Repository

    Siddiq, Amir

    2011-01-01

    In this paper, a phenomenological crystal plasticity model is modified to account for acoustic (ultrasonic) softening effects based on the level of ultrasonic intensity supplied to single and polycrystalline metals. The material parameters are identified using the inverse modeling approach by interfacing the crystal plasticity model with an optimization tool. The proposed model is validated and verified by comparing the microstructure evolution with experimental EBSD results reported in the literature. The model is able to capture the ultrasonic softening effect and the results show that as the ultrasonic intensity increases, the plastic deformation also increases. Differences in the stress-strain response are explained based on the slip system orientation tensor (Schmidt factors) which depends upon the crystal orientation. © 2010 Elsevier B.V. All rights reserved.

  10. Constitutive equations for energy balance evaluation in metals under inelastic deformation

    Science.gov (United States)

    Kostina, A.; Plekhov, O.; Venkatraman, B.

    2017-12-01

    The work is devoted to the development of constitutive equations for energy balance evaluation in plastically deformed metals. The evolution of the defect system is described by a previously obtained model based on the Boltzmann-Gibbs statistics. In the framework of this model, a collective behavior of mesodefect ensembles is taken into account by the introduction of an internal variable representing additional structural strain. This parameter enables the partition of plastic work into dissipated heat and stored energy. The proposed model is applied to energy balance calculation in a Ti-1Al-1Mn specimen subjected to cyclic loading. Simulation results have shown that the model is able to describe an upward trend in the stored energy value with the increase in the load ratio.

  11. High performance permanent magnet materials

    International Nuclear Information System (INIS)

    Sankar, S.G.; Herbst, J.F.; Koon, N.C.

    1987-01-01

    This book contains 25 selections. Some of the titles are: Initial magnetization behavior of rapidly quenched neodymium-iron-boron magnets; Optimization of liquid dynamic compaction for Fe-Nd-B magnet alloys; Misch-metal and/or aluminum substitutions in Nd-Fe-B permanent magnets; and NdFeB magnets with improved temperature characteristics

  12. Analysis of Deformation and Failure Behaviors of TIG Welded Dissimilar Metal Joints Using Miniature Tensile Specimens

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ji-Hwan; Jahanzeb, Nabeel; Kim, Min-Seong; Hwang, Ji-Hyun; Choi, Shi-Hoon [Sunchon National University, Suncheon (Korea, Republic of)

    2017-02-15

    The deformation and failure behaviors of dissimilar metal joints between SS400 steel and STS316L steel were investigated. The dissimilar metal joints were fabricated using the tungsten inert gas (TIG) welding process with STS309 steel as a filler metal. The microstructures of the dissimilar metal joints were investigated using an optical microscope and EBSD technique. The mechanical properties of the base metal (BM), heat affected zone (HAZ) and weld metal (WM) were measured using a micro-hardness and micro-tension tester combined with the digital image correlation (DIC) technique. The HAZ of the STS316L steel exhibited the highest micro-hardness value, and yield/tensile strengths, while the BM of the SS440 steel exhibited the lowest micro-hardness value and yield /tensile strengths. The grain size refinement in the HAZ of SS400 steel induced an enhancement of micro-hardness value and yield/tensile strengths compared to the BM of the SS400 steel. The WM, which consists of primary δ-ferrite and a matrix of austenite phase, exhibited relatively a high micro-hardness value, yield /tensile strengths and elongation compared to the BM and HAZ of the SS400 steel.

  13. Effect of contact deformation on contact electrification: a first-principles calculation

    International Nuclear Information System (INIS)

    Zhang, Yuanyue; Shao, Tianmin

    2013-01-01

    The effect of contact deformation on contact electrification of metallic materials was studied by the first-principles method. The results of charge population and the densities of states of the deformed contact models demonstrated that the magnitude of the transferred charge increased with deformation. The mechanism of the effect of deformation was investigated by studying the electronic properties of the deformed surface slabs. The results showed that crystal deformation led to a change in the electrostatic potential of the metal, where the number of nearly free electrons and unoccupied orbitals for charge transfer increased, and their energy barrier decreased. (paper)

  14. Permanent magnet with MgB{sub 2} bulk superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Akiyasu, E-mail: yamamoto@appchem.t.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ishihara, Atsushi; Tomita, Masaru [Railway Technical Research Institute, 2-8-38 Hikari, Kokubunji, Tokyo 185-8540 (Japan); Kishio, Kohji [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2014-07-21

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

  15. Particle deformation during stirred media milling

    Science.gov (United States)

    Hamey, Rhye Garrett

    Production of high aspect ratio metal flakes is an important part of the paint and coating industry. The United States Army also uses high aspect ratio metal flakes of a specific dimension in obscurant clouds to attenuate infrared radiation. The most common method for their production is by milling a metal powder. Ductile metal particles are initially flattened in the process increasing the aspect ratio. As the process continues, coldwelding of metal flakes can take place increasing the particle size and decreasing the aspect ratio. Extended milling times may also result in fracture leading to a further decrease in the particle size and aspect ratio. Both the coldwelding of the particles and the breakage of the particles are ultimately detrimental to the materials performance. This study utilized characterization techniques, such as, light scattering and image analysis to determine the change in particle size as a function of milling time and parameters. This study proved that a fundamental relationship between the milling parameters and particle deformation could be established by using Hertz's theory to calculate the stress acting on the aluminum particles. The study also demonstrated a method by which milling efficiency could be calculated, based on the amount of energy required to cause particle deformation. The study found that the particle deformation process could be an energy efficient process at short milling times with milling efficiency as high as 80%. Finally, statistical design of experiment was used to obtain a model that related particle deformation to milling parameters, such as, rotation rate and milling media size.

  16. Permanent magnet material and process for producing the same

    International Nuclear Information System (INIS)

    Yoneyama, T.; Hori, T.; Ohima, T.

    1978-01-01

    This invention relates to an improvement of a permanent magnet material consisting, apart from impurities, of intermetallic compounds of the general formula of R 2 Co 17 , wherein the R component is at least one rare earth metal excluding radioactive elements and the Co component is cobalt. A suitable process to produce the permanent magnet material according to the invention is described. (U.K.)

  17. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    International Nuclear Information System (INIS)

    Trinkaus, H.; Singh, B.N.

    2008-04-01

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly observed in PITs. An increase in the pre-yield dose results in an increase in the level of hardening over the whole test periods and a decrease in the uniform elongation suggesting that the materials 'remember' the impact of the pre-yield damage level. These features are modelled in terms of the decoration of dislocations with glissile dislocation loops. During pre-yield irradiation, dislocation decoration is due to the one-dimensional (1D) diffusion of cascade induced self-interstitial (SIA) clusters and their trapping in the stress field of the static grown-in dislocations. During post-yield irradiation and deformation, moving dislocations are decorated by the sweeping of matrix loops. The interaction of dislocations with loops and between loops is discussed as a function of the relevant parameters. On this basis, the kinetics of decoration is treated in terms of fluxes of loops to and reactions with each other in a conceived 2D space of decoration. In this space, loop coalescence, alignment and mutual blocking reactions are characterised by appropriate reaction cross sections. In the kinetic equations for 'dynamic decoration' under deformation, the evolution of the dislocation density is taken into account. Simple solutions of the kinetic equations are discussed. The apparent memory of the system for the pre-yield dose is identified as the result of simultaneous and closely parallel transient evolutions of the cascade damage and the dislocations up to the end of the IRTs. The contributions of dislocation decoration to yield and flow stresses are attributed to the interaction of dislocations with aligned loops temporarily or permanently immobilized by other loops or

  18. 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

  19. 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

  20. Nucleation reactions during deformation and crystallization of metallic glass

    International Nuclear Information System (INIS)

    Perepezko, J.H.; Imhoff, S.D.; Chen, M.W.; Gonzalez, S.; Inoue, A.

    2012-01-01

    Highlights: ► New approach to the examination and analysis of shear band nucleation. ► Discovery of multiple shear band nucleation sites. ► Identification of a method of using transient kinetic behavior to provide a more realistic evaluation of the diffusivity that is relevant to nucleation. - Abstract: Nucleation reactions play a central role in the synthesis of both bulk metallic glasses and nanostructured materials. For nanostructured materials it is necessary to promote a high nucleation density without significant growth or coarsening. Beyond crystallization reactions nucleation of shear bands is critical for promoting a homogeneous flow and useful ductility for structural applications of bulk metallic glass. The study and analysis of nucleation reactions for these different situations requires a consideration of the stochastic nature of nucleation, the influence of heterogeneous sites, and the controlling transport properties. For shear band nucleation, the stochastic nature can be effectively probed by instrumented nanoindentation tests. The analysis of a statistically significant number of measurements of the first pop-in shear band nucleation events reveals at least two main nucleation sites. In nanostructured composites, the initial nucleation stage is influenced by transient effects as reflected in the delay time prior to steady state nucleation and by heterogeneous nucleation sites that are related to medium range order regions in Al-base amorphous alloys. Moreover, the early growth characteristics are linked to the maximum achievable particle density. The new developments and insight on the fundamental understanding of nanostructure reaction mechanisms offer valuable guidance for control of nanoscale microstructures and for promoting ductile deformation behavior.

  1. Static devices with new permanent magnets

    International Nuclear Information System (INIS)

    Chavanne, J.; Laforest, J.; Pauthenet, R.

    1987-01-01

    The high remanence and coercivity of the new permanent magnet materials are of special interest in the static applications. High ordering temperature and are uniaxial anisotropy at the origin of their good permanent magnet properties are obtained in rare earth-transition metal compounds. Binary SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ and ternary Nd/sub 2/Fe/sub 14/B compounds are the basis materials of the best permanent magnets. new concepts of calculations of static devices with these magnets can be applied: the magnetization can be considered as ridig, the density of the surface Amperian current is constant, the relative permeability is approximately 1 and the induction calculations are linear. Examples of hexapoles with Sm-Co and NdFeB magnets are described and the performances are compared. The problems of temperature behavior and corrosion resistance are underlined

  2. 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

  3. Non-proportional deformation paths for sheet metal: experiments and models

    NARCIS (Netherlands)

    van den Boogaard, Antonius H.; van Riel, M.; Hora, P.

    2009-01-01

    For mild steel, after significant plastic deformation in one direction, a subsequent deformation in an orthogonal direction shows a typical stress overshoot compared to monotonic deformation. This phenomenon is investigated experimentally and numerically on a DC06 material. Two models that

  4. 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...

  5. Bed-Deformation Experiments Beneath a Temperate Glacier

    Science.gov (United States)

    Iverson, N. R.; Hooyer, T. S.; Fischer, U. H.; Cohen, D.; Jackson, M.; Moore, P. L.; Lappegard, G.; Kohler, J.

    2002-12-01

    Fast flow of glaciers and genesis of glacial landforms are commonly attributed to shear deformation of subglacial sediment. Although models of this process abound, data gathered subglacially on the kinematics and mechanics of such deformation are difficult to interpret. Major difficulties stem from the necessity of either measuring deformation near glacier margins, where conditions may be abnormal, or at the bottoms of boreholes, where the scope of instrumentation is limited, drilling disturbs sediment, and local boundary conditions are poorly known. A different approach is possible at the Svartisen Subglacial Laboratory, where tunnels melted in the ice provide temporary human access to the bed of Engabreen, a temperate outlet glacier of the Svartisen Ice Cap in Norway. A trough (2 m x 1.5 m x 0.5 m deep) was blasted in the rock bed, where the glacier is 220 m thick and sliding at 0.1-0.2 m/d. During two spring field seasons, this trough was filled with 2.5 tons of simulated till. Instruments in the till recorded shear (tiltmeters), volume change, total normal stress, and pore-water pressure as ice moved across the till surface. Pore pressure was brought to near the total normal stress by feeding water to the base of the till with a high-pressure pump, operated in a rock tunnel 4 m below the bed surface. Results illustrate some fundamental aspects of bed deformation. Permanent shear deformation requires low effective normal stress and hence high pore-water pressure, owing to the frictional nature of till. Shear strain generally increases upward in the bed toward the glacier sole, consistent with previous measurements beneath thinner ice at glacier margins. At low effective normal stresses, ice sometimes decouples from underlying till. Overall, bed deformation accounts for 10-35 % of basal motion, although this range excludes shear in the uppermost 0.05 m of till where shear was not measured. Pump tests with durations ranging from seconds to hours highlight the need

  6. New permanent magnets

    Science.gov (United States)

    Müller, K.-H.; Krabbes, G.; Fink, J.; Gruß, S.; Kirchner, A.; Fuchs, G.; Schultz, L.

    2001-05-01

    Permanent magnets play an important role and are widely spread in daily-life applications. Due to their very low costs, large availability of the row materials and their high chemical stability, hard ferrites are still dominant in the permanent magnet market although their relatively poor magnetic properties are a distinct disadvantage. Today's high-performance magnets are mostly made from Nd 2Fe 14B. The aim of research is to combine the large spontaneous magnetization of 3d metals with strong anisotropy fields known from rare-earth transition-metal compounds and, at the same time, to maintain a high value of the Curie temperature. However, the number of iron-rich rare-earth intermetallics is very limited and, consequently, not much success can be noted in this field for the last 10 years. One alternative concept is to use magnetic fields trapped in type II superconductors where much higher fields can be achieved compared to conventional rare-earth magnets. Very recently, we obtained a trapped field as high as 14.4 T in a melt-textured YBCO bulk sample of a few centimeters in diameter. This is the highest value ever achieved in a bulk superconductor. The trapped field of a superconductor is not governed by the Laplace equation and, therefore, levitation works without any additional (active) stabilization. The disadvantage of these magnets is their low working temperature (of liquid nitrogen and below).

  7. Influence of deformation rate on plasticity of metals under pressure

    International Nuclear Information System (INIS)

    Churbaev, R.V.; Dobromyslov, A.V.; Kolmogorov, V.L.; Taluts, G.G.

    1990-01-01

    Change of polycrystalline molybdenum (BCC) and titanium (HCP) plasticity under pressure depeding on the deformation rate at the room temperature is studied. It is shown that the reduction of molybdenum and titanium deformation rate leads to a substantial growth of their plastic properties with the effect being increased with pressure growth. Production of several necks testifying to the transition to a superplastic state is observed at high pressures and low deformation rates. A functional dependence of plasticity change on the deformation rate under pressure is ascertained

  8. 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

  9. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Trinkaus, H. [Institut fuer Festkoerperforschung, Forschungszentrum Juelich (Germany); Singh, B.N. [Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Materials Research Dept., Roskilde (Denmark)

    2008-04-15

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly observed in PITs. An increase in the pre-yield dose results in an increase in the level of hardening over the whole test periods and a decrease in the uniform elongation suggesting that the materials 'remember' the impact of the pre-yield damage level. These features are modelled in terms of the decoration of dislocations with glissile dislocation loops. During pre-yield irradiation, dislocation decoration is due to the one-dimensional (1D) diffusion of cascade induced self-interstitial (SIA) clusters and their trapping in the stress field of the static grown-in dislocations. During post-yield irradiation and deformation, moving dislocations are decorated by the sweeping of matrix loops. The interaction of dislocations with loops and between loops is discussed as a function of the relevant parameters. On this basis, the kinetics of decoration is treated in terms of fluxes of loops to and reactions with each other in a conceived 2D space of decoration. In this space, loop coalescence, alignment and mutual blocking reactions are characterised by appropriate reaction cross sections. In the kinetic equations for 'dynamic decoration' under deformation, the evolution of the dislocation density is taken into account. Simple solutions of the kinetic equations are discussed. The apparent memory of the system for the pre-yield dose is identified as the result of simultaneous and closely parallel transient evolutions of the cascade damage and the dislocations up to the end of the IRTs. The contributions of dislocation decoration to yield and flow stresses are attributed to the interaction of dislocations with aligned loops temporarily or permanently immobilized

  10. Interactions of reactor helium and simulating gas mixtures with high-temperature metals with particular regard to simultaneous deformation

    International Nuclear Information System (INIS)

    Berchtold, L.

    1983-01-01

    For the observation of multicomponent alloys (Inconel 617 and 713LC, chroman (Ni20Cr), vacromium (Ni20Cr+Si), TZM) in multicomponent HTR atmospheres (HHT search gas), interaction between gases and metals was studied, both in theoretical descriptions and experimentally. From the experimental viewpoint, gradual simplification employs, on the one hand, tests effected in undiluted atmospheres with exclusively oxidizing or carburizing properties; on the other hand, more simple alloys and pure metals are applied specifically in the helium atmosphere. For an evaluation of the materials, it is maintained that in a strongly oxidizing (H 2 O-rich) atmosphere, e.g. in HHT search gas, materials with sufficient chrome content (e.g. 20% Cr in Ni alloys such as IN 617) offer favourable conditions for an almost complete interruption of carburizing reactions. In that case, the maintenance of the shielding effect of coating during rapid deformation and a tendency to planar delamination during deformation, which becomes stronger as the layer thickness increases, appear to be critical. Concentrations of oxide-forming agents stronger than chromium offer disadvantages rather than advantages. Owing to its tendency to flake off as the covering oxide SiO 2 or as part of a cover layer, silicon may more than destroy the light advantage of a slowed down process of carbon diffusion. The cast alloy IN 713LC shows a deep-reaching carburation in HHT search gas, both with and without deformation. No deep-reaching corrosive damage is noticeable on the molybdenum alloy TZM. (orig./MM) [de

  11. Changes to the morphology, structure and properties as a consequence of polyethylene working in a polymer-metal kinematic pair

    International Nuclear Information System (INIS)

    Maszybrocka, Joanna; Cybo, Jerzy; Cwajna, Jan

    2009-01-01

    A change is presented of the orientation of lamellar structure, degree of crystallinity, the degree of the spatial arrangement of the structure, micromechanical properties, and the surface morphology and thickness of a plastically deformed upper layer. These changes are the effect of work in a polymer-metal kinematic pair, which have occurred as a result of plastic deformation of polyethylene during its service. It has been shown that, as a result of selecting proper parameters of UHMW polyethylene via the initial draft and electron-beam irradiation, such a structure of the polymer can be obtained, which will enable the above-mentioned changes in morphology and structure to take place during service. This in turn, will allow a reduction of the susceptibility of the polymer to permanent deformation by 3-6 times, and its wear by more than 5 times, compared to the initial material.

  12. Size effects of nano-spaced basal stacking faults on the strength and deformation mechanisms of nanocrystalline pure hcp metals

    Science.gov (United States)

    Wang, Wen; Jiang, Ping; Yuan, Fuping; Wu, Xiaolei

    2018-05-01

    The size effects of nano-spaced basal stacking faults (SFs) on the tensile strength and deformation mechanisms of nanocrystalline pure cobalt and magnesium have been investigated by a series of large-scale 2D columnar and 3D molecular dynamics simulations. Unlike the strengthening effect of basal SFs on Mg alloys, the nano-spaced basal SFs are observed to have no strengthening effect on the nanocrystalline pure cobalt and magnesium from MD simulations. These observations could be attributed to the following two reasons: (i) Lots of new basal SFs are formed before (for cobalt) or simultaneously with (for magnesium) the other deformation mechanisms (i.e. the formation of twins and the edge dislocations) during the tensile deformation; (ii) In hcp alloys, the segregation of alloy elements and impurities at typical interfaces, such as SFs, can stablilise them for enhancing the interactions with dislocation and thus elevating the strength. Without such segregation in pure hcp metals, the edge dislocations can cut through the basal SFs although the interactions between the dislocations and the pre-existing SFs/newly formed SFs are observed. The nano-spaced basal SFs are also found to have no restriction effect on the formation of deformation twins.

  13. Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB2 and IrB2

    Science.gov (United States)

    Zhang, R. F.; Legut, D.; Wen, X. D.; Veprek, S.; Rajan, K.; Lookman, T.; Mao, H. K.; Zhao, Y. S.

    2014-09-01

    The energetically most stable orthorhombic structure of OsB2 and IrB2 is dynamically stable for OsB2 but unstable for IrB2. Both diborides have substantially lower shear strength in their easy slip systems than their metal counterparts. This is attributed to an easy sliding facilitated by out-of-plane weakening of metallic Os-Os bonds in OsB2 and by an in-plane bond splitting instability in IrB2. A much higher shear resistance of Os-B and B-B bonds than Os-Os ones is found, suggesting that the strengthened Os-B and B-B bonds are responsible for hardness enhancement in OsB2. In contrast, an in-plane electronic instability in IrB2 limits its strength. The electronic structure of deformed diborides suggests that the electronic instabilities of 5d orbitals are their origin of different bond deformation paths. Neither IrB2 nor OsB2 can be intrinsically superhard.

  14. Plastic deformation of YBa2Cu3O7-x superconductor compound

    International Nuclear Information System (INIS)

    Torres V, G.; Moreno, J.E.

    1988-01-01

    The high temperature superconductor YBa 2 Cu 3 O 7-x shown a brittle behavior when deformed under ambient conditions. If a hydrostatic state of stress is imposed with a metal matrix, it is possible to induce exttended plastic deformations as a great as 200% were achieved using this method without loosing the superconductivity in the ceramic. The observed deformations mechanisms are similar to those observed in the superplastic metals and the boundary ceramic metal matrix was found to be highly coherent. This method opens a new technique that can be apllied in the manufacture of superconductor wire. (author) [pt

  15. Water surface deformation in strong electrical fields and its influence on electrical breakdown in a metal pin-water electrode system

    International Nuclear Information System (INIS)

    Bruggeman, Peter; Graham, Leigh; Groote, Joris de; Vierendeels, Jan; Leys, Christophe

    2007-01-01

    Electrical breakdown and water surface deformation in a metal pin-water electrode system with dc applied voltages is studied for small inter-electrode distances (2-12 mm). The radius of curvature of the metal pin is 0.5 cm to exclude corona before breakdown at these small inter-electrode spacings. Calculations of the water surface deformation as a function of the applied voltage and initial inter-electrode spacing are compared with measurements of the water elevation. For distances smaller than 7 mm the calculated stability limit of the water surface corresponds with the experimentally obtained breakdown voltage. It is proved with fast CCD images and calculations of the electrical field distribution that the water surface instability triggers the electrical breakdown in this case. The images show that at breakdown the water surface has a Taylor cone-like shape. At inter-electrode distance of 7 mm and larger the breakdown voltage is well below the water stability limit and the conductive channel at breakdown is formed between the pin electrode and the static water surface. Both cases are discussed and compared

  16. Non-proportional deformation paths for sheet metal: experiments and models

    OpenAIRE

    van den Boogaard, Antonius H.; van Riel, M.; Hora, P.

    2009-01-01

    For mild steel, after significant plastic deformation in one direction, a subsequent deformation in an orthogonal direction shows a typical stress overshoot compared to monotonic deformation. This phenomenon is investigated experimentally and numerically on a DC06 material. Two models that incorporate the observed overshoot are compared. In the Teodosiu-Hu model, pre-strain influences the rate of kinematic hardening by a rather complex set of evolution equations. The shape of the elastic doma...

  17. Dynamics of viscoplastic deformation in amorphous solids

    International Nuclear Information System (INIS)

    Falk, M.L.; Langer, J.S.

    1998-01-01

    We propose a dynamical theory of low-temperature shear deformation in amorphous solids. Our analysis is based on molecular-dynamics simulations of a two-dimensional, two-component noncrystalline system. These numerical simulations reveal behavior typical of metallic glasses and other viscoplastic materials, specifically, reversible elastic deformation at small applied stresses, irreversible plastic deformation at larger stresses, a stress threshold above which unbounded plastic flow occurs, and a strong dependence of the state of the system on the history of past deformations. Microscopic observations suggest that a dynamically complete description of the macroscopic state of this deforming body requires specifying, in addition to stress and strain, certain average features of a population of two-state shear transformation zones. Our introduction of these state variables into the constitutive equations for this system is an extension of earlier models of creep in metallic glasses. In the treatment presented here, we specialize to temperatures far below the glass transition and postulate that irreversible motions are governed by local entropic fluctuations in the volumes of the transformation zones. In most respects, our theory is in good quantitative agreement with the rich variety of phenomena seen in the simulations. copyright 1998 The American Physical Society

  18. Texture evolution maps for upset deformation of body-centered cubic metals

    International Nuclear Information System (INIS)

    Lee, Myoung-Gyu; Wang, Jue; Anderson, Peter M.

    2007-01-01

    Texture evolution maps are used as a tool to visualize texture development during upset deformation in body-centered cubic metals. These maps reveal initial grain orientations that tend toward normal direction (ND)|| versus ND|| . To produce these maps, a finite element analysis (FEA) with a rate-dependent crystal plasticity constitutive relation for tantalum is used. A reference case having zero workpiece/die friction shows that ∼64% of randomly oriented grains rotate toward ND|| and ∼36% rotate toward ND|| . The maps show well-established trends that increasing strain rate sensitivity and decreasing latent-to-self hardening ratio reduce both and percentages, leading to more diffuse textures. Reducing operative slip systems from both {1 1 0}/ and {1 1 2}/ to just {1 1 0}/ has a mixed effect: it increases the percentage but decreases the percentage. Reducing the number of slip systems and increasing the number of FEA integration points per grain strengthen - texture bands that are observed experimentally

  19. Deformation Parameters and Fatigue of the Recycled Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Šrámek Juraj

    2015-12-01

    Full Text Available The deformational properties of asphalt mixtures measured by dynamic methods and fatigue allow a design the road to suit the expected traffic load. Quality of mixtures is also expressed by the resistance to permanent deformation. Complex modulus of stiffness and fatigue can reliably characterize the proposed mixture of asphalt pavement. The complex modulus (E* measurement of asphalt mixtures are carried out in laboratory of Department of Construction Management at University of Žilina by two-point bending test method on trapezoid-shaped samples. Today, the fatigue is verified on trapezoid-shaped samples and is assessed by proportional strain at 1 million cycles (ε6. The test equipment and software is used to evaluate fatigue and deformation characteristics.

  20. Deformation During Friction Stir Welding

    Science.gov (United States)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  1. Design and Fabrication of a Large-Stroke Deformable Mirror Using a Gear-Shape Ionic-Conductive Polymer Metal Composite

    Directory of Open Access Journals (Sweden)

    Guo-Dung John Su

    2012-08-01

    Full Text Available Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young’s modulus and Poisson’s ratio. We divided an ion exchange polymer, also known as Nafion®, into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

  2. Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

    International Nuclear Information System (INIS)

    Gou, Dezhi; Kuang, Xiaoyu; Gao, Yufeng; Huo, Dongming

    2015-01-01

    In this paper, we systematically investigate the electronic structure for the 2 Σ + ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained

  3. Simulations of Recrystallization in Metals

    DEFF Research Database (Denmark)

    Godiksen, Rasmus Brauner

    2007-01-01

    structures in the deformed metal due to local effects: Inhomogeneous boundary morphologies and dislocation-structure-dependent migration rates are observed. The effects that the dislocation structures have must be taken into account in order to create realistic recrystallization models, and through......The growth of new near-perfect grains during recrystallization of deformed metals is governed by the migration of the grain boundaries surrounding the new grains. The grain boundaries migrate through the deformed metal driven by the excess energy of the dislocation structures created during...... deformation. Recently, it has been found that recrystallization is far more inhomogeneous than previously thought. The purpose of this PhD-project is to study recrystallization by computer simulations with special focus on inhomogeneous growth. Two types of simulations have been employed: geometric...

  4. Present day crustal deformation of the Italian peninsula observed by permanent GPS stations

    Science.gov (United States)

    Devoti, Roberto; Esposito, Alessandra; Galvani, Alessandro; Pietrantonio, Grazia; Pisani, Anna Rita; Riguzzi, Federica; Sepe, Vincenzo

    2010-05-01

    Italian penisula is a crucial area in the Mediterranean region to understand the active deformation processes along Nubia-Eurasia plate boundary. We present the velocity and strain rate fields of the Italian area derived from continuous GPS observations of more than 300 sites in the time span 1998-2009. The GPS networks were installed and managed by different institutions and for different purposes; altogether they cover the whole country with a mean inter-site distance of about 50 km and provide a valuable source of data to map the present day kinematics of the region. The data processing is performed by BERNESE software ver. 5.0, adopting a distributed session approach, with more than 10 clusters, sharing common stations, each of them consisting of about 40 stations. Daily loosely constrained solutions are routinely produced for each cluster and then combined into a network daily loose solution. Subsequently daily solutions are transformed on the chosen reference frame and the constrained time series are fitted using the complete covariance matrix, simultaneously estimating site velocities together with annual signals and sporadic offsets at epochs of instrumental changes. In this work we provide an updated detailed picture of the horizontal and vertical kinematics (velocity maps) and deformation pattern (strain rate maps) of the Italian area. The results show several crustal domains characterized by different velocity rates and styles of deformation.

  5. Reliability of Structural Systems with regard to Permanent Displacements

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1991-01-01

    approach - a differential equation approach - a superposition approach - the simple method These three approaches are described in Sørensen & Thoft-Christensen [5], Sørensen et al. [6] and Sørensen & Thoft-Christensen [7]. It is assumed that the structural system can be modelled by a multi-linear elastic......In this paper the problem of estimating the accumulated permanent displacements of an offshore platform during one storm is considered. For dynamically sensitive structural systems subjected to wave loads this problem is generally very difficult. However, for dynamic insensitive systems some...... methods/experience related to permanent deformations are described in Grinda et al. [1] and Papadrakakis & Loukakis [2]. For general dynamic systems modelled by one-degree-of-freedom (and two-degrees-of freedom) systems a number of methods exist, see e.g. Nielsen et al. [3] and Toro & Cornell [4]. However...

  6. Half-metallic zinc-blende pnictides in real environments

    International Nuclear Information System (INIS)

    Shi Lijie; Liu Banggui

    2005-01-01

    The structural stability of half-metallic zinc-blende pnictides and the robustness of their half-metallic ferromagnetism in the presence of tetragonal and orthorhombic crystalline deformations are studied using a full-potential linear augmented plane wave method within the density-functional theory. The total energies of zinc-blende MnAs, CrAs, and CrSb are proved to increase with deformation increase, in contrast to those of other zinc-blende half-metallic pnictides, and therefore these three are stable against the deformations but the others are not. This is consistent with the experimental fact that only these three have been fabricated. On the other hand, the half-metallic ferromagnetism of the latter two is proved to be robust enough to survive large crystal deformations. This implies that half-metallic ferromagnetism may be achieved experimentally even in substantially deformed zinc-blende ultrathin films or layers of CrAs and CrSb in real environments

  7. Effect of plastic deformation on the niobium thermal expansion

    International Nuclear Information System (INIS)

    Savitskij, E.M.; Bychkova, M.I.; Kanikovskij, V.B.

    1978-01-01

    Using dilatometric method the effect of plastic deformation on change of thermal expansion coefficient (TEC) of niobium of different purity was studied. It was shown that deformation affected the TEC in different ways. At first the deformation degree rising causes linear decrease of the TEC and then linear increase. Carbon intensifies the TEC decrease of deformed niobium. The linear correlation was established between the TEC and the value of macroscopic stresses in plastic deformed niobium. The expression indicating the metal TEC change under loading was defined for case of strain hardening

  8. An experimental study of plastic deformation of materials

    DEFF Research Database (Denmark)

    Knudsen, Tine

    The thesis falls in three parts, focusing on different aspects of plastic deformation of metals. Part I investigates the dislocation structures induced by hot deformation and compares these with the structures after cold deformation. In particular, it is shown that the dislocation structures...... after cold deformation by calorimetry and by analysis of the dislocation structure. The stored energy measured by calorimetry is found to be larger than that determined from the dislocation structure by a factor between 1.9 and 2.7, and this factor decreases with the plastic strain. Part III aimed...

  9. 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.

  10. Measurement of the differential pressure of liquid metals

    International Nuclear Information System (INIS)

    Metz, H.J.

    1975-01-01

    This patent relates to an improved means for measuring the differential pressure between any two points in a process liquid metal coolant loop, wherein the flow of liquid metal in a pipe is opposed by a permanent magnet liquid metal pump until there is almost zero flow shown by a magnetic type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of high-temperature bellows or diaphragm seals, and a permanent magnet liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed

  11. Measurement of the differential pressure of liquid metals

    Science.gov (United States)

    Metz, H.J.

    1975-09-01

    This patent relates to an improved means for measuring the differential pressure between any two points in a process liquid metal coolant loop, wherein the flow of liquid metal in a pipe is opposed by a permanent magnet liquid metal pump until there is almost zero flow shown by a magnetic type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of high-temperature bellows or diaphragm seals, and a permanent magnet liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed. (auth)

  12. Interactions between Dislocations and Grain Boundaries

    NARCIS (Netherlands)

    Soer, Wouter Anthon

    2006-01-01

    Dislocations (line defects) and grain boundaries (planar defects) are two types of lattice defects that are crucial to the deformation behavior of metals. Permanent deformation of a crystalline material is microscopically associated with the nucleation and propagation of dislocations, and extensive

  13. Creep deformation behavior of weld metal and heat affected zone on 316FR steel thick plate welded joint

    International Nuclear Information System (INIS)

    Hongo, Hiromichi; Yamazaki, Masayoshi; Watanabe, Takashi; Kinugawa, Junichi; Tanabe, Tatsuhiko; Monma, Yoshio; Nakazawa, Takanori

    1999-01-01

    Using hot-rolled 316FR stainless plate (50 mm thick) and 16Cr-8Ni-2Mo filler wire, a narrow-gap welded joint was prepared by GTAW (gas tungsten arc welding) process. In addition to conventional round bar specimens of base metals and weld metal, full-thickness joint specimens were prepared for creep test. Creep tests were conducted at 550degC in order to examine creep deformation and rupture behavior in the weld metal of the welded joint. Creep strain distribution on the surface of the joint specimen was measured by moire interferometry. In the welded joint, creep strength of the weld metal zone apart from the surface was larger than that in the vicinity of the surface due to repeating heat cycles during welding. Creep strain and creep rate within the HAZ adjacent to the weld metal zone were smaller than those within the base metal zone. Creep rate of the weld metal zone in the welded joint was smaller than that of the weld metal specimen due to the restraint of the hardened HAZ adjacent to the zone. The full-thickness welded joint specimens showed longer lives than weld metal specimens, though the lives of the latter was shorter than those of the base metal (undermatching). In the full-thickness welded joint specimen, crack started from the last pass layer of the weld metal zone and fracture occurred at the zone. From the results mentioned above, in order to evaluate the creep properties of the welded joint correctly, it is necessary to conduct the creep test using the full-thickness welded joint specimen which includes the weakest zones of the weld metal, the front and back sides of the plate. (author)

  14. Cold-Based Glaciation on Mercury: Accumulation and Flow of Ice in Permanently-Shadowed Circum-Polar Crater Interiors

    Science.gov (United States)

    Fastook, J. L.; Head, J. W.

    2018-05-01

    Examining the potential for dynamic flow of ice deposits in permanently-shadowed craters, it is determined that the cold environment of the polar craters yields very small velocities and deformation is minimal on a time scale of millions of years.

  15. Parameter studies on the effect of pulse shape on the dynamic plastic deformation of a hexagon

    International Nuclear Information System (INIS)

    Youngdahl, C.K.

    1973-10-01

    Results of a parameter study on the dynamic plastic response of a hexagonal subassembly duct subjected to an internal pressure pulse of arbitrary shape are presented. Plastic distortion of the cross section and large-deformation geometric effects that result in redistribution of the internal forces between bending and membrane stresses in the hexagon wall are included in the analytical model. Correlation procedures are established for relating permanent plastic deformation to simple properties of the pressure pulse, for both the small- and large-deformation ranges. Characteristic response times are determined, and the dynamic load factor for large-deformation plastic response is computed

  16. Anisotropic deformation of metallo-dielectric core-shell colloids under MeV ion irradiation

    International Nuclear Information System (INIS)

    Penninkhof, J.J.; Dillen, T. van; Roorda, S.; Graf, C.; Blaaderen, A. van; Vredenberg, A.M.; Polman, A.

    2006-01-01

    We have studied the deformation of metallo-dielectric core-shell colloids under 4 MeV Xe, 6 and 16 MeV Au, 30 MeV Si and 30 MeV Cu ion irradiation. Colloids of silica surrounded by a gold shell, with a typical diameter of 400 nm, show anisotropic plastic deformation under MeV ion irradiation, with the metal flowing conform the anisotropically deforming silica core. The 20 nm thick metal shell imposes a mechanical constraint on the deforming silica core, reducing the net deformation strain rate compared to that of pure silica. In colloids consisting of a Au core and a silica shell, the silica expands perpendicular to the ion beam, while the metal core shows a large elongation along the ion beam direction, provided the silica shell is thick enough (>40 nm). A minimum electronic energy loss of 3.3 keV/nm is required for shape transformation of the metal core. Silver cores embedded in a silica shell show no elongation, but rather disintegrate. Also in planar SiO 2 films, Au and Ag colloids show entirely different behavior under MeV irradiation. We conclude that the deformation model of core-shell colloids must include ion-induced particle disintegration in combination with thermodynamical effects, possibly in combination with mechanical effects driven by stresses around the ion tracks

  17. Anisotropic deformation of metallo-dielectric core shell colloids under MeV ion irradiation

    Science.gov (United States)

    Penninkhof, J. J.; van Dillen, T.; Roorda, S.; Graf, C.; van Blaaderen, A.; Vredenberg, A. M.; Polman, A.

    2006-01-01

    We have studied the deformation of metallo-dielectric core-shell colloids under 4 MeV Xe, 6 and 16 MeV Au, 30 MeV Si and 30 MeV Cu ion irradiation. Colloids of silica surrounded by a gold shell, with a typical diameter of 400 nm, show anisotropic plastic deformation under MeV ion irradiation, with the metal flowing conform the anisotropically deforming silica core. The 20 nm thick metal shell imposes a mechanical constraint on the deforming silica core, reducing the net deformation strain rate compared to that of pure silica. In colloids consisting of a Au core and a silica shell, the silica expands perpendicular to the ion beam, while the metal core shows a large elongation along the ion beam direction, provided the silica shell is thick enough (>40 nm). A minimum electronic energy loss of 3.3 keV/nm is required for shape transformation of the metal core. Silver cores embedded in a silica shell show no elongation, but rather disintegrate. Also in planar SiO2 films, Au and Ag colloids show entirely different behavior under MeV irradiation. We conclude that the deformation model of core-shell colloids must include ion-induced particle disintegration in combination with thermodynamical effects, possibly in combination with mechanical effects driven by stresses around the ion tracks.

  18. Elastic properties of Gum Metal

    International Nuclear Information System (INIS)

    Kuramoto, Shigeru; Furuta, Tadahiko; Hwang, Junghwan; Nishino, Kazuaki; Saito, Takashi

    2006-01-01

    In situ X-ray diffraction measurements under tensile loading and dynamic mechanical analysis were performed to investigate the mechanisms of elastic deformation in Gum Metal. Tensile stress-strain curves for Gum Metal indicate that cold working substantially decreases the elastic modulus while increasing the yield strength, thereby confirming nonlinearity in the elastic range. The gradient of each curve decreased continuously to about one-third its original value near the elastic limit. As a result of this decrease in elastic modulus and nonlinearity, elastic deformability reaches 2.5% after cold working. Superelasticity is attributed to stress-induced martensitic transformations, although the large elastic deformation in Gum Metal is not accompanied by a phase transformation

  19. A Complete Design of a Rare Earth Metal-Free Permanent Magnet Generator

    Directory of Open Access Journals (Sweden)

    Petter Eklund

    2014-05-01

    Full Text Available The price of rare-earth metals used in neodymium-iron-boron (NdFeB permanent magnets (PMs has fluctuated greatly recently. Replacing the NdFeB PMs with more abundant ferrite PMs will avoid the cost insecurity and insecurity of supply. Ferrite PMs have lower performance than NdFeB PMs and for similar performance more PM material has to be used, requiring more support structure. Flux concentration is also necessary, for example, by a spoke-type rotor. In this paper the rotor of a 12 kW NdFeB PM generator was redesigned to use ferrite PMs, reusing the existing stator and experimental setup. Finite element simulations were used to calculate both electromagnetic and mechanical properties of the design. Focus was on mechanical design and feasibility of construction. The result was a design of a ferrite PM rotor to be used with the old stator with some small changes to the generator support structure. The new generator has the same output power at a slightly lower voltage level. It was concluded that it is possible to use the same stator with either a NdFeB PM rotor or a ferrite PM rotor. A ferrite PM generator might require a larger diameter than a NdFeB generator to generate the same voltage.

  20. Effect of preliminary plastic deformation on low temperature strength of carbon steels

    International Nuclear Information System (INIS)

    Gur'ev, A.V.; Alkhimenkov, T.B.

    1979-01-01

    Considered is the effect of preliminary plastic deformation on the following low-temperature strength (at -196 deg C) of structural carbon steels at the room temperature. The study of regularities of microheterogenetic deformations by alloy structure elements at room and low temperatures shows that the transition on low -temperature loading is built on the base of inheritance of the general mechanism of plastic deformation, which took place at preliminary deformation; in this effect the ''memory'' of metal to the history of loading is shown. It is established that physical strengthening (cold hardening), received by the metal during preliminary loading at the room temperature is put over the strengthening connected only with decrease of test temperature

  1. Superductile bulk metallic glass

    International Nuclear Information System (INIS)

    Yao, K.F.; Ruan, F.; Yang, Y.Q.; Chen, N.

    2006-01-01

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<2%) at room temperature. We report a newly developed Pd-Si binary bulk metallic glass, which exhibits a uniform plastic deformation and a large plastic engineering strain of 82% and a plastic true strain of 170%, together with initial strain hardening, slight strain softening and final strain hardening characteristics. The uniform shear deformation and the ultrahigh plasticity are mainly attributed to strain hardening, which results from the nanoscale inhomogeneity due to liquid phase separation. The formed nanoscale inhomogeneity will hinder, deflect, and bifurcate the propagation of shear bands

  2. Creep recovery behaviour of bituminous binders - relevance to permanent deformation of asphalt pavements

    CSIR Research Space (South Africa)

    Mturi, GAJ

    2012-05-01

    Full Text Available different modifiers has expanded the range of PMBs to select from when designing pavements in order to avoid pavement deformation. The new binder selection criterion using the Multiple Stress Creep and Recovery (MSCR) protocol as per ASTM D7405 is meant...

  3. Deformation twinning: Influence of strain rate

    Energy Technology Data Exchange (ETDEWEB)

    Gray, G.T. III

    1993-11-01

    Twins in most crystal structures, including advanced materials such as intermetallics, form more readily as the temperature of deformation is decreased or the rate of deformation is increased. Both parameters lead to the suppression of thermally-activated dislocation processes which can result in stresses high enough to nucleate and grow deformation twins. Under high-strain rate or shock-loading/impact conditions deformation twinning is observed to be promoted even in high stacking fault energy FCC metals and alloys, composites, and ordered intermetallics which normally do not readily deform via twinning. Under such conditions and in particular under the extreme loading rates typical of shock wave deformation the competition between slip and deformation twinning can be examined in detail. In this paper, examples of deformation twinning in the intermetallics TiAl, Ti-48Al-lV and Ni{sub 3}A as well in the cermet Al-B{sub 4}C as a function of strain rate will be presented. Discussion includes: (1) the microstructural and experimental variables influencing twin formation in these systems and twinning topics related to high-strain-rate loading, (2) the high velocity of twin formation, and (3) the influence of deformation twinning on the constitutive response of advanced materials.

  4. On the role of initial void geometry in plastic deformation of metallic thin films: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yanqing [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-0340 (United States); Xu, Shuozhi, E-mail: shuozhixu@gatech.edu [GWW School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0405 (United States)

    2016-12-15

    Void growth is usually considered one of the most critical phases leading to dynamic fracture of ductile materials. Investigating the detailed process of void growth at the nanoscale aids in understanding the damage mechanism of metals. While most atomistic simulations by far assume circular or spherical voids for simplicity, recent studies highlight the significance of the initial void ellipticity in mechanical response of voided metals. In this work, we perform large scale molecular dynamics simulations with millions of atoms to investigate the void growth in plastic deformation of thin films in face-centered cubic Cu. It is found that the initial ellipticity and the initial orientation angle of the void have substantial impacts on the dislocation nucleation, the void evolution, and the stress-strain response. In particular, the initial dislocation emission sites and the sequence of slip plane activation vary with the initial void geometry. For the void size evolution, three regimes are identified: (I) the porosity increases relatively slowly in the absence of dislocations, (II) the porosity grows much more rapidly after dislocations start to glide on different slip planes, and (III) the rate of porosity variation becomes much more slowly when dislocations are saturated in the model, and the void surface becomes irregular, non-smooth. In terms of the stress-strain response, the effects of the initial orientation angle are more pronounced when the initial void ellipticity is large; the influence of the initial void ellipticity is different for different initial orientation angles. The effects of the temperature, the strain rate, the loading direction, and the initial porosity in the void growth are also explored. Our results reveal the underlying mechanisms of initial void geometry-dependent plastic deformation of metallic thin films and shed light on informing more accurate theoretical models.

  5. On the role of initial void geometry in plastic deformation of metallic thin films: A molecular dynamics study

    International Nuclear Information System (INIS)

    Su, Yanqing; Xu, Shuozhi

    2016-01-01

    Void growth is usually considered one of the most critical phases leading to dynamic fracture of ductile materials. Investigating the detailed process of void growth at the nanoscale aids in understanding the damage mechanism of metals. While most atomistic simulations by far assume circular or spherical voids for simplicity, recent studies highlight the significance of the initial void ellipticity in mechanical response of voided metals. In this work, we perform large scale molecular dynamics simulations with millions of atoms to investigate the void growth in plastic deformation of thin films in face-centered cubic Cu. It is found that the initial ellipticity and the initial orientation angle of the void have substantial impacts on the dislocation nucleation, the void evolution, and the stress-strain response. In particular, the initial dislocation emission sites and the sequence of slip plane activation vary with the initial void geometry. For the void size evolution, three regimes are identified: (I) the porosity increases relatively slowly in the absence of dislocations, (II) the porosity grows much more rapidly after dislocations start to glide on different slip planes, and (III) the rate of porosity variation becomes much more slowly when dislocations are saturated in the model, and the void surface becomes irregular, non-smooth. In terms of the stress-strain response, the effects of the initial orientation angle are more pronounced when the initial void ellipticity is large; the influence of the initial void ellipticity is different for different initial orientation angles. The effects of the temperature, the strain rate, the loading direction, and the initial porosity in the void growth are also explored. Our results reveal the underlying mechanisms of initial void geometry-dependent plastic deformation of metallic thin films and shed light on informing more accurate theoretical models.

  6. Mechanisms of liquid-metal embrittlement

    International Nuclear Information System (INIS)

    Popovich, V.V.

    1979-01-01

    The mechanism of the embrittlement of metals and alloys during deformation in contact with liquid metals are discussed. With 20Kh13 steel in a Pb-Sn melt and polycrystalline Al in the presence of various mercury solutions a.s examples, considered are the three main processes - adsorption, corrosion (dissolution), formation of new phases which cause the disintegration of materials under the action of liquid-metallic media. Presented are data on plastic ductile and strength properties of the above materials in the presence of liquid-metallic media. A model is described that takes into account the effect of the medium upon the plastic deformation and the part the medium plays in liquid-metallic embrittlement

  7. Local Stress States and Microstructural Damage Response Associated with Deformation Twins in Hexagonal Close Packed Metals

    Directory of Open Access Journals (Sweden)

    Indranil Basu

    2017-12-01

    Full Text Available The current work implements a correlative microscopy method utilizing electron back scatter diffraction, focused ion beam and digital image correlation to accurately determine spatially resolved stress profiles in the vicinity of grain/twin boundaries and tensile deformation twin tips in commercially pure titanium. Measured local stress gradients were in good agreement with local misorientation values. The role of dislocation-boundary interactions on the buildup of local stress gradients is elucidated. Stress gradients across the twin-parent interface were compressive in nature with a maximum stress magnitude at the twin boundary. Stress profiles near certain grain boundaries initially display a local stress minimum, followed by a typically observed “one over square root of distance” variation, as was first postulated by Eshelby, Frank and Nabarro. The observed trends allude to local stress relaxation mechanisms very close to the grain boundaries. Stress states in front of twin tips showed tensile stress gradients, whereas the stress state inside the twin underwent a sign reversal. The findings highlight the important role of deformation twins and their corresponding interaction with grain boundaries on damage nucleation in metals.

  8. Screening for deformed teeth; Screening for saere taender

    Energy Technology Data Exchange (ETDEWEB)

    Vermeulen, A.; Dall, P.C.; Hansen, F.G.

    1996-04-01

    Water pollution by pesticides and heavy metals causes sublethal effects in larvae of the Chironomidae midges. These effects are particularly noticeable in the deformities of the oral parts and antennae. Possibilities of using these deformities for the purpose of water/sediment biomonitoring are very promising. Here the first results of screening in a Danish stream are presented. (EG) 9 refs.

  9. 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

  10. Stress Analysis of Non-Ferrous Metals Welds by Numerical Simulation

    Directory of Open Access Journals (Sweden)

    Kravarikova Helena

    2017-01-01

    Full Text Available Thermal energy welded material unevenly heated and thus supports the creation of tension. During the fusing process welding transient tensions generated in the welded material. Generation of the transient tensions depends on the thermal expansion and fixed permanently welded parts. Tensions are the result of the interaction of material particles. For welded parts and constructions it is necessary to know the size and direction of application of tensions. The emerging tensions can cause local change or a total deformation of welded materials. Deformations and residual stresses impair the performance of a welded construction, reduces the stability of the parts. To reduce or eliminate of action or a screening direction stresses and strains it is necessary to know the mechanism of their emergence. It is now possible to examine the emergence of tensions numerical experiments on any model using numerical simulation using FEM. Results of numerical experiment is the analysis of stress and deformation course. In the plane the tension it divided into normal σ and τ tangential folders. Decomposition stress on components simplifies the stress analysis. The results obtained from numerical analysis are correct to predict the stress distribution and size. The paper presents the results of numerical experiments stress analysis solutions fillet welds using FEM numerical simulation of welding of non-ferrous metals.

  11. Metal working and dislocation structures

    DEFF Research Database (Denmark)

    Hansen, Niels

    2007-01-01

    Microstructural observations are presented for different metals deformed from low to high strain by both traditional and new metal working processes. It is shown that deformation induced dislocation structures can be interpreted and analyzed within a common framework of grain subdivision on a finer...... and finer scale down to the nanometer dimension, which can be reached at ultrahigh strains. It is demonstrated that classical materials science and engineering principles apply from the largest to the smallest structural scale but also that new and unexpected structures and properties characterize metals...

  12. A fully-coupled approach combining plastic deformation and liquid lubrication

    DEFF Research Database (Denmark)

    Üstünyagiz, Esmeray; Christiansen, Peter; Nielsen, Chris Valentin

    This paper presents a new approach based on a fully coupled procedure in which the lubricant flow and theplastic deformation of the metallic material are solved simultaneously. The approach is applied to strip reduction of asheet with surface pockets in order to investigate the escape of the lubr......This paper presents a new approach based on a fully coupled procedure in which the lubricant flow and theplastic deformation of the metallic material are solved simultaneously. The approach is applied to strip reduction of asheet with surface pockets in order to investigate the escape...

  13. Induction of mouthpart deformities in chironomid larvae exposed to contaminated sediments.

    NARCIS (Netherlands)

    Di Veroli, A.; Goretti, E.; León Paumen, M.; Kraak, M.H.S.; Admiraal, W.

    2012-01-01

    The aim of the present study was to improve the cause-effect relationship between toxicant exposure and chironomid mouthpart deformities, by linking induction of mouthpart deformities to contaminated field sediments, metal mixtures and a mutagenic polycyclic aromatic compound metabolite (acridone).

  14. High-energy X-ray measurements of structural anisotropy and excess free volume in a homogenously deformed Zr-based metallic glass

    International Nuclear Information System (INIS)

    Ott, R.T.; Kramer, M.J.; Besser, M.F.; Sordelet, D.J.

    2006-01-01

    We have used high-energy X-ray scattering to measure the structural anisotropy and excess free volume in a homogeneously deformed Zr-based metallic glass alloy. The scattering results show that bond length anisotropy is present in the samples following isothermal tensile creep deformation. The average atomic bond length in the direction parallel to the tensile loading axis is larger than that in the direction normal to the loading axis. The magnitude of the bond length anisotropy is found to be dependent on the gradient of macroscopic plastic strain along the gauge length. Furthermore, the scattering results show that the excess free volume also increases with increasing macroscopic plastic strain. Results from differential scanning calorimetry analysis of free volume variations along the gauge length of the creep samples are consistent with results from the X-ray scattering experiments

  15. Modelling of real area of contact between tool and workpiece in metal forming processes including the influence of subsurface deformation

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, Paulo A. F.; Bay, Niels Oluf

    2016-01-01

    New equipment for testing asperity deformation at various normal loads and subsurface elongations is presented. Resulting real contact area ratios increase heavily with increasing subsurface expansion due to lowered yield pressure on the asperities when imposing subsurface normal stress parallel ...... for estimating friction in the numerical modelling of metal forming processes.......New equipment for testing asperity deformation at various normal loads and subsurface elongations is presented. Resulting real contact area ratios increase heavily with increasing subsurface expansion due to lowered yield pressure on the asperities when imposing subsurface normal stress parallel...... to the surface. Finite element modelling supports the presentation and contributes by extrapolation of results to complete the mapping of contact area as function of normal pressure and one-directional subsurface strain parallel to the surface. Improved modelling of the real contact area is the basis...

  16. Anion Effects on the Ion Exchange Process and the Deformation Property of Ionic Polymer Metal Composite Actuators

    Directory of Open Access Journals (Sweden)

    Wataru Aoyagi

    2016-06-01

    Full Text Available An ionic polymer-metal composite (IPMC actuator composed of a thin perfluorinated ionomer membrane with electrodes plated on both surfaces undergoes a large bending motion when a low electric field is applied across its thickness. Such actuators are soft, lightweight, and able to operate in solutions and thus show promise with regard to a wide range of applications, including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. However, the variations induced by changing the type of anion on the device deformation properties are not well understood; therefore, the present study investigated the effects of different anions on the ion exchange process and the deformation behavior of IPMC actuators with palladium electrodes. Ion exchange was carried out in solutions incorporating various anions and the actuator tip displacement in deionized water was subsequently measured while applying a step voltage. In the step voltage response measurements, larger anions such as nitrate or sulfate led to a more pronounced tip displacement compared to that obtained with smaller anions such as hydroxide or chloride. In AC impedance measurements, larger anions generated greater ion conductivity and a larger double-layer capacitance at the cathode. Based on these mechanical and electrochemical measurements, it is concluded that the presence of larger anions in the ion exchange solution induces a greater degree of double-layer capacitance at the cathode and results in enhanced tip deformation of the IPMC actuators.

  17. A novel safety device with metal counter meshing gears discriminator directly driven by axial flux permanent magnet micromotors based on MEMS technology

    Science.gov (United States)

    Zhang, Weiping; Chen, Wenyuan; Zhao, Xiaolin; Li, Shengyong; Jiang, Yong

    2005-08-01

    In a novel safety device based on MEMS technology for high consequence systems, the discriminator consists of two groups of metal counter meshing gears and two pawl/ratchet wheel mechanisms. Each group of counter meshing gears is onepiece and driven directly by an axial flux permanent magnet micromotor respectively. The energy-coupling element is an optical shutter with two collimators and a coupler wheel. The safety device's probability is less than 1/106. It is fabricated by combination of an LiGA-like process and precision mechanical engineering. The device has simple structure, few dynamic problems, high strength and strong reliability.

  18. Constitutive relations for non-elastic deformation

    International Nuclear Information System (INIS)

    Hart, E.W.

    1978-01-01

    A new class of constitutive equations is described for non-elastic deformation of metals. The relations are embodied in a model that has had considerable experimental investigation. The model employs two deformation state variables of which one is a scalar hardness variable and the other is a stored anelastic strain. The description is entirely in terms of real time strain rates. The model and its experimental background is discussed. The relationship to mechanical calculations and a possible extension to radiation environment is also considered. (Auth.)

  19. Study on Hot Deformation Behavior of 7085 Aluminum Alloy during Backward Extrusion Process

    Directory of Open Access Journals (Sweden)

    R. B. Mei

    2015-01-01

    Full Text Available Compression test was carried out and the true stress-strain curves were obtained from the hot compression of 7085 alloy. A numerical simulation on the deformation behavior of 7085 aluminum alloy during the backward extrusion was also performed by finite element method. The results show that dynamic recrystallization occurs in the hot compression of 7085 alloy and the peak stress reaches higher values as the strain rate increases and deformation temperature decreases. The backward extrusion processes include contact deformation, initial deformation, and steady deformation. Severe plastic deformation of shear and compression occurs when the metal flowed into the channel between fillet of punch and wall of die so that the grain size can be refined by backward extrusion. The deformation in the region of top of wall is too small to meet the mechanical properties of requirements and the metal usually needs to be trimmed. The experiments with the same parameters as simulation had been carried out and the experimental cup after extrusion has better quality.

  20. Experience with the SLC permanent magnet multipoles

    International Nuclear Information System (INIS)

    Gross, G.; Spencer, J.

    1994-06-01

    Permanent magnets have been used in the SLC Damping Rings and their injection and extraction lines since 1985. Recent upgrades of the DR vacuum chambers provided an opportunity to check DR magnets prior to higher beam current operation. Several PM sextupoles downstream of the injection kickers in the electron ring had exceeded their thermal stabilization values of 80 degrees C and some showed serious mechanical deformations and radiation >1 R at contact. We discuss our observations, measurements and a few inexpensive modifications that should improve these magnets under such conditions. A new, block matching algorithm allowed us to use magnet blocks that had been considered unusable because of very different remament field strengths and easy axis errors

  1. GPS deformation measurements at Olkiluoto in 2013

    International Nuclear Information System (INIS)

    Nyberg, S.; Kallio, U.; Koivula, H.

    2014-08-01

    The Finnish Geodetic Institute has monitored crustal deformations since mid-1990s at Olkiluoto, Kivetty and Romuvaara. The research was focused on the Olkiluoto area in 2001, when Olkiluoto was chosen to the site for the final disposal facility of the spent nuclear fuel. The work and the results of the GPS deformation monitoring at Olkiluoto in 2013 are presented. The measurement consisted of two GPS measurement campaigns, observations at local permanent stations and control markers measurements at four stations. In spring six new stations were set up for permanent tracking. In total 12 permanent stations were operating continuously from April to the end of the year. The residual time series of the stations showed periodic trends up to 3 mm in height and 1 mm in horizontal component relative to the GPS1 station. A few stations were still measured as campaign-based and analysed baseline by baseline. The data from permanent stations (GPS1-GPS9, and GPS13) were included. The analysis of the inner network based on campaign sessions showed very small motions as in previous years: 75 % of change rates are smaller than 0.10 mm/y. Roughly one third of the change rates could be considered statistically significant at 1 % significance level. Statistically significant change rates were estimated for baselines from GPS1 and GPS5. The trends and strains differed at some baselines clearly from the earlier analysis because of different troposphere modelling. The results of the outer network showed the largest difference on the baseline GPS1-GPS11 where the trend decreased from -0.42 mm/y to -0.28 mm/y. The strain pattern of the outer network shows an eastwards motion of GPS1. The estimated strains for the baselines east of GPS1 were -0.03/-0.04 ppm/y. The control marker measurements were carried at the stations GPS1, GPS2, GPS4 and GPS6. A comparison of the results with the previous measurements showed that the distance between control markers at GPS6 continues to increase. Also

  2. GPS deformation measurements at Olkiluoto in 2013

    Energy Technology Data Exchange (ETDEWEB)

    Nyberg, S.; Kallio, U.; Koivula, H. [Finnish Geodetic Institute, Masala (Finland)

    2014-08-15

    The Finnish Geodetic Institute has monitored crustal deformations since mid-1990s at Olkiluoto, Kivetty and Romuvaara. The research was focused on the Olkiluoto area in 2001, when Olkiluoto was chosen to the site for the final disposal facility of the spent nuclear fuel. The work and the results of the GPS deformation monitoring at Olkiluoto in 2013 are presented. The measurement consisted of two GPS measurement campaigns, observations at local permanent stations and control markers measurements at four stations. In spring six new stations were set up for permanent tracking. In total 12 permanent stations were operating continuously from April to the end of the year. The residual time series of the stations showed periodic trends up to 3 mm in height and 1 mm in horizontal component relative to the GPS1 station. A few stations were still measured as campaign-based and analysed baseline by baseline. The data from permanent stations (GPS1-GPS9, and GPS13) were included. The analysis of the inner network based on campaign sessions showed very small motions as in previous years: 75 % of change rates are smaller than 0.10 mm/y. Roughly one third of the change rates could be considered statistically significant at 1 % significance level. Statistically significant change rates were estimated for baselines from GPS1 and GPS5. The trends and strains differed at some baselines clearly from the earlier analysis because of different troposphere modelling. The results of the outer network showed the largest difference on the baseline GPS1-GPS11 where the trend decreased from -0.42 mm/y to -0.28 mm/y. The strain pattern of the outer network shows an eastwards motion of GPS1. The estimated strains for the baselines east of GPS1 were -0.03/-0.04 ppm/y. The control marker measurements were carried at the stations GPS1, GPS2, GPS4 and GPS6. A comparison of the results with the previous measurements showed that the distance between control markers at GPS6 continues to increase. Also

  3. Deformation, Stress Relaxation, and Crystallization of Lithium Silicate Glass Fibers Below the Glass Transition Temperature

    Science.gov (United States)

    Ray, Chandra S.; Brow, Richard K.; Kim, Cheol W.; Reis, Signo T.

    2004-01-01

    The deformation and crystallization of Li(sub 2)O (center dot) 2SiO2 and Li(sub 2)O (center dot) 1.6SiO2 glass fibers subjected to a bending stress were measured as a function of time over the temperature range -50 to -150 C below the glass transition temperature (Tg). The glass fibers can be permanently deformed at temperatures about 100 C below T (sub)g, and they crystallize significantly at temperatures close to, but below T,, about 150 C lower than the onset temperature for crystallization for these glasses in the no-stress condition. The crystallization was found to occur only on the surface of the glass fibers with no detectable difference in the extent of crystallization in tensile and compressive stress regions. The relaxation mechanism for fiber deformation can be best described by a stretched exponential (Kohlrausch-Williams-Watt (KWW) approximation), rather than a single exponential model.The activation energy for stress relaxation, Es, for the glass fibers ranges between 175 and 195 kJ/mol, which is considerably smaller than the activation energy for viscous flow, E, (about 400 kJ/mol) near T, for these glasses at normal, stress-free condition. It is suspected that a viscosity relaxation mechanism could be responsible for permanent deformation and crystallization of the glass fibers below T,

  4. Phase transformation and microstructure evolution of the deformed Ti-30Zr-5Nb shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Wentao, E-mail: wtqu@xsyu.edu.cn [School of Mechanical Engineering, Xi' an Shiyou University, Xi' an 710065 (China); Sun, Xuguang; Yuan, Bifei [School of Mechanical Engineering, Xi' an Shiyou University, Xi' an 710065 (China); Xiong, Chengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Nie, Yongsheng [Lanzhou Seemine SMA Co. Ltd., Lanzhou 730010 (China)

    2017-04-15

    The phase transformation and microstructures of the deformed Ti-30Zr-5Nb shape memory alloy were investigated. The X-ray diffraction measurements indicated that the Ti-30Zr-5Nb alloy was composed of a single orthorhombic α″-martensite phase. The alloy exhibited one yielding behavior in the tensile test, with a critical stress of ~ 600 MPa and a tensile strain of approximately 15%. A shape memory recovery accompanied by a permanent strain was exhibited in the deformed alloys when heated at 873 K. The permanent strain increased with increasing pre-strain. The microstructure evolution of the deformed alloy was investigated by transmission electron microscopy. The results showed that the martensite reorientation occurred and the dislocations were generated during deformation. The alloy displayed a reversible martensite transformation start temperature as high as 763 K. However, no strain-induced martensite stabilization was found in the deformed alloy with different pre-strain levels, potentially because the large chemical energy of the Ti-30Zr-5Nb alloy depressed the effects of the elastic energy and the dissipative energy. - Highlights: • Ti-30Zr-5Nb alloy is composed of single orthorhombic α″-martensite phase with M{sub s} of 721 K. • No martensite stabilization has been found in Ti-30Zr-5Nb alloy with different pre-strain. • Ti-30Zr-5Nb shows the maximum shape memory effect of 2.75% with a pre-strain of 8%.

  5. Brittle-to-Ductile Transition in Metallic Glass Nanowires.

    Science.gov (United States)

    Şopu, D; Foroughi, A; Stoica, M; Eckert, J

    2016-07-13

    When reducing the size of metallic glass samples down to the nanoscale regime, experimental studies on the plasticity under uniaxial tension show a wide range of failure modes ranging from brittle to ductile ones. Simulations on the deformation behavior of nanoscaled metallic glasses report an unusual extended strain softening and are not able to reproduce the brittle-like fracture deformation as found in experiments. Using large-scale molecular dynamics simulations we provide an atomistic understanding of the deformation mechanisms of metallic glass nanowires and differentiate the extrinsic size effects and aspect ratio contribution to plasticity. A model for predicting the critical nanowire aspect ratio for the ductile-to-brittle transition is developed. Furthermore, the structure of brittle nanowires can be tuned to a softer phase characterized by a defective short-range order and an excess free volume upon systematic structural rejuvenation, leading to enhanced tensile ductility. The presented results shed light on the fundamental deformation mechanisms of nanoscaled metallic glasses and demarcate ductile and catastrophic failure.

  6. Plasticity margin recovery during annealing after cold deformation

    International Nuclear Information System (INIS)

    Bogatov, A.A.; Smirnov, S.V.; Kolmogorov, V.L.

    1978-01-01

    Restoration of the plasticity margin in steel 20 after cold deformation and annealing at 550 - 750 C and soaking for 5 - 300 min was investigated. The conditions of cold deformation under which the metal acquires microdefects unhealed by subsequent annealing were determined. It was established that if the degree of utilization of the plasticity margin is psi < 0.5, the plasticity margin in steel 20 can be completely restored by annealing. A mathematical model of restoration of the plasticity margin by annealing after cold deformation was constructed. A statistical analysis showed good agreement between model and experiment

  7. 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.

  8. Permanent tattoos: evidence of pseudolymphoma in three patients and metal composition of the dyes.

    Science.gov (United States)

    Cristaudo, Antonio; Forte, Giovanni; Bocca, Beatrice; Petrucci, Francesco; Muscardin, Luca; Trento, Elisabetta; Di Carlo, Aldo

    2012-01-01

    Tattoo-induced pseudolymphoma is a cutaneous inflammatory response, the pathogenesis of which is still unknown. The objective of the present work was to find a possible causal relationship between pseudolymphomatous reactions on the red areas of tattoos and the metals contained in tattoo pigments and skin biopsies. Three individuals with cutaneous lesions on the red areas of tattoos were observed. Clinical and immunohistochemical examinations of the lesions were performed, and the concentrations of Cd, Co, Cr, Hg, Ni and Pb were measured in pigments and biopsy samples. Pseudolymphomas in the red areas were diagnosed in all three cases; one showed the prevalence of B-lymphocytes, whereas the other two showed a prevalence of T cells with a lichenoid pattern. Patch tests were negative. Corticosteroid therapy was ineffective. Cadmium, Co, Hg and Pb in the pigments were probably present as impurities, whereas Cr and Ni were the main components. Chromium and Ni had the highest concentrations, also in the biopsy samples. Permanent tattoos appear to be unsafe, considering the increasing number of diagnosed pseudolymphomas. It can be excluded that Hg was responsible for the reactions, given that the concentration in the red dyes and biopsies was very low. Significant levels of Cr and Ni should be considered as the causes of possible dermal reactions.

  9. A brittle-fracture methodology for three-dimensional visualization of ductile deformation micromechanisms

    NARCIS (Netherlands)

    Tasan, C.C.; Hoefnagels, J.P.M.; Geers, M.G.D.

    2009-01-01

    An improved experimental methodology is developed and successfully evaluated to visualize deformation-induced microevents in ductile sheet metal. This easy-to-use methodology consists in a well-controlled brittle separation of samples previously deformed in a ductile manner, whereby a

  10. Permanent scatterer InSAR processing: Forsmark

    International Nuclear Information System (INIS)

    Dehls, John F.

    2006-04-01

    It has been speculated that slow, aseismic movement may be occurring along some of the fracture zones crosscutting the Forsmark area. The purpose of this study is to determine if it is possible to measure such movement using dInSAR. Differential SAR Interferometry (DInSAR) is a technique that compares the phases of multiple radar images of an area to measure surface change. The method has the potential to detect millimetric surface deformation along the sensor - target line-of-sight. Differences in phase between two images are easily viewed by combining, or interfering, the two phase-images. In the resulting image, the waves will either reinforce or cancel one another, depending upon the relative phases. The resulting image is called an interferogram and contains concentric bands of colour, or fringes, that are related to topography and/or surface deformation. New algorithms use many images acquired over a long time period to determine the movement history of individual objects, referred to as permanent scatterers. In the current project, standard PSInSAR processing was performed on 40 ERS-1 and ERS-2 scenes. The total area processed is approximately 1,500 km 2 . Slightly less than 20,000 permanent scatterers were identified.The highest densities were obtained along the coast and on the islands, where natural outcrops are more abundant. Two main classes of objects act as permanent scatterers in this area. The first are natural reflectors, such as rocks. The second are man-made reflectors, such as parts of buildings. Numerous local movements were found in the study area, relating to building subsidence, or compaction of anthropogenic fill. The dataset was divided into three groups for analysis, based upon the location of regional lineaments provided by SKB. Both statistical and geostatistical techniques were used. The median velocity of the three blocks did not differ by more than 0.2 mm/yr. This is not considered significant, given the possible magnitude of errors

  11. Permanent scatterer InSAR processing: Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Dehls, John F [Geological Survey of Norway, Trondheim (Norway)

    2006-04-15

    It has been speculated that slow, aseismic movement may be occurring along some of the fracture zones crosscutting the Forsmark area. The purpose of this study is to determine if it is possible to measure such movement using dInSAR. Differential SAR Interferometry (DInSAR) is a technique that compares the phases of multiple radar images of an area to measure surface change. The method has the potential to detect millimetric surface deformation along the sensor - target line-of-sight. Differences in phase between two images are easily viewed by combining, or interfering, the two phase-images. In the resulting image, the waves will either reinforce or cancel one another, depending upon the relative phases. The resulting image is called an interferogram and contains concentric bands of colour, or fringes, that are related to topography and/or surface deformation. New algorithms use many images acquired over a long time period to determine the movement history of individual objects, referred to as permanent scatterers. In the current project, standard PSInSAR processing was performed on 40 ERS-1 and ERS-2 scenes. The total area processed is approximately 1,500 km{sup 2}. Slightly less than 20,000 permanent scatterers were identified.The highest densities were obtained along the coast and on the islands, where natural outcrops are more abundant. Two main classes of objects act as permanent scatterers in this area. The first are natural reflectors, such as rocks. The second are man-made reflectors, such as parts of buildings. Numerous local movements were found in the study area, relating to building subsidence, or compaction of anthropogenic fill. The dataset was divided into three groups for analysis, based upon the location of regional lineaments provided by SKB. Both statistical and geostatistical techniques were used. The median velocity of the three blocks did not differ by more than 0.2 mm/yr. This is not considered significant, given the possible magnitude of

  12. Vertebral Column Resection for Rigid Spinal Deformity.

    Science.gov (United States)

    Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G

    2017-05-01

    Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.

  13. Correlation between relaxations and plastic deformation, and elastic model of flow in metallic glasses and glass-forming liquids

    International Nuclear Information System (INIS)

    Wang Weihua

    2011-01-01

    We study the similarity and correlations between relaxations and plastic deformation in metallic glasses (MGs) and MG-forming liquids. It is shown that the microscope plastic events, the initiation and formation of shear bands, and the mechanical yield in MGs where the atomic sites are topologically unstable induced by applied stress, can be treated as the glass to supercooled liquid state transition induced by external shear stress. On the other hand, the glass transition, the primary and secondary relaxations, plastic deformation and yield can be attributed to the free volume increase induced flow, and the flow can be modeled as the activated hopping between the inherent states in the potential energy landscape. We then propose an extended elastic model to describe the flow based on the energy landscape theory. That is, the flow activation energy density is linear proportional to the instantaneous elastic moduli, and the activation energy density ρ E is determined to be a simple expression of ρ E =(10/11)G+(1/11)K. The model indicates that both shear and bulk moduli are critical parameters accounting for both the homogeneous and inhomogeneous flows in MGs and MG-forming liquids. The elastic model is experimentally certified. We show that the elastic perspectives offers a simple scenario for the flow in MGs and MG-forming liquids and are suggestive for understanding the glass transition, plastic deformation, and nature and characteristics of MGs

  14. Micromechanics of deformation of metallic-glass-matrix composites from in situ synchrotron strain measurements and finite element modeling

    International Nuclear Information System (INIS)

    Ott, R.T.; Sansoz, F.; Molinari, J.F.; Almer, J.; Ramesh, K.T.; Hufunagel, T.C.

    2005-01-01

    In situ X-ray scattering and finite element modeling (FEM) were used to examine the micromechanics of deformation of in situ formed metallic-glass-matrix composites consisting of Ta-rich particles dispersed in an amorphous matrix. The strain measurements show that under uniaxial compression the second-phase particles yield at an applied stress of approx. 325 MPa. After yielding, the particles do not strain harden significantly; we show that this is due to an increasingly hydrostatic stress state arising from the lateral constraint on deformation of the particles imposed by the elastic matrix. Shear band initiation in the matrix is not due to the difference in elastic properties between the matrix and the particles. Rather, the development of a plastic misfit strain causes stress concentrations around the particles, resulting in localized yielding of the matrix by shear band formation at an applied stress of approx. 1450 MPa, considerably lower than the macroscopic yield stress of the composite (approx. 1725 MPa). Shear bands do not propagate at the lower stress because the yield criterion of the matrix is only satisfied in the region immediately around the particles. At the higher stresses, the yield criterion is satisfied in large regions of the matrix, allowing extensive shear band propagation and significant macroscopic plastic deformation. However, the presence of the particles makes the stress state highly inhomogeneous, which may partially explain why fracture is suppressed in the composite, allowing the development of large plastic strains

  15. Connectedness percolation of hard deformed rods

    NARCIS (Netherlands)

    Drwenski, Tara; Dussi, Simone; Dijkstra, Marjolein; van Roij, Rene; van der Schoot, Paul

    2017-01-01

    Nanofiller particles, such as carbon nanotubes or metal wires, are used in functional polymer composites to make them conduct electricity. They are often not perfectly straight cylinders but may be tortuous or exhibit kinks. Therefore we investigate the effect of shape deformations of the rod-like

  16. Elastic source model of the North Mono eruption (1325-1368 A.D.) based on shoreline deformation

    Science.gov (United States)

    Shaffer, Wil; Bursik, Marcus; Renshaw, Carl

    2010-12-01

    Topographic data from the Shuttle Radar Topography Mission (SRTM) captures the permanent deformation of a prominent highstand of Mono Lake, California USA. Deformation of the Dechambeau Ranch highstand shoreline was measured using the elevation of the beach berm—shoreline bluff break-in-slope. Point source models and a boundary element dike model were used to approximate the source of deformation underneath the northern end of the Mono Craters. The point source model could not adequately explain the observed deformation. The dike model yielded the best results for a NW trending dike dipping 60° NE and inflated to widths greater than 60 m. The results suggest that the geometry of the source is more complex than a simple vertical dike and that the deformation is better explained with a dipping dike following a normal fault, or an elongated cryptodome.

  17. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weiming [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Sun, Baoan [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Zhao, Yucheng, E-mail: zhaoyc1972@163.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Li, Qiang [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Hou, Long; Luo, Ning [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Dun, Chaochao [Department of Physics, Wake Forest University, Winston Salem, NC 27109 (United States); Zhao, Chengliang [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Ma, Zhanguo [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Haishun, E-mail: liuhaishun@126.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Shen, Baolong [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-08-15

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  18. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Yang, Weiming; Sun, Baoan; Zhao, Yucheng; Li, Qiang; Hou, Long; Luo, Ning; Dun, Chaochao; Zhao, Chengliang; Ma, Zhanguo; Liu, Haishun; Shen, Baolong

    2016-01-01

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe_5_0Ni_3_0P_1_3C_7 glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe_5_0Ni_3_0P_1_3C_7 metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  19. Recrystallization - Fundamental aspects and relations to deformation microstructure

    International Nuclear Information System (INIS)

    Hansen, N.; Huang, X.; Juul Jensen, D.; Lauridsen, E.M.; Leffers, T.; Pantleon, W.; Sabin, T.J.; Wert, J.A.

    2000-01-01

    This Symposium, and hence this proceedings volume, is concerned with the mechanisms that control recrystallization of deformed metals and alloys. Central themes are the fundamental microstructural, orientational, and kinetic aspects of the recrystallization process; especially as they relate to the nature of the deformed state, to nucleation and growth of recrystallizing grains, and to models based on experimental observations. In recent years, significant progress has been made using a plethora of advanced techniques to characterize the morphology and local orientations in deformed metals and alloys. Thus, a key topic of the Symposium is enhanced insight into the characteristics of the deformation substructure, and into modification of the substructure by recovery, which is essential for understanding fundamental recrystallization mechanisms. Microstructures in highly strained materials will be a topic of special interest. Elucidation of the deformation substructure, and thus the local distribution of stored energy, sets the stage for progress in understanding nucleation of recrystallizing grains. It also provides a basis for new insights into the growth of nuclei, in particular concerning the means by which the deformation substructure is absorbed by and becomes incorporated into the recrystallization interface. Aspects of recrystallization of relevance to this symposium span the range from experimental and model exploration of fundamental mechanisms to methods that link scientific understanding to industrial practice. Models developed by considering the physical mechanisms elucidated by experimental studies will be addressed, as will models that enable industrial exploitation of the fundamental knowledge. Altogether, one of the significant aims of the symposium is to enhance the exploitation of the expanding knowledge of fundamental recrystallization mechanisms in industrial practice (au)

  20. Liquid Segregation Phenomenological Behaviors of Ti14 Alloy during Semisolid Deformation

    Directory of Open Access Journals (Sweden)

    Y. N. Chen

    2014-05-01

    Full Text Available The liquid segregation phenomenon and its effect on deformation mechanism of Ti14 alloy in semisolid metal processing were investigated by thermal simulation test. Microstructure of depth profile was determined by cross-section quantitative metallography, and liquid segregation phenomenon was described by Darcy's law. The results show that segregation phenomenon was affected by solid fraction, strain rate, and deformation rate. More liquid segregated from center to edge portion with high strain rate and/or deformation ratio as well as low solid fraction, which caused different distribution of dominating deformation mechanism. The relationship between liquid segregation and main deformation mechanism was also discussed by phenomenological model.

  1. On the applicability of deformed jellium model to the description of metal clusters

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Matveentsev, Anton; Solov'yov, Ilia

    2003-01-01

    -density approximation deformed jellium model we have calculated the binding energies per atom, ionization potentials, deformation parameters and the optimized values of the Wigner-Seitz radii for neutral and singly charged sodium clusters with the number of atoms $N0$. These characteristics are compared...... shape deformations in the formation cluster properties and the quite reasonable level of applicability of the deformed jellium model.......This work is devoted to the elucidation the applicability of jellium model to the description of alkali cluster properties on the basis of comparison the jellium model results with those derived from experiment and within ab initio theoretical framework. On the basis of the Hartree-Fock and local...

  2. Plastic deformation of aluminium under continuous electron irradiation

    International Nuclear Information System (INIS)

    Dubinko, V.I.; Dovbnya, A.N.; Kushnir, V.A.; Khodak, I.V.; Mitrochenko, V.V.; Lebedev, V.P.; Krylovskij, V.S.; Lebedev, S.V.; Klepikov, V.F.

    2010-01-01

    Plastic deformation of polycrystalline aluminum (99.5%) was investigated in the absence and presence of a high-energy electron beam (E = 0.5 MeV, φ = (0.5...5)·10 13 cm -2 ·c -1 ). Reduction of the yield stress and hardening coefficient was determined as a function of deformation, the sample thickness and the beam density. The increase of plasticity of the metal due to the impact of the electron beam has been established. The temperature in the deformation process was measured, which allowed separating the contribution of radiation-induced effects on the mechanical characteristics of aluminum. Possible mechanisms of the phenomenon are discussed.

  3. Geochemistry of trace metals in shelf sediments affected by seasonal and permanent low oxygen conditions off central Chile, SE Pacific (˜36°S)

    Science.gov (United States)

    Muñoz, Praxedes; Dezileau, Laurent; Cardenas, Lissette; Sellanes, Javier; Lange, Carina B.; Inostroza, Jorge; Muratli, Jesse; Salamanca, Marco A.

    2012-02-01

    Trace metals (Cd, U, Co, Ni, Cu, Ba, Fe, Mn), total organic carbon (TOC) and C and N stable isotope signatures (δ 13C and δ 15N) were determined in short sediments cores from the inner and outer shelf off Concepción, Chile (˜36°S). The objectives were to establish the effect of environmental conditions on trace metal distributions at two shelf sites, one affected by seasonal oxygenation and the other by permanent low oxygen conditions due to the presence of the oxygen minimum zone (OMZ). We evaluate trace metals as proxies of past changes in primary productivity and the bottom water oxygen regime. Concentrations of pore water sulfides and NH4+ were also measured as indicators of the main diagenetic pathways at each site. Our results for the inner shelf (seasonal suboxia) suggest that the oxidative state of the sediments responds to seasonal pulses of organic matter and that seasonal oxygenation develops during high and low primary productivity in the water column. Here, positive fluxes (to the water column) estimated from pore water concentrations of several elements were observed (Ba, Co, Ni, Fe and Mn). The less reduced environment at this site produces authigenic enrichment of Cu associated with the formation of oxides in the oxic surface sediment layer, and the reduction of U within deeper sediment sections occur consistently with negative estimated pore water fluxes. In the outer shelf sediments (permanent suboxia, OMZ site), negative fluxes (to the sediment) were estimated for all elements, but these sediments showed authigenic enrichments only for Cd, Cu and U. The short oxygenation period during the winter season did not affect the accumulation of these metals on the shelf. The distribution of Cu, Cd and U have been preserved within the sediments and the authigenic accumulation rates estimated showed a decrease from the deep sections of the core to the surface sediments. This could be explained by a gradual decrease in the strength of the OMZ in the

  4. A biomimetic jellyfish robot based on ionic polymer metal composite actuators

    International Nuclear Information System (INIS)

    Yeom, Sung-Weon; Oh, Il-Kwon

    2009-01-01

    A biomimetic jellyfish robot based on ionic polymer metal composite actuators was fabricated and activated to mimic real locomotive behavior with pulse and recovery processes. To imitate the curved shape of the jellyfish, a thermal treatment was applied to obtain a permanent initial deformation of a hemispherical form. The bio-inspired input signal was generated for mimicking real locomotion of the jellyfish. The vertical floating displacement and the thrust force of the biomimetic jellyfish robot under various input signals were measured and compared. The present results show that the bio-inspired electrical input signal with pulse-recovery process generates much higher floating velocity of the biomimetic jellyfish robot in comparison with pure sinusoidal excitations. The curved shape of the IPMC actuator through thermal treatments can be successfully applied to mimic the real biomimetic robots with smooth curves

  5. Sensorless control of interior permanent-magnet synchronous motors with compressor load

    DEFF Research Database (Denmark)

    Huang, Shoudao; Gao, Jian; Xiao, Lei

    2013-01-01

    This paper analyzes the mathematical model of the interior permanent-magnet synchronous motors (IPMSM). Through the mathematical deformation, the paper proposes the new sensorless method based on sliding mode observer for a IPMSM. The model is only associated with the q-axis inductance, and without...... the d-axis inductance. Dual filter is set series to extract the electromotive force information, and then filter phase shift is measured real-time at different speeds for angle compensation. An I-F strategy is adopted to start the IPMSM with compressor load. Finally, the experimental proves the validity...

  6. Developments in the processing and properties of NdFeb-type permanent magnets

    International Nuclear Information System (INIS)

    Brown, David; Ma, B.-M.; Chen Zhongmin

    2002-01-01

    The composition, microstructure and processing of NdFeB-type permanent magnets are all critical factors for the successful production of high performance magnet components. Three common fabrication routes can be used to categorize these NdFeB-based bulk magnets: sintering, polymer bonding and hot deformation. Generally, the former type of magnet has a high-energy product (30-50 MGOe), full density and a relatively simple shape. Bonded magnets have intermediate energy products (10-18 MGOe), lower density and can be formed into intricate net-shapes. Hot deformed magnets possess full density, intermediate to high-energy products (15-46 MGOe), isotropic or anisotropic properties and have the potential to be formed into net shapes. This article discusses the critical issues of improved magnetic performance, environmental stability, net-shape formability and magnetization behavior for the main categories of NdFeB magnets

  7. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

    Ott, Ryan T.; McCallum, Ralph W.; Jones, Lawrence L.

    2017-08-08

    A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

  8. 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.

  9. Coexistence of ductile and brittle fracture in metals

    International Nuclear Information System (INIS)

    Ohr, S.M.; Chang, S.J.; Park, C.G.; Thomson, R.

    1985-01-01

    It is well known that semibrittle body-centered cubic (bcc) metals fail at low temperatures by cleavage that is preceded by crack tip deformation. Sinclair and Finnis proposed a mechanism by which crack tip deformation may be combined with brittle crack extension. In this model, edge dislocations are emitted from a crack tip on an inclined plane under pure mode I loading conditions. The authors propose a new mechanism of brittle fracture of semibrittle metals preceded by crack tip deformation by extending the model of Sinclair and Finnis and by incorporating experimental evidence on mixed mode crack propagation observed by transmission electron microscopy (TEM). They have shown experimentally that, even when the orientation of the dislocations in the plastic zone indicated pure mode III crack tip deformation, the crack opening displacement determined from the relative displacement of the crack flanks showed the presence of an additional mode I component. They have also shown that zigzag crack propagation observed in many metals can occur only if mode I cleavage is superimposed to mode II crack tip deformation

  10. Permanent magnetism in phosphine- and chlorine-capped gold: from clusters to nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Marquez, Miguel A., E-mail: miguel.angel@icmse.csic.es; Guerrero, Estefania; Fernandez, Asuncion [Instituto de Ciencia de Materiales de Sevilla (CSIC-US) (Spain); Crespo, Patricia; Hernando, Antonio [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC) (Spain); Lucena, Raquel; Conesa, Jose C. [Instituto de Catalisis y Petroleoquimica (CSIC) (Spain)

    2010-05-15

    Magnetometry results have shown that gold NPs ({approx}2 nm in size) protected with phosphine and chlorine ligands exhibit permanent magnetism. When the NPs size decreases down to the subnanometric size range, e.g. undecagold atom clusters, the permanent magnetism disappears. The near edge structure of the X-ray absorption spectroscopy data points out that charge transfer between gold and the capping system occurs in both cases. These results strongly suggest that nearly metallic Au bonds are also required for the induction of a magnetic response. Electron paramagnetic resonance observations indicate that the contribution to magnetism from eventual iron impurities can be disregarded.

  11. 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.

  12. 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.

  13. The limit of grain refinement on equal channel angular deformation

    International Nuclear Information System (INIS)

    Kopylov, V.I.; Chuvil'deev, V.N.

    2004-01-01

    Experimental and theoretical study results on the process of strain-induced grain refinement under severe plastic deformation are described. A generalization is made for experimental results on deformation dispersing of copper, magnesium and aluminium base alloys as well as unalloyed metals. The model is developed which allows calculating the minimal grain size being able to result from equal channel angular pressing. The expressions describing the dependence of the limit of grain refinement on the nature of the material and severe plastic deformation rate and temperature are obtained [ru

  14. 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

  15. Transient regimes during high-temperature deformation of a bulk metallic glass: A free volume approach

    International Nuclear Information System (INIS)

    Bletry, M.; Guyot, P.; Brechet, Y.; Blandin, J.J.; Soubeyroux, J.L.

    2007-01-01

    The homogeneous deformation of a zirconium-based bulk metallic glass is investigated in the glass transition range. Compression and stress-relaxation tests have been conducted. The stress-strain curves are modeled in the framework of the free volume theory, including transient phenomena (overshoot and undershoot). This approach allows several physical parameters (activation volume, flow defect creation and relaxation coefficient) to be determined from a mechanical experiment. This model is able to rationalize the dependency of stress overshoot on relaxation time. It is shown that, due to the relationship between flow defect concentration and free volume model, it is impossible to determine the equilibrium flow defect concentration. However, the relative variation of flow defect is always the same, and all the model parameters depend on the equilibrium flow defect concentration. The methodology presented in this paper should, in the future, allow the consistency of the free volume model to be assessed

  16. Deformed liquid marbles: Freezing drop oscillations with powders

    KAUST Repository

    Marston, Jeremy; Zhu, Y.; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur T

    2012-01-01

    In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

  17. Deformed liquid marbles: Freezing drop oscillations with powders

    KAUST Repository

    Marston, Jeremy

    2012-09-01

    In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

  18. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haoran; Wang, Zhenxing, E-mail: zxwang@xjtu.edu.cn; Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-08-07

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E{sup −3}, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  19. Co2 and Co3 Mixed Cluster Secondary Building Unit Approach toward a Three-Dimensional Metal-Organic Framework with Permanent Porosity

    Directory of Open Access Journals (Sweden)

    Meng-Yao Chao

    2018-03-01

    Full Text Available Large and permanent porosity is the primary concern when designing metal-organic frameworks (MOFs for specific applications, such as catalysis and drug delivery. In this article, we report a MOF Co11(BTB6(NO34(DEF2(H2O14 (1, H3BTB = 1,3,5-tris(4-carboxyphenylbenzene; DEF = N,N-diethylformamide via a mixed cluster secondary building unit (SBU approach. MOF 1 is sustained by a rare combination of a linear trinuclear Co3 and two types of dinuclear Co2 SBUs in a 1:2:2 ratio. These SBUs are bridged by BTB ligands to yield a three-dimensional (3D non-interpenetrated MOF as a result of the less effective packing due to the geometrically contrasting SBUs. The guest-free framework of 1 has an estimated density of 0.469 g cm−3 and exhibits a potential solvent accessible void of 69.6% of the total cell volume. The activated sample of 1 exhibits an estimated Brunauer-Emmett-Teller (BET surface area of 155 m2 g−1 and is capable of CO2 uptake of 58.61 cm3 g−1 (2.63 mmol g−1, 11.6 wt % at standard temperature and pressure in a reversible manner at 195 K, showcasing its permanent porosity.

  20. Deformation at Lava Lake Volcanoes: Lessons from Karthala

    Science.gov (United States)

    Biggs, J.; Rust, A.; Owens, C.

    2014-12-01

    To remain hot, permanent lava lakes require a continuous connection to a magma reservoir. Depending on the state of the conduit, changes in magma pressure could result in changes in the lake level (hydraulic head) or be accommodated elastically leading to surface deformation. Observing deformation is therefore key to understanding the plumbing system associated with lava lakes. However, the majority of the world's lava lakes lie in difficult socio-economic or remote locations meaning that there are few ground-based observations, and it is often necessary to rely on satellite imagery. Karthala volcano experienced a sequence of eruptions in April 2005, Nov 2005, May 2006 and Jan 2007. The first 3 took place at the Choungou Chahale crater, which typically contains either a water or lava lake; the last formed a new pit crater to the north. Satellite thermal imagery (Hirn et al, 2008) does not show an anomaly during the first eruption, which had a phreatomagmatic component, but large thermal anomalies, associated with an ephemeral lava lake were detected during the Nov 2005 and May 2006 eruptions. The final eruption produced a smaller anomaly attributed to a minor lava flow. Here we present InSAR observations from 2004-2010. We find no significant deformation associated with the first three eruptions, but the January 2007 eruption was associated with ~25 cm of deformation near the volcano's summit, characteristic of a dyke intrusion aligned with the northern rift zone. We also observe an unusual pattern deformation along the coast which may be attributed to rapid settling of soft sediment or recent volcanic deposits triggered by seismic activity. We propose that the first eruption cleared the reservoir-summit connection and interacted with the water in Choungou Chahale. The following eruptions formed a lava lake, but without causing deformation. By the final eruption, the conduit had become blocked and magma intruded along the rift zone causing deformation but no

  1. Introduction of a deformable x-ray CT polymer gel dosimetry system

    Science.gov (United States)

    Maynard, E.; Heath, E.; Hilts, M.; Jirasek, A.

    2018-04-01

    This study introduces the first 3D deformable dosimetry system based on x-ray computed tomography (CT) polymer gel dosimetry and establishes the setup reproducibility, deformation characteristics and dose response of the system. A N-isopropylacrylamide (NIPAM)-based gel formulation optimized for x-ray CT gel dosimetry was used, with a latex balloon serving as the deformable container and low-density polyethylene and polyvinyl alcohol providing additional oxygen barrier. Deformable gels were irradiated with a 6 MV calibration pattern to determine dosimetric response and a dosimetrically uniform plan to determine the spatial uniformity of the response. Wax beads were added to each gel as fiducial markers to track the deformation and setup of the gel dosimeters. From positions of the beads on CT images the setup reproducibility and the limits and reproducibility of gel deformation were determined. Comparison of gel measurements with Monte Carlo dose calculations found excellent dosimetric accuracy, comparable to that of an established non-deformable dosimetry system, with a mean dose discrepancy of 1.5% in the low-dose gradient region and a gamma pass rate of 97.9% using a 3%/3 mm criterion. The deformable dosimeter also showed good overall spatial dose uniformity throughout the dosimeter with some discrepancies within 20 mm of the edge of the container. Tracking of the beads within the dosimeter found that sub-millimetre setup accuracy is achievable with this system. The dosimeter was able to deform and relax when externally compressed by up to 30 mm without sustaining any permanent damage. Internal deformations in 3D produced average marker movements of up to 12 mm along the direction of compression. These deformations were also shown to be reproducible over 100 consecutive deformations. This work has established several important characteristics of a new deformable dosimetry system which shows promise for future clinical applications, including the

  2. The permanent process

    DEFF Research Database (Denmark)

    Møller, Jesper; McCullagh, Peter

    We extend the boson process first to a large class of Cox processes and second an even larger class of infinitely divisible point processes. Density and moment results are studied in detail. These results are obtained in closed form as weighted permanents, so the extension is called a permanent...... process. Temporal extensions and a particularly tractable case of the permanent process are also studied. Extensions of the ferminon process along similar lines, leading to so-called determinant processes, are discussed at the end. While the permanent process is attractive, the determinant process...

  3. Atomistic simulation on the plastic deformation and fracture of bio-inspired graphene/Ni nanocomposites

    Science.gov (United States)

    Yang, Zhenyu; Wang, Dandan; Lu, Zixing; Hu, Wenjun

    2016-11-01

    Molecular dynamics simulations were performed to investigate the plastic deformation and fracture behaviors of bio-inspired graphene/metal nanocomposites, which have a "brick-and-mortar" nanostructure, consisting of hard graphene single-layers embedded in a soft Ni matrix. The plastic deformation mechanisms of the nanocomposites were analyzed as well as their effects on the mechanical properties with various geometrical variations. It was found that the strength and ductility of the metal matrix can be highly enhanced with the addition of the staggered graphene layers, and the plastic deformation can be attributed to the interfacial sliding, dislocation nucleation, and cracks' combination. The strength of the nanocomposites strongly depends on the length scale of the nanostructure and the interlayer distance as well. In addition, slip at the interface releases the stress in graphene layers, leading to the stress distribution on the graphene more uniform. The present results are expected to contribute to the design of the nanolayered graphene/metal composites with high performance.

  4. Friction and Wear of Metals With a Single-Crystal Abrasive Grit of Silicon Carbide - Effect of Shear Strength of Metal

    National Research Council Canada - National Science Library

    Miyoshi, Kazuhisa

    1978-01-01

    An investigation was conducted to examine the removal and plastic deformation of metal as a function of the metal properties when the metal is in sliding contact with a single-crystal abrasive grit of silicon carbide...

  5. UTILIZATION OF STEREOLOGY FOR QUANTITATIVE ANALYSIS OF PLASTIC DEFORMATION OF FORMING PIECES

    Directory of Open Access Journals (Sweden)

    Maroš Martinkovič

    2012-01-01

    Full Text Available Mechanical working leads to final properties of forming pieces, which are affected by conditions of production technology. Utilization of stereology leads to the detail analysis of three-dimensional plastic deformed material structure by different forming technologies, e.g. forging, extruding, upsetting, metal spinning, drawing etc. The microstructure of cold drawing wires was analyzed. Grain boundaries orientation was measured on the parallel section of wire with a different degree of deformation and direct axis plastic deformation was evaluated in bulk formed part. The strain of probes on their sections was obtained using stereology by measurement of degree of grain boundary orientation which was converted to deformation using model of conversion of grain boundary orientation degree to deformation.

  6. An interatomic potential for studying CuZr bulk metallic glasses

    DEFF Research Database (Denmark)

    Paduraru, Anca; Kenoufi, Abdel; Bailey, Nicholas

    2007-01-01

    -scale deformation events and may furthermore involve localization through formation of shear bands. In this paper, an Effective Medium Theory (EMT) potential optimized for modeling the mechanical and thermodynamic properties of CuZr bulk metallic glass is studied. The late transition metals crystallizing in close......The mechanical properties of BMGs are remarkably different from the ones of ordinary metallic alloys due to the atomic level disorder in the glassy state. Unlike crystalline materials plastic deformation in metallic glasses cannot be caused by lattice defects but takes place through atomic...

  7. Microstructural evolution at multiple scales during plastic deformation

    DEFF Research Database (Denmark)

    Winther, Grethe

    During plastic deformation metals develop microstructures which may be analysed on several scales, e.g. bulk textures, the scale of individual grains, intragranular phenomena in the form of orientation spreads as well as dislocation patterning by formation of dislocation boundaries in metals of m......, which is backed up by experimental data [McCabe et al. 2004; Wei et al., 2011; Hong, Huang, & Winther, 2013]. The current state of understanding as well as the major challenges are discusse....

  8. PSInSAR technology and its use for monitoring of the Earth's surface deformation; Technologia PSInSAR a jej vyuzitie na monitorovanie deformacii zemskeho povrchu

    Energy Technology Data Exchange (ETDEWEB)

    Batorova, K [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra inzinierskej geologie, 84215 Bratislava (Slovakia)

    2012-04-25

    Method of permanent reflex points (PSInSAR) allows to monitor the time evolution of deformations of the Earth's surface with a millimeter precision. For deformation size determination there are used the maps of movement speed or time delay of line set of data that are obtained by evaluating of SAR images. SAR files must be processed using the basic mathematical calculation presented in the work, with an emphasis on the parameters used in geology. Extensive processing of multiple SAR imagery showed that they can be used during monitoring of the field with an accurate identification of the objects on the Earth's surface, which provide a stable reflection of radar rays transmitted from the satellite. These objects are known as permanent reflection points (PS). PS can be geo-referenced, allowing accurate determination of the movement size of the Earth's surface deformation. In this paper an example of using of PSInSAR technology for monitoring of slope movements on the territory of Slovakia is presented. (authors)

  9. Measuring co-seismic deformation of the Sichuan earthquake by satellite differential INSAR

    Science.gov (United States)

    Zhang, Yonghong; Gong, Wenyu; Zhang, Jixian

    2008-12-01

    The Sichuan Earthquake, occurred on May 12, 2008, is the strongest earthquake to hit China since the 1976 Tangshan earthquake. The earthquake had a magnitude of M 8.0, and caused surface deformation greater than 3 meters. This paper presents the research work of measuring the co-seismic deformations of the earthquake with satellite differential interferometric SAR technique. Four L-band SAR images were used to form the interferogram with 2 pre- scenes imaged on Feb 17, 2008 and 2 post- scenes on May 19, 2008. The Digital Elevation Models extracted from 1:50,000-scale national geo-spatial database were used to remove the topographic contribution and form a differential interferogram. The interferogram presents very high coherence in most areas, although the pre- and post- images were acquired with time interval of 92 days. This indicates that the L-band PALSAR sensor is very powerful for interferometry applications. The baseline error is regarded as the main phase error source in the differential interferogram. Due to the difficulties of doing field works immediately after the earthquake, only one deformation measurement recorded by a permanent GPS station is obtained for this research. An approximation method is proposed to eliminate the orbital phase error with one control point. The derived deformation map shows similar spatial pattern and deformation magnitude compared with deformation field generated by seismic inversion method.

  10. Recrystallization of magnesium deformed at low temperatures

    International Nuclear Information System (INIS)

    Fromageau, R.; Pastol, J.L.; Revel, G.

    1978-01-01

    The recrystallization of magnesium was studied after rolling at temperatures ranging between 248 and 373 K. For zone refined magnesium the annealing behaviour as observed by electrical resistivity measurements showed two stages at about 250 K and 400 K due respectively to recrystallization and grain growth. The activation energy associated with the recrystallization stage was 0.75 +- 0.01 eV. In less pure magnesium, with nominal purity 99.99 and 99.9%, the recrystallization stage was decomposed into two substages. Activation energies were determined in relation with deformation temperature and purity. The magnesium of intermediate purity (99.99%) behaved similarly to the lowest purity metal when it was deformed at high temperature and to the purest magnesium when the deformation was made at low temperature. This behaviour was discussed in connection with the theories of Luecke and Cahn. (Auth.)

  11. Metals and Neurodegeneration

    Science.gov (United States)

    Chen, Pan; Miah, Mahfuzur Rahman; Aschner, Michael

    2016-01-01

    Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain–Barré disease, Gulf War syndrome, Huntington’s disease, multiple sclerosis, Parkinson’s disease, and Wilson’s disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration. PMID:27006759

  12. Deformation twinning in metals and ordered intermetallics-Ti and Ti-aluminides

    Science.gov (United States)

    Yoo, M. H.; Fu, C. L.; Lee, J. K.

    1991-06-01

    The role of deformation twinning in the strength and ductility of metals and ordered intermetallic alloys is examined on the basis of crystallography, energetics and kinetics of deformation twinning. A systematic analysis is made by taking Ti, Ti3AI, TiAl, and A13Ti as four model systems. In comparison with profuse twinning in Ti, the intrinsic difficulty of twinning in Ti3A1 is rationalized in terms of the interchange shuffling mechanism. A fault (SISF) dragging mechanism based on the interaction torque explains the physical source for the low mobility of screw superdislocations in TiAl, which may lead to (111) [ 11bar{2}] twin nucleation. In TiAl and A13Ti alloys, the twin-slip (ordinary) conjugate relationship makes an important contribution to the strain compatibility for high-temperature plasticity. Potentially beneficial alloying additions to promote twinning are discussed. Les conséquences de la déformation par maclage sur la fracture et la ductilité des métaux et alliages intermétalliques ordonnés sont étudiées en fonction de la cristallographie, de l'énergie et de la cinétique des déformations par maclage. Une analyse systématique a été faite en considérant Ti, Ti3AI, TiAl et A13Ti comme quatre systèmes modèles. En comparaison avec le nombre important de maclages observés dans Ti, la difficulté intrinsèque des maclages dans Ti3AI est rationalisée en terme de mécanisme d'“interchange shuffling”. Un mécanisme de “dragging fault” basé sur l'interaction “torque” explique l'origine physique de la faible mobilité des superdislocations vissées dans TiAl qui peuvent conduire à la nucléation des macles (111) 112. Dans les alliages tels TiAl et A13Ti, la relation conjuguée entre la macle et le glissement (ordinaire) contribue de façon importante à la compatibilité des contraintes lors de la déformation plastique à haute température. Des effets bénéfiques potentiels liés à des éléments d'addition sur le processus

  13. Metal-fuel modeling for inherently safe reactor designs

    International Nuclear Information System (INIS)

    Miles, K.J. Jr.

    1987-01-01

    Current development of breeder reactor systems has led to the renewed interest in metal fuels. These fuels have properties that enhance the inherent safety of the system, such as high thermal conductivity, compatibility with liquid sodium, and low fuel/cladding mechanical interaction. While metal-fuel irradiation behavior is well understood, there are some areas where more information is needed to fully understand the various safety-related phenomena, such as fuel/cladding chemical interaction, eutectic melting and penetration, and axial relocation of molten fuel prior to cladding breach. Because many of these phenomena can cause changes in the reactivity state of the system, their effects on whole-core normal, anticipated, and hypothetical accident scenarios need to be studied. The metal-fuel behavior model DEFORM-5 is being developed to provide the necessary phenomenological basis for these studies. The first stage in the DEFORM-5 development has been completed. Presently, DEFORM-5 calculates the cladding strain, life fraction, and eutectic penetration thinning for Types D9, HT9, or 316 steels. This first stage of DEFORM-5 has been used to analyze the TREAT M2, M3, and M4 transients with irradiated Experimental Breeder Reactor-II driver fuel. The paper shows the DEFORM-5 and experimental results for failure times for the test pins. The results provide confidence and validation of the DEFORM-5 modeling of the cladding behavior

  14. Retention and Deformation of Cobalt-Chromium and High-Impact Polyamide Clasps

    Directory of Open Access Journals (Sweden)

    Övül Kümbüloğlu

    2018-04-01

    Full Text Available Objective: The use of metal clasps especially in anterior region may cause aesthetic problems. Polyamide resin has been suggested as an alternative aesthetic denture clasp material. This study compared the retentive force and deformation of cobalt-chromium and polyamide clasps after 36 months of simulated clinical use. Materials and Methods: The retentive force for clasp removal was measured in distilled water using a custom-made apparatus with intervals corresponding to 0, 6, 12, 18, 24, 30 and 36 months of simulated clinical use. The distance (mm between the retentive and reciprocal clasp tips was measured using a microscope before and after the insertion-removal procedures. Results: Significant difference was observed in distance between clasp tips for metal clasps between baseline and 36 months for molars and premolars (p0.05. Conclusion: Polyamide clasps could be alternative to metal clasps particularly on premolars with reliable retention and deformation.

  15. 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.

  16. The Question of Decalage Between Object Permanence and Person Permanence

    Science.gov (United States)

    And Others; Jackson, Elaine

    1978-01-01

    Presents a study of decalage between object permanence and person permanence. Decalage was influenced by environmental as well as stimulus factors with infants tested between 6- and 81/4-months/of-age. (BD)

  17. An Iterative Method for Estimating Airfoil Deformation due to Solid Particle Erosion

    Directory of Open Access Journals (Sweden)

    Valeriu DRAGAN

    2014-04-01

    Full Text Available Helicopter blades are currently constructed with composite materials enveloping honeycomb cores with only the leading and trailing edges made of metal alloys. In some cases, the erosive wear of the bound between the composite skin and metallic leading edge leads to full blade failure. It is therefore the goal of this paper to provide a method for simulating the way an airfoil is deformed through the erosion process. The method involves computational fluid dynamics simulations, scripts for automatic meshing and spreadsheet calculators for estimating the erosion and, ultimately, the airfoil deformation. Further work could include more complex meshing scripts allowing the use of similar methods for turbo-machineries.

  18. Essure Permanent Birth Control

    Science.gov (United States)

    ... Prosthetics Essure Permanent Birth Control Essure Permanent Birth Control Share Tweet Linkedin Pin it More sharing options ... Print Essure is a a permanently implanted birth control device for women (female sterilization). Implantation of Essure ...

  19. Pressure-induced irreversible metallization accompanying the phase transitions in S b2S3

    Science.gov (United States)

    Dai, Lidong; Liu, Kaixiang; Li, Heping; Wu, Lei; Hu, Haiying; Zhuang, Yukai; Yang, Linfei; Pu, Chang; Liu, Pengfei

    2018-01-01

    We have revealed S b2S3 to have two phase transitions and to undergo metallization using a diamond anvil cell at around 5.0, 15.0, and 34.0 GPa, respectively. These results were obtained on the basis of high-pressure Raman spectroscopy, temperature-dependent conductivity measurements, atomic force microscopy, high-resolution transmission electron microscopy, and first-principles calculations. The first phase transition at ˜5.0 GPa is an isostructural phase transition, which is manifested in noticeable changes in five Raman-active modes and the slope of the conductivity because of a change in the electronic structure. The second pressure-induced phase transition was characterized by a discontinuous change in the slope of conductivity and a new low-intensity Raman mode at ˜15.0 GPa . Furthermore, a semiconductor-to-metal transition was found at ˜34.0 GPa , which was accompanied by irreversible metallization, and it could be attributed to the permanently plastic deformation of the interlayer spacing. This high-pressure behavior of S b2S3 will help us to understand the universal crystal structure evolution and electrical characteristics for A2B3 -type compounds, and to facilitate their application in electronic devices.

  20. Simulation of Stamping Process of Automotive Panel Considering Die Deformation

    International Nuclear Information System (INIS)

    Keum, Y.T.; Ahn, I.H.; Lee, I.K.; Song, M.H.; Kwon, S.O.; Park, J.S.

    2005-01-01

    In order to see the effect of die deformation on the forming of sheet metals, the draw-ins, strains, and spring-backs of an automotive fender panels are numerically simulated considering the die deformation, which is found by the simultaneous structural analysis of press and dies. By coupling the forming analysis and the structural analysis, the die deformation is simultaneously taken into account in the forming process. Furthermore, for the consideration of load difference transferred among the upper die, punch, and blank holder due to the changes in sheet thickness, the gap elements are employed instead of the blank sheet in the structural analysis. The numerical simulation results of an automotive fender draw panel are compared with the measurements. The comparison of the forming and spring-back analysis results between the rigid die and the deformed die shows that the deformed tool provides more accurate forming and spring-back prediction

  1. Cell response to nanocrystallized metallic substrates obtained through severe plastic deformation.

    Science.gov (United States)

    Bagherifard, Sara; Ghelichi, Ramin; Khademhosseini, Ali; Guagliano, Mario

    2014-06-11

    Cell-substrate interface is known to control the cell response and subsequent cell functions. Among the various biophysical signals, grain structure, which indicates the repeating arrangement of atoms in the material, has also proved to play a role of significant importance in mediating the cell activities. Moreover, refining the grain size through severe plastic deformation is known to provide the processed material with novel mechanical properties. The potential application of such advanced materials as biomedical implants has recently been evaluated by investigating the effect of different substrate grain sizes on a wide variety of cell activities. In this review, recent advances in biomedical applications of severe plastic deformation techniques are highlighted with special attention to the effect of the obtained nano/ultra-fine-grain size on cell-substrate interactions. Various severe plastic deformation techniques used for this purpose are discussed presenting a brief description of the mechanism for each process. The results obtained for each treatment on cell morphology, adhesion, proliferation, and differentiation, as well as the in vivo studies, are discussed. Finally, the advantages and challenges regarding the application of these techniques to produce multifunctional bio-implant materials are addressed.

  2. Gate-tunable gigantic lattice deformation in VO2

    International Nuclear Information System (INIS)

    Okuyama, D.; Hatano, T.; Nakano, M.; Takeshita, S.; Ohsumi, H.; Tardif, S.; Shibuya, K.; Yumoto, H.; Koyama, T.; Ohashi, H.; Takata, M.; Kawasaki, M.; Tokura, Y.; Iwasa, Y.; Arima, T.

    2014-01-01

    We examined the impact of electric field on crystal lattice of vanadium dioxide (VO 2 ) in a field-effect transistor geometry by in-situ synchrotron x-ray diffraction measurements. Whereas the c-axis lattice parameter of VO 2 decreases through the thermally induced insulator-to-metal phase transition, the gate-induced metallization was found to result in a significant increase of the c-axis length by almost 1% from that of the thermally stabilized insulating state. We also found that this gate-induced gigantic lattice deformation occurs even at the thermally stabilized metallic state, enabling dynamic control of c-axis lattice parameter by more than 1% at room temperature

  3. Estimation of strength parameters of small-bore metal-polymer pipes

    Science.gov (United States)

    Shaydakov, V. V.; Chernova, K. V.; Penzin, A. V.

    2018-03-01

    The paper presents results from a set of laboratory studies of strength parameters of small-bore metal-polymer pipes of type TG-5/15. A wave method was used to estimate the provisional modulus of elasticity of the metal-polymer material of the pipes. Longitudinal deformation, transverse deformation and leak-off pressure were determined experimentally, with considerations for mechanical damage and pipe bend.

  4. METHODS FOR LOCAL CHANGES IN THE PLASTIC DEFORMATION DIAGNOSTICS ON THE WORK FUNCTION

    Directory of Open Access Journals (Sweden)

    K. V. Panteleyev

    2015-01-01

    Full Text Available The paper describes the electronic work function measurements by the contact potential difference technique, and experimental demonstration of the possibility of these methods application for the stress-strain state of the surface layer of the metals and alloys. The techniques end examples of their application of localization of plastic deformation studies using the Kelvin probe are developed and present. The study topology of work function the deformed surface possible to determine the type of deformation and dynamics of

  5. Permanences GAG-EPA

    CERN Document Server

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  6. 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

  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. Effect of Prior Deformation on Welding Microstructure of Steel 304L

    Directory of Open Access Journals (Sweden)

    WU Luo-fei

    2017-01-01

    Full Text Available This subject was raised by an automotive company.Based on the welding design on the curved surface,the effect of prior deformation on the weld structure was studied.Metal active-gas welding was used on the T-joint and pre-deformed plates of austenitic stainless steel 304L to find the proper welding parameters and observe the effect of prior deformation on the microstructure.The proper parameters acquired are:the speed of the torch is 4mm/s,the speed of delivery of welding wire is 2.5m/min and the voltage is 17V.In the T-joint and pre-deformed joint,the weld toes are in the zone with strain of 0% and 30%.In the pre-deformed welding specimen,it was observed that the fusion zone and partially melted zone are narrowed,carbide precipitation and ferrites are found less.In all,the microstructure in the pre-deformed weld joints on 304L is more uniform.

  9. A Brief Overview of a Scale Independent Deformation Theory and Application to Diagnosis of Deformational Status of Solid-State Materials

    International Nuclear Information System (INIS)

    Yoshida, Sanichiro

    2012-01-01

    A field theoretical approach to deformation and fracture of solid-state material is outlined, and its application to diagnosis of deformational status of metal specimens is discussed. Being based on a fundamental physical principle known as local symmetry, this approach is intrinsically scale independent, and capable of describing all stages of deformation on the same theoretical foundation. This capability enables us to derive criteria that can be used to diagnose transitions from the elastic to plastic regime, and the plastic to fracturing regime. For practical applications of these criteria, an optical interferometric technique known as electronic speckle-pattern interferometry is proved to be quite powerful; it is able to visualize the criteria as a whole image of the object on a real-time basis without numerical processing. It is demonstrated that this method is able to reveal loading hysteresis as well

  10. Predicting Shear Transformation Events in Metallic Glasses

    Science.gov (United States)

    Xu, Bin; Falk, Michael L.; Li, J. F.; Kong, L. T.

    2018-03-01

    Shear transformation is the elementary process for plastic deformation of metallic glasses, the prediction of the occurrence of the shear transformation events is therefore of vital importance to understand the mechanical behavior of metallic glasses. In this Letter, from the view of the potential energy landscape, we find that the protocol-dependent behavior of shear transformation is governed by the stress gradient along its minimum energy path and we propose a framework as well as an atomistic approach to predict the triggering strains, locations, and structural transformations of the shear transformation events under different shear protocols in metallic glasses. Verification with a model Cu64 Zr36 metallic glass reveals that the prediction agrees well with athermal quasistatic shear simulations. The proposed framework is believed to provide an important tool for developing a quantitative understanding of the deformation processes that control mechanical behavior of metallic glasses.

  11. The use of expanded polytetrafluoroethylene in depressed deformities of the face.

    Science.gov (United States)

    Liu, Xiaowei; Zhang, Yiming; Wang, Shaoliang; Lei, Zeyuan; Li, Xiang; Fan, Dongli

    2016-11-01

    Expanded polytetrafluoroethylene (ePTFE) has been extensively used for facial soft tissue augmentation procedures, and is regarded as safe and reliable and suitable as a permanent implant. This implant is generally used in the lower third of the face for lips filling, nasal augmentation, nasolabial folds and chin augmentation, and rarely for congenital or acquired depressed deformities of the face. The aim of the present study was to assess the effects of ePTFE in congenital or acquired depressed deformities of the face. From September, 2008 to January, 2014, 26 patients were implanted with the material ePTFE to correct depressed deformities of the face. The average age at operation was 23.2 years, with a range of 17-45 years. The depressed deformities were lateralized. The follow-up period was 6-18 months (average 9 months). The etiologies of the depressed deformities included stable hemifacial atrophy (3 cases), craniofacial microsomia (13 cases), bony depression after trauma (8 cases), and other unclear reasons (2 cases). The operations were performed under local anesthesia. ePTFE was inserted in different tissue planes that varied among the different subanatomical areas in the face: beneath the superficial temporal fascia in the temporal area, and on the surface of the superficial musculoaponeurotic system in the zygomatic area, cheek and mandibular area. All of the patients were followed up. Most of the patients [25 of 26 patients (96.2%)] were satisfied with the results, while 1 patient (3.8%) was not satisfied for incomplete correction of the depressed deformity. In conclusion, aside from lipofilling and a free flap transfer, the results showed that ePTFE was an alternative treatment for facial depressed deformity.

  12. A study of thermal deformation in the carriage of a permanent magnet direct drive linear motor stage

    International Nuclear Information System (INIS)

    Chow, J.H.; Zhong, Z.W.; Lin, W.; Khoo, L.P.

    2012-01-01

    Carriage deformation due to temperature gradients within the materials of the carriage affects the accuracy of precision machines. This is largely due to the indeterminist temperature distribution in the carriage's material caused by the non-linearity of heat transfer. The joule heat from the motor coil forms the main heat source. When coupled with the heat loss through convection and radiation, the temperature variation in the motor's carriage also increases. In this study, the Finite Element Analysis was used together with a set of boundary conditions, which was obtained empirically, to analyze the distortion of the motor's carriage. The simulated results were compared with those obtained through experiments. The study shows that it is important to know, rather than to assume, the thermal boundary conditions of the motor's carriage of a precision machine in order to accurately estimate the thermal deformation of the carriage in precision machining. - Highlights: ► Deformation occurs in carriages which are mounted with linear motor. ► The convective coefficient, which is assumed to be 10 W mm −2 , is shown to be invalid. ► The perfect contact conductance is shown to be invalid too. ► To have an accurate thermal model, boundary conditions have to be realistic. ► Boundary conditions are the heat source, convective and conductance values.

  13. Modelling the void deformation and closure by hot forging of ingot castings

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Kotas, Petr

    2012-01-01

    by mechanical deformation. The aim of this paper is to analyze numerically if and to what degree the voids areclosed by the forging. Using the commercial simulation software ABAQUS, both simplified model ingots and physically manufactured ingots containing prescribed void distributions are deformed and analyzed....... The analysis concernsboth the void density change and the location of the voids in the part after deformation. The latter can be important for the subsequent reliability of the parts, for instance regarding fatigue properties. The analysis incorporates the Gurson yield criterion for metals containing voids...... and focuses on how the voids deform depending on their size and distribution in the ingot as well ashow the forging forces are applied....

  14. Modeling of macrosegregation caused by volumetric deformation in a coherent mushy zone

    Science.gov (United States)

    Nicolli, Lilia C.; Mo, Asbjørn; M'hamdi, Mohammed

    2005-02-01

    A two-phase volume-averaged continuum model is presented that quantifies macrosegregation formation during solidification of metallic alloys caused by deformation of the dendritic network and associated melt flow in the coherent part of the mushy zone. Also, the macrosegregation formation associated with the solidification shrinkage (inverse segregation) is taken into account. Based on experimental evidence established elsewhere, volumetric viscoplastic deformation (densification/dilatation) of the coherent dendritic network is included in the model. While the thermomechanical model previously outlined (M. M’Hamdi, A. Mo, and C.L. Martin: Metall. Mater. Trans. A, 2002, vol. 33A, pp. 2081-93) has been used to calculate the temperature and velocity fields associated with the thermally induced deformations and shrinkage driven melt flow, the solute conservation equation including both the liquid and a solid volume-averaged velocity is solved in the present study. In modeling examples, the macrosegregation formation caused by mechanically imposed as well as by thermally induced deformations has been calculated. The modeling results for an Al-4 wt pct Cu alloy indicate that even quite small volumetric strains (≈2 pct), which can be associated with thermally induced deformations, can lead to a macroscopic composition variation in the final casting comparable to that resulting from the solidification shrinkage induced melt flow. These results can be explained by the relatively large volumetric viscoplastic deformation in the coherent mush resulting from the applied constitutive model, as well as the relatively large difference in composition for the studied Al-Cu alloy in the solid and liquid phases at high solid fractions at which the deformation takes place.

  15. Metal Organic Frameworks (MOFs)

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 11. Molecule Matters - Metal Organic Frameworks (MOFs). R Sarvanakumar S Sankararaman. Feature Article Volume 12 Issue 11 November 2007 pp 77-86. Fulltext. Click here to view fulltext PDF. Permanent link:

  16. Casting characteristics of Al-Mg alloy 535 cast in permanent moulds

    International Nuclear Information System (INIS)

    Fasoyinu, F.A.; Thomson, J.; Cousineau, D.; Castles, T.; Sahoo, M.

    2002-01-01

    Aluminum alloy 535 could be used for automotive and marine applications because of its good corrosion resistance against mild alkaline and salt spray exposure. The majority of components from this alloy are usually produced by sand casting because it is prone to hot shortness and has poor fluidity when poured in permanent moulds. In an attempt to improve its castability in permanent moulds, casting characteristics such as casting fluidity and hot tear resistance have been studied. In addition, the effectiveness of titanium, boron, scandium, zirconium and a combination of selected elements from this group as grain refiners were evaluated. It s shown that alloy 535 exhibits good casting fluidity when poured with adequate metal superheat and that there is significant improvement in hot tear resistance following grain refinement. (author)

  17. Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

    Science.gov (United States)

    Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

    2015-01-01

    Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

  18. Metal viscoplasticity with two-temperature thermodynamics and two dislocation densities

    Science.gov (United States)

    Roy Chowdhury, Shubhankar; Kar, Gurudas; Roy, Debasish; Reddy, J. N.

    2018-03-01

    Posed within the two-temperature theory of non-equilibrium thermodynamics, we propose a model for thermoviscoplastic deformation in metals. We incorporate the dynamics of dislocation densities-mobile and forest—that play the role of internal state variables in the formulation. The description based on two temperatures appears naturally when one recognizes that the thermodynamic system undergoing viscoplastic deformation is composed of two weakly interacting subsystems, viz. a kinetic-vibrational subsystem of the vibrating atomic lattices and a configurational subsystem of the slower degrees of freedom relating to defect motion, each with its own temperature. Starting with a basic model that involves only homogeneous deformation, a three-dimensional model for inhomogeneous viscoplasticity applicable to finite deformation is charted out in an overstress driven viscoplastic deformation framework. The model shows how the coupled evolutions of mobile and forest dislocation densities, which are critically influenced by the dynamics of configurational temperature, govern the strength and ductility of the metal. Unlike most contemporary models, the current proposal also affords a prediction of certain finer details as observed in the experimental data on stress-strain behaviour of metals and this in turn enhances the understanding of the evolving and interacting dislocation densities.

  19. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.T.; Hong, S.H.; Lee, C.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, J.M., E-mail: jinman_park@hotmail.com [Materials Research Center, Samsung Advanced Institute of Technology (SAIT), San 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of); Kim, T.W.; Lee, W.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yim, H.I. [Department of Physics, Sookmyung Women’s University, Hyochangwongil 52, Yongsan-ku, Seoul 140-742 (Korea, Republic of); Kim, K.B., E-mail: kbkim@sejong.ac.kr [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2014-02-25

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe{sub 52}Co{sub 20−x}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub x} alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe{sub 52}Co{sub 17}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub 3} bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept.

  20. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    International Nuclear Information System (INIS)

    Kim, J.T.; Hong, S.H.; Lee, C.H.; Park, J.M.; Kim, T.W.; Lee, W.H.; Yim, H.I.; Kim, K.B.

    2014-01-01

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe 52 Co 20−x B 20 Si 4 Nb 4 Cr x alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe 52 Co 17 B 20 Si 4 Nb 4 Cr 3 bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept

  1. Werkstoffwoche 98. Vol. 6. Symposium 8: Metals. Symposium 14: Metals modelling

    International Nuclear Information System (INIS)

    Kopp, R.; Beiss, P.; Herfurth, K.; Boehme, D.; Bormann, R.; Arzt, E.; Riedel, H.

    1999-01-01

    The proceedings volume contains the papers of the symposia dealing with metals and the focus is on the following subjects: Deformation, powder metallurgy, forming by casting processes, joining, materials physics (ferrous materials, light metal materials, composite materials, high-temperature materials, functional materials), intermetallic phases and foams, modelling calculations. 26 of the papers have been analysed and processed for individual document retrieval from the ENERGY database. (orig/MM) [de

  2. Stress factors for the deformation systems of zirconium under multiaxial stress

    International Nuclear Information System (INIS)

    Hobson, D.O.

    1976-01-01

    Calculation of the resolved shear stresses (rss) that act on various deformation systems in metals and, in particular, the determination of those systems subjected to the highest rss by a given set of multiaxial stresses is of importance in the study of texture development, yielding and plastic flow. This study examines the geometrical influences of any stress state on the deformation modes of zirconium. One slip mode and three twinning modes, comprising twenty-one deformation systems, are considered. Stress factors computed for these systems are shown on a coordinate system that allows specimen orientation, most highly stressed deformation system, and stress factor to be shown without ambiguity. The information in this report allows the determination of the rss that results from any multiaxial stress state; this information also allows the prediction of the deformation modes that might operate for any specimen orientation in that strss state

  3. Study beryllium microplastic deformation

    International Nuclear Information System (INIS)

    Papirov, I.I.; Ivantsov, V.I.; Nikolaenko, A.A.; Shokurov, V.S.; Tuzov, Yu.V.

    2015-01-01

    Microplastic flow characteristics systematically studied for different varieties beryllium. In isostatically pressed beryllium it decreased with increasing particle size of the powder, increasing temperature and increasing the pressing metal purity. High initial values of the limit microelasticity and microflow in some cases are due a high level of internal stresses of thermal origin and over time it can relax slowly. During long-term storage of beryllium materials with high initial resistance values microplastic deformation microflow limit and microflow stress markedly reduced, due mainly to the relaxation of thermal microstrain

  4. Net Shape 3D Printed NdFeB Permanent Magnet

    OpenAIRE

    Jacimovic, J.; Binda, F.; Herrmann, L. G.; Greuter, F.; Genta, J.; Calvo, M.; Tomse, T.; Simon, R. A.

    2016-01-01

    For two decades, NdFeB based magnets have been a critical component in a range of electrical devices engaged in energy production and conversion. The magnet shape and the internal microstructure of the selected NdFeB grade govern their efficiency and size. However, stricter requirements on device efficiency call for better performing magnets preferably with novel functionality not achievable today. Here we use 3D metal printing by Selective Laser Melting to fabricate dense net shape permanent...

  5. Metallic artifact mitigation and organ-constrained tissue assignment for Monte Carlo calculations of permanent implant lung brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, J. G. H.; Miksys, N.; Thomson, R. M., E-mail: rthomson@physics.carleton.ca [Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Furutani, K. M. [Department of Radiation Oncology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905 (United States)

    2014-01-15

    assignment within lung contours are employed in generated phantoms, this erroneous assignment is reduced, generally resulting in higher doses. Lung-constrained tissue assignment also results in increased doses in regions of interest due to a reduction in the erroneous assignment of adipose to voxels within lung contours. Differences in dose metrics calculated for different computational phantoms are sensitive to radionuclide photon spectra with the largest differences for{sup 103}Pd seeds and smallest but still considerable differences for {sup 131}Cs seeds. Conclusions: Despite producing differences in CT images, dose metrics calculated using the STR, fan beam + STR, and 3D median filter techniques produce similar dose metrics. Results suggest that the accuracy of dose distributions for permanent implant lung brachytherapy is improved by applying lung-constrained tissue assignment schemes to metallic artifact corrected images.

  6. Incremental deformation: A literature review

    Directory of Open Access Journals (Sweden)

    Nasulea Daniel

    2017-01-01

    Full Text Available Nowadays the customer requirements are in permanent changing and according with them the tendencies in the modern industry is to implement flexible manufacturing processes. In the last decades, metal forming gained attention of the researchers and considerable changes has occurred. Because for a small number of parts, the conventional metal forming processes are expensive and time-consuming in terms of designing and manufacturing preparation, the manufacturers and researchers became interested in flexible processes. One of the most investigated flexible processes in metal forming is incremental sheet forming (ISF. ISF is an advanced flexible manufacturing process which allows to manufacture complex 3D products without expensive dedicated tools. In most of the cases it is needed for an ISF process the following: a simple tool, a fixing device for sheet metal blank and a universal CNC machine. Using this process it can be manufactured axis-symmetric parts, usually using a CNC lathe but also complex asymmetrical parts using CNC milling machines, robots or dedicated equipment. This paper aim to present the current status of incremental sheet forming technologies in terms of process parameters and their influences, wall thickness distribution, springback effect, formability, surface quality and the current main research directions.

  7. Formation of incoherent deformation twin boundaries in a coarse-grained Al-7Mg alloy

    Science.gov (United States)

    Jin, S. B.; Zhang, K.; Bjørge, R.; Tao, N. R.; Marthinsen, K.; Lu, K.; Li, Y. J.

    2015-08-01

    Deformation twinning has rarely been observed in coarse grained Al and its alloys except under some extreme conditions such as ultrahigh deformation strain or strain rates. Here, we report that a significant amount of Σ3 deformation twins could be generated in a coarse-grained Al-7 Mg alloy by dynamic plastic deformation (DPD). A systematic investigation of the Σ3 boundaries shows that they are Σ3{112} type incoherent twin boundaries (ITBs). These ITBs have formed by gradual evolution from copious low-angle deformation bands through -twist Σ boundaries by lattice rotation. These findings provide an approach to generate deformation twin boundaries in high stacking fault energy metallic alloys. It is suggested that high solution content of Mg in the alloy and the special deformation mode of DPD played an important role in formation of the Σ and ITBs.

  8. 3-D analysis of eddy current in permanent magnet of interior permanent magnet motors

    International Nuclear Information System (INIS)

    Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi

    2002-01-01

    Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)

  9. Rotation of small clusters in sheared metallic glasses

    International Nuclear Information System (INIS)

    Delogu, Francesco

    2011-01-01

    Graphical abstract: When a Cu 50 Ti 50 metallic glass is shear-deformed, the irreversible rearrangement of local structures allows the rigid body rotation of clusters. Highlights: → A shear-deformed Cu 50 Ti 50 metallic glass was studied by molecular dynamics. → Atomic displacements occur at irreversible rearrangements of local structures. → The dynamics of such events includes the rigid body rotation of clusters. → Relatively large clusters can undergo two or more complete rotations. - Abstract: Molecular dynamics methods were used to simulate the response of a Cu 50 Ti 50 metallic glass to shear deformation. Attention was focused on the atomic displacements taking place during the irreversible rearrangement of local atomic structures. It is shown that the apparently disordered dynamics of such events hides the rigid body rotation of small clusters. Cluster rotation was investigated by evaluating rotation angle, axis and lifetimes. This permitted to point out that relatively large clusters can undergo two or more complete rotations.

  10. Comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement

    International Nuclear Information System (INIS)

    Stumberger, Bojan; Stumberger, Gorazd; Hadziselimovic, Miralem; Hamler, Anton; Gorican, Viktor; Jesenik, Marko; Trlep, Mladen

    2007-01-01

    The paper presents a comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement. Motors with the following permanent magnet topologies were accounted for in the comparison: the surface-mounted permanent magnet synchronous motor (SMPMSM), the interior permanent magnet synchronous motor (IPMSM), the permanent magnet-assisted synchronous reluctance motor (PMASRM) and the flux reversal permanent magnet motor (FRPMM). Finite element method analysis is employed to determine the performance of each motor. Calculated performance of four-pole IPMSM determined by finite element method calculation is confirmed with the measurements at nearly constant nominal output power in the range of speed 3000-10,000 rpm

  11. Plasma metallization of aluminium oxide powder

    International Nuclear Information System (INIS)

    Smirnov, A.I.; Petrunichev, V.A.

    1981-01-01

    The sintering ability of cermets of metallized granulas of aluminium and matrix materials, such as chromium, nickel and nichrome is studied. Deformation tests of samples of cermets with molybdenum coated granules show satisfactory results at normal and high temperatures without fracture of metall-oxide interfaces [ru

  12. Effect of Chord Splice Joints on Force Distribution and Deformations in Trusses with Punched Metal Plate Fasteners

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    2007-01-01

    The span of roof trusses with punched metal plate fasteners (nail plates) makes it often necessary to use splice joints in the top and bottom chords. In the finite element models used for design of the trusses these splice joints are normally assumed to be either rotationally stiff or pinned....... Timber-to-timber contact and non-linear elastic behaviour are included in the model. Results from tests with joints under fourpoint bending are compared with predictions given by TrussLab, and a good agreement is found. Splice joints in trusses with nail plates may be assumed to be rotationally stiff...... if their deformation has no significant effect upon the distribution of member forces according to Eurocode 5. Two simple guidelines for the design and location of splice joints are given in Eurocode 5 for treating the splice joints as rotationally stiff. The reasonability of these guidelines and the influence...

  13. On the nature of low temperature internal friction peaks in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Khonik, V.A. [State Pedagogical Univ., Voronezh (Russian Federation); Spivak, L.V. [State Univ., Perm (Russian Federation)

    1996-01-01

    Low temperature (30 < T < 300 K) internal friction in a metallic glass Ni{sub 60}Nb{sub 40} subjected to preliminary inhomogeneous deformation by cold rolling, homogeneous tensile deformation or electrolytic charging with hydrogen is investigated. Cold rolling or hydrogenation result in appearance of similar internal friction peaks and hysteresis damping. Homogeneous deformation has no influence on low temperature internal friction. The phenomenon of microplastic deformation during hydrogenation of weakly stressed samples is revealed. It is argued that microplastic deformation of metallic glasses during hydrogenation without external stress takes place too. Plastic flow both on cold rolling and hydrogenation occurs via formation and motion of dislocation-like defects which are the reason of the observed anelastic anomalies. It is concluded that low temperature internal friction peaks described in the literature for as-cast, cold deformed and hydrogenated samples have common dislocation-like origin.

  14. Discrete element modeling of deformable particles in YADE

    Directory of Open Access Journals (Sweden)

    Martin Haustein

    2017-01-01

    Full Text Available In this paper we describe the open-source discrete element framework YADE and the implementation of a new deformation engine. YADE is a highly expandable software package that allows the simulation of current industrial problems in the field of granular materials using particle-based numerical methods. The description of the compaction of powders and granular material like metal pellets is now possible with a pure and simple discrete element approach in a modern DEM-framework. The deformation is realized by expanding the radius of the spherical particles, depending on their overlap, so that the volume of the material is kept constant.

  15. 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.

  16. Observation of Compressive Deformation Behavior of Nuclear Graphite by Digital Image Correlation

    International Nuclear Information System (INIS)

    Kim, Hyunju; Kim, Eungseon; Kim, Minhwan; Kim, Yongwan

    2014-01-01

    Polycrystalline nuclear graphite has been proposed as a fuel element, moderator and reflector blocks, and core support structures in a very high temperature gas-cooled reactor. During reactor operation, graphite core components and core support structures are subjected to various stresses. It is therefore important to understand the mechanism of deformation and fracture of nuclear graphites, and their significance to structural integrity assessment methods. Digital image correlation (DIC) is a powerful tool to measure the full field displacement distribution on the surface of the specimens. In this study, to gain an understanding of compressive deformation characteristic, the formation of strain field during a compression test was examined using a commercial DIC system. An examination was made to characterize the compressive deformation behavior of nuclear graphite by a digital image correlation. The non-linear load-displacement characteristic prior to the peak load was shown to be mainly dominated by the presence of localized strains, which resulted in a permanent displacement. Young's modulus was properly calculated from the measured strain

  17. Permanent quadrupole magnets

    International Nuclear Information System (INIS)

    Bush, E.D. Jr.

    1976-01-01

    A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. Based on preliminary tests, it was seen that permanent quadrupole magnets can offer a low cost, reliable solution in applications requiring small, fixed-field focusing devices for use in ion or electron-beam transport systems. Permanent magnets do require special considerations in design, fabrication, handling, and service that are different than encountered in conventional quadrupole magnets. If these basic conditions are satisfied, the resulting beam-focusing device would be stable, maintenance free, with virtually an indefinite lifetime

  18. 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.

  19. Ionic imbalance induced self-propulsion of liquid metals

    Science.gov (United States)

    Zavabeti, Ali; Daeneke, Torben; Chrimes, Adam F.; O'Mullane, Anthony P.; Zhen Ou, Jian; Mitchell, Arnan; Khoshmanesh, Khashayar; Kalantar-Zadeh, Kourosh

    2016-08-01

    Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems.

  20. Gate-tunable gigantic lattice deformation in VO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, D., E-mail: okuyama@riken.jp, E-mail: nakano@imr.tohoku.ac.jp, E-mail: iwasa@ap.t.u-tokyo.ac.jp; Hatano, T. [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Nakano, M., E-mail: okuyama@riken.jp, E-mail: nakano@imr.tohoku.ac.jp, E-mail: iwasa@ap.t.u-tokyo.ac.jp [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Takeshita, S.; Ohsumi, H.; Tardif, S. [RIKEN SPring-8 Center, Hyogo 679-5148 (Japan); Shibuya, K. [National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8562 (Japan); Yumoto, H.; Koyama, T.; Ohashi, H. [Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198 (Japan); Takata, M. [RIKEN SPring-8 Center, Hyogo 679-5148 (Japan); Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198 (Japan); Kawasaki, M.; Tokura, Y.; Iwasa, Y., E-mail: okuyama@riken.jp, E-mail: nakano@imr.tohoku.ac.jp, E-mail: iwasa@ap.t.u-tokyo.ac.jp [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Tokyo 113-8656 (Japan); Arima, T. [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); RIKEN SPring-8 Center, Hyogo 679-5148 (Japan); Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561 (Japan)

    2014-01-13

    We examined the impact of electric field on crystal lattice of vanadium dioxide (VO{sub 2}) in a field-effect transistor geometry by in-situ synchrotron x-ray diffraction measurements. Whereas the c-axis lattice parameter of VO{sub 2} decreases through the thermally induced insulator-to-metal phase transition, the gate-induced metallization was found to result in a significant increase of the c-axis length by almost 1% from that of the thermally stabilized insulating state. We also found that this gate-induced gigantic lattice deformation occurs even at the thermally stabilized metallic state, enabling dynamic control of c-axis lattice parameter by more than 1% at room temperature.

  1. Orbital magnetism and dynamics in alkali metal clusters

    International Nuclear Information System (INIS)

    Nesterenko, V.O.; Kleinig, W.; Souza Cruz, FF. de; Marinelli, J.R.

    2000-01-01

    Two remarkable orbital magnetic resonances, M1 scissor mode and M2 twist mode, are predicted in deformed and spherical metal clusters, respectively. We show that these resonances provide a valuable information about many cluster properties (quadrupole deformation, magnetic susceptibility, single-particle spectrum, etc.)

  2. Interaction domains in permanent-magnetic rare-earth transition-metal compounds

    International Nuclear Information System (INIS)

    Thielsch, Juliane

    2015-01-01

    In the framework of this dissertation the phenomenon of the interaction domains was studied both experimentally and by means of micromagnetic simulation. Object of the study were one-phase NdFeB magnets, which were fabricated from commercial MQU-F powders of the Magnequench Inc. company by hot pressing and subsequent warm deformation in the IWF Dresden. Additionally via the same fabrication way also composite samples of NdFeB and Fe with different original particle sizes ere obtained and studied. Supported wer the experimental works by simulations with the FEMME software package, which is based on a hybrid finite-element method/boundary-element method.

  3. Dynamic compressive constitutive relation and shearing instability of metallic neodymium

    International Nuclear Information System (INIS)

    Wang Huanran; Cai Canyuan; Chen Danian; Ma Dongfang; Hou Yanjun; Wu Shanxing

    2011-01-01

    Highlights: → Dynamic constitutive relation of Nd was determined in first compression of SHPB. → Deformation of Nd in multi-compression of SHPB were recorded by high-speed camera. → Constitutive relation of Nd was adjusted in modeling large deformation of Nd. → Results of SDDM investigation of recovered Nd specimens showed shearing fracture. → Shearing instability of Nd was estimated with constitutive relation. - Abstract: Based on static tests on MTS and dynamic tests on split Hopkinson pressure bar (SHPB) during the first loading, this study determined the dynamic compressive constitutive relation of metallic Nd. Based on large deformations of metallic Nd specimens generated by the multi-compressive loadings during SHPB tests, and recorded by a high-speed camera, the results of numerical simulations for SHPB test processes were used to extend the determined constitutive relation from small strain to large strain. The shearing instability strain in dynamic compressive deformations of metallic Nd was estimated with the extended constitutive relation according to the criterion given by Batra and Wei, and was compared with the average strain of recovered specimens.

  4. Transient deformational properties of high temperature alloys used in solid oxide fuel cell stacks

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kwok, Kawai; Frandsen, Henrik Lund

    2017-01-01

    Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... to describe the high temperature inelastic deformational behaviors of Crofer 22 APU used for metallic interconnects in SOFC stacks.......Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... transients in operation including temporary shut downs. These stresses are highly affected by the transient creep behavior of metallic components in the SOFC stack. This study investigates whether a variation of the so-called Chaboche's unified power law together with isotropic hardening can represent...

  5. Deformation behaviors of Cu29Zr32Ti15Al5Ni19 high entropy bulk metallic glass during nanoindentation

    Science.gov (United States)

    Fang, Qihong; Yi, Ming; Li, Jia; Liu, Bin; Huang, Zaiwang

    2018-06-01

    The deformation behaviors of Cu29Zr32Ti15Al5Ni19 high entropy bulk metallic glass (HE-BMG) during the nanoindentation are presented via the large-scale molecular dynamics (MD) simulations. The indentation tests are carried out using spherical rigid indenter to investigate the microstructural evolution on the mechanical properties of HE-BMGs in terms of shear strain, indentation force, and surface morphology as well as radial distribution function (RDF). Based on the Hertzian fitting the load-displacement curve, HE-BMG Cu29Zr32Ti15Al5Ni19 has the Young's modulus of 93.1 GPa and hardness of 8.8 GPa. The indentation force requiring for the continual increasing contacted area between the indenter and the substrate goes up with the increasing of indentation depth. In addition, the symmetrical distribution of atomic displacement reveals the isotropic of HE-BMG after the indentation treatment. In the deformation region, the Al element would lead to the serious fluctuation in the first peak of RDF, which is much stronger than the other elements. The severe distortion from the atomic size difference maybe reduce the activation energy to the occurrence of shear deformation in HE-BMG, leading to the transition from brittle to ductile observed by the whole sliding of the local atom group. Through the indentation load-displacement curves at various temperatures, the softening of HE-BMG at high temperatures is in qualitative agreement with the experimental findings. Moreover, this effective strategy is used to accelerate the discovery of excellent mechanical properties of HE-BMGs by means of MD simulation, as well as understand the fundamental nanoindentation response of HE-BMGs.

  6. 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.

  7. The Response of Clamped Shallow Sandwich Arches with Metallic Foam Cores to Projectile Impact Loading

    Directory of Open Access Journals (Sweden)

    Yanping Fan

    Full Text Available Abstract The dynamic response and energy absorption capabilities of clamped shallow sandwich arches with aluminum foam core were numerically investigated by impacting the arches at mid-span with metallic foam projectiles. The typical deformation modes, deflection response, and core compression of sandwich arches obtained from the tests were used to validate the computation model. The resistance to impact loading was quantified by the permanent transverse deflection at mid-span of the arches as a function of projectile momentum. The sandwich arches have a higher shock resistance than the monolithic arches of equal mass, and shock resistance could be significantly enhanced by optimizing geometrical configurations. Meanwhile, decreasing the face-sheet thickness and curvature radius could enhance the energy absorption capability of the sandwich arches. Finite element calculations indicated that the ratio of loading time to structural response time ranged from 0.1 to 0.4. The projectile momentum, which was solely used to quantify the structural response of sandwich arches, was insufficient. These findings could provide guidance in conducting further theoretical studies and producing the optimal design of metallic sandwich structures subjected to impact loading.

  8. Deterministic Model for Rubber-Metal Contact Including the Interaction Between Asperities

    NARCIS (Netherlands)

    Deladi, E.L.; de Rooij, M.B.; Schipper, D.J.

    2005-01-01

    Rubber-metal contact involves relatively large deformations and large real contact areas compared to metal-metal contact. Here, a deterministic model is proposed for the contact between rubber and metal surfaces, which takes into account the interaction between neighboring asperities. In this model,

  9. Modelación y análisis de susceptibilidad a la deformación permanente de mezclas asfálticas Modeling and analysis of susceptibility to permanent deformation in asphalt mixtures

    Directory of Open Access Journals (Sweden)

    Julián Vidal V

    2011-08-01

    Full Text Available La deformación permanente de mezclas asfálticas del Área Metropolitana del Valle de Aburra - Antioquia, las cuales se fabrican en nuestro medio bajo las especificaciones INVIAS (Instituto Nacional de Vías y del Valle de Aburrá, se estudiaron utilizando un modelo constitutivo propuesto anteriormente. Este modelo mostró previamente ser efectivo en predecir la deformación de mezclas asfálticas en el Reino Unido bajo diferentes tipos de carga bajo condiciones uniaxiales y triaxiales, y temperaturas comprendidas entre 0 °C y 40 °C. Para el caso de las mezclas del Valle de Aburrá se emplearon temperaturas en un intervalo de 20 °C a 50 °C y se implementó el modelo propuesto con el fin de predecir la susceptibilidad a la deformación permanente. Mediante el estudio experimental de las mezclas se encontró que el comportamiento de estado estable de estas siguió el modelo modificado de Cross (Wang, 2011, con las mezclas exhibiendo comportamiento viscoso lineal y no-lineal a bajos y altos niveles de esfuerzos, respectivamente. Tanto para condiciones de carga como de recuperación se observó una dependencia de la temperatura en el material que fue adecuadamente predicha por el modelo de Arrheniusbajo el intervalo de temperaturas estudiado. Al realizar la modelación del comportamiento de las mezclas se encontró que el modelo propuesto por Ossa et al. (2010 aplica a las mezclas estudiadas y se determinó que la susceptibilidad a la deformación de estas varía considerablemente dependiendo de los materiales utilizados por el productor y en especial el agregado empleado, a pesar de ser mezclas teóricamente similares.Permanent deformation of asphaltic mixtures in the Metropolitan Area of Valle de Aburra - Antioquia, which are built under IVIAS' specifications (Instituto Nacional de Vías and Valle de Aburrá, were studied by employing a constitutive model proposed previously. This model had proved to be effective in predicting deformations of

  10. Mechanically driven phase separation and corresponding microhardness change in Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.

    2005-01-01

    Rolling deformation of bulk Cu60Zr20Ti20 metallic glass has been performed at cryogenic temperature. The specimens exhibit excellent ductility, and are rolled up to 97% reduction in thickness without fracture. Crystallization is suppressed during the deformation, however, phase separation is obse...... is observed in the glassy matrix when the thickness reduction exceeds 89%. Once the phase separation occurs, the microhardness of the specimen increases drastically, indicating the existence of work hardening by severe plastic deformation of the metallic glass.......Rolling deformation of bulk Cu60Zr20Ti20 metallic glass has been performed at cryogenic temperature. The specimens exhibit excellent ductility, and are rolled up to 97% reduction in thickness without fracture. Crystallization is suppressed during the deformation, however, phase separation...

  11. Subsurface deformation and the role of surface texture—A study with ...

    Indian Academy of Sciences (India)

    research has been done by Suh and his co-workers (Suh 1986, 1973; Suh & Saka 1977; ..... Dautzenberg J H, Zaat J H 1973 Quantitative determination of deformation by sliding wear. Wear ... Int. Seminar on Metal Forming Process Design.

  12. Review on progressive microforming of bulk metal parts directly using sheet metals (Keynote Paper

    Directory of Open Access Journals (Sweden)

    Fu M.W.

    2015-01-01

    Full Text Available Due to the ubiquitous trend of product miniaturization, energy saving and weight reduction, micro/meso-scale parts have been widely used in many industrial clusters. Micromanufacturing processes for production of such micro/meso-scale parts are thus critically needed. Microforming, as one of these micro manufacturing processes, is a promising process and thus got many explorations and researches. Compared with the research on size effect affected deformation behaviours, less attention has been paid to the process development for mass production of micro-parts. The product quality and fabrication productivity of micro-parts depend on the involved process chain. To address the difficulty in handling and transporting of the micro-sized workpiece, development of a progressive microforming process for directly fabricating bulk micro-parts using sheet metals seems quite promising as it avoids or facilitates billet handling, transportation, positioning, and ejection in the process chain. In this paper, an intensive review on the latest development of progressive microforming technologies is presented. First of all, the paper summarizes the characteristic of progressive microforming directly using sheet metal. The size effect-affected deformation behaviour and the dimensional accuracy, deformation load, ductile fracture, and the surface finish of the microformed parts by progressive microforming using sheet metals are then presented. Finally, some research issues from the implementation of mass production perspective are also discussed.

  13. Monitoring Building Deformation with InSAR: Experiments and Validation

    Science.gov (United States)

    Yang, Kui; Yan, Li; Huang, Guoman; Chen, Chu; Wu, Zhengpeng

    2016-01-01

    Synthetic Aperture Radar Interferometry (InSAR) techniques are increasingly applied for monitoring land subsidence. The advantages of InSAR include high accuracy and the ability to cover large areas; nevertheless, research validating the use of InSAR on building deformation is limited. In this paper, we test the monitoring capability of the InSAR in experiments using two landmark buildings; the Bohai Building and the China Theater, located in Tianjin, China. They were selected as real examples to compare InSAR and leveling approaches for building deformation. Ten TerraSAR-X images spanning half a year were used in Permanent Scatterer InSAR processing. These extracted InSAR results were processed considering the diversity in both direction and spatial distribution, and were compared with true leveling values in both Ordinary Least Squares (OLS) regression and measurement of error analyses. The detailed experimental results for the Bohai Building and the China Theater showed a high correlation between InSAR results and the leveling values. At the same time, the two Root Mean Square Error (RMSE) indexes had values of approximately 1 mm. These analyses show that a millimeter level of accuracy can be achieved by means of InSAR technique when measuring building deformation. We discuss the differences in accuracy between OLS regression and measurement of error analyses, and compare the accuracy index of leveling in order to propose InSAR accuracy levels appropriate for monitoring buildings deformation. After assessing the advantages and limitations of InSAR techniques in monitoring buildings, further applications are evaluated. PMID:27999403

  14. Monitoring Building Deformation with InSAR: Experiments and Validation

    Directory of Open Access Journals (Sweden)

    Kui Yang

    2016-12-01

    Full Text Available Synthetic Aperture Radar Interferometry (InSAR techniques are increasingly applied for monitoring land subsidence. The advantages of InSAR include high accuracy and the ability to cover large areas; nevertheless, research validating the use of InSAR on building deformation is limited. In this paper, we test the monitoring capability of the InSAR in experiments using two landmark buildings; the Bohai Building and the China Theater, located in Tianjin, China. They were selected as real examples to compare InSAR and leveling approaches for building deformation. Ten TerraSAR-X images spanning half a year were used in Permanent Scatterer InSAR processing. These extracted InSAR results were processed considering the diversity in both direction and spatial distribution, and were compared with true leveling values in both Ordinary Least Squares (OLS regression and measurement of error analyses. The detailed experimental results for the Bohai Building and the China Theater showed a high correlation between InSAR results and the leveling values. At the same time, the two Root Mean Square Error (RMSE indexes had values of approximately 1 mm. These analyses show that a millimeter level of accuracy can be achieved by means of InSAR technique when measuring building deformation. We discuss the differences in accuracy between OLS regression and measurement of error analyses, and compare the accuracy index of leveling in order to propose InSAR accuracy levels appropriate for monitoring buildings deformation. After assessing the advantages and limitations of InSAR techniques in monitoring buildings, further applications are evaluated.

  15. Non-localized deformation in Cu−Zr multi-layer amorphous films under tension

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, C. [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, H. [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Cao, Q.P.; Wang, X.D. [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, D.X. [State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027 (China); Hu, J.W. [Hangzhou Workers Amateur University, Hangzhou 310027 (China); Liaw, P.K. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Jiang, J.Z., E-mail: jiangjz@zju.edu.cn [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-09-05

    In metallic glasses (MGs), plastic deformation at room temperature is dominated by highly localized shear bands. Here we report the non-localized deformation under tension in Cu−Zr multi-layer MGs with a pure amorphous structure using large-scale atomistic simulations. It is demonstrated that amorphous samples with high layer numbers, composed of Cu{sub 64}Zr{sub 36} and Cu{sub 40}Zr{sub 60}, or Cu{sub 64}Zr{sub 36} and Cu{sub 50}Zr{sub 50}, present obviously non-localized deformation behavior. We reveal that the deformation behavior of the multi-layer-structured MG films is related but not determined by the deformation behavior of the composed individual layers. The criterion for the deformation mode change for MGs with a pure amorphous structure, in generally, was suggested, i.e., the competition between the elastic-energy density stored and the energy density needed for forming one mature shear band in MGs. Our results provide a promising strategy for designing tensile ductile MGs with a pure amorphous structure at room temperature. - Highlights: • Tensile deformation behaviors in multi-layer MG films. • Films with high layer numbers confirmed with a non-localized deformation behavior. • The deformation mode is reasonably controlled by whether U{sub p} larger than U{sub SB.}.

  16. Elastic Band Causing Exfoliation of the Upper Permanent Central Incisors

    Directory of Open Access Journals (Sweden)

    Monica Ghislaine Oliveira Alves

    2015-01-01

    Full Text Available Objective. This study reports a case in which elastic band use culminated in the loss of the incisors. Case Report. An 11-year-old white girl was seen complaining of pain, with purulent discharge and severe tooth mobility. The bone destruction detected radiographically in the region, despite its single location and absence in posterior quadrants of the maxilla and/or mandible, was similar to that observed in Langerhans cell disease. To our surprise, an elastic band involving the midportion of the roots of the two upper central incisors was found during biopsy. The debris was removed and a metal wire was placed in permanent maxillary right and left incisors. The patient was followed up, but no improvement in tooth mobility was observed. Bone loss increased, and internal resorption and root exposure occurred, which culminated in the extraction of permanent maxillary right and left incisors. Conclusion. The present case highlights the fact that professionals sometimes are confronted by anamnestic reports never seen before.

  17. A non-linear elastic constitutive framework for replicating plastic deformation in solids.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Scott Alan; Schunk, Peter Randall

    2014-02-01

    Ductile metals and other materials typically deform plastically under large applied loads; a behavior most often modeled using plastic deformation constitutive models. However, it is possible to capture some of the key behaviors of plastic deformation using only the framework for nonlinear elastic mechanics. In this paper, we develop a phenomenological, hysteretic, nonlinear elastic constitutive model that captures many of the features expected of a plastic deformation model. This model is based on calculating a secant modulus directly from a materials stress-strain curve. Scalar stress and strain values are obtained in three dimensions by using the von Mises invariants. Hysteresis is incorporated by tracking an additional history variable and assuming an elastic unloading response. This model is demonstrated in both single- and multi-element simulations under varying strain conditions.

  18. Skeletal deformities in smallmouth bass, Micropterus dolomieui, from southern Appalachian reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Van den Avyle, M J; Garvick, S J; Blazer, V S; Hamilton, S J; Brumbaugh, W G

    1989-09-01

    Smallmouth bass (Micropterus dolomieui) populations in two of five reservoirs sampled in the southern Appalachian Mountains contained high percentages of individuals with lordosis, kyphosis, or scoliosis. Deformities of the vertebral column occurred in several year classes and varied with fish size; they were absent in small fish, present in 25-30% of the fish 241-300 mm long, and then decreased in occurrence with increased length. Because environmental contamination is often responsible for high occurrences of deformed fish, whole-body concentrations of contaminants, bone development characteristics, and blood plasma concentrations of calcium and phosphorus in normal and deformed fish were measured and compared the results with those for fish from reservoirs where no deformities were found. Vertebrae were significantly weaker and more elastic in deformed than in normal fish, but biochemical properties of vertebrae were similar among the groups tested. Concentrations of pesticides and metals were not elevated in deformed fish, and concentrations of calcium and phosphorus in blood plasma were similar in normal and deformed groups. Most environmental contaminants that have been shown to cause fish deformities could be discounted as causative agents on the basis of these results; however, the exact cause was not determined. Further attempts to diagnose the cause of the deformities were limited by the lack of background information on relationships among bone development processes, types of stresses that cause deformities, and types of bone tissue in fish.

  19. Half-Metallic Ferromagnetism and Stability of Transition Metal Pnictides and Chalcogenides

    Science.gov (United States)

    Liu, Bang-Gui

    It is highly desirable to explore robust half-metallic ferromagnetic materials compatible with important semiconductors for spintronic applications. A state-of-the-art full potential augmented plane wave method within the densityfunctional theory is reliable enough for this purpose. In this chapter we review theoretical research on half-metallic ferromagnetism and structural stability of transition metal pnictides and chalcogenides. We show that some zincblende transition metal pnictides are half-metallic and the half-metallic gap can be fairly wide, which is consistent with experiment. Systematic calculations reveal that zincblende phases of CrTe, CrSe, and VTe are excellent half-metallic ferromagnets. These three materials have wide half-metallic gaps, are low in total energy with respect to the corresponding ground-state phases, and, importantly, are structurally stable. Halfmetallic ferromagnetism is also found in wurtzite transition metal pnictides and chalcogenides and in transition-metal doped semiconductors as well as deformed structures. Some of these half-metallic materials could be grown epitaxially in the form of ultrathin .lms or layers suitable for real spintronic applications.

  20. Experimental evaluation of coating delamination in vinyl coated metal forming

    International Nuclear Information System (INIS)

    Son, Young Ki; Lee, Chan Joo; Kim, Byung Min; Lee, Jung Min; Byoen, Sang Doek; Lee, Soen Bong

    2012-01-01

    In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications

  1. Experimental evaluation of coating delamination in vinyl coated metal forming

    Energy Technology Data Exchange (ETDEWEB)

    Son, Young Ki; Lee, Chan Joo; Kim, Byung Min [Pusan National Univ., Busan (Korea, Republic of); Lee, Jung Min [Korea Institute of Industrial Technology, Busan (Korea, Republic of); Byoen, Sang Doek [HA Digital Engineering Gr., Seongsan Gu (Korea, Republic of); Lee, Soen Bong [Keimyung Univ., Daegu (Korea, Republic of)

    2012-10-15

    In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications.

  2. Tensile deformation behavior and deformation twinning of an equimolar CoCrFeMnNi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Joo, S.-H.; Kato, H. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Jang, M.J.; Moon, J. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Tsai, C.W.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Kim, H.S., E-mail: hskim@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Center for High Entropy Alloys, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of)

    2017-03-24

    The tensile deformation and strain hardening behaviors of an equimolar CoCrFeMnNi high-entropy alloy (HEA) were investigated and compared with low and medium entropy equiatomic alloys (LEA and MEA). The HEA had a lower yield strength than the MEA because the addition of Mn weakens solid solution hardening in the HEA. However, deformation twinning induced the multiple stage strain hardening behavior of the HEA and enhanced strength and elongation. Using tensile-interrupted electron backscatter diffraction analysis, geometrically necessary dislocations were observed as plume-shaped features in grain interior, and a considerable texture was characterized, which is typical of face centered cubic metals. Moreover, the relationship between favorably oriented grains and twinning in the HEA bore a clear resemblance to the same tendency in TWIP steels. The thickness of the twin bundles was less than 100 nm. A high density of stacking defects was found in the nanotwins. Nano twinning and stacking faults were found to contribute to the remarkable mechanical properties. Deformation induced twinning not only demonstrated the dynamic Hall-Petch effect but also changed dislocation cell substructures into microband structures.

  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. 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

  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. Determination of stable shapes of a thin liquid metal layer using a boundary integral method

    Energy Technology Data Exchange (ETDEWEB)

    Hinaje, M [Groupe de Recherche en Electrotechnique et Electronique de Nancy, 2 avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy (France); Vinsard, G [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, 2 avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy (France); Dufour, S [Groupe de Recherche en Electrotechnique et Electronique de Nancy, 2 avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy (France)

    2006-03-21

    This paper deals with a thin liquid metal layer submitted to an ac magnetic field. Experimentally, we have noticed that even if the system (inductor+liquid metal) is axisymmetric, when an ac magnetic field is applied the symmetry is broken. The observed deformations of the liquid metal are in three dimensions. Therefore, our aim is to investigate this deformation using a numerical method as boundary element method in three dimensions.

  7. Determination of stable shapes of a thin liquid metal layer using a boundary integral method

    International Nuclear Information System (INIS)

    Hinaje, M; Vinsard, G; Dufour, S

    2006-01-01

    This paper deals with a thin liquid metal layer submitted to an ac magnetic field. Experimentally, we have noticed that even if the system (inductor+liquid metal) is axisymmetric, when an ac magnetic field is applied the symmetry is broken. The observed deformations of the liquid metal are in three dimensions. Therefore, our aim is to investigate this deformation using a numerical method as boundary element method in three dimensions

  8. Method for compensating bellows pressure loads while accommodating thermal deformations

    International Nuclear Information System (INIS)

    Woodle, M.H.

    1985-01-01

    Many metal bellows are used on storage ring vacuum chambers. They allow the ring to accommodate deformations associated with alignment, mechanical assembly and thermal expansion. The NSLS has two such electron storage rings, the vuv ring and the x-ray ring. Both rings utilize a number of welded metal bellows within the ring and at every beam port. There are provisions for 16 beam ports on the vuv and 28 ports in the x-ray ring. At each of these locations the bellows are acted on by an external pressure of 1 atmosphere, which causes a 520 lb reaction at the vacuum chamber beam port and at the beamline flange downstream of the bellows. The use of rigid tie rods across the bellows flanges to support this load is troublesome because most storage ring vacuum chambers are baked in situ to achieve high internal vacuum. Significant forces can develop on components if thermal deformation is restrained and damage could occur

  9. Dirac cones in isogonal hexagonal metallic structures

    Science.gov (United States)

    Wang, Kang

    2018-03-01

    A honeycomb hexagonal metallic lattice is equivalent to a triangular atomic one and cannot create Dirac cones in its electromagnetic wave spectrum. We study in this work the low-frequency electromagnetic band structures in isogonal hexagonal metallic lattices that are directly related to the honeycomb one and show that such structures can create Dirac cones. The band formation can be described by a tight-binding model that allows investigating, in terms of correlations between local resonance modes, the condition for the Dirac cones and the consequence of the third structure tile sustaining an extra resonance mode in the unit cell that induces band shifts and thus nonlinear deformation of the Dirac cones following the wave vectors departing from the Dirac points. We show further that, under structure deformation, the deformations of the Dirac cones result from two different correlation mechanisms, both reinforced by the lattice's metallic nature, which directly affects the resonance mode correlations. The isogonal structures provide new degrees of freedom for tuning the Dirac cones, allowing adjustment of the cone shape by modulating the structure tiles at the local scale without modifying the lattice periodicity and symmetry.

  10. MESOSCALE SIMULATIONS OF MICROSTRUCTURE AND TEXTURE EVOLUTION DURING DEFORMATION OF COLUMNAR GRAINS

    International Nuclear Information System (INIS)

    Sarma, G.

    2001-01-01

    In recent years, microstructure evolution in metals during deformation processing has been modeled at the mesoscale by combining the finite element method to discretize the individual grains with crystal plasticity to provide the constitutive relations. This approach allows the simulations to capture the heterogeneous nature of grain deformations due to interactions with neighboring grains. The application of this approach to study the deformations of columnar grains present in solidification microstructures is described. The microstructures are deformed in simple compression, assuming the easy growth direction of the columnar grains to be parallel to the compression axis in one case, and perpendicular in the other. These deformations are similar to those experienced by the columnar zones of a large cast billet when processed by upsetting and drawing, respectively. The simulations show that there is a significant influence of the initial microstructure orientation relative to the loading axis on the resulting changes in grain shape and orientation

  11. Flow and Fracture of Bulk Metallic Glass Alloys and their Composites

    International Nuclear Information System (INIS)

    Flores, K M; Suh, D; Howell, R; Asoka-Kumar, P; Dauskardt, R H

    2001-01-01

    The fracture and plastic deformation mechanisms of a Zr-Ti-Ni-Cu-Be bulk metallic glass and a composite utilizing a crystalline reinforcement phase are reviewed. The relationship between stress state, free volume and shear band formation are discussed. Positron annihilation techniques were used to confirm the predicted increase in free volume after plastic straining. Strain localization and failure were examined for a wide range of stress states. Finally, methods for toughening metallic glasses are considered. Significant increases in toughness are demonstrated for a composite bulk metallic glass containing a ductile second phase which stabilizes shear band formation and distributes plastic deformation

  12. Deformation-induced microstructural evolution at grain scale

    DEFF Research Database (Denmark)

    Winther, Grethe

    During plastic deformation metals develop microstructures which may be analysed on several scales,spanning from crystallographic textures averaged over the entire sample to the scale of individualgrains. Even within individual grains, intragranular phenomena in the form of orientation gradients...... aswell as dislocation patterning by formation of dislocation boundaries occur. Experimental data andassociated data analysis at the grain scale and below will be presented to illustrate our current level ofunderstanding. The basis for the analysis is the crystallographic orientation of the grain as well...... is presented for both fcc and bcc materials inseveral deformation modes, demonstrating a clear grain orientation dependence [Huang & Winther,2007]. This dependence has its origin in a dependence on the slip systems [Winther & Huang, 2007].This further implies that the dislocations in the boundaries come from...

  13. Structure vs chemistry: friction and wear of Pt-based metallic surfaces.

    Science.gov (United States)

    Caron, A; Louzguine-Luzguin, D V; Bennewitz, R

    2013-11-13

    In comparison of a Pt57.5Cu14.7Ni5.3P22.5 metallic glass with a Pt(111) single crystal we find that wearless friction is determined by chemistry through bond formation alloying, while wear is determined by structure through plasticity mechanisms. In the wearless regime, friction is affected by the chemical composition of the counter body and involves the formation of a liquid-like neck and interfacial alloying. The wear behavior of Pt-based metallic surfaces is determined by their structural properties and corresponding mechanisms for plastic deformation. In the case of Pt(111) wear occurs by dislocation-mediated homogeneous plastic deformation. In contrast the wear of Pt57.5Cu14.7Ni5.3P22.5 metallic glass occurs through localized plastic deformation in shear bands that merge together in a single shear zone above a critical load and corresponds to the shear softening of metallic glasses. These results open a new route in the control of friction and wear of metals and are relevant for the development of self-lubricated and wear-resistant mechanical devices.

  14. Failure of metals III: Fracture and fatigue of nanostructured metallic materials

    International Nuclear Information System (INIS)

    Pineau, André; Amine Benzerga, A.; Pardoen, Thomas

    2016-01-01

    Pushing the internal or external dimensions of metallic alloys down to the nanometer scale gives rise to strong materials, though most often at the expense of a low ductility and a low resistance to cracking, with negative impact on the transfer to engineering applications. These characteristics are observed, with some exceptions, in bulk ultra-fine grained and nanocrystalline metals, nano-twinned metals, thin metallic coatings on substrates and freestanding thin metallic films and nanowires. This overview encompasses all these systems to reveal commonalities in the origins of the lack of ductility and fracture resistance, in factors governing fatigue resistance, and in ways to improve properties. After surveying the various processing methods and key deformation mechanisms, we systematically address the current state of the art in terms of plastic localization, damage, static and fatigue cracking, for three classes of systems: (1) bulk ultra-fine grained and nanocrystalline metals, (2) thin metallic films on substrates, and (3) 1D and 2D freestanding micro and nanoscale systems. In doing so, we aim to favour cross-fertilization between progress made in the fields of mechanics of thin films, nanomechanics, fundamental researches in bulk nanocrystalline metals and metallurgy to impart enhanced resistance to fracture and fatigue in high-strength nanostructured systems. This involves exploiting intrinsic mechanisms, e.g. to enhance hardening and rate-sensitivity so as to delay necking, or improve grain-boundary cohesion to resist intergranular cracks or voids. Extrinsic methods can also be utilized such as by hybridizing the metal with another material to delocalize the deformation - as practiced in stretchable electronics. Fatigue crack initiation is in principle improved by a fine structure, but at the expense of larger fatigue crack growth rates. Extrinsic toughening through hybridization allows arresting or bridging cracks. The content and discussions are based on

  15. 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

  16. Permanent magnets including undulators and wigglers

    CERN Document Server

    Bahrdt, J

    2010-01-01

    After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrates on the applications of permanent magnets in accelerators starting from dipoles and quadrupoles on to wigglers and undulators.

  17. Marxism as permanent revolution

    NARCIS (Netherlands)

    van Ree, E.

    2013-01-01

    This article argues that the 'permanent revolution' represented the dominant element in Karl Marx and Friedrich Engels' political discourse, and that it tended to overrule considerations encapsulated in 'historical materialism'. In Marx and Engels's understanding, permanent revolution did not

  18. Modelling and optimization of a deformable mirror for laser beam control

    CSIR Research Space (South Africa)

    Loveday, PW

    2008-03-01

    Full Text Available for this application. The unimorph consists of a metallic disc, with a mirror finish, bonded to a piezoelectric disc. In adaptive optics the deformations that the mirror is required to perform are described by the Zernike polynomials, which are a complete set...

  19. Artificial cranial deformation in newborns in the pre-Columbian Andes.

    Science.gov (United States)

    Schijman, Edgardo

    2005-11-01

    Artificial deformation of the neonatal cranial vault is one form of permanent alteration of the body that has been performed by the human being from the beginning of history as a way of differentiating from others. These procedures have been observed on all continents, although it became widespread practice among the aborigines who lived in the Andean region of South America. It has been suggested that the expansion of this practice started with the Scythians from their original settlements in central Asia and spread toward the rest of Asia and Europe, and it is believed that Asiatic people carried this cultural custom to America when they arrived on the current coasts of Alaska after crossing the Strait of Behring. The practice of deforming newborn heads was present in the whole of the American continent, from North America to Patagonia, but cranial molding in neonates was most widely practiced in the Andean region, from Venezuela to Guyana, Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. Intentional deformation of the head in neonates was carried out in different ways: by compression of the head with boards and pads; by compression with adjusted bindings; or by restraining the child on specially designed cradle-boards. The purpose of head shaping varied according to culture and region: while in certain regions it was a symbol of nobility or separated the different social groups within society, in others it served to emphasize ethnic differences or was performed for aesthetic, magical or religious reasons. There is no evidence of any neurological impairment among indigenous groups who practiced cranial deformations in newborns.

  20. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, Bachu Narain

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly...... observed in PITs. An increase in the pre-yield dose results in an increase in the level of hardening over the whole test periods and a decrease in the uniform elongation suggesting that the materials “remember” the impact of the pre-yield damage level. These features are modelled in terms of the decoration...... and deformation, moving dislocations are decorated by the sweeping of matrix loops. The interaction of dislocations with loops and between loops is discussed as a function of the relevant parameters. On this basis, the kinetics of decoration is treated in terms of fluxes of loops to and reactions with each other...

  1. Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al{sub 13}Co{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, Ayan, E-mail: a.bhowmik@ic.ac.uk; Britton, T. Ben; Sernicola, Giorgio; Dye, David [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Dolbnya, Igor P. [Diamond Light Source, Didcot, Oxfordshire OX11 0DE (United Kingdom); Jones, Nicholas G.; Walter, Claudia; Clegg, William J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS (United Kingdom); Gille, Peter [Crystallographic Section, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich D-80333 (Germany); Giuliani, Finn [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department of Mechanical Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-03-14

    In this study, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al{sub 13}Co{sub 4} complex metallic alloy to investigate the evolution of deformation in Al{sub 13}Co{sub 4}. Streaking of the Laue spots shows that the onset of plastic flow occurs at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enable the geometrically necessary dislocation density to be estimated as 1.1 × 10{sup 13 }m{sup −2}.

  2. Two-parametric model of metals hardening during cold working

    International Nuclear Information System (INIS)

    Khajkin, B.E.

    1985-01-01

    Mathematical models of cold working metal resistance σ depending on deformation degree have been analyzed. Advantage of two-parametric formula combining simplicity with satisfactory accuracy of experimental data approximation is noted. The formula is convenient when determining value σ, which is average with respect of deformation location, as average geometric value

  3. Earthquake-induced crustal deformation and consequences for fault displacement hazard analysis of nuclear power plants

    International Nuclear Information System (INIS)

    Gürpinar, Aybars; Serva, Leonello; Livio, Franz; Rizzo, Paul C.

    2017-01-01

    Highlights: • A three-step procedure to incorporate coseismic deformation into PFDHA. • Increased scrutiny for faults in the area permanently deformed by future strong earthquakes. • These faults share with the primary structure the same time window for fault capability. • VGM variation may occur due to tectonism that has caused co-seismic deformation. - Abstract: Readily available interferometric data (InSAR) of the coseismic deformation field caused by recent seismic events clearly show that major earthquakes produce crustal deformation over wide areas, possibly resulting in significant stress loading/unloading of the crust. Such stress must be considered in the evaluation of seismic hazards of nuclear power plants (NPP) and, in particular, for the potential of surface slip (i.e., probabilistic fault displacement hazard analysis - PFDHA) on both primary and distributed faults. In this study, based on the assumption that slip on pre-existing structures can represent the elastic response of compliant fault zones to the permanent co-seismic stress changes induced by other major seismogenic structures, we propose a three-step procedure to address fault displacement issues and consider possible influence of surface faulting/deformation on vibratory ground motion (VGM). This approach includes: (a) data on the presence and characteristics of capable faults, (b) data on recognized and/or modeled co-seismic deformation fields and, where possible, (c) static stress transfer between source and receiving faults of unknown capability. The initial step involves the recognition of the major seismogenic structures nearest to the site and their characterization in terms of maximum expected earthquake and the time frame to be considered for determining their “capability” (as defined in the International Atomic Energy Agency - IAEA Specific Safety Guide SSG-9). Then a GIS-based buffer approach is applied to identify all the faults near the NPP, possibly influenced by

  4. Earthquake-induced crustal deformation and consequences for fault displacement hazard analysis of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Gürpinar, Aybars, E-mail: aybarsgurpinar2007@yahoo.com [Nuclear & Risk Consultancy, Anisgasse 4, 1221 Vienna (Austria); Serva, Leonello, E-mail: lserva@alice.it [Independent Consultant, Via dei Dauni 1, 00185 Rome (Italy); Livio, Franz, E-mail: franz.livio@uninsubria.it [Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell’Insubria, Via Velleggio, 11, 22100 Como (Italy); Rizzo, Paul C., E-mail: paul.rizzo@rizzoasoc.com [RIZZO Associates, 500 Penn Center Blvd., Suite 100, Pittsburgh, PA 15235 (United States)

    2017-01-15

    Highlights: • A three-step procedure to incorporate coseismic deformation into PFDHA. • Increased scrutiny for faults in the area permanently deformed by future strong earthquakes. • These faults share with the primary structure the same time window for fault capability. • VGM variation may occur due to tectonism that has caused co-seismic deformation. - Abstract: Readily available interferometric data (InSAR) of the coseismic deformation field caused by recent seismic events clearly show that major earthquakes produce crustal deformation over wide areas, possibly resulting in significant stress loading/unloading of the crust. Such stress must be considered in the evaluation of seismic hazards of nuclear power plants (NPP) and, in particular, for the potential of surface slip (i.e., probabilistic fault displacement hazard analysis - PFDHA) on both primary and distributed faults. In this study, based on the assumption that slip on pre-existing structures can represent the elastic response of compliant fault zones to the permanent co-seismic stress changes induced by other major seismogenic structures, we propose a three-step procedure to address fault displacement issues and consider possible influence of surface faulting/deformation on vibratory ground motion (VGM). This approach includes: (a) data on the presence and characteristics of capable faults, (b) data on recognized and/or modeled co-seismic deformation fields and, where possible, (c) static stress transfer between source and receiving faults of unknown capability. The initial step involves the recognition of the major seismogenic structures nearest to the site and their characterization in terms of maximum expected earthquake and the time frame to be considered for determining their “capability” (as defined in the International Atomic Energy Agency - IAEA Specific Safety Guide SSG-9). Then a GIS-based buffer approach is applied to identify all the faults near the NPP, possibly influenced by

  5. A two-dimensional deformable phantom for quantitatively verifying deformation algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, Neil; Chuang, Cynthia; Pouliot, Jean [Department of Radiation Oncology, University of California San Francisco, San Francisco, California 94143-1708 (United States)

    2011-08-15

    Purpose: The incorporation of deformable image registration into the treatment planning process is rapidly advancing. For this reason, the methods used to verify the underlying deformation algorithms must evolve equally fast. This manuscript proposes a two-dimensional deformable phantom, which can objectively verify the accuracy of deformation algorithms, as the next step for improving these techniques. Methods: The phantom represents a single plane of the anatomy for a head and neck patient. Inflation of a balloon catheter inside the phantom simulates tumor growth. CT and camera images of the phantom are acquired before and after its deformation. Nonradiopaque markers reside on the surface of the deformable anatomy and are visible through an acrylic plate, which enables an optical camera to measure their positions; thus, establishing the ground-truth deformation. This measured deformation is directly compared to the predictions of deformation algorithms, using several similarity metrics. The ratio of the number of points with more than a 3 mm deformation error over the number that are deformed by more than 3 mm is used for an error metric to evaluate algorithm accuracy. Results: An optical method of characterizing deformation has been successfully demonstrated. For the tests of this method, the balloon catheter deforms 32 out of the 54 surface markers by more than 3 mm. Different deformation errors result from the different similarity metrics. The most accurate deformation predictions had an error of 75%. Conclusions: The results presented here demonstrate the utility of the phantom for objectively verifying deformation algorithms and determining which is the most accurate. They also indicate that the phantom would benefit from more electron density heterogeneity. The reduction of the deformable anatomy to a two-dimensional system allows for the use of nonradiopaque markers, which do not influence deformation algorithms. This is the fundamental advantage of this

  6. Dynamic control of knee axial deformities

    Directory of Open Access Journals (Sweden)

    E. E. Malyshev

    2013-01-01

    Full Text Available The authors have evaluated the clinical examination of the patients with axial malalignments in the knee by the original method and device which was named varovalgometer. The measurements were conducted by tension of the cord through the spina iliaca anterior superior and the middle of the lower pole of patella. The deviation of the center of the ankle estimated by metal ruler which was positioned perpendicular to the lower leg axis on the level of the ankle joint line. The results of comparison of our method and computer navigation in 53 patients during the TKA show no statistically significant varieties but they differ by average 5° of valgus in clinical examination in comparison with mechanical axis which was identified by computer navigation. The dynamic control of axial malalignment can be used in clinical practice for estimation of the results of treatment of pathology with axial deformities in the knee; for the control of reduction and secondary displacement of the fractures around the knee; for assessment of instability; in planning of correctional osteotomies and intraoperative control of deformity correction; for estimation of Q angle in subluxation and recurrent dislocation of patella; in planning of TKA; during the growth of child it allows to assess the progression of deformity.

  7. Characterization of local plastic instability during deformation of D9 clad tubes for fast breeder nuclear fuel by infrared thermography

    International Nuclear Information System (INIS)

    Kapoor, K.; Somasekhar Reddy, K.; Ramana Rao, A.V.

    2009-01-01

    Plastic instability is a condition occurring ahead of ductile fracture in materials subjected to deformation. This condition is a warning before the final failure occurring by ductile fracture. This condition manifests during necking in tensile deformation and crack propagation during plastic deformation. Early detection of such a condition can prevent permanent damage. In the present case, a novel approach by use of infrared thermography is proposed for characterization of local plastic instability during deformation of D9 clad tube material. Infrared thermal imaging was used for acquiring data during deformation by plug drawing, pilgering and uniaxial tension tests. The local plastic instability due to propagation of defects was monitored by use of Taylor-Quinney coefficient (β). Where, the Taylor-Quinney coefficient is defined as the ratio of plastic work converted into heat, which was evaluated by using thermal imaging data. In our study, an analysis of the heat generated during the process of plastic deformation was measured thereby correlating the abnormal temperature variations with the defects appearing in the material. In our study, an analysis of the heat generated during the process of plastic deformation was measured thereby correlating the abnormal temperature variations with the defects appearing in the material

  8. Elastic stresses and plastic deformations in 'Santa Clara' tomato fruits caused by package dependent compression

    Directory of Open Access Journals (Sweden)

    PEREIRA ADRIANA VARGAS

    2000-01-01

    Full Text Available The objective of this work was to study the fruit compression behavior aiming to develop new tomato packages. Deformations caused by compression forces were observed inside packages and in individual 'Santa Clara' tomato fruit. The forces applied by a transparent acrylic lever to the fruit surface caused pericarp deformation and the flattened area was proportional to the force magnitude. The deformation was associated to the reduction in the gas volume (Vg, caused by expulsion of the air from the loculus cavity and reduction in the intercellular air volume of the pericarp. As ripening advanced, smaller fractions of the Vg reduced by the compressive force were restored after the stress was relieved. The lack of complete Vg restoration was an indication of permanent plastic deformations of the stressed cells. Vg regeneration (elastic recovery was larger in green fruits than in the red ones. The ratio between the applied force and the flattened area (flattening pressure, which depends on cell turgidity, decreased during ripening. Fruit movements associated with its depth in the container were observed during storage in a transparent glass container (495 x 355 x 220 mm. The downward movement of the fruits was larger in the top layers because these movements seem to be driven by a summation of the deformation of many fruits in all layers.

  9. Stretchable and Soft Electronics using Liquid Metals.

    Science.gov (United States)

    Dickey, Michael D

    2017-07-01

    The use of liquid metals based on gallium for soft and stretchable electronics is discussed. This emerging class of electronics is motivated, in part, by the new opportunities that arise from devices that have mechanical properties similar to those encountered in the human experience, such as skin, tissue, textiles, and clothing. These types of electronics (e.g., wearable or implantable electronics, sensors for soft robotics, e-skin) must operate during deformation. Liquid metals are compelling materials for these applications because, in principle, they are infinitely deformable while retaining metallic conductivity. Liquid metals have been used for stretchable wires and interconnects, reconfigurable antennas, soft sensors, self-healing circuits, and conformal electrodes. In contrast to Hg, liquid metals based on gallium have low toxicity and essentially no vapor pressure and are therefore considered safe to handle. Whereas most liquids bead up to minimize surface energy, the presence of a surface oxide on these metals makes it possible to pattern them into useful shapes using a variety of techniques, including fluidic injection and 3D printing. In addition to forming excellent conductors, these metals can be used actively to form memory devices, sensors, and diodes that are completely built from soft materials. The properties of these materials, their applications within soft and stretchable electronics, and future opportunities and challenges are considered. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Size-dependent deformation behavior of nanocrystalline graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhi [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Huang, Yuhong [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, Shaanxi (China); Ma, Fei, E-mail: mafei@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Sun, Yunjin [Faculty of Food Science and Engineering, Beijing University of Agriculture, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Laboratory of Food Quality and Safety, Beijing 102206 (China); Xu, Kewei, E-mail: kwxu@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Opt-electronic Engineering, Xi’an University of Arts and Science, Xi’an 710065, Shaanxi (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-08-15

    Highlights: • MD simulation is conducted to study the deformation of nanocrystalline graphene. • Unexpectedly, the elastic modulus decreases with the grain size considerably. • But the fracture stress and strain are nearly insensitive to the grain size. • A composite model with grain domains and GBs as two components is suggested. - Abstract: Molecular dynamics (MD) simulation is conducted to study the deformation behavior of nanocrystalline graphene sheets. It is found that the graphene sheets have almost constant fracture stress and strain, but decreased elastic modulus with grain size. The results are different from the size-dependent strength observed in nanocrystalline metals. Structurally, the grain boundaries (GBs) become a principal component in two-dimensional materials with nano-grains and the bond length in GBs tends to be homogeneously distributed. This is almost the same for all the samples. Hence, the fracture stress and strain are almost size independent. As a low-elastic-modulus component, the GBs increase with reducing grain size and the elastic modulus decreases accordingly. A composite model is proposed to elucidate the deformation behavior.

  11. Casting technology for manufacturing metal rods from simulated metallic spent fuels

    Science.gov (United States)

    Leeand, Y. S.; Lee, D. B.; Kim, C. K.; Shin, Y. J.; Lee, J. H.

    2000-09-01

    A uranium metal rod 13.5 mm in diameter and 1,150 mm long was produced from simulated metallic spent fuels with advanced casting equipment using the directional-solidification method. A vacuum casting furnace equipped with a four-zone heater to prevent surface oxidation and the formation of surface shrinkage holes was designed. By controlling the axial temperature gradient of the casting furnace, deformation by the surface shrinkage phenomena was diminished, and a sound rod was manufactured. The cooling behavior of the molten uranium was analyzed using the computer software package MAGMAsoft.

  12. Permanent quadrupole magnets

    International Nuclear Information System (INIS)

    Bush, E.D. Jr.

    1976-01-01

    A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. (author)

  13. Investigations on thermal properties, stress and deformation of Al/SiC metal matrix composite based on finite element method

    Directory of Open Access Journals (Sweden)

    K. A. Ramesh Kumar

    2014-09-01

    Full Text Available AlSiC is a metal matrix composite which comprises of aluminium matrix with silicon carbide particles. It is characterized by high thermal conductivity (180-200 W/m K, and its thermal expansion are attuned to match other important materials that finds enormous demand in industrial sectors. Although its application is very common, the physics behind the Al-SiC formation, functionality and behaviors are intricate owing to the temperature gradient of hundreds of degrees, over the volume, occurring on a time scale of a few seconds, involving multiple phases. In this study, various physical, metallurgical and numerical aspects such as equation of continuum for thermal, stress and deformation using finite element (FE matrix formulation, temperature dependent material properties, are analyzed. Modelling and simulation studies of Al/SiC composites are a preliminary attempt to view this research work from computational point of view.

  14. Plastic deformation of particles of zirconium and titanium carbide subjected to vibration grinding

    Energy Technology Data Exchange (ETDEWEB)

    Kravchik, A.E.; Neshpor, V.S.; Savel' ev, G.A.; Ordan' yan, S.S.

    1976-12-01

    A study is made of the influence of stoichiometry on the characteristics of microplastic deformation in powders of zirconium and titanium carbide subjected to vibration grinding. The carbide powders were produced by direct synthesis from the pure materials: metallic titanium and zirconium and acetylene black. As to the nature of their elastic deformation, zirconium and titanium carbides can be considered elastic-isotropic materials. During vibration grinding, the primary fracture planes are the (110) planes. Carbides of nonstoichiometric composition are more brittle.

  15. Thermo-plastic finite element analysis for metal honeycomb structure

    Directory of Open Access Journals (Sweden)

    Ji Zhanling

    2013-01-01

    Full Text Available This paper deals with thermal-plastic analysis for the metal honeycomb structure. The heat transfer equation and thermal elastoplastic constitutive equation of a multilayer panel are established and studied numerically using ANSYS software. The paper elucidates that only the outer skin produces easily plastic deformation, and the outer skin still exists some residual stress and residual deformation after cooling. The dynamic evolution of plastic deformation and material performance degradation under high energy thermal load are revealed.

  16. Dislocation Dynamics During Plastic Deformation

    CERN Document Server

    Messerschmidt, Ulrich

    2010-01-01

    The book gives an overview of the dynamic behavior of dislocations and its relation to plastic deformation. It introduces the general properties of dislocations and treats the dislocation dynamics in some detail. Finally, examples are described of the processes in different classes of materials, i.e. semiconductors, ceramics, metals, intermetallic materials, and quasicrystals. The processes are illustrated by many electron micrographs of dislocations under stress and by video clips taken during in situ straining experiments in a high-voltage electron microscope showing moving dislocations. Thus, the users of the book also obtain an immediate impression and understanding of dislocation dynamics.

  17. GRINDING OF SURFACES WITH COATINGS FORMED BY ELECTROMAGNETIC FACING WITH SURFACE PLASTIC DEFORMATION

    Directory of Open Access Journals (Sweden)

    Zh. A. Mrochek

    2011-01-01

    Full Text Available The paper presents investigation results on machining of surfaces having a coating formed by electromagnetic facing with surface plastic deformation and using abrasive and diamond wheels having a porous metal binder with orientated drains.

  18. In-situ neutron diffraction during biaxial deformation

    OpenAIRE

    Van Petegem, S.; Wagner, J.; Panzner, T.; Upadhyay, M.V.; Trang, T.T.T.; Van Swygenhoven, H.

    2016-01-01

    A change in strain path may have a significant effect on the mechanical response of metals. In order to understand or even predict the macroscopic behaviour under such conditions a detailed knowledge on the microstructural evolution is crucial. Yet relatively little work has been done to quantify and understand how the inter- and intragranular strains are affected during a change in strain path. In this work we present a new multiaxial deformation rig that allows performing in situ proportion...

  19. Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shintaro; Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture. 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic / optical properties of metal phthalocyanine complexes were studied by quantum calculations using density functional theory. Effects of central metal and expansion of π orbital on aromatic ring as conjugation system on the electronic structures, magnetic, optical properties and vibration modes of infrared and Raman spectra of metal phthalocyanines were investigated. Electron and charge density distribution and energy levels near frontier orbital and excited states were influenced by the deformed structures varied with central metal and charge. The magnetic parameters of chemical shifts in {sup 13}C-nuclear magnetic resonance ({sup 13}C-NMR), principle g-tensor, A-tensor, V-tensor of electric field gradient and asymmetry parameters derived from the deformed structures with magnetic interaction of nuclear quadruple interaction based on electron and charge density distribution with a bias of charge near ligand under crystal field.

  20. Effect of GFRP spacer on local deformation of large superconductor in coil pack

    International Nuclear Information System (INIS)

    Nishimura, Arata; Tamura, Hitoshi; Mito, Toshiyuki; Yamamoto, Junya

    1994-01-01

    Design and construction of the Large Helical Device (LHD) are in progress at the National Institute for Fusion Science (NIFS) in Japan. The LHD has superconducting poloidal and helical coils, and many efforts have been undertaken to develop these large superconductors. When designing a large superconducting magnet, the mechanical behavior of the wound structure becomes a very important factor since the apparent rigidity affects the design of a coil support structure and the superconducting coil needs to endure the large electro-magnetic force it creates. Also, non-linear mechanical behavior should yield the instability of the magnet. In this paper, local deformation in a large conductor caused by GFRP spacers and epoxy adhesives was investigated after compressive rigidity testing. The epoxy adhesive used for attaching the GFRP spacers to the superconductor changed shape from an almost square sheet into a lens-like sheet during deformation, and a dent appeared on the surface of the superconductor. Three-dimensional FEM analysis showed that a compressive stress in the vertical direction of the loading axis existed in the adhesive plane. This stress component makes the adhesive lens-like and it results in the dent created during the compressive testing. This local deformation should yield a part of the permanent deformation observed after the compressive load cycle at 4.2 K

  1. Deformations of temporary wooden supports used to reduce building deflections in mining areas

    Science.gov (United States)

    Gromysz, Krzysztof

    2018-04-01

    Temporary supports, consisting of a stack of wooden elements and a hydraulic jack, are used in the process of removing deflections in buildings with one to three aboveground floors in mining areas. During uneven raising, the supports are loaded monotonically, unloaded and loaded cyclically. Laboratory tests were designed for the supports. For the investigated range of loads of 0 to 400 kN, under a growing load, a linear relationship exists between a load and the change in the stack length, which signifies that the deformations of wooden elements and displacements related to their mutual interactions increase proportionally. A seemingly higher stack stiffness is seen at the beginning of the unloading process and for cyclical loads, meaning that in this phase of loading, the material deformation of the wooden elements and the jack is responsible for changing the jack length in this load phase, with a negligible presence of mutual displacements of wooden elements. The support, after being unloaded, returns to the initial position and its permanent deformations are not observed. The stiffness of a temporary support decreases as the height of the stack of wooden elements increases.

  2. Deformations of temporary wooden supports used to reduce building deflections in mining areas

    Directory of Open Access Journals (Sweden)

    Gromysz Krzysztof

    2018-01-01

    Full Text Available Temporary supports, consisting of a stack of wooden elements and a hydraulic jack, are used in the process of removing deflections in buildings with one to three aboveground floors in mining areas. During uneven raising, the supports are loaded monotonically, unloaded and loaded cyclically. Laboratory tests were designed for the supports. For the investigated range of loads of 0 to 400 kN, under a growing load, a linear relationship exists between a load and the change in the stack length, which signifies that the deformations of wooden elements and displacements related to their mutual interactions increase proportionally. A seemingly higher stack stiffness is seen at the beginning of the unloading process and for cyclical loads, meaning that in this phase of loading, the material deformation of the wooden elements and the jack is responsible for changing the jack length in this load phase, with a negligible presence of mutual displacements of wooden elements. The support, after being unloaded, returns to the initial position and its permanent deformations are not observed. The stiffness of a temporary support decreases as the height of the stack of wooden elements increases.

  3. Change and anisotropy of elastic modulus in sheet metals due to plastic deformation

    Science.gov (United States)

    Ishitsuka, Yuki; Arikawa, Shuichi; Yoneyama, Satoru

    2015-03-01

    In this study, the effect of the plastic deformation on the microscopic structure and the anisotropy of the elastic modulus in the cold-rolled steel sheet (SPCC) is investigated. Various uniaxial plastic strains (0%, 2.5%, 5%, 7.5%, and 10%) are applied to the annealed SPCC plates, then, the specimens for the tensile tests are cut out from them. The elastic moduli in the longitudinal direction and the transverse direction to the direction that are pre-strained are measured by the tensile tests. Cyclic tests are performed to investigate the effects of the internal friction caused by the movable dislocations in the elastic deformation. Also, the movable dislocations are quantified by the boundary tracking for TEM micrographs. In addition, the behaviors of the change of the elastic modulus in the solutionized and thermal aged aluminum alloy (A5052) are measured to investigate the effect on the movable dislocations with the amount of the depositions. As a result in SPCC, the elastic moduli of the 0° and 90° directions decrease more than 10% as 10% prestrain applied. On the other hand, the elastic modulus shows the recovery behavior after the strain aging and the annealing. The movable dislocation and the internal friction show a tendency to increase as the plastic strain increases. The marked anisotropy is not observed in the elastic modulus and the internal friction. The elastic modulus in A5052 with many and few depositions decreases similarly by the plastic deformation. From the above, the movable dislocations affect the elastic modulus strongly without depending on the deposition amount. Moreover, the elastic modulus recovers after the plastic deformation by reducing the effects of them with the strain aging and the heat treatment.

  4. HTGR Metallic Reactor Internals Core Shell Cutting & Machining Antideformation Technique Study

    International Nuclear Information System (INIS)

    Xing Huiping; Xue Song

    2014-01-01

    The reactor shell assembly of HTGR nuclear power station demonstration project metallic reactor internals is key components of reactor, remains with high-precision large component with large-sized thin-walled straight cylinder-shaped structure, and is the first manufacture in China. As compared with other reactor shell, it has a larger ID (Φ5360mm), a longer length (19000mm), a smaller wall thickness (40mm) and a higher precision requirement. During the process of manufacture, the deformation due to cutting & machining will directly affect the final result of manufacture, the control of structural deformation and cutting deformation shall be throughout total manufacture process of such assembly. To realize the control of entire core shell assembly geometry, the key is to innovate and make breakthroughs on anti-deformation technique and then provide reliable technological foundations for the manufacture of HTGR metallic reactor internals. (author)

  5. Optimization of the uniformity of a metal flow during continuous extrusion by the Conform method

    Science.gov (United States)

    Lyubanova, A. Sh.; Gorokhov, Yu. V.; Solopko, I. V.; Ziborov, A. Yu.

    2010-03-01

    The scheme of plastic deformation of a billet in a container is considered as part of continuous extrusion by the Conform method. A mathematical model of the motion of a viscoplastic Bingham liquid is used to determine the metal velocity distribution in the plastic-deformation zone. As a result, the optimum angle between the longitudinal axes of the die and container is estimated. This angle is found to be one of the main factors affecting the nonuniformity of deformation when a metal flows into the die. The calculated results are compared to experimental data.

  6. Investigation of the deformation stability in the incremental sheet forming process

    Directory of Open Access Journals (Sweden)

    Ai S.

    2015-01-01

    Full Text Available Incremental sheet forming (ISF is a highly versatile and flexible process for rapid manufacturing of complex sheet metal parts. One of the unique characters of the ISF process is the improved formability comparing to conventional sheet forming process. This may be due to the localized deformation nature, which increases the deformation stability in the ISF process. Although many hypotheses have been proposed, there is no direct modelling and calculation of the ISF deformation stability. Aiming to obtain a better understanding of the ISF process, an analytical model was developed to investigate and analyse the material deformation stability in this work. Based on the analytical evaluation of stress variations and force equilibrium, a mathematical relationship between the maximum forming angle and the process stability condition was established. To validate the developed model, experiments were carried out by forming a hyperbolic part made of AA1100 material. The maximum forming angle, as an indicator to the ISF formability, was employed compare the analytical evaluation and experimental result. It was found that the ISF deformation stability is one of the key factors that affect the ISF formability.

  7. 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.

  8. Mutual capacitance of liquid conductors in deformable tactile sensing arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin [Electrical and Computer Engineering Department, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Fontecchio, Adam K. [Electrical and Computer Engineering and Materials Science and Engineering Departments, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Visell, Yon [Electrical and Computer Engineering Department, Media Arts and Technology, California NanoSystems Institute, University of California, Santa Barbara, California 93106 (United States)

    2016-01-04

    Advances in highly deformable electronics are needed in order to enable emerging categories of soft computing devices ranging from wearable electronics, to medical devices, and soft robotic components. The combination of highly elastic substrates with intrinsically stretchable conductors holds the promise of enabling electronic sensors that can conform to curved objects, reconfigurable displays, or soft biological tissues, including the skin. Here, we contribute sensing principles for tactile (mechanical image) sensors based on very low modulus polymer substrates with embedded liquid metal microfluidic arrays. The sensors are fabricated using a single-step casting method that utilizes fine nylon filaments to produce arrays of cylindrical channels on two layers. The liquid metal (gallium indium alloy) conductors that fill these channels readily adopt the shape of the embedding membrane, yielding levels of deformability greater than 400%, due to the use of soft polymer substrates. We modeled the sensor performance using electrostatic theory and continuum mechanics, yielding excellent agreement with experiments. Using a matrix-addressed capacitance measurement technique, we are able to resolve strain distributions with millimeter resolution over areas of several square centimeters.

  9. Crystalline structure of metals

    International Nuclear Information System (INIS)

    Holas, A.

    1972-01-01

    An attempt is made to find the crystalline structure of metals on the basis of the existing theory of metals. The considerations are limited to the case of free crystals, that is, not subjected to any stresses and with T=0. The energy of the crystal lattice has been defined and the dependence of each term on structures and other properties of metals has been described. The energy has been used to find the values of crystalline structure parameters as the values at which the energy has an absolute minimum. The stability of the structure has been considered in cases of volume changes and shearing deformations. A semiqualitative description has been obtained which explains characteristic properties of one-electron metals. (S.B.)

  10. Deformation of the Durom acetabular component and its impact on tribology in a cadaveric model--a simulator study.

    Science.gov (United States)

    Liu, Feng; Chen, Zhefeng; Gu, Yanqing; Wang, Qing; Cui, Weiding; Fan, Weimin

    2012-01-01

    Recent studies have shown that the acetabular component frequently becomes deformed during press-fit insertion. The aim of this study was to explore the deformation of the Durom cup after implantation and to clarify the impact of deformation on wear and ion release of the Durom large head metal-on-metal (MOM) total hips in simulators. Six Durom cups impacted into reamed acetabula of fresh cadavers were used as the experimental group and another 6 size-paired intact Durom cups constituted the control group. All 12 Durom MOM total hips were put through a 3 million cycle (MC) wear test in simulators. The 6 cups in the experimental group were all deformed, with a mean deformation of 41.78 ± 8.86 µm. The average volumetric wear rate in the experimental group and in the control group in the first million cycle was 6.65 ± 0.29 mm(3)/MC and 0.89 ± 0.04 mm(3)/MC (t = 48.43, p = 0.000). The ion levels of Cr and Co in the experimental group were also higher than those in the control group before 2.0 MC. However there was no difference in the ion levels between 2.0 and 3.0 MC. This finding implies that the non-modular acetabular component of Durom total hip prosthesis is likely to become deformed during press-fit insertion, and that the deformation will result in increased volumetric wear and increased ion release. This study was determined to explore the deformation of the Durom cup after implantation and to clarify the impact of deformation on wear and ion release of the prosthesis. Deformation of the cup after implantation increases the wear of MOM bearings and the resulting ion levels. The clinical use of the Durom large head prosthesis should be with great care.

  11. Moving Particle Semi-implicit method: a numerical method for thermal hydraulic analysis with topological deformations

    International Nuclear Information System (INIS)

    Koshizuka, S.; Oka, Y.

    1997-01-01

    Moving Particle Semi-implicit (MPS) method is presented. Partial differential operators in the governing equations, such as gradient and Laplacian, are modeled as particle interactions without grids. A semi-implicit algorithm is used for incompressible flow analysis. In the present study, calculation models of moving solids, thin structures and phase change between liquid and gas are developed. Interaction between breaking waves and a floating solid is simulated using the model of moving solids. Calculations of collapsing water with a vertical thin plate show that water spills out over the plate which is largely deformed. Impingement of water jets on a molten metal pool is analyzed to investigate fundamental processes of vapor explosions. Water, vapor and molten metal are simultaneously calculated with evaporation. This calculation reveals that filaments of the molten metal emerge as the fragmentation process of vapor explosions. The MPS method is useful for complex problems involving moving interfaces even if topological deformations occur. (author)

  12. Rare earth permanent-magnet alloys’ high temperature phase transformation in situ and dynamic observation and its application in material design

    CERN Document Server

    Pan, Shuming

    2013-01-01

    The process of high temperature phase transition of rare earth permanent-magnet alloys is revealed by photographs taken by high voltage TEM. The relationship between the formation of nanocrystal and magnetic properties is discussed in detail, which effects alloys composition and preparation process. The experiment results verified some presumptions, and were valuable for subsequent scientific research and creating new permanent-magnet alloys. The publication is intended for researchers, engineers and managers in the field of material science, metallurgy, and physics. Prof. Shuming Pan is senior engineer of Beijing General Research Institute of Non-ferrous Metal.

  13. Metal forming and lubrication

    DEFF Research Database (Denmark)

    Bay, Niels

    2000-01-01

    Lubrication is essential in most metal forming processes. The lubricant film has two basic functions, [1]: i. to separate the work piece and tool surfaces and ii. to cool the workpiece and the tool. Separation of the two surfaces implies lower friction facilitating deformation and lowering the tool...

  14. 31 CFR 515.335 - Permanent resident alien.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States. [61 FR 37386, July 18...

  15. Lawful Permanent Residents - Annual Report

    Data.gov (United States)

    Department of Homeland Security — A lawful permanent resident (LPR) or 'green card' recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

  16. Proceedings of the sixth international workshop on rare earth-cobalt permanent magnets and their applications, August 31 - September 2, 1982, and third international symposium on magnetic anisotropy and coercivity in rare earth-transition metal alloys, September 3, 1982

    International Nuclear Information System (INIS)

    Fidler, J.

    1982-01-01

    The first part (workshop) is concerned specifically with applications of rare earth-cobalt permanent magnets. The session headings are 1) electro-mechanical applications 2) electronic and miscellaneous applications 3) magneto-mechanical applications plus workshop on measurement methods 4) new materials and processes 5) industrial applications of REPM and future aspects. The second part (symposium) is concerned with physical properties of specific rare earth-transition metal alloys. (G.Q.)

  17. Reinforcement of Underground Excavation with Expansion Shell Rock Bolt Equipped with Deformable Component

    Directory of Open Access Journals (Sweden)

    Korzeniowski Waldemar

    2017-03-01

    Full Text Available The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod. There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.

  18. Metal extrusion using hydrostatic pressures

    International Nuclear Information System (INIS)

    Sauve, Ch.

    1965-01-01

    The main problems connected with the deformation of metals due to extrusion are described. A method is put forward for calculating the rational rate of percentage deformation in the case of bar extrusion using a cylindrical container; reference is made to previous work on extrusion using a hydrostatic pressure with or without back-pressure. An extrusion process is described using hydrostatic pressure, without back-pressure, and using the lubricant for transmitting the thrust. This process has been used for eight years by the C.E.A. for the extrusion of a very wide range of metals, from beryllium to uranium and including steels; it leads to excellent surface textures. A very fine crystallization can be obtained on extruded products when the rate of extrusion is very low. There appears to be nothing against the use of high extrusion rates using this method. (author) [fr

  19. Investigation of coercivity mechanism in hot deformed Nd-Fe-B permanent magnets by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Yano, M.; Manabe, A.; Shoji, T.; Kato, A.; Ono, K.; Harada, M.; Kohlbrecher, J.

    2014-01-01

    The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd 2 Fe 14 B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the Teubner–Stray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains

  20. Cell-wall recovery after irreversible deformation of wood

    Science.gov (United States)

    Keckes, Jozef; Burgert, Ingo; Frühmann, Klaus; Müller, Martin; Kölln, Klaas; Hamilton, Myles; Burghammer, Manfred; Roth, Stephan V.; Stanzl-Tschegg, Stefanie; Fratzl, Peter

    2003-12-01

    The remarkable mechanical properties of biological materials reside in their complex hierarchical architecture and in specific molecular mechanistic phenomena. The fundamental importance of molecular interactions and bond recovery has been suggested by studies on deformation and fracture of bone and nacre. Like these mineral-based materials, wood also represents a complex nanocomposite with excellent mechanical performance, despite the fact that it is mainly based on polymers. In wood, however, the mechanistic contribution of processes in the cell wall is not fully understood. Here we have combined tensile tests on individual wood cells and on wood foils with simultaneous synchrotron X-ray diffraction analysis in order to separate deformation mechanisms inside the cell wall from those mediated by cell-cell interactions. We show that tensile deformation beyond the yield point does not deteriorate the stiffness of either individual cells or foils. This indicates that there is a dominant recovery mechanism that re-forms the amorphous matrix between the cellulose microfibrils within the cell wall, maintaining its mechanical properties. This stick-slip mechanism, rather like Velcro operating at the nanometre level, provides a 'plastic response' similar to that effected by moving dislocations in metals. We suggest that the molecular recovery mechanism in the cell matrix is a universal phenomenon dominating the tensile deformation of different wood tissue types.

  1. [Permanent education in health: a review].

    Science.gov (United States)

    Miccas, Fernanda Luppino; Batista, Sylvia Helena Souza da Silva

    2014-02-01

    To undertake a meta-synthesis of the literature on the main concepts and practices related to permanent education in health. A bibliographical search was conducted for original articles in the PubMed, Web of Science, LILACS, IBECS and SciELO databases, using the following search terms: "public health professional education", "permanent education", "continuing education", "permanent education health". Of the 590 articles identified, after applying inclusion and exclusion criteria, 48 were selected for further analysis, grouped according to the criteria of key elements, and then underwent meta-synthesis. The 48 original publications were classified according to four thematic units of key elements: 1) concepts, 2) strategies and difficulties, 3) public policies and 4) educational institutions. Three main conceptions of permanent education in health were found: problem-focused and team work, directly related to continuing education and education that takes place throughout life. The main strategies for executing permanent education in health are discussion, maintaining an open space for permanent education , and permanent education clusters. The most limiting factor is mainly related to directly or indirect management. Another highlight is the requirement for implementation and maintenance of public policies, and the availability of financial and human resources. The educational institutions need to combine education and service aiming to form critical-reflexive graduates. The coordination between health and education is based as much on the actions of health services as on management and educational institutions. Thus, it becomes a challenge to implement the teaching-learning processes that are supported by critical-reflexive actions. It is necessary to carry out proposals for permanent education in health involving the participation of health professionals, teachers and educational institutions. To undertake a meta-synthesis of the literature on the main concepts and

  2. On the nature of low temperature internal friction peaks in metallic glasses

    NARCIS (Netherlands)

    Khonik, VA; Spivak, LV

    Low temperature (30 metallic glass Ni60Nb40 subjected to preliminary inhomogeneous deformation by cold rolling, homogeneous tensile deformation or electrolytic charging with hydrogen is investigated. Cold rolling or hydrogenation result in appearance of similar

  3. Deformed Materials: Towards a Theory of Materials Morphology Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sethna, James P [Laboratory of Atomic and Solid State Physics, Cornell University

    2017-06-28

    This grant supported work on the response of crystals to external stress. Our primary work described how disordered structural materials break in two (statistical models of fracture in disordered materials), studied models of deformation bursts (avalanches) that mediate deformation on the microscale, and developed continuum dislocation dynamics models for plastic deformation (as when scooping ice cream bends a spoon, Fig. 9). Glass is brittle -- it breaks with almost atomically smooth fracture surfaces. Many metals are ductile -- when they break, the fracture surface is locally sheared and stretched, and it is this damage that makes them hard to break. Bone and seashells are made of brittle material, but they are strong because they are disordered -- lots of little cracks form as they are sheared and near the fracture surface, diluting the external force. We have studied materials like bone and seashells using simulations, mathematical tools, and statistical mechanics models from physics. In particular, we studied the extreme values of fracture strengths (how likely will a beam in a bridge break far below its design strength), and found that the traditional engineering tools could be improved greatly. We also studied fascinating crackling-noise precursors -- systems which formed microcracks of a broad range of sizes before they broke. Ductile metals under stress undergo irreversible plastic deformation -- the planes of atoms must slide across one another (through the motion of dislocations) to change the overall shape in response to the external force. Microscopically, the dislocations in crystals move in bursts of a broad range of sizes (termed 'avalanches' in the statistical mechanics community, whose motion is deemed 'crackling noise'). In this grant period, we resolved a longstanding mystery about the average shape of avalanches of fixed duration (using tools related to an emergent scale invariance), we developed the fundamental theory

  4. Deformation-Induced Precession of a Robot Moving on Curved Space

    Science.gov (United States)

    Li, Shengkai; Aydin, Yasemin; Lofaro, Olivia; Rieser, Jennifer; Goldman, Daniel

    Previous studies have demonstrated that passive particles rolling on a deformed surface can mimic aspects of general relativity [Ford et al, AJP, 2015]. However, these systems are dissipative. To explore steady-state dynamics, we study the movement of a self-propelled robot car on a large deformable elastic membrane: a spandex sheet stretched over a metal frame with a diameter of 2.5 m. Two wheels in the rear of the car are differentially-driven by a DC motor, and a caster in the front helps maintain directional stability; in the absence of curvature the car drives straight. A linear actuator attached below the membrane allows for controlled deformation at the center of the membrane. We find that closed elliptic orbits occur when the membrane is highly depressed ( 10 cm). However, when the center is only slightly indented, the elliptical orbits precess at a rate depending on the orbit shape and the depression. Remarkably, this dynamic is well described by the Schwarzschild metric solution, typically used to describe the effects of gravity on bodies orbiting a massive object. Experiments with multiple cars reveal complex interactions that are mediated through car-induced deformations of the membrane.

  5. Effect of method for plastic working procedure on deformability of heat resisting alloys

    International Nuclear Information System (INIS)

    Nikiforov, B.A.

    1979-01-01

    Presented are the results of investigation of deformability of the heat resisting KhN56BMTYUR, KhN67BMTYU alloys at the wire drawing and rolling. The deformability has been evaluated by the results of macro- and micro-analyses, by the change of metal density and mechanical properties in the process of deformation. It is found that by the rolling it is possible to obtain 3-6 mm diameter wire with high surface quality avoiding intermediate heat treatments, cleaning and grinding the wire surface. The production of the wire of the same diameter by drawing is connected with intermediate heat treatments and with the presence of surface and internal defects in the form of longitudinal and transverse cracks, tears, laminations

  6. The effect of 210Pb and stable lead on the induction of mouthpart deformities in chironomid larvae

    International Nuclear Information System (INIS)

    Bird, G.A.; Schwartz, W.J.; Hoffman, D.

    1995-07-01

    To determine whether mouthpart deformities in chironomid larvae from Port Hope Harbour, Ontario, are the result of exposure to ionizing radiation or heavy metals in the sediment, Chironomus tentans larvae were exposed in the laboratory to concentrations of 210 Pb and stable lead representative of contaminant levels in the harbour. Exposure to 100, 1000, and 2000 Bq 210 Pb·g -1 dry sediment had no effect on the survival, growth of the larvae or frequency of deformities. Likewise, exposure to 0.5 and 5.0 mg lead·g -1 dry sediment had no effect on the larvae, but exposure to 35.0 mg lead·g -1 dry sediment resulted in 100% mortality of the larvae. These results indicate that the observed mouthpart deformities in chironomid larvae in Port Hope Harbour are not the result of radiation exposure. They also indicate that heavy metals (lead) may be having an impact on the population. (author). 28 refs., 9 tabs., 4 figs

  7. Periodic permanent magnet focused klystron

    Science.gov (United States)

    Ferguson, Patrick; Read, Michael; Ives, R Lawrence

    2015-04-21

    A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

  8. Evaluation of spontaneous space closure and development of permanent dentition after extraction of hypomineralized permanent first molars.

    Science.gov (United States)

    Jälevik, Birgitta; Möller, Marie

    2007-09-01

    The aim of this study was to evaluate spontaneous space closure, development of the permanent dentition, and need for orthodontic treatment after extraction of permanent first molars due to severe molar-incisor hypomineralization (MIH). Twenty-seven children aged 5.6-12.7 (median 8.2) years had one to four permanent first molars extracted due to severe MIH. Each case was followed up on individual indications 3.8-8.3 (median 5.7) years after extractions. The eruption of the permanent dentition, and space closure were documented by orthopantomograms, casts, photographs, and/or bitewings. Fifteen children were judged to have a favourable spontaneous development of their permanent dentition without any orthodontic intervention. Seven children were or should be subjected to orthodontic treatment for other reasons registered prior to the extraction. Five children were judged to have a treatment at least caused by the extractions, but three of them abstained because of no subjective treatment need. Extraction of permanent first molars severely affected by MIH is a good treatment alternative. Favourable spontaneous space reduction and development of the permanent dentition positioning can be expected without any intervention in the majority of cases extracted prior to the eruption of the second molar.

  9. Modern permanent magnetic materials - preparation and properties

    International Nuclear Information System (INIS)

    Rodewald, W.

    1989-01-01

    First of all, the basic properties of the classical (steel, AlNiCo) permanent magnetic materials and the modern rare-earth (RE) permanent magnetic materials are compared. Since the properties of RE permanent magnets depend on the particular production process, the fundamentals of the main industrial processes (powder metallurgy, rapid-solidification technique) are described and the typical properties are explained. Furthermore the production processes in development such as mechanical alloying, melt spinning technique and extrusion upsetting are briefly outlined. For applying the permanent magnets, they have to be completely magnetized. The magnetization behaviour of the various RE permanent magnets is discussed by means of the internal demagnetization curve. Finally the various influences on the temperature stability of RE permanent magnets are compiled. (orig./MM) [de

  10. Study of resistance to deformation dependence on temperature and strain degree during working with different rates for ABM-1 alloy

    International Nuclear Information System (INIS)

    Kharlamov, V.V.; Dvinskij, V.M.; Vashlyaev, Eh.V.; Dyblenko, Z.A.; Khamatov, R.I.; Zverev, K.P.

    1981-01-01

    On the basis of approximation of the experimental curves partial differential equations relating ABM-1 alloy deformation resistance to the deformation parameters are obtained. Using statistical processing of the experimental data the regression equations of the dependence of the deformation resistance on temperature rate and relative reduction of the samples are found. In the 2.1-23.6 1/c deformation rate range hardening and weakening rates of the AMB-1 alloy increases with the increase of the latter. The data obtained permit to calculate the deformation parameters of the studied alloy for different processes of metal plastic working in the studied temperature range [ru

  11. Lawful Permanent Residents Fiscal Year 2015 State

    Data.gov (United States)

    Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

  12. Lawful Permanent Residents Fiscal Year 2014 Country

    Data.gov (United States)

    Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

  13. Lawful Permanent Residents Fiscal Year 2011 State

    Data.gov (United States)

    Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

  14. Lawful Permanent Residents Fiscal Year 2015 Country

    Data.gov (United States)

    Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

  15. Lawful Permanent Residents Fiscal Year 2016 State

    Data.gov (United States)

    Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

  16. Lawful Permanent Residents Fiscal Year 2014 State

    Data.gov (United States)

    Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

  17. Electron microscopy and plastic deformation of HCP metals and alloys

    International Nuclear Information System (INIS)

    Poirier, J.-P.; Le Hazif, Roger

    1976-01-01

    The recent literature on the slip systems of the h.c.p. metals is reviewed and the contribution of transmission electron microscopy assessed. It is now clear that the stress-strain curves and the dislocation configurations in the slip plane are very similar, whether the principal slip system is basal or prismatic. The important problem of the relative ease of slip systems is linked to the ease of splitting of dislocations in the slip planes and to the electronic band structure of the metal [fr

  18. Three-dimensional shear transformation zone dynamics model for amorphous metals

    International Nuclear Information System (INIS)

    Homer, Eric R; Schuh, Christopher A

    2010-01-01

    A fully three-dimensional (3D) mesoscale modeling framework for the mechanical behavior of amorphous metals is proposed. The model considers the coarse-grained action of shear transformation zones (STZs) as the fundamental deformation event. The simulations are controlled through the kinetic Monte Carlo algorithm and the mechanical response of the system is captured through finite-element analysis, where STZs are mapped onto a 3D finite-element mesh and are allowed to shear in any direction in three dimensions. Implementation of the technique in uniaxial creep tests over a wide range of conditions validates the model's ability to capture the expected behaviors of an amorphous metal, including high temperature flow conforming to the expected constitutive law and low temperature localization in the form of a nascent shear band. The simulation results are combined to construct a deformation map that is comparable to experimental deformation maps. The flexibility of the modeling framework is illustrated by performing a contact test (simulated nanoindentation) in which the model deforms through STZ activity in the region experiencing the highest shear stress

  19. Topology optimized permanent magnet systems

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian; Insinga, Andrea Roberto

    2017-01-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron...... and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a ΛcoolΛcool figure of merit of 0...

  20. Metal-on-metal hip joint tribology.

    Science.gov (United States)

    Dowson, D; Jin, Z M

    2006-02-01

    The basic tribological features of metal-on-metal total hip replacements have been reviewed to facilitate an understanding of the engineering science underpinning the renaissance of these hard-on-hard joints. Metal-on-polymer hip replacements operate in the boundary lubrication regime, thus leading to the design guidance to reduce the femoral head diameter as much as is feasible to minimize frictional torque and volumetric wear. This explains why the gold-standard implant of this form from the past half-century had a diameter of only 22.225 mm (7/8 in). Metal-on-metal implants can operate in the mild mixed lubrication regime in which much of the applied load is supported by elastohydrodynamic films. Correct tribological design leads to remarkably low steady state wear rates. Promotion of the most effective elastohydrodynamic films calls for the largest possible head diameters and the smallest clearances that can reasonably be adopted, consistent with fine surface finishes, good sphericity and minimal structural elastic deformation of the cup on its foundations. This guidance, which is opposite in form to that developed for metal-on-polymer joints, is equally valid for solid (monolithic) metallic heads on metallic femoral stems and surface replacement femoral shells. Laboratory measurements of friction and wear in metal-on-metal joints have confirmed their potential to achieve a very mild form of mixed lubrication. The key lies in the generation of effective elastohydrodynamic lubricating films of adequate thickness compared with the composite roughness of the head and cup. The calculation of the film thickness is by no means easy, but the full procedure is outlined and the use of an empirical formula that displays good agreement with calculations based upon the full numerical solutions is explained. The representation of the lambda ratio, lambda, embracing both film thickness and composite roughness, is described.

  1. Object permanence in lemurs.

    Science.gov (United States)

    Deppe, Anja M; Wright, Patricia C; Szelistowski, William A

    2009-03-01

    Object permanence, the ability to mentally represent objects that have disappeared from view, should be advantageous to animals in their interaction with the natural world. The objective of this study was to examine whether lemurs possess object permanence. Thirteen adult subjects representing four species of diurnal lemur (Eulemur fulvus rufus, Eulemur mongoz, Lemur catta and Hapalemur griseus) were presented with seven standard Piagetian visible and invisible object displacement tests, plus one single visible test where the subject had to wait predetermined times before allowed to search, and two invisible tests where each hiding place was made visually unique. In all visible tests lemurs were able to find an object that had been in clear view before being hidden. However, when lemurs were not allowed to search for up to 25-s, performance declined with increasing time-delay. Subjects did not outperform chance on any invisible displacements regardless of whether hiding places were visually uniform or unique, therefore the upper limit of object permanence observed was Stage 5b. Lemur species in this study eat stationary foods and are not subject to stalking predators, thus Stage 5 object permanence is probably sufficient to solve most problems encountered in the wild.

  2. Microstructure and Strain Rate-Dependent Tensile Deformation Behavior of Fiber Laser-Welded Butt Joints of Dual-Phase Steels

    Science.gov (United States)

    Liu, Yang; Dong, Danyang; Han, Zhiqiang; Yang, Zhibin; Wang, Lu; Dong, Qingwei

    2018-05-01

    The microstructure and tensile deformation behavior of the fiber laser-welded similar and dissimilar dual-phase (DP) steel joints over a wide range of strain rates from 10-3 to 103 s-1 were investigated for the further applications on the lightweight design of vehicles. The high strain rate dynamic tensile deformation process and full-field strain distribution of the base metals and welded joints were examined using the digital image correlation method and high-speed photography. The strain rate effects on the stress-strain responses, tensile properties, deformation, and fracture behavior of the investigated materials were analyzed. The yield stress (YS) and ultimate tensile strength (UTS) of the dissimilar DP780/DP980 welded joints were lying in-between those of the DP780 and DP980 base metals, and all materials exhibited positive strain rate dependence on the YS and UTS. Owing to the microstructure heterogeneity, the welded joints showed relatively lower ductility in terms of total elongation (TE) than those of the corresponding base metals. The strain localization started before the maximum load was reached, and the strain localization occurred earlier during the whole deformation process with increasing strain rate. As for the dissimilar welded joint, the strain localization tended to occur in the vicinity of the lowest hardness value across the welded joint, which was in the subcritical HAZ at the DP780 side. As the strain rate increased, the typical ductile failure characteristic of the investigated materials did not change.

  3. Microstructure and Strain Rate-Dependent Tensile Deformation Behavior of Fiber Laser-Welded Butt Joints of Dual-Phase Steels

    Science.gov (United States)

    Liu, Yang; Dong, Danyang; Han, Zhiqiang; Yang, Zhibin; Wang, Lu; Dong, Qingwei

    2018-04-01

    The microstructure and tensile deformation behavior of the fiber laser-welded similar and dissimilar dual-phase (DP) steel joints over a wide range of strain rates from 10-3 to 103 s-1 were investigated for the further applications on the lightweight design of vehicles. The high strain rate dynamic tensile deformation process and full-field strain distribution of the base metals and welded joints were examined using the digital image correlation method and high-speed photography. The strain rate effects on the stress-strain responses, tensile properties, deformation, and fracture behavior of the investigated materials were analyzed. The yield stress (YS) and ultimate tensile strength (UTS) of the dissimilar DP780/DP980 welded joints were lying in-between those of the DP780 and DP980 base metals, and all materials exhibited positive strain rate dependence on the YS and UTS. Owing to the microstructure heterogeneity, the welded joints showed relatively lower ductility in terms of total elongation (TE) than those of the corresponding base metals. The strain localization started before the maximum load was reached, and the strain localization occurred earlier during the whole deformation process with increasing strain rate. As for the dissimilar welded joint, the strain localization tended to occur in the vicinity of the lowest hardness value across the welded joint, which was in the subcritical HAZ at the DP780 side. As the strain rate increased, the typical ductile failure characteristic of the investigated materials did not change.

  4. Deformation-specific and deformation-invariant visual object recognition: pose vs identity recognition of people and deforming objects

    Directory of Open Access Journals (Sweden)

    Tristan J Webb

    2014-04-01

    Full Text Available When we see a human sitting down, standing up, or walking, we can recognise one of these poses independently of the individual, or we can recognise the individual person, independently of the pose. The same issues arise for deforming objects. For example, if we see a flag deformed by the wind, either blowing out or hanging languidly, we can usually recognise the flag, independently of its deformation; or we can recognise the deformation independently of the identity of the flag. We hypothesize that these types of recognition can be implemented by the primate visual system using temporo-spatial continuity as objects transform as a learning principle. In particular, we hypothesize that pose or deformation can be learned under conditions in which large numbers of different people are successively seen in the same pose, or objects in the same deformation. We also hypothesize that person-specific representations that are independent of pose, and object-specific representations that are independent of deformation and view, could be built, when individual people or objects are observed successively transforming from one pose or deformation and view to another. These hypotheses were tested in a simulation of the ventral visual system, VisNet, that uses temporal continuity, implemented in a synaptic learning rule with a short-term memory trace of previous neuronal activity, to learn invariant representations. It was found that depending on the statistics of the visual input, either pose-specific or deformation-specific representations could be built that were invariant with respect to individual and view; or that identity-specific representations could be built that were invariant with respect to pose or deformation and view. We propose that this is how pose-specific and pose-invariant, and deformation-specific and deformation-invariant, perceptual representations are built in the brain.

  5. Permanent Pacemaker-Induced Superior Vena Cava Syndrome: Successful Treatment by Endovascular Stent

    International Nuclear Information System (INIS)

    Lanciego, Carlos; Rodriguez, Mario; Rodriguez, Adela; Carbonell, Miguel A.; Garcia, Lorenzo Garcia

    2003-01-01

    The use of metallic stents in the management of benign and malignant superior vena cava syndrome (SVCS) is well documented. Symptomatic stenosis or occlusion of the SVC is a rare complication of a transvenous permanent pacemaker implant. Suggested treatments have included anticoagulation therapy, thrombolysis, balloon angioplasty and surgery. More recently, endovascular stenting has evolved as an attractive alternative but the data available in the literature are limited. We describe a case in which venous stenting with a Wallstent endoprosthesis was used successfully. The patient remains symptom free and with normal pacemaker function 36 months later

  6. Enhancement of surface integrity of titanium alloy with copper by means of laser metal deposition process

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-04-01

    Full Text Available The laser metal deposition process possesses the combination of metallic powder and laser beam respectively. However, these combinations create an adhesive bonding that permanently solidifies the laser-enhanced-deposited powders. Titanium alloys (Ti...

  7. Hydrogen induced crack propagation in metal under plain-strain deformation

    International Nuclear Information System (INIS)

    Fishgojt, A.V.; Kolachev, B.A.

    1981-01-01

    A model of subcritical crack propagation conditioned by the effect of dissolved hydrogen in the case of plane-strain deformation of high-strength materials, is suggested. It is supposed that diffusion takes place in the isotropic material and hydrogen diffuses in the region of tensile stress maximum before crack tip under the effect of the stress gradient. When hydrogen achieves the critical concentration, microcrack growth takes place. Values of crack growth rates experimentally obtained agree with values calculated according to the suggested formula. Calculation and experimental data on the Ti-6Al-4V alloy, are presented [ru

  8. 14 CFR 23.967 - Fuel tank installation.

    Science.gov (United States)

    2010-01-01

    ... the engine compartment may act as the wall of an integral tank. (d) Each fuel tank must be isolated... loads without permanent deformation or failure under the conditions of §§ 23.365 and 23.843 of this part. A bladder-type fuel cell, if used, must have a retaining shell at least equivalent to a metal fuel...

  9. ANALYSIS OF DEFORMATION PROCESSES IN THE LITHOSPHERE FROM GEODETIC MEASUREMENTS BASED ON THE EXAMPLE OF THE SAN ANDREAS FAULT

    Directory of Open Access Journals (Sweden)

    Yury V. Gabsatarov

    2012-01-01

    Full Text Available Analysis of data from permanent GPS observation stations located in tectonically active regions provides for direct observation of deformation processes of the earth's surface which result from elastic interaction of the lithospheric plates and also occur when accumulated stresses are released by seismic events and postseismic processes.This article describes the methodology of applying the regression analysis of time series of data from GPS-stations for identification of individual components of the stations’ displacements caused by the influence of various deformation processes. Modelling of the stations’ displacements caused only by deformations of the marginal zone, wherein the lithospheric plates interact, allows us to study variations of the steady-state deformation in the marginal zone.he proposed methodology is applied to studies of variations of fields of cumulative surface displacements, surface displacement velocity and maximum shear strain velocity which are determined from the GPS data recorded prior to the Parkfield earthquake of 28 September 2004 (Mw=6.0.Combined analysis of the variations of the above-mentioned fields shows that measurable anomalies of the elastic deformation of the transform fault’s edge took place prior to the seismic event of 28 September 2004, and such anomalies were coincident in space and time with the focal area of the future seismic event.

  10. Towards high velocity deformation characterisation of metals and composites using Digital Image Correlation

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken; Berggreen, Christian; Boyd, S.W

    2010-01-01

    images and then extracting deformation data using Digital Image Correlation (DIC) from tensile testing in the intermediate strain rate regime available with the test machines. Three different materials, aluminium alloy 1050, S235 steel and glass fibre reinforced plastic (GFRP) were tested at different......Characterisation of materials subject to high velocity deformation is necessary as many materials behave differently under such conditions. It is particularly important for accurate numerical simulation of high strain rate events. High velocity servo-hydraulic test machines have enabled material...... testing in the strain rate regime from 1 – 500 ε/s. The range is much lower than that experienced under ballistic, shock or impact loads, nevertheless it is a useful starting point for the application of optical techniques. The present study examines the possibility of using high speed cameras to capture...

  11. Blood metal levels and metal-influenced immune functions of harbour seals in captivity

    International Nuclear Information System (INIS)

    Kakuschke, Antje; Valentine-Thon, Elizabeth; Griesel, Simone; Rosenberger, Tanja; Mundry, Roger; Siebert, Ursula; Prange, Andreas

    2008-01-01

    Immunological blood parameters and the effects of environmental pollutants on the immune system are important to assess the health status of seals. Animals living permanently in seal centres are useful for development and validation of diagnostic tools for free-ranging animals. In this study, parameters of cellular immunity as well as metal concentrations in blood and metal influence on cell proliferation of seven seals from a seal centre were investigated repeatedly using multi-element analysis and a lymphocyte proliferation assay. The metal concentrations, except for tin and chromium, were in general comparable to those of free-ranging animals of the North Sea. The unstimulated and mitogen-stimulated lymphocyte proliferation showed strong intra- and inter-individual variability, which reflected variability in activation of the immune status. Furthermore, both immunosuppressive and stimulative influences of metals on lymphocytes were found. Summarising, the methods used in this investigation provided useful information on these animals, and their application to free-ranging animals can be recommended

  12. Blood metal levels and metal-influenced immune functions of harbour seals in captivity

    Energy Technology Data Exchange (ETDEWEB)

    Kakuschke, Antje [GKSS Research Centre, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany)], E-mail: antje.kakuschke@gkss.de; Valentine-Thon, Elizabeth [Department of Immunology, Laboratory Center Bremen, Friedrich-Karl-Strasse 22, 28205 Bremen (Germany); Griesel, Simone [GKSS Research Centre, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany); Rosenberger, Tanja [Seal Centre Friedrichskoog e.V., 25718 Friedrichskoog (Germany); Mundry, Roger [Research and Technology Centre Westcoast (FTZ), University of Kiel, Hafentoern 1, 25761 Buesum (Germany); Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig (Germany); Siebert, Ursula [Research and Technology Centre Westcoast (FTZ), University of Kiel, Hafentoern 1, 25761 Buesum (Germany); Prange, Andreas [GKSS Research Centre, Institute for Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht (Germany)

    2008-04-15

    Immunological blood parameters and the effects of environmental pollutants on the immune system are important to assess the health status of seals. Animals living permanently in seal centres are useful for development and validation of diagnostic tools for free-ranging animals. In this study, parameters of cellular immunity as well as metal concentrations in blood and metal influence on cell proliferation of seven seals from a seal centre were investigated repeatedly using multi-element analysis and a lymphocyte proliferation assay. The metal concentrations, except for tin and chromium, were in general comparable to those of free-ranging animals of the North Sea. The unstimulated and mitogen-stimulated lymphocyte proliferation showed strong intra- and inter-individual variability, which reflected variability in activation of the immune status. Furthermore, both immunosuppressive and stimulative influences of metals on lymphocytes were found. Summarising, the methods used in this investigation provided useful information on these animals, and their application to free-ranging animals can be recommended.

  13. Marxism as permanent revolution

    OpenAIRE

    van Ree, E.

    2013-01-01

    This article argues that the 'permanent revolution' represented the dominant element in Karl Marx and Friedrich Engels' political discourse, and that it tended to overrule considerations encapsulated in 'historical materialism'. In Marx and Engels's understanding, permanent revolution did not represent a historical shortcut under exceptional circumstances, but the course revolutions in the modern era would normally take. Marx and Engels traced back the pattern to the sixteenth century. It is ...

  14. Correlations in rare-earth transition-metal permanent magnets

    International Nuclear Information System (INIS)

    Skomski, R.; Manchanda, P.; Kashyap, A.

    2015-01-01

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo 5 . On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy

  15. Correlations in rare-earth transition-metal permanent magnets

    Science.gov (United States)

    Skomski, R.; Manchanda, P.; Kashyap, A.

    2015-05-01

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

  16. Deformation of the Durom acetabular component and its impact on tribology in a cadaveric model--a simulator study.

    Directory of Open Access Journals (Sweden)

    Feng Liu

    Full Text Available BACKGROUND: Recent studies have shown that the acetabular component frequently becomes deformed during press-fit insertion. The aim of this study was to explore the deformation of the Durom cup after implantation and to clarify the impact of deformation on wear and ion release of the Durom large head metal-on-metal (MOM total hips in simulators. METHODS: Six Durom cups impacted into reamed acetabula of fresh cadavers were used as the experimental group and another 6 size-paired intact Durom cups constituted the control group. All 12 Durom MOM total hips were put through a 3 million cycle (MC wear test in simulators. RESULTS: The 6 cups in the experimental group were all deformed, with a mean deformation of 41.78 ± 8.86 µm. The average volumetric wear rate in the experimental group and in the control group in the first million cycle was 6.65 ± 0.29 mm(3/MC and 0.89 ± 0.04 mm(3/MC (t = 48.43, p = 0.000. The ion levels of Cr and Co in the experimental group were also higher than those in the control group before 2.0 MC. However there was no difference in the ion levels between 2.0 and 3.0 MC. CONCLUSIONS: This finding implies that the non-modular acetabular component of Durom total hip prosthesis is likely to become deformed during press-fit insertion, and that the deformation will result in increased volumetric wear and increased ion release. CLINICAL RELEVANCE: This study was determined to explore the deformation of the Durom cup after implantation and to clarify the impact of deformation on wear and ion release of the prosthesis. Deformation of the cup after implantation increases the wear of MOM bearings and the resulting ion levels. The clinical use of the Durom large head prosthesis should be with great care.

  17. Metals and Neurodegeneration [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Pan Chen

    2016-03-01

    Full Text Available Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain–Barré disease, Gulf War syndrome, Huntington’s disease, multiple sclerosis, Parkinson’s disease, and Wilson’s disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration.

  18. Canadian Eskimo permanent tooth emergence timing.

    Science.gov (United States)

    Mayhall, J T; Belier, P L; Mayhall, M F

    1978-08-01

    To identify the times of emergence of the permanent teeth of Canadian Eskimos (Inuit), 368 children and adolescents were examined. The presence or absence of all permanent teeth except the third molars was recorded and these data subjected to probit analysis. Female emergence times were advanced over males. Generally, the Inuit of both sexes showed statistically significant earlier emergence times than Montreal children, except for the incisors. The present results do not support hypotheses indicating that premature extraction of the deciduous teeth advances the emergence of their succedaneous counterparts. There is some indication the controls of deciduous tooth emergence continue to play some part in emergence of the permanent dentition, especially the first permanent teeth that emerge.

  19. Challenges of in-vacuum and cryogenic permanent magnet undulator technologies

    Directory of Open Access Journals (Sweden)

    Jui-Che Huang

    2017-06-01

    Full Text Available An in-vacuum undulator (IVU provides a means to reach high-brilliance x rays in medium energy storage rings. The development of short period undulators with low phase errors creates the opportunity for an unprecedented brilliant light source in a storage ring. Since the spectral quality from cryogenic permanent magnet undulators (CPMUs has surpassed that of IVUs, NdFeB or PrFeB CPMUs have been proposed for many new advanced storage rings to reach high brilliance x-ray photon beams. In a low emittance ring, not only the performance of the undulator but also the choice of the lattice functions are important design considerations. Optimum betatron functions and a zero-dispersion function shall be provided in the straight sections for IVU/CPMUs. In this paper, relevant factors and design issues for IVUs and CPMUs are discussed together with many technological challenges in short period undulators associated with beam induced–heat load, phase errors, and the deformation of support girders.

  20. Challenges of in-vacuum and cryogenic permanent magnet undulator technologies

    Science.gov (United States)

    Huang, Jui-Che; Kitamura, Hideo; Yang, Chin-Kang; Chang, Cheng-Hsing; Chang, Cheng-Hsiang; Hwang, Ching-Shiang

    2017-06-01

    An in-vacuum undulator (IVU) provides a means to reach high-brilliance x rays in medium energy storage rings. The development of short period undulators with low phase errors creates the opportunity for an unprecedented brilliant light source in a storage ring. Since the spectral quality from cryogenic permanent magnet undulators (CPMUs) has surpassed that of IVUs, NdFeB or PrFeB CPMUs have been proposed for many new advanced storage rings to reach high brilliance x-ray photon beams. In a low emittance ring, not only the performance of the undulator but also the choice of the lattice functions are important design considerations. Optimum betatron functions and a zero-dispersion function shall be provided in the straight sections for IVU/CPMUs. In this paper, relevant factors and design issues for IVUs and CPMUs are discussed together with many technological challenges in short period undulators associated with beam induced-heat load, phase errors, and the deformation of support girders.

  1. 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.)

  2. Quantification of the free volume in Zr45.0Cu39.3Al7.0Ag8.7 bulk metallic glasses subjected to plastic deformation by calorimetric and dilatometric measurements

    International Nuclear Information System (INIS)

    Zhang Yue; Hahn, Horst

    2009-01-01

    Zr 45.0 Cu 39.3 Al 7.0 Ag 8.7 bulk metallic glasses (BMGs) were prepared using suction casting technique. Plastic deformations were carried out by cold rolling and high-pressure torsion (HPT). The absolute contents of free volume in the as-cast, preheated and deformed samples were determined by differential scanning calorimetry (DSC) and dilatometry using the free volume model (FVM). The parameters required in the FVM are experimentally determined to be b = 0.107, β = 642.1 kJ/mol, D * = 10.3 and T 0 = 496.9 K, respectively. The equilibrium free volume determined by these parameters is in good agreement with that calculated from previous enthalpy relaxation experiments, showing the reliability of the values of the parameters. It is found that the content of free volume in the as-cast sample is 0.533% with respect to the atomic volume of the BMG. The free volume in the HPT deformed sample is determined to be 0.672%, which is the largest among all the samples. The excess free volume introduced by cold rolling is found to increase with the deformation strain and show weak strain rate dependent behavior. Finally, attempts are made to simulate the experimental DSC curve using a bimolecular kinetics in the flow defect model. However, the result shows that the kinetics of free volume may be more complicated than as described as a bimolecular process.

  3. 13 CFR 120.900 - Sources of permanent financing.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Sources of permanent financing... Development Company Loan Program (504) Permanent Financing § 120.900 Sources of permanent financing. Permanent financing for each Project must come from three sources: the Borrower's contribution, Third-Party Loans, and...

  4. An On-Chip RBC Deformability Checker Significantly Improves Velocity-Deformation Correlation

    Directory of Open Access Journals (Sweden)

    Chia-Hung Dylan Tsai

    2016-10-01

    Full Text Available An on-chip deformability checker is proposed to improve the velocity–deformation correlation for red blood cell (RBC evaluation. RBC deformability has been found related to human diseases, and can be evaluated based on RBC velocity through a microfluidic constriction as in conventional approaches. The correlation between transit velocity and amount of deformation provides statistical information of RBC deformability. However, such correlations are usually only moderate, or even weak, in practical evaluations due to limited range of RBC deformation. To solve this issue, we implemented three constrictions of different width in the proposed checker, so that three different deformation regions can be applied to RBCs. By considering cell responses from the three regions as a whole, we practically extend the range of cell deformation in the evaluation, and could resolve the issue about the limited range of RBC deformation. RBCs from five volunteer subjects were tested using the proposed checker. The results show that the correlation between cell deformation and transit velocity is significantly improved by the proposed deformability checker. The absolute values of the correlation coefficients are increased from an average of 0.54 to 0.92. The effects of cell size, shape and orientation to the evaluation are discussed according to the experimental results. The proposed checker is expected to be useful for RBC evaluation in medical practices.

  5. Fluid Structure Interaction Analysis in Manufacturing Metal/Polymer Macro-Composites

    International Nuclear Information System (INIS)

    Baesso, R.; Lucchetta, G.

    2007-01-01

    Polymer Injection Forming (PIF) is a new manufacturing technology for sheet metal-polymer macro-composites, which results from the combination of injection moulding and sheet metal forming. This process consists on forming the sheet metal according to the boundary of the mould cavity by means of the injected polymer. After cooling, the polymer bonds permanently to the metal resulting in a sheet metal-polymer macro-composite product. Comparing this process to traditional ones (where the polymeric and metal parts are joined together after separate forming) the main advantages are both reduction of production costs and increase of part quality. This paper presents a multi-physics numerical simulation of the process performed in the Ansys/CFX environment

  6. [The Object Permanence Fallacy.] Commentary.

    Science.gov (United States)

    Bradley, Ben S.

    1996-01-01

    Suggests that Greenberg's challenge to the centrality of object permanence in developmental thinking reveals that developmentalists' theories about childhood speak about their own self-images. Notes that developmentalists have been guilty of not only the object permanence fallacy but also the genetic fallacy, or the mistaken belief that describing…

  7. Disintegration and size reduction of slags and metals after melt refining of contaminated metallic wastes

    International Nuclear Information System (INIS)

    Heshmatpour, B.; Copeland, G.L.; Heestand, R.L.

    1981-04-01

    Melting under an oxidizing slag is an attractive method of decontaminating and reducing the volume of radioactively contaminated metal scrap. The contaminants are concentrated in a relatively small volume of slag, which leaves the metal essentially clean. A potential method of permanently disposing of the resulting slags (and metals if necessary) is emplacing them into deep shale by grout hydrofracture. Suspension in grout mixtures requires that the slag and metal be granular. The feasibility of size-reducing slags and disintegrating metals and subsequently incorporating both into grout mixtures was demonstrated. Various types of slags were crushed with a small jaw crusher into particles smaller than 3 mm. Several metals were also melted and water-blasted into coarse metal powder or shot ranging in size from 0.05 to 3 mm. A simple low-pressure water atomizer having a multiple nozzle with a converging-line jet stream was developed and used for this purpose. No significant slag dust and steam were generated during slag crushing and liquid-metal water-blasting tests, indicating that contamination can be well contained within the system. The crushed slags and the coarse metal powders were suspendable in group fluids, which indicates probable disposability by shale hydrofracture. The granulation of slags and metals facilitates their containment, transport, and storage

  8. Deformation behavior, corrosion resistance, and cytotoxicity of Ni-free Zr-based bulk metallic glasses.

    Science.gov (United States)

    Liu, L; Qiu, C L; Chen, Q; Chan, K C; Zhang, S M

    2008-07-01

    Two Ni-free bulk metallic glasses (BMGs) of Zr(60)Nb(5)Cu(22.5)Pd(5)Al(7.5) and Zr(60)Nb(5)Cu(20)Fe(5)Al(10) were successfully prepared by arc-melting and copper mold casting. The thermal stability and crystallization were studied using differential scanning calorimetry. It demonstrates that the two BMGs exhibit very good glass forming ability with a wide supercooled liquid region. A multi-step process of crystallization with a preferential formation of quasicrystals occurred in both BMGs under continuous heating. The deformation behavior of the two BMGs was investigated using quasi-static compression testing. It reveals that the BMGs exhibit not only superior strength but also an extended plasticity. Corrosion behaviors of the BMGs were investigated in phosphate buffered solution by electrochemical polarization. The result shows that the two BMGs exhibit excellent corrosion resistance characterized by low corrosion current densities and wide passive regions. X-ray photoelectron spectroscopy analysis revealed that the passive film formed after anodic polarization was highly enriched in zirconium, niobium, and aluminum oxides. This is attributed to the excellent corrosion resistance. Additionally, the potential cytotoxicity of the two Ni-free BMGs was evaluated through cell culture for 1 week followed by 3-(4,5-Dimethylthiazol-2-yl-)-2,5-diphenyltetrazolium bromide assay and SEM observation. The results indicate that the two Ni-free BMGs exhibit as good biocompatibility as Ti-6Al-4V alloy, and thus show a promising potential for biomedical applications. (c) 2007 Wiley Periodicals, Inc.

  9. Single-magnet rotary flowmeter for liquid metals

    OpenAIRE

    Priede, Jānis; Buchenau, Dominique; Gerbeth, Gunter

    2010-01-01

    We present a theory of single-magnet flowmeter for liquid metals and compare it with experimental results. The flowmeter consists of a freely rotating permanent magnet, which is magnetized perpendicularly to the axle it is mounted on. When such a magnet is placed close to a tube carrying liquid metal flow, it rotates so that the driving torque due to the eddy currents induced by the flow is balanced by the braking torque induced by the rotation itself. The equilibrium rotation rate, which var...

  10. Investigation of inhomogeneous deformation in band amorphous alloys at constant heating rate

    Science.gov (United States)

    Fedorov, Victor; Berezner, Arseniy; Pluzhnikova, Tatiana; Beskrovnyi, Anatolyi

    2017-11-01

    The present paper contains investigations of the creep process in the cobalt-based amorphous metallic alloy within the temperature range from 300 up to 1023 K. In all the curves of deformation there were observed jumps and dying oscillations. It is noted that the creep of the sample ribbons is unstable and results in the thinning of ribbons with tightening and crimping. There is suggested the mechanism of inhomogeneous deformation, which takes place in course of the process of creep under intermittent heating. For the evaluation of amorphism in the treated samples there have been carried out neutron-graphical and X-ray diffraction investigations, as well as thermal analysis.

  11. Topology optimized permanent magnet systems

    Science.gov (United States)

    Bjørk, R.; Bahl, C. R. H.; Insinga, A. R.

    2017-09-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a Λcool figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

  12. Sinuous Flow in Cutting of Metals

    Science.gov (United States)

    Yeung, Ho; Viswanathan, Koushik; Udupa, Anirudh; Mahato, Anirban; Chandrasekar, Srinivasan

    2017-11-01

    Using in situ high-speed imaging, we unveil details of a highly unsteady plastic flow mode in the cutting of annealed and highly strain-hardening metals. This mesoscopic flow mode, termed sinuous flow, is characterized by repeated material folding, large rotation, and energy dissipation. Sinuous flow effects a very large shape transformation, with local strains of ten or more, and results in a characteristic mushroomlike surface morphology that is quite distinct from the well-known morphologies of metal-cutting chips. Importantly, the attributes of this unsteady flow are also fundamentally different from other well-established unsteady plastic flows in large-strain deformation, like adiabatic shear bands. The nucleation and development of sinuous flow, its dependence on material properties, and its manifestation across material systems are demonstrated. Plastic buckling and grain-scale heterogeneity are found to play key roles in triggering this flow at surfaces. Implications for modeling and understanding flow stability in large-strain plastic deformation, surface quality, and preparation of near-strain-free surfaces by cutting are discussed. The results point to the inadequacy of the widely used shear-zone models, even for ductile metals.

  13. DEA deformed stretchable patch antenna

    International Nuclear Information System (INIS)

    Jiang, X-J; Jalali Mazlouman, S; Menon, C; Mahanfar, A; Vaughan, R G

    2012-01-01

    A stretchable patch antenna (SPA) whose frequency is tuned by a planar dielectric elastomer actuator (DEA) is presented in this paper. This mechanically reconfigurable antenna system has a configuration resembling a pre-stretched silicone belt. Part of the belt is embedded with a layer of conductive liquid metal to form the patch antenna. Part of the belt is sandwiched between conductive electrodes to form the DEA. Electrical activation of the DEA results in a contraction of the patch antenna, and as a result, in a variation of its resonance frequency. Design and fabrication steps of this system are presented. Measurement results for deformation, resonance frequency variation and efficiency of the patch antenna are also presented. (paper)

  14. Fabrication of subwavelength metallic structures by using a metal direct imprinting process

    International Nuclear Information System (INIS)

    Hsieh, C W; Hsiung, H Y; Lu, Y T; Sung, C K; Wang, W H

    2007-01-01

    This work employs a metal direct imprinting process, which possesses the characteristics of simplicity, low-cost and high resolution, for the fabrication of subwavelength structures on a metallic thin film. Herein, the mould featuring periodic line structures is manufactured by using E-beam lithography and followed by a dry etching process; meanwhile, the thin film is fabricated by sputtering Al on a silicon substrate. AFM section analyses are employed to measure imprinting depths of the subwavelength metallic structures and it is found that the uniformity of the imprinting depths is affected by the designed patterns, the material property of thin film and mould deformation. The process temperature and the mould filling that influence the transferred quality are investigated. In addition, TEM is also utilized to examine defects in the subwavelength metallic structures. Finally, good quality subwavelength metallic structures are fabricated under a pressure of 300 MPa for 60 s at room temperature. In this study, we have demonstrated that subwavelength metallic structures with a minimum linewidth of less than 100 nm on the Al thin film are successfully constructed by the metal direct imprinting process

  15. Teaching Object Permanence: An Action Research Study

    Science.gov (United States)

    Bruce, Susan M.; Vargas, Claudia

    2013-01-01

    "Object permanence," also known as "object concept" in the field of visual impairment, is one of the most important early developmental milestones. The achievement of object permanence is associated with the onset of representational thought and language. Object permanence is important to orientation, including the recognition of landmarks.…

  16. Commercial Implementation of Model-Based Manufacturing of Nanostructured Metals

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, Terry C. [Los Alamos National Laboratory

    2012-07-24

    Computational modeling is an essential tool for commercial production of nanostructured metals. Strength is limited by imperfections at the high strength levels that are achievable in nanostructured metals. Processing to achieve homogeneity at the micro- and nano-scales is critical. Manufacturing of nanostructured metals is intrinsically a multi-scale problem. Manufacturing of nanostructured metal products requires computer control, monitoring and modeling. Large scale manufacturing of bulk nanostructured metals by Severe Plastic Deformation is a multi-scale problem. Computational modeling at all scales is essential. Multiple scales of modeling must be integrated to predict and control nanostructural, microstructural, macrostructural product characteristics and production processes.

  17. Atomic mechanism of shear localization during indentation of a nanostructured metal

    International Nuclear Information System (INIS)

    Sansoz, F.; Dupont, V.

    2007-01-01

    Shear localization is an important mode of deformation in nanocrystalline metals. However, it is very difficult to verify the existence of local shear planes in nanocrystalline metals experimentally. Sharp indentation techniques may provide novel opportunities to investigate the effect of shear localization at different length scales, but the relationship between indentation response and atomic-level shear band formation has not been fully addressed. This paper describes an effort to provide direct insight on the mechanism of shear localization during indentation of nanocrystalline metals from atomistic simulations. Molecular statics is performed with the quasi-continuum method to simulate the indentation of single crystal and nanocrystalline Al with a sharp cylindrical probe. In the nanocrystalline regime, two grain sizes are investigated, 5 nm and 10 nm. We find that the indentation of nanocrystalline metals is characterized by serrated plastic flow. This effect seems to be independent of the grain size. Serration in nanocrystalline metals is found to be associated with the formation of shear bands by sliding of aligned interfaces and intragranular slip, which results in deformation twinning

  18. Intrusive luxation of 60 permanent incisors

    DEFF Research Database (Denmark)

    Tsilingaridis, Georgios; Malmgren, Barbro; Andreasen, Jens O

    2012-01-01

      Intrusive luxation in the permanent dentition is an uncommon injury but it is considered one of the most severe types of dental trauma because of the risk for damage to the periodontal ligament, pulp and alveolar bone. Management of intrusive luxation in the permanent dentition is controversial....... The purpose of this study was to evaluate pulp survival and periodontal healing in intrusive luxated permanent teeth in relation to treatment alternatives, degree of intrusion and root development....

  19. Modeling of vibrations isolation and arrest by shape memory parts and permanent magnets

    Science.gov (United States)

    Belyaev, Fedor S.; Volkov, Aleksandr E.; Evard, Margarita E.; Vikulenkov, Andrey V.; Uspenskiy, Evgeniy S.

    2018-05-01

    A vibration protection system under consideration consists of a payload connected to a vibrating housing by shape memory alloy (SMA) slotted springs. To provide an arrest function two permanent magnets are inserted into the system. The slotted SMA elements are preliminary deformed in the martensitic state. Activation of one element by heating initiates force and displacement generation, which provide an arrest of the payload by magnets. The magnets also secure the arrest mode after cooling of the SMA element. Activation of the other element results in uncaging of the payload and switching to the vibration isolation mode. Computer simulations of arrest and uncaging when the housing is quiescent or producing sine-wave displacements were carried out. Functional-mechanical behavior of SMA parts was described by means of a microstructural model.

  20. An Interconnected Network of Core-Forming Melts Produced by Shear Deformation

    Science.gov (United States)

    Bruhn, D.; Groebner, N.; Kohlstedt, D. L.

    2000-01-01

    The formation mechanism of terrestrial planetary is still poorly understood, and has been the subject of numerous experimental studies. Several mechanisms have been proposed by which metal-mainly iron with some nickel-could have been extracted from a silicate mantle to form the core. Most recent models involve gravitational sinking of molten metal or metal sulphide through a partially or fully molten mantle that is often referred to as a'magma ocean. Alternative models invoke percolation of molten metal along an interconnected network (that is, porous flow) through a solid silicate matrix. But experimental studies performed at high pressures have shown that, under hydrostatic conditions, these melts do not form an interconnected network, leading to the widespread assumption that formation of metallic cores requires a magma ocean. In contrast, here we present experiments which demonstrate that shear deformation to large strains can interconnect a significant fraction of initially isolated pockets of metal and metal sulphide melts in a solid matrix of polycrystalline olivine. Therefore, in a dynamic (nonhydrostatic) environment, percolation remains a viable mechanism for the segregation and migration of core-forming melts in a solid silicate mantle.

  1. Constitutive relations describing creep deformation for multi-axial time-dependent stress states

    Science.gov (United States)

    McCartney, L. N.

    1981-02-01

    A THEORY of primary and secondary creep deformation in metals is presented, which is based upon the concept of tensor internal state variables and the principles of continuum mechanics and thermodynamics. The theory is able to account for both multi-axial and time-dependent stress and strain states. The wellknown concepts of elastic, anelastic and plastic strains follow naturally from the theory. Homogeneous stress states are considered in detail and a simplified theory is derived by linearizing with respect to the internal state variables. It is demonstrated that the model can be developed in such a way that multi-axial constant-stress creep data can be presented as a single relationship between an equivalent stress and an equivalent strain. It is shown how the theory may be used to describe the multi-axial deformation of metals which are subjected to constant stress states. The multi-axial strain response to a general cyclic stress state is calculated. For uni-axial stress states, square-wave loading and a thermal fatigue stress cycle are analysed.

  2. Permanent magnet materials and their application

    International Nuclear Information System (INIS)

    Campbell, P.

    1994-01-01

    Permanent magnets are of great industrial importance in industrial drives, consumer products, computers, and automobiles. Since 1970, new classes of magnet materials have been developed. This book reviews the older and newer materials and is presented as a comprehensive design text for permanent magnets and their applications. After an initial chapter on the fundamentals of magnetism, the author discusses magnetic physics considerations specific to permanent magnets and describes the fabrications and characteristics of commercial materials: alnico, samarium-cobalt, ferrite, and neodymium-iron-boron. Thermal stability, magnet design procedures, magnetic field analysis methods, and measurement methods are discussed in subsequent chapters, followed by a concluding chapter reviewing commercial and industrial products that use permanent magnets. The chapter on thermal properties of magnet materials is of particular interest, bringing together information not readily found elsewhere. The review of applications is also deserving of attention, specifically the sections on motors and actuators. Although particle accelerator applications are discussed, the use of permanent magnet sextuples in modern ECR ion sources is not mentioned

  3. q-deformed Weinberg-Salam model and q-deformed Maxwell equations

    International Nuclear Information System (INIS)

    Alavi, S.A.; Sarbishaei, M.; Mokhtari, A.

    2000-01-01

    We study the q-deformation of the gauge part of the Weinberg-Salam model and show that the q-deformed theory involves new interactions. We then obtain q-deformed Maxwell equations from which magnetic monopoles appear naturally. (author)

  4. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  5. Two-functional sensor of magnetic field and deformation based on Si microcrystals

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2017-06-01

    Full Text Available This research investigates complex studies of electrical conductivity and magnetoresistance of both strain and non-strain samples of p-type Si whiskers with different degrees of doping with boron and nickel in a wide temperature range from 4.2 to 300 K. It is established that the greatest manifestation of the piezoresistive effect is observed in the vicinity of concentrations which correspond to the metal-insulator transition. Investigation of the magnetoresistance of crystals was carried out in the range of fields with induction up to 14 T. Whiskers of silicon with a doping concentration of boron of 5·1018 cm-3 can be used as a sensitive element for two-functional deformation and magnetic field sensors in difficult operating conditions. Microwires for research were grown by chemical transport reactions with the crystallographic orientation and with the concentration of charge carriers, which corresponds to the vicinity of metal-insulator transition (5·1018 см-3. The nickel doping was conducted by the low-temperature diffusion from the precipitated film on the surface of the crystal. The uniaxial strain of Si microcrystals was carried out by fixing them on substrates with the different coefficient of thermal. The metallic-type temperature dependence on the resistivity is typical for heavily doped silicon microcrystals (with the bor concenctation >5·1018 сm-3 for both deformed and non deformed samples. Significant influence of the deformation on characteristics of microcrystals wasn't found. The maximum magnetoresistance of such samples doesn't exceed 4% in magnetic fields with induction of 14 T at the temperature of liquefied helium. The resistivity of Si crystals with ρ300К = 0.012 Оhm·сm (which corresponds to the dielectric side of MIT is reduced in several times at the the temperature of liquefied helium and under the uniaxial deformation. Decreasing of boron concentration reduces this effect. This is also confirmed by the

  6. Process Development And Simulation For Cold Fabrication Of Doubly Curved Metal Plate By Using Line Array Roll Set

    International Nuclear Information System (INIS)

    Shim, D. S.; Jung, C. G.; Seong, D. Y.; Yang, D. Y.; Han, J. M.; Han, M. S.

    2007-01-01

    For effective manufacturing of a doubly curved sheet metal, a novel sheet metal forming process is proposed. The suggested process uses a Line Array Roll Set (LARS) composed of a pair of upper and lower roll assemblies in a symmetric manner. The process offers flexibility as compared with the conventional manufacturing processes, because it does not require any complex-shaped die and loss of material by blank-holding is minimized. LARS allows flexibility of the incremental forming process and adopts the principle of bending deformation, resulting in a slight deformation in thickness. Rolls composed of line array roll sets are divided into a driving roll row and two idle roll rows. The arrayed rolls in the central lines of the upper and lower roll assemblies are motor-driven so that they deform and transfer the sheet metal using friction between the rolls and the sheet metal. The remaining rolls are idle rolls, generating bending deformation with driving rolls. Furthermore, all the rolls are movable in any direction so that they are adaptable to any size or shape of the desired three-dimensional configuration. In the process, the sheet is deformed incrementally as deformation proceeds simultaneously in rolling and transverse directions step by step. Consequently, it can be applied to the fabrication of doubly curved ship hull plates by undergoing several passes. In this work, FEM simulations are carried out for verification of the proposed incremental forming system using the chosen design parameters. Based on the results of the simulation, the relationship between the roll set configuration and the curvature of a sheet metal is determined. The process information such as the forming loads and torques acting on every roll is analyzed as important data for the design and development of the manufacturing system

  7. Application of adiabatic calorimetry to metal systems. Progress report, 1976--1977

    International Nuclear Information System (INIS)

    Stansbury, E.E.; Brooks, C.R.

    1977-01-01

    Research to measure the heat capacity of liquid metals, and to measure the heat effects in plastically deformed austenitic stainless steels is described. The liquid metals require a container. The deformed stainless steel is necessarily in strips; these are too small to make a specimen directly and thus also requires a container. For both types of samples the heat capacity of the empty container is measured, then that of the full container and from the two sets of data one calculates the desired heat capacity. This procedure assumes the heat losses are the same for both conditions, which is approximated best when the heat losses are small. In general, other laboratories have found this technique to yield very accurate heat capacity data (error less than +-1%). Since this accuracy is required to properly analyze the data for both the liquid metals and the deformed stainless steel, the heat loss problem was studied. An improved calorimeter was designed and built, and the heat loss problem in the present calorimeter was evaluated. In addition, development of the necessary computer software and its application to convert the calorimeters to computer control is described

  8. Design of multi materials combining crystalline and amorphous metallic alloys

    International Nuclear Information System (INIS)

    Volland, A.; Ragani, J.; Liu, Y.; Gravier, S.; Suéry, M.; Blandin, J.J.

    2012-01-01

    Highlights: ► Elaboration of multi materials associating metallic glasses and conventional crystalline alloys by co-deformation performed at temperatures close to the glass transition temperature of the metallic glasses. ► Elaboration of filamentary metal matrix composites with a core in metallic glass by co extrusion. ► Sandwich structures produced by co-pressing. ► Detection of atomic diffusion from the glass to the crystalline alloys during the processes. ► Good interfaces between the metallic glasses and the crystalline alloys, as confirmed by mechanical characterisation. - Abstract: Multi materials, associating zirconium based bulk metallic glasses and crystalline metallic alloys like magnesium alloys or copper are elaborated by co-deformation processing performed in the supercooled liquid regions (SLR) of the bulk metallic glasses. Two processes are investigated: co-extrusion and co-pressing. In the first case, filamentary composites with various designs can be produced whereas in the second case sandwich structures are obtained. The experimental window (temperature, time) in which processing can be carried out is directly related to the crystallisation resistance of the glass which requires getting information about the crystallisation conditions in the selected metallic glasses. Thermoforming windows are identified for the studied BMGs by thermal analysis and compression tests in their SLR. The mechanical properties of the produced multi materials are investigated thanks to specifically developed mechanical devices and the interfaces between the amorphous and the crystalline alloys are characterised.

  9. A new theory for the static contact between rough, unmated surfaces in non-elastically deforming rock and its implications for rock friction

    Science.gov (United States)

    Stesky, R. M.; Hannan, S. S.

    The closure behavior of fractures in marble and alabaster is markedly different from that in quartzite. The aperture decreases considerably more under normal stress and remains permanently reduced, for the same ratio of normal stress to unconfined compressive strength. Also, a larger permanent relative contact area develops between the surfaces of marble and alabaster than it does between surfaces of quartzite. The permanent contact area increases at an increasing rate with normal stress in marble and alabaster, unlike the nearly linear increase in quartzite. The failure of surface asperities of calcite and gypsum during closure accounts for these differences. We modeled this process by considering the surfaces to consist of paraboloids lying on a flat plane and having a range of initial heights. Closure occurs by pressing a plane rigid surface against the 'hills', flattening their peaks, keeping the base area of the hills constant. To allow for a changing resistance to deformation, the contact stress is assumed to vary linearly with the shortening strain, to a first approximation. This model was tested against measurements of fracture closure and contact area of rough surfaces of calcite marble with a known initial height distribution of surface peaks. The fit to the data is quite good. In all cases, the model shows that closure is accompanied by a decrease in contact strength of deforming asperities, suggested also by the cataclastic deformation observed petrographically. The number of contact spots and the total length of contact seen in profile are also reasonably well modeled. These results have important implications for our understanding of frictional strength of fractures. The overall resistance to shear along rough surfaces depends upon the product of the shear strength and true area of the contacts, both of which are affected by normal stress. Application of this model approach shows that the initial frictional resistance of some fractures in ductile

  10. Nanomaterials derived from metal-organic frameworks

    Science.gov (United States)

    Dang, Song; Zhu, Qi-Long; Xu, Qiang

    2018-01-01

    The thermal transformation of metal-organic frameworks (MOFs) generates a variety of nanostructured materials, including carbon-based materials, metal oxides, metal chalcogenides, metal phosphides and metal carbides. These derivatives of MOFs have characteristics such as high surface areas, permanent porosities and controllable functionalities that enable their good performance in sensing, gas storage, catalysis and energy-related applications. Although progress has been made to tune the morphologies of MOF-derived structures at the nanometre scale, it remains crucial to further our knowledge of the relationship between morphology and performance. In this Review, we summarize the synthetic strategies and optimized methods that enable control over the size, morphology, composition and structure of the derived nanomaterials. In addition, we compare the performance of materials prepared by the MOF-templated strategy and other synthetic methods. Our aim is to reveal the relationship between the morphology and the physico-chemical properties of MOF-derived nanostructures to optimize their performance for applications such as sensing, catalysis, and energy storage and conversion.

  11. The correlation of local deformation and stress-assisted local phase transformations in MMC foams

    Energy Technology Data Exchange (ETDEWEB)

    Berek, H., E-mail: harry.berek@ikgb.tu-freiberg.de [TU Bergakademie Freiberg, Agricolastraße 17, D-09599 Freiberg (Germany); Ballaschk, U.; Aneziris, C.G. [TU Bergakademie Freiberg, Agricolastraße 17, D-09599 Freiberg (Germany); Losch, K.; Schladitz, K. [Fraunhofer ITWM, Fraunhoferplatz 1, D-67663 Kaiserslautern (Germany)

    2015-09-15

    Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they can trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated.

  12. The correlation of local deformation and stress-assisted local phase transformations in MMC foams

    International Nuclear Information System (INIS)

    Berek, H.; Ballaschk, U.; Aneziris, C.G.; Losch, K.; Schladitz, K.

    2015-01-01

    Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they can trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated

  13. STRUCTURAL AND TECHNOLOGICAL ASPECTS OF DECREASE IN WIRE ANNEALING AT A TWIST OF A HIGH-STRENGTH METAL CORD

    Directory of Open Access Journals (Sweden)

    V. Р. Fetisov

    2016-01-01

    Full Text Available Deformation by drawing with the raised share of the squeezing tension and application of additional deformation with small degrees in the line of a drawing camp allow to minimize a wire annealing of a cold-deformed wire during a twist of a highstrength metal cord.

  14. Mesoscale modeling of amorphous metals by shear transformation zone dynamics

    International Nuclear Information System (INIS)

    Homer, Eric R.; Schuh, Christopher A.

    2009-01-01

    A new mesoscale modeling technique for the thermo-mechanical behavior of metallic glasses is proposed. The modeling framework considers the shear transformation zone (STZ) as the fundamental unit of deformation, and coarse-grains an amorphous collection of atoms into an ensemble of STZs on a mesh. By employing finite element analysis and a kinetic Monte Carlo algorithm, the modeling technique is capable of simulating glass processing and deformation on time and length scales greater than those usually attainable by atomistic modeling. A thorough explanation of the framework is presented, along with a specific two-dimensional implementation for a model metallic glass. The model is shown to capture the basic behaviors of metallic glasses, including high-temperature homogeneous flow following the expected constitutive law, and low-temperature strain localization into shear bands. Details of the effects of processing and thermal history on the glass structure and properties are also discussed.

  15. Uncovering the true nature of deformation microstructures using 3D analysis methods

    Science.gov (United States)

    Ferry, M.; Quadir, M. Z.; Afrin, N.; Xu, W.; Loeb, A.; Soe, B.; McMahon, C.; George, C.; Bassman, L.

    2015-08-01

    Three-dimensional electron backscatter diffraction (3D EBSD) has emerged as a powerful technique for generating 3D crystallographic information in reasonably large volumes of a microstructure. The technique uses a focused ion beam (FIB) as a high precision serial sectioning device for generating consecutive ion milled surfaces of a material, with each milled surface subsequently mapped by EBSD. The successive EBSD maps are combined using a suitable post-processing method to generate a crystallographic volume of the microstructure. The first part of this paper shows the usefulness of 3D EBSD for understanding the origin of various structural features associated with the plastic deformation of metals. The second part describes a new method for automatically identifying the various types of low and high angle boundaries found in deformed and annealed metals, particularly those associated with grains exhibiting subtle and gradual variations in orientation. We have adapted a 2D image segmentation technique, fast multiscale clustering, to 3D EBSD data using a novel variance function to accommodate quaternion data. This adaptation is capable of segmenting based on subtle and gradual variation as well as on sharp boundaries within the data. We demonstrate the excellent capabilities of this technique with application to 3D EBSD data sets generated from a range of cold rolled and annealed metals described in the paper.

  16. Adaptive metal mirror for high-power CO2 lasers

    Science.gov (United States)

    Jarosch, Uwe-Klaus

    1996-08-01

    Spherical mirrors with a variable radius of curvature are used inside laser resonators as well as in the beam path between the laser and the workpiece. Commercially-available systems use piezoelectric actuators, or the pressure of the coolant, to deform the mirror surface. In both cases, the actuator and the cooling system influence each other. This interaction is avoided through the integration of the cooling system with the flexible mirror membrane. A multi- channel design leads to an optimized cooling effect, which is necessary for high power applications. The contour of the variable metal mirror depends on the mounting between the membrane and the mirror body and on the distribution of forces. Four cases of deformation can be distinguished for a circular elastic membrane. The realization of an adaptive metal mirror requires a technical compromise to be made. A mechanical construction is presented which combines an elastic hinge with the inlet and outlet of the coolant. For the deformation of the mirror membranes two actuators with different character of deformation are used. The superposition of the two deformations results in smaller deviations from the spherical surface shape than can be achieved using a single actuator. DC proportional magnets have been introduced as cheap and rigid actuators. The use of this adaptive mirror, either in a low pressure atmosphere of a gas laser resonator, or in an extra-cavity beam path is made possible through the use of a ventilation system.

  17. Development of dynamic explicit crystallographic homogenization finite element analysis code to assess sheet metal formability

    International Nuclear Information System (INIS)

    Nakamura, Yasunori; Tam, Nguyen Ngoc; Ohata, Tomiso; Morita, Kiminori; Nakamachi, Eiji

    2004-01-01

    The crystallographic texture evolution induced by plastic deformation in the sheet metal forming process has a great influence on its formability. In the present study, a dynamic explicit finite element (FE) analysis code is newly developed by introducing a crystallographic homogenization method to estimate the polycrystalline sheet metal formability, such as the extreme thinning and 'earing'. This code can predict the plastic deformation induced texture evolution at the micro scale and the plastic anisotropy at the macro scale, simultaneously. This multi-scale analysis can couple the microscopic crystal plasticity inhomogeneous deformation with the macroscopic continuum deformation. In this homogenization process, the stress at the macro scale is defined by the volume average of those of the corresponding microscopic crystal aggregations in satisfying the equation of motion and compatibility condition in the micro scale 'unit cell', where the periodicity of deformation is satisfied. This homogenization algorithm is implemented in the conventional dynamic explicit finite element code by employing the updated Lagrangian formulation and the rate type elastic/viscoplastic constitutive equation.At first, it has been confirmed through a texture evolution analyses in cases of typical deformation modes that Taylor's 'constant strain homogenization algorithm' yields extreme concentration toward the preferred crystal orientations compared with our homogenization one. Second, we study the plastic anisotropy effects on 'earing' in the hemispherical cup deep drawing process of pure ferrite phase sheet metal. By the comparison of analytical results with those of Taylor's assumption, conclusions are drawn that the present newly developed dynamic explicit crystallographic homogenization FEM shows more reasonable prediction of plastic deformation induced texture evolution and plastic anisotropy at the macro scale

  18. Evaluation of the deformation parameters of the northern part of Eg

    Directory of Open Access Journals (Sweden)

    Abdel-Monem S. Mohamed

    2016-06-01

    Full Text Available The northern part of Egypt is a rapidly growing development accompanied by the increased levels of standard living particularly in its urban areas. From tectonic and seismic point of views, the northern part of Egypt is one of the interested regions. It shows an active geologic structure attributed to the tectonic movements of the African and Eurasian plates from one side and the Arabian plate from the other side. From historical point of view and recent instrumental records, the northern part of Egypt is one of the seismo-active regions in Egypt. The investigations of the seismic events and their interpretations had led to evaluate the seismic hazard for disaster mitigation, for the safety of the densely populated regions and the vital projects. In addition to the monitoring of the seismic events, the most powerful technique of Global Navigation Satellite System (GNSS will be used in determining crustal deformation where a geodetic network covers the northern part of Egypt. Joining the GPS Permanent stations of the northern part of Egypt with the Southern part of Europe will give a clear picture about the recent crustal deformation and the African plate velocity. The results from the data sets are compared and combined in order to determine the main characteristics of the deformation and hazard estimation for specified regions. Final compiled output from the seismological and geodetic analysis will throw lights upon the geodynamical regime of these seismo-active regions. This work will throw lights upon the geodynamical regime and to delineate the crustal stress and strain fields in the study region. This also enables to evaluate the active tectonics and surface deformation with their directions from repeated geodetic observations. The results show that the area under study suffers from continuous seismic activity related to the crustal movements taken place along trends of major faults

  19. Evaluation of the deformation parameters of the northern part of Eg

    Science.gov (United States)

    Mohamed, Abdel-Monem S.; Radwan, Ali M.; Sharf, Mohamed; Hamimi, Zakaria; Hegazy, Esraa E.; Abou Aly, Nadia; Gomaa, Mahmoud

    2016-06-01

    The northern part of Egypt is a rapidly growing development accompanied by the increased levels of standard living particularly in its urban areas. From tectonic and seismic point of views, the northern part of Egypt is one of the interested regions. It shows an active geologic structure attributed to the tectonic movements of the African and Eurasian plates from one side and the Arabian plate from the other side. From historical point of view and recent instrumental records, the northern part of Egypt is one of the seismo-active regions in Egypt. The investigations of the seismic events and their interpretations had led to evaluate the seismic hazard for disaster mitigation, for the safety of the densely populated regions and the vital projects. In addition to the monitoring of the seismic events, the most powerful technique of Global Navigation Satellite System (GNSS) will be used in determining crustal deformation where a geodetic network covers the northern part of Egypt. Joining the GPS Permanent stations of the northern part of Egypt with the Southern part of Europe will give a clear picture about the recent crustal deformation and the African plate velocity. The results from the data sets are compared and combined in order to determine the main characteristics of the deformation and hazard estimation for specified regions. Final compiled output from the seismological and geodetic analysis will throw lights upon the geodynamical regime of these seismo-active regions. This work will throw lights upon the geodynamical regime and to delineate the crustal stress and strain fields in the study region. This also enables to evaluate the active tectonics and surface deformation with their directions from repeated geodetic observations. The results show that the area under study suffers from continuous seismic activity related to the crustal movements taken place along trends of major faults

  20. Creep deformation of restorative resin-composites intended for bulk-fill placement.

    Science.gov (United States)

    El-Safty, S; Silikas, N; Watts, D C

    2012-08-01

    To determine the creep deformation of several "bulk-fill" resin-composite formulations in comparison with some other types. Six resin-composites; four bulk-fill and two conventional were investigated. Stainless steel split molds (4 mm × 6 mm) were used to prepare cylindrical specimens for creep testing. Specimens were thoroughly irradiated with 650 mW cm(-2). A total of 10 specimens for each material were divided into two groups (n = 5) according to the storage condition; Group A stored dry at 37 °C for 24h and Group B stored in distilled water at 37 °C in an incubator for 24h. Each specimen was loaded (20 MPa) for 2h and unloaded for 2h. The strain deformation was recorded continuously for 4h. Statistical analysis was performed using a two-way ANOVA followed by one-way ANOVA and the Bonferroni post hoc test at a significance level of a = 0.05. The maximum creep strain % ranged from 0.72% up to 1.55% for Group A and the range for Group B increased from 0.79% up to 1.80% due to water sorption. Also, the permanent set ranged from 0.14% up to 0.47% for Group A and from 0.20% up to 0.59% for Group B. Dependent on the material and storage condition, the percentage of creep strain recovery ranged between 64% and 81%. Increased filler loading in the bulk-fill materials decreased the creep strain magnitude. Creep deformation of all studied resin-composites increased with wet storage. The "bulk-fill" composites exhibited an acceptable creep deformation and within the range exhibited by other resin-composites. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.