Готові списки джерел за темами / Viscoplastic deformation

Добірка наукової літератури з теми "Viscoplastic deformation"

Автор: Grafiati
Опубліковано: 30 травня 2022
Оновлено: 31 травня 2022

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Статті в журналах з теми "Viscoplastic deformation"

1

Aleksandrov, A. S., T. V. Semenova, and N. P. Aleksandrova. "MATERIALS USED IN THE ROAD BASES: METHOD OF THE RESIDUAL DEFORMATIONS’ CALCULATION." Russian Automobile and Highway Industry Journal 16, no. 4 (September 8, 2019): 456–71. http://dx.doi.org/10.26518/2071-7296-2019-4-456-471.

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Materials and methods. The authors performed the analysis of the models for calculating residual deformations accumulated by granular materials and under the influence of repeated loads. The research showed the hereditary nature of the strain granular materials’ accumulation. Therefore, the authors used integral calculus for analytical solution of the residual deformation’s dependence on the number of repeated loads and on the magnitude of the main stresses. Moreover, the authors obtained the solution in the form of logarithmic and power functions, which associated the accumulated deformation with the deformation arising from the first load application. In determining the deformation from the first load application, the authors took into account the model of the theory of plasticity, in which the elastoplastic deformation was determined by the sum of two components elastic and plastic, as well as rheological models considering the deformation as the sum of three or four components. Generalizing the model for various materials, the authors gave the preference to the model, in which the elastoplastic deformation was determined by four components: instantaneous elastic and residual deformations, elastic (elastic-viscous) deformation and a viscoplastic component. Therefore, the residual strain from the first load application was represented by the sum of the two components, instantaneous irreversible and viscoplastic. The viscoplastic component of the deformation was a result of stress relaxation in a relatively short period of time equal to the duration of the load impact. Such research allowed taking into account the effect of speed on the duration of the load and the magnitude of the viscoplastic component of the residual deformation. The authors emphasized that taking into account the viscous-plastic component of residual deformation was most appropriate when calculating residual deformations of soils and materials treated with an organic binder. Granular materials were less sensitive to viscoplastic deformation under a single load application, but, when the voltage exceeded the elastic limit, and the more plastic adaptability of crushed stone, gravel, etc. viscoplastic deformation made a significant contribution to the accumulated residual deformation.Results. As a result, the authors carried out the analysis of experimental data on the triaxial compression of various granular materials and determined the parameters obtained for the power and logarithmic functions. The authors studied such materials as granite, gneissic, granodiorite and diorite crushed stone, sand, gravel and crushed stone, gravel mixtures with a mineral part from various rocks and fortified sands.Discussion and conclusions. The paper demonstrates the possibility of using the solutions for calculation of the surface displacement of the pavement layers of granular materials. The authors formulate the tasks for further research.
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2

Kosorukov, S. N. "Viscoplastic deformation of annular plates." Journal of Applied Mechanics and Technical Physics 26, no. 5 (1986): 746–51. http://dx.doi.org/10.1007/bf00915330.

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3

Zhang, Yuqing, Fan Gu, Bjorn Birgisson, and Robert L. Lytton. "Viscoelasticplastic–Fracture Modeling of Asphalt Mixtures Under Monotonic and Repeated Loads." Transportation Research Record: Journal of the Transportation Research Board 2631, no. 1 (January 2017): 20–29. http://dx.doi.org/10.3141/2631-03.

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Rutting and cracking occur simultaneously in asphalt mixtures as observed in the field and in the laboratory. Existing mechanical models have not properly addressed viscoelastic and viscoplastic deformation together with cracking attributable to model deficiencies, parameter calibration, and numerical inefficiency. This study developed viscoelasticplastic–fracture (VEPF) models for the characterization of viscoelasticity by Prony model and viscoplasticity by Perzyna’s flow rule with a generalized Drucker–Prager yield surface and a nonassociated plastic potential. Viscofracture damage was modeled by a viscoelastic Griffith criterion and a pseudo J-integral Paris’s law for crack initiation and propagation, respectively. The VEPF models were implemented in a finite element program by using a weak form partial differential equation modeling technique without the need for programming user-defined material subroutines. Model parameters were derived from fundamental material properties by using dynamic modulus, strength, and repeated load tests. Simulations indicated that the viscoelastic–viscoplastic–viscofracture characteristics were effectively modeled by the VEPF models for asphalt mixtures at different confinements and temperatures. An asphalt mixture under monotonic compressive loads exhibited a sequenced process including a pure viscoelastic deformation stage, a coupled viscoelastic–viscoplastic deformation stage, a viscoelastic–viscoplastic deformation coupled with a viscofracture initiation and a propagation stage, and then a viscoelastic–viscofracture rupture stage with saturated viscoplastic deformation. The asphalt mixture under repeated loads yielded an increasing viscoplastic strain at an increasing rate during the first half of the haversine load, while the increment of the viscoplastic strain (per load cycle) decreased with load cycles. The finite element program, which is based on a partial differential equation, effectively modeled the coupled viscoelastic–viscoplastic–viscofracture behaviors of the asphalt mixtures.
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4

Miguel, M. Carmen, Alessandro Vespignani, Stefano Zapperi, Jérôme Weiss, and Jean-Robert Grasso. "Intermittent dislocation flow in viscoplastic deformation." Nature 410, no. 6829 (April 2001): 667–71. http://dx.doi.org/10.1038/35070524.

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5

Pan, Wen-Fung. "Endochronic simulation for finite viscoplastic deformation." International Journal of Plasticity 13, no. 6-7 (January 1997): 571–86. http://dx.doi.org/10.1016/s0749-6419(97)00026-0.

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6

Drozdov, A. D. "Multi-cycle viscoplastic deformation of polypropylene." Computational Materials Science 50, no. 7 (May 2011): 1991–2000. http://dx.doi.org/10.1016/j.commatsci.2011.01.045.

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7

Song, Yongjun, Leitao Zhang, Huimin Yang, Jianxi Ren, and Yongxin Che. "Experimental Study on the Creep Behavior of Red Sandstone under Low Temperatures." Advances in Civil Engineering 2019 (October 9, 2019): 1–9. http://dx.doi.org/10.1155/2019/2328065.

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Анотація:
In cold regions, the deformation characteristics and long-term mechanical properties of rocks under low-temperature conditions are considerably different from those in other regions. To study the deformation characteristics and long-term mechanical properties of rocks in a low-temperature environment and the effect of different temperatures, we perform a multilevel loading-unloading uniaxial creep test on red sandstone samples and obtain the creep curves at different temperatures (20°C, −10°C, and −20°C). The results demonstrate that the total strain at each temperature can be divided into instantaneous and creep strains; the instantaneous strain includes instantaneous elastic and plastic strains, and the creep strain includes viscoelastic and viscoplastic strains. Temperature has a significant effect on the deformation properties of red sandstone. A decrease in temperature reduces the instantaneous and creep deformations of the rocks at all levels of stress. In addition, a decrease in temperature exponentially attenuates the total creep and viscoplastic strains of the rocks. 0°C is a critical point for the reduction of the total creep and viscoplastic strains of the rocks. When the temperature is greater than 0°C, the total creep and viscoplastic strains of the rocks decrease rapidly and linearly with decrease in temperature; however, when the temperature is less than 0°C, the decrease in the total creep and viscoplastic strains of the rocks is slow. The steady-state creep rate of the rock samples decreases with decrease in temperature, whereas the creep duration increases with decrease in temperature, especially in the case of the accelerated creep stage. The accelerated creep durations of the rock samples S4 (20°C) and S7 (–10°C) are 0.07 h and 0.23 h, respectively.
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8

Heffes, M. J., and H. F. Nied. "Analysis of Interfacial Cracking in Flip Chip Packages With Viscoplastic Solder Deformation." Journal of Electronic Packaging 126, no. 1 (March 1, 2004): 135–41. http://dx.doi.org/10.1115/1.1649242.

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This paper examines the modeling of viscoplastic solder behavior in the vicinity of interfacial cracking for flip chip semiconductor packages. Of particular interest is the relationship between viscoplastic deformation in the solder bumps and any possible interface cracking between the epoxy underfill layer and the silicon die. A 3-D finite element code, developed specifically for the study of interfacial fracture problems, was modified to study how viscoplastic solder material properties would affect fracture parameters such as strain energy release rate and phase angle for nearby interfacial cracks. Simplified two-layer periodic symmetry models were developed to investigate these interactions. Comparison of flip chip results using different solder material models showed that viscoplastic models yielded lower stress and fracture parameters than time independent elastic-plastic simulations. It was also found that adding second level attachment greatly increases the magnitude of the solder strain and fracture parameters. As expected, the viscoplastic and temperature dependent elastic-plastic results exhibited greater similarity to each other than results based solely on linear elastic properties.
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9

Dörlich, Vanessa, Joachim Linn, Tobias Scheffer, and Stefan Diebels. "Towards Viscoplastic Constitutive Models for Cosserat Rods." Archive of Mechanical Engineering 63, no. 2 (June 1, 2016): 215–30. http://dx.doi.org/10.1515/meceng-2016-0012.

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Abstract Flexible, slender structures like cables, hoses or wires can be described by the geometrically exact Cosserat rod theory. Due to their complex multilayer structure, consisting of various materials, viscoplastic behavior has to be expected for cables under load. Classical experiments like uniaxial tension, torsion or three-point bending already show that the behavior of e.g. electric cables is viscoplastic. A suitable constitutive law for the observed load case is crucial for a realistic simulation of the deformation of a component. Consequently, this contribution aims at a viscoplastic constitutive law formulated in the terms of sectional quantities of Cosserat rods. Since the loading of cables in applications is in most cases not represented by these mostly uniaxial classical experiments, but rather multiaxial, new experiments for cables have to be designed. They have to illustrate viscoplastic effects, enable access to (viscoplastic) material parameters and account for coupling effects between different deformation modes. This work focuses on the design of such experiments.
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10

Wang, Jun, Yingjie Xu, Weihong Zhang, and Xuanchang Ren. "Thermomechanical Modeling of Amorphous Glassy Polymer Undergoing Large Viscoplastic Deformation: 3-Points Bending and Gas-Blow Forming." Polymers 11, no. 4 (April 10, 2019): 654. http://dx.doi.org/10.3390/polym11040654.

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Анотація:
Polymeric products are mostly manufactured by warm mechanical processes, wherein large viscoplastic deformation and the thermomechanical coupling effect are highly involved. To capture such intricate behavior of the amorphous glassy polymers, this paper develops a finite-strain and thermomechanically-coupled constitutive model, which is based on a tripartite decomposition of the deformation gradient into elastic, viscoplastic, and thermal components. Constitutive equations are formulated with respect to the spatial configuration in terms of the Eulerian Hencky strain rate and the Jaumann rate of Kirchhoff stress. Hyperelasticity, the viscoplastic flow rule, strain softening and hardening, the criterion for viscoplasticity, and temperature evolution are derived within the finite-strain framework. Experimental data obtained in uniaxial tensile tests and three-point bending tests of polycarbonates are used to validate the numerical efficiency and stability of the model. Finally, the proposed model is used to simulate the gas-blow forming process of a polycarbonate sheet. Simulation results demonstrate well the capability of the model to represent large viscoplastic deformation and the thermomechanical coupling effect of amorphous glassy polymers.
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Більше джерел

Дисертації з теми "Viscoplastic deformation"

1

Tashman, Laith. "Microstructural viscoplastic continuum model for asphalt concrete." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/313.

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Анотація:
This dissertation presents the development of an anisotropic viscoplastic continuum damage model to describe the permanent deformation of asphalt pavements. The model is developed to account for several phenomena that influence the permanent deformation of Asphalt Concrete (AC) at high temperatures. These phenomena include strain rate dependency, confining pressure dependency, dilation, aggregate friction, anisotropy, and damage. The model is based on Perzyna's theory of viscoplasticity with Drucker-Prager yield function modified to account for the microstructure anisotropy and damage. A parametric study was conducted to study the effect of key factors such as inherent anisotropy and damage on the model response. A preliminary investigation was conducted to demonstrate the capabilities of the model and its sensitivity to changes in the microstructure distribution and loading conditions. The model was used to describe laboratory experimental measurements obtained from the Federal Highway Administration (FHWA) Accelerated Loading Facility (ALF). The model had a good match with these experimental measurements. In particular, using the damage parameter, the model was able to capture the point at which AC experienced tertiary creep in a static creep test. A comprehensive experiment was conducted to systematically determine the model parameters and the evolution laws that describe AC hardening, anisotropy, and damage. The experiment consisted of a set of compressive triaxial strength tests conducted at three confining pressures and five strain rates. Based on these experimental measurements, the model was modified to include a nonassociated flow rule. The model was shown to capture the experimental measurements very well. Furthermore, an experiment was conducted to capture and characterize damage evolution in AC due to permanent deformation. AC specimens were loaded using a triaxial compression setup to four predefined strain levels at three confining pressures. X-Ray computed tomography and image analysis techniques were used to capture and characterize the evolution of cracks and air voids in the deformed specimens. Damage was found to be a localized phenomenon in the sense that there exists a critical section in an AC specimen that is mainly responsible for failure. The results of the damage experiment supported the damage evolution function proposed in the viscoplastic model.
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2

SHAHBODAGH, KHAN Babak. "Large Deformation Dynamic Analysis Method for Partially Saturated Elasto-Viscoplastic Soils." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/151955.

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3

Feng, Huaiping. "Multiphase Deformation Analysis of Elasto-viscoplastic Unsaturated Soil and Modeling of Bentonite." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/57266.

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Анотація:
The deformation behavior of unsaturated soil has been the subject of numerous experimental and theoretical investigations. However, this phenomenon is not fully understood. Problems, such as the adoption of the proper stress variables, reduction of suction inducing collapse, suction effect on soil stiffness, rate dependency and air trapped within the soil under rainfall infiltration still need additional studies. In the present studies, an elasto-viscoplastic model for unsaturated soil is used based on two stress variables: 1) the skeleton stress is adopted as the stress variable; 2) suction is incorporated into the constitutive model to describe the collapse behavior. In addition, to investigate the multiphase behavior of unsaturated soil, a three-phase coupled model has been proposed based on the Theory of Porous Media (TPM) and finite deformation theory. Van Genuchten type of equation is employed as a constitutive equation between the saturation and the suction. Three-dimensional multiphase simulations are carried out to reproduce the behavior of unsaturated soil during monotonic loading triaxial tests under drained and undrained conditions for water and air. Compared with experimental results and the simulated results, it is seen that the proposed formulation is very suitable to describe the mechanical behaviors of unsaturated soil. Cyclic behavior of unsaturated soil has attracted much attention during the past few years. An elasto-viscoplastic cyclic model for saturated soil is extended for modeling of unsaturated soil. Based on finite deformation theory, three-dimensional multiphase analyses for unsaturated soil under cyclic loading are presented. The simulations are verified with cyclic triaxial tests on unsaturated silty clay under undrained for water and air conditions. It shows that the proposed multiphase formulation can be used to simulate the behaviors of unsaturated soil under cyclic loading. The high expansiveness of bentonite is another significant problem in unsaturated soil mechanics. In this research, an elasto-viscoplastic model for unsaturated expansive soil has been developed. An evolutional equation is adopted for describing the absorption of water into interlayer of clay platelets. In addition, the internal compaction effect caused by swelling of clay unit is expressed with the expansion of overconsolidation boundary surface and static yield surface. Based on the model, one-dimensional finite element analysis is conducted to study the development of swelling pressure. Compared with experimental results and simulated results, it is found that the proposed model can reproduce the effects of dry density and initial water content on swelling behavior. Using the proposed swelling model, two-dimensional swelling behaviors of the waste barrier are simulated.
Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第13775号
工博第2879号
新制||工||1425(附属図書館)
25991
UT51-2008-C691
京都大学大学院工学研究科社会基盤工学専攻
(主査)教授 岡 二三生, 教授 松岡 俊文, 准教授 木元 小百合
学位規則第4条第1項該当
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4

Mimura, Mamoru. "ELASTO-VISCOPLASTIC CONSTITUTIVE MODELING FOR CLAY AND DEFORMATION ANALYSIS OF SOFT CLAY FOUNDATION." Kyoto University, 1991. http://hdl.handle.net/2433/74590.

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5

Borges, RÃmulo Luiz. "Permanent deformation in asphalt mixtures from viscoplastic shift model and triaxial repeated load test." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13192.

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Анотація:
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
Permanent deformation or rutting is a major distress in asphalt pavements. To predict permanent deformation of asphalt mixtures the dynamic creep test is often used in laboratory, with the result presented in terms of the so called flow number. However, for this work it was performed the triaxial repeated permanent deformation load test, a confined test that better represents field conditions. The models that incorporate the flow number do not represent the main zone of the dynamic creep test result, denoted secondary region, in which the permanent deformation rate of growth is constant. In this work the Shift Model was used, which is a viscoplastic model that accesses the permanent deformation from the superposition principles, i.e., time-temperature superposition and time-stress superposition. Thus, the asphalt mixtures were tested under different loading conditions, temperature, load time and rest period, in order to assess three parameters of the test: parameter C, which indicates where the secondary region begins (parameter that governs the primary region of the test); the parameter α (alpha) is the slope of the secondary region; and the parameter B represents the level of permanent deformation of the secondary region. The results show that the TRLPD test is more severe than the conventional dynamic creep test. Nevertheless, the use of TRLPD test represents an advance in the understanding of the behavior of asphalt mixtures with respect to rutting performance, and has the advantage of allowing the use of results in computational simulations.
A deformaÃÃo permanente à um dos principais defeitos em pavimentos asfÃlticos. Para prever esta falha em revestimentos, por meio de ensaios laboratoriais, à frequentemente utilizado o ensaio de creep dinÃmico cujo resultado final à apresentado em termos do chamado flow number. No entanto, para este trabalho foi realizado o triaxial repeated load permanent deformation (TRLPD) test, que à um ensaio sob condiÃÃes de confinamento, a fim de melhor se aproximar das condiÃÃes encontradas em campo. Os modelos que incorporam o flow number nÃo representam a principal regiÃo de ensaio de creep dinÃmico, denominada regiÃo secundÃria, na qual o incremento de deformaÃÃo permanente cresce em valor constante. No presente trabalho utilizou-se o Shift Model, o qual à um modelo viscoplÃstico que avalia a deformaÃÃo permanente a partir da superposiÃÃo dos efeitos tempo-temperatura e tempo-tensÃo. Dessa forma, as misturas asfÃlticas foram testadas sob diferentes condiÃÃes de carregamento, temperatura, tempo de aplicaÃÃo de carga e perÃodo de repouso. Foram avaliados trÃs parÃmetros do ensaio em questÃo: o parÃmetro C, que fornece os dados de onde a regiÃo secundÃria se inicia (parÃmetro que governa a regiÃo primÃria do ensaio); o parÃmetro α (alfa), que à o aclive da regiÃo secundÃria; e o parÃmetro B, que representa o nÃvel de deformaÃÃo permanente da regiÃo secundÃria. Os resultados obtidos mostram que o ensaio TRLPD à mais severo do que o ensaio convencional de creep dinÃmico, porÃm considera-se que a utilizaÃÃo de ensaios confinados representa um avanÃo para o entendimento do comportamento das misturas asfÃlticas quanto à resistÃncia à deformaÃÃo permanente das mesmas, e este traz a vantagem de poder ser usado em simulaÃÃes computacionais.
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Danielsson, Mats 1973. "Micromechanics, macromechanics and constitutive modeling of the elasto-viscoplastic deformation of rubber-toughened glassy polymers." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17608.

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Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references (p. 251-258).
Glassy polymers, such as polystyrene (PS), poly(methyl methacrylate) (PMMA) and polycarbonate (PC), are common engineering polymers that have found uses in consumer products ranging from portable computers and optical lenses, to automotive components and appliance housings. PMMA and PS are typically considered to be brittle polymers, since they fail in a brittle manner under low triaxiality conditions, such as under uniaxial tension. Polycarbonate is considered to be a more ductile polymer than PMMA and PS, since it will deform plastically under uniaxial tension. However, PC does exhibit brittle behavior under certain loading conditions, such as low temperatures, high strain rates, or highly (tensile) triaxial stress states. A technique used for reducing the brittleness (increasing the fracture toughness) of glassy polymers is rubber-toughening. The technology of rubber-toughening, which involves blending a small volume fraction (5-20%) of rubber particles with the homopolymer, has been used commercially since the 1940s, and has been of major importance to the plastics industry. The technology of rubber-toughening is qualitatively well understood, but quantitative tools to study the material response are still at an early stage of development. The purpose of this thesis is to develop numerical tools to investigate the mechanical behavior of rubber-toughened glassy polymers, with emphasis on rubber-toughened PC. To this end, several tools are developed.
(cont.) Three-dimensional micromechanical models of the heterogeneous microstructure are developed to study the effects of particle volume fraction on the underlying elastic visco-plastic deformation mechanisms in the material, and how these mechanisms influence the macroscopic [continuum-level] response of the material. A continuum-level constitutive model is developed for the homogenized large-strain elastic-viscoplastic behavior of the material. The model is calibrated against micromechanical modeling results for rubber-toughened polycarbonate. The constitutive model is used to study boundary value problems such as notched tensile bars, where a multi-scale modeling approach enables assessment of failure due to local stress and strain levels in the material. The results are compared to experimental studies to establish correlations between the continuum-level response of the material, and observed failure mechanisms in the material.
by Mats Danielsson.
Ph.D.
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7

Wen, Wei. "Simulation of large deformation response of polycrystals, deforming by slip and twinning, using the viscoplastic Ø-model." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00959709.

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Анотація:
The computation of the macroscopic response of polycrystalline aggregates from the properties of their single-crystal is a main problem in materials mechanics. During the mechanical deformation processing, all the grains in the polycrystalline material sample are reoriented. A crystallographic texture may thus be developed which is responsible for the material anisotropy. Therefore, the modeling of the texture evolution is important to predict the anisotropy effects present in industrial processes. The formulation of polycrystals plasticity has been the subject of many studies and different approaches have been proposed. Ahzi and M'Guil developed a viscoplastic phi-model. This model takes into account the grains interaction effects without involving the Eshelby inclusion problems.In this thesis, the phi-model was applied to different crystallographic structures and under different loading conditions. The mechanical twinning has been taken into account in the model. The FCC rolling texture transition from copper-type to brass-type texture is studied. The shear tests in FCC metals are also studied. The predicted results are compared with experimental shear textures for a range of metals having a high SFE to low SFE. For BCC metal, we compare our predicted results with those predicted by the VPSC model. We study the slip activities, texture evolutions and the evolution of yield loci. We also present a comparison with experimental textures from literatures for several BCC metals under cold rolling tests. The model has also been extended to HCP metals. We predict the deformation behavior of the magnesium alloy for different interaction strengths. We also compare our predicted results with experimental data from literatures. We show that the results predicted by the phi-model are in good agreement with the experimental ones.
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8

Santos, Tiago dos. "Experimental characterization and constitutive modeling of viscoplastic effects in high strain-rate deformation of polycrystalline FCC metals." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/150625.

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O presente trabalho tem como objetivo a caracterização experimental e modelagem constitutiva do comportamento de metais CFC (Cúbicos de Face Centrada) policristalinos quando submetidos a altas taxas de deformação. O material empregado no desenvolvimento do trabalho é uma liga de alumínio comercialmente pura: o alumínio AA1050. No âmbito da presente investigação, os experimentos são conduzidos à temperatura ambiente. O desenvolvimento experimental tem por objetivo evidenciar as principais características constitutivas que descrevem o comportamento macroscópico desta classe de metais quando submetidos a processos de deformação envolvendo altas taxas de deformação: (i) o endurecimento induzido pela deformação; (ii) o endurecimento induzido pela taxa de deformação; e (iii) a sensibilidade instantânea em relação à taxa de deformação. Para a caracterização de cada uma destes aspectos constitutivos, são realizados experimentos específicos utilizando equipamentos desenvolvidos, em sua maioria, no contexto da presente investigação. De forma geral, os experimentos consistem em ensaios de compressão envolvendo uma ampla faixa de taxas de deformação, variando desde condições quasi-estáticas a taxas na ordem de 104 s−1. Os resultados experimentais, juntamente com evidências experimentais macro e microscópicas disponíveis na literatura, dão suporte ao desenvolvimento de um modelo constitutivo elasto-viscoplástico. A formulação constitutiva segue uma abordagem semi-física, na qual a escolha das variáveis inelásticas e proposição de suas regras de evolução são qualitativamente guiadas por considerações metalúrgicas baseadas no acúmulo e organização de discordâncias O modelo proposto, embora consista em uma abordagem simplificada quando comparado a modelos de base física, é capaz de representar separadamente cada uma das características constitutivas destacadas anteriormente. Com base nos resultados experimentais aqui obtidos, o modelo elasto-viscoplástico proposto é então ajustado e posteriormente validado. Na sequência é desenvolvida a formulação numérica relacionada ao modelo proposto. A abordagem como um todo é inserida em um contexto de deformações finitas seguindo uma descrição Lagrangiana Total. O desenvolvimento numérico descreve o procedimento utilizado para solução de problemas de equilíbrio não lineares seguindo uma formulação incremental implícita empregando o método dos elementos finitos. Em um contexto local, é utilizado um esquema de integração implícito seguindo um mapeamento exponencial. A linearização das equações de mapeamento de retorno possibilita a derivação analítica do módulo tangente consistente. O modelo constitutivo, bem como o procedimento numérico, são utilizados para a solução de problemas numéricos clássicos como: ensaio de compressão em condições de deformações homogêneas, e compressão envolvendo contato com atrito. As simulações numéricas avaliam tanto a capacidade constitutiva do modelo proposto em descrever o comportamento de estruturas quando deformadas sob condições envolvendo elevadas taxas de deformação, quanto à eficiência do procedimento numérico a partir de análises de convergência Em conclusão, com o procedimento experimental adotado é possível evidenciar as principais características macroscópicas inerentes ao comportamento de metais quando submetidos a processos de deformação envolvendo altas velocidades. Além disso, com base nos resultados analíticos e numéricos, observa-se que o modelo constitutivo proposto é capaz de reproduzir de forma satisfatória os comportamentos evidenciados experimentalmente.
The present work aims at performing the experimental characterization and constitutive modeling associated with the mechanical behavior of polycrystalline FCC (Face Centered Cubic) metals when subjected to high strain-rate deformations. The material to be employed in the experiments is a commercially pure aluminum alloy: aluminum AA1050. Within the present investigation context, experiments are performed at room temperatures. The primary objective of the laboratory experiments is to assess the main constitutive features associated with the macroscopic mechanical behavior observed for FCC metals subjected to high strain-rate deformation processes: (i) strain-hardening; (ii) strain-rate-hardening; and (iii) instantaneous rate-sensitivity. In order to characterize each constitutive feature, experiments using equipments specifically devised to achieve the objectives are performed. The laboratory investigation consists of compression tests involving a wide strain-rate range, from quasi-static conditions to strain-rates of the order of 104 s−1. Experimental results together with micro and macroscopic experimental evidences available in the literature give support to the development of a elastic-viscoplastic model. The stress-strain formulation follows a semi-physical approach, in which inelastic variables and their evolution equations are qualitatively motivated by metallurgical considerations based on the storage and arrangement of dislocations. Although its simplified nature when compared to physically-based models, the proposed model is capable of representing separately each one of the constitutive features highlighted early In addition, in analogy to the stress-strain proposition, a model describing the material hardness evolution in terms of strain and strain-rate histories is also provided. Based on the obtained experimental results, the proposed elastic-viscoplastic and hardness evolution models are adjusted and then validated. The corresponding stress-strain numerical formulation is developed in a subsequent step. The approach as a whole is integrated into finite strain framework following a Total Lagrangian description. The procedure employed to solve nonlinear equilibrium problem follows an implicit incremental formulation implemented in the context of the finite element method. At a local level, an implicit integration scheme based on an exponential mapping is adopted. From linearization of return mapping equations, an analytical consistent tangent modulus is obtained. Both constitutive model and numerical approach are employed to simulated classical problems: a compression test involving homogeneous deformation and a compression test involving contact and frictional conditions. Numerical simulations evaluate the constitutive capabilities associated with the proposed model when predicting the structural behavior at high strain-rate loadings. Furthermore, numerical efficiency and robustness related to the present procedure are also assessed by means of convergence analysis. While the adopted experimental procedure gave fundamental evidences of the main macroscopic features inherent in the metallic material behavior when subjected to high strain-rate deformations, the analytical and numerical results demonstrated that the proposed constitutive model is able to suitably reproduce the observed behavior.
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Srivastava, Vikas. "A large-deformation thermo-mechanically coupled elastic-viscoplastic theory for amorphous polymers : modeling of micro-scale forming and the shape memory phenomenon." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/57787.

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Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 185-193).
Amorphous polymers are important engineering materials; however, their nonlinear, strongly temperature- and rate-dependent elastic-viscoplastic behavior is still not very well understood, and is modeled by existing constitutive theories with varying degrees of success. There is no generally agreed upon theory to model the large-deformation, thermo-mechanically coupled response of these materials in a temperature range which spans their glass transition temperature. Such a theory is crucial for the development of a numerical capability for the simulation and design of important polymer processing operations, and also for predicting the relationship between processing methods and the subsequent mechanical properties of polymeric products. We have developed a large-deformation thermo-mechanically coupled elastic-viscoplastic theory for thermoplastic amorphous polymers and shape memory polymers which spans their glass transition temperature. The theory has been specialized to represent the major features of the thermo-mechanical response of three technologically important thermoplastic amorphous polymers - a cyclo-olefin polymer (Zeonex-690R), polycarbonate, poly(methyl methacrylate) and a representative thermoset shape memory polymer - in a temperature range from room temperature to approximately 40 C above the glass transition temperature of each material, in a strain-rate range of ~ 10-4 to 101 s-1, and compressive true strains exceeding 100%. Our theory has been implemented in the finite element program ABAQUS. In order to validate the predictive capability of our constitutive theory, we have performed a variety of macro- and micro-scale validation experiments involving complex inhomogeneous deformations and thermal processing cycles. By comparing some key features, such as the experimentally-measured deformed shapes and the load-displacement curves from various validation experiments against corresponding results from numerical simulations, we show that our theory is capable of reasonably accurately reproducing the results obtained in the validation experiments.
by Vikas Srivastava.
Ph.D.
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10

Diehl, Ted. "Modeling of elastic-viscoplastic behavior and its finite element implementation /." Online version of thesis, 1988. http://hdl.handle.net/1850/10461.

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Книги з теми "Viscoplastic deformation"

1

Pandey, Ajay K. Finite element thermo-viscoplastic analysis of aerospace structures. Hampton, Va: NASA Langley Research Center, 1990.

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International Symposium on Plasticity and Its Current Applications (6th 1997 Juneau, Alaska). Physics and mechanics of finite plastic and viscoplastic deformation: Proceedings of Plasticity '97 : the Sixth International Symposium on Plasticity and Its Current Applications. Fulton, Maryland: Neat Press, 1997.

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3

1952-, Saleeb Atef F., Castelli Michael G, and United States. National Aeronautics and Space Administration., eds. A fully associative, nonisothermal, nonlinear kinematic, unified viscoplastic model for titanium alloys. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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4

Pramote, Dechaumphai, Thornton Earl A. 1936-, and Langley Research Center, eds. Finite element thermo-viscoplastic analysis of aerospace structures. Hampton, Va: NASA Langley Research Center, 1990.

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5

Pramote, Dechaumphai, Thornton Earl A. 1936-, and Langley Research Center, eds. Finite element thermo-viscoplastic analysis of aerospace structures. Hampton, Va: NASA Langley Research Center, 1990.

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6

Pramote, Dechaumphai, Thornton Earl A. 1936-, and Langley Research Center, eds. Finite element thermo-viscoplastic analysis of aerospace structures. Hampton, Va: NASA Langley Research Center, 1990.

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Частини книг з теми "Viscoplastic deformation"

1

Sansour, Carlo, and Franz G. Kollmann. "Large Deformation of Axisymmetric Viscoplastic Shells." In Computational Mechanics ’95, 1241–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79654-8_201.

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2

Zhang, X. T., and R. C. Batra. "Shear Band Development in a Viscoplastic Cylinder." In Anisotropy and Localization of Plastic Deformation, 103–6. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_24.

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3

Tomita, Yoshihiro, and Kenichi Hayashi. "Deformation Behavior in Elasto-Viscoplastic Polymeric Bars under Tension." In Anisotropy and Localization of Plastic Deformation, 524–27. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_122.

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4

Alber, Hans-Dieter. "Justification of Homogenized Models for Viscoplastic Bodies with Microstructure." In Deformation and Failure in Metallic Materials, 295–319. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-36564-8_12.

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5

Molinari, A. "Self-Consistent Modelling of Plastic and Viscoplastic Polycrystalline Materials." In Large Plastic Deformation of Crystalline Aggregates, 173–246. Vienna: Springer Vienna, 1997. http://dx.doi.org/10.1007/978-3-7091-2672-1_5.

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6

Shao, J. F., M. Bederiat, and J. P. Henry. "Elasto-Viscoplastic Modelling of Porous Rock under High Confining Pressure." In Anisotropy and Localization of Plastic Deformation, 266–69. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_63.

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7

Molinari, Alain, and Yves M. Leroy. "On The Stability of Steady Shear Flows of Thermo-Viscoplastic Materials." In Anisotropy and Localization of Plastic Deformation, 69–72. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_16.

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8

Olschewski, J., R. Sievert, and A. Bertram. "Comparative Viscoplastic Fe-Calculations of a Notched Specimen under Cyclic Loadings." In Anisotropy and Localization of Plastic Deformation, 397–400. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_92.

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9

Mihailescu-Suliciu, M., and I. Suliciu. "An Energetic Control on Numerical Instability for a Rate-Type Viscoplastic Oscillator." In Anisotropy and Localization of Plastic Deformation, 639–42. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_149.

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10

Bruhns, O. T. "Some Remarks on the Concept of Viscoplastic Models of the Overstress-Type." In Anisotropy and Localization of Plastic Deformation, 381–84. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_88.

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Тези доповідей конференцій з теми "Viscoplastic deformation"

1

Tetambe, Ravi P., and Sunil S. Saigal. "Adaptive Large Deformation Viscoplastic Finite Element Analysis." In ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium collocated with the ASME 1995 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/cie1995-0747.

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Abstract The adaptive remeshing and rezoning procedures developed for large deformation finite element analysis using viscoplastic material model are presented in two dimensions. The adaptive procedure is driven by the posteriori error estimation technique. The nonlinear error estimators based on the energy rate norm error and the L2 norm error of incremental total strains are used for error computation. The remeshing algorithm creates new acceptable meshes in the course of the deformation process without any loss of geometric information. The remeshing of the current geometry is achieved using the boundary refinement technique. This technique is observed to be sufficiently accurate in problems where mesh refinement is largely required at the boundary or very close to the boundary of the structure. The rezoning procedure is then used to accurately interpolate the solution variables from the existing mesh to the new adaptively created mesh. The element subdivision approach is used during the rezoning process. The adaptive remeshing and rezoning procedures are developed for 6-node triangular element. These procedures are implemented in the general purpose finite element program, ANSYS [13], and are validated by solving two complex large strain examples. In both examples, these procedures are successful in achieving very high deformation levels in a structure.
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2

Fortov, V. E., A. V. Gavrikov, D. N. Goranskaya, A. S. Ivanov, O. F. Petrov, R. A. Timirkhanov, José Tito Mendonça, David P. Resendes, and Padma K. Shukla. "Viscoplastic Deformation of Crystal-like Dusty Plasma Structures." In MULTIFACETS OF DUSTRY PLASMAS: Fifth International Conference on the Physics of Dusty Plasmas. AIP, 2008. http://dx.doi.org/10.1063/1.2997255.

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3

Chentanez, Nuttapong. "Real-time simulation of solids with large viscoplastic deformation." In SIGGRAPH '16: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2933540.2933552.

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4

Heffes, M. J., and H. F. Nied. "Analysis of Interface Cracking in Flip Chip Packages With Viscoplastic Solder Deformation." In ASME 2003 International Electronic Packaging Technical Conference and Exhibition. ASMEDC, 2003. http://dx.doi.org/10.1115/ipack2003-35346.

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This paper examines the modeling of viscoplastic solder behavior in the vicinity of interfacial cracking for flip chip semiconductor packages. Of particular interest is the relationship between viscoplastic deformation in the solder bumps and any possible interface cracking between the epoxy underfill layer and the silicon die. A 3-D finite element code, developed specifically for the study of interfacial fracture problems, was modified to study how viscoplastic solder material properties would affect fracture parameters such as strain energy release rate and phase angle for nearby interfacial cracks. Simplified two-layer periodic symmetry models were developed to investigate these interactions. Comparison of flip chip results using different solder material models showed that viscoplastic models yielded lower stress and fracture parameters than time independent elastic-plastic simulations. It was also found that adding second level attachment greatly increases the magnitude of the solder strain and fracture parameters. As expected, the viscoplastic and temperature dependent elastic-plastic results exhibited greater similarity to each other than results based solely on linear elastic properties.
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5

Ladani, Leila J., and A. Dasgupta. "Partitioned Cyclic Fatigue Damage Evolution Model for PB-Free Solder Materials." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/creep2007-26306.

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This study presents an approach to predict the degree of material degradation and the resulting changes in constitutive properties during cyclic loading in viscoplastic materials in micro-scale applications. The objective in the modeling approach is to address the initiation and growth of distributed micro-damage, in the form of micro-cracks and micro-voids, as a result of cyclic, plastic and creep deformations of material. This study extends an existing micromechanics-based approach, developed for unified viscoplastic models [Wen, et al, 2001], which uses dislocation mechanics to predict damage due to distributed micro-scale fatigue crack initiation [Mura and Nakasone, 1990]. In the present study, the approach is extended to a partitioned viscoplastic framework, because the micro-scale mechanisms of deformation and damage are different for plastic and creep deformation. In this approach, the model constants for estimating cyclic damage evolution are allowed to be different for creep and plastic deformations. A partitioned viscoplastic constitutive model is coupled with an energy partitioning (E-P) damage model [Oyan and Dasgupta, 1992] to assess fatigue damage evolution due to cyclic elastic, plastic and creep deformations. Wen’s damage evolution model is extended to include damage evolution due to both plastic and creep deformations. The resulting progressive degradation of elastic, plastic and creep constitutive properties are continuously assessed and updated. The approach is implemented on a viscoplastic Pb-free solder. Dominant deformation modes in this material are dislocation slip for plasticity and diffusion-assisted dislocation climb/glide for creep. The material’s behavior shows a good correlation with the proposed damage evolution model. Damage evolution constants for plastic and creep deformation were obtained for this Pb-free solder from load drop data collected from the mechanical cycling experiments at different temperatures. The amount of cyclic damage is evaluated and compared with experiment.
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6

Yang, X. J., C. L. Chow, and K. J. Lau. "A Unified Viscoplastic Fatigue Damage Model for 63Sn-37Pb Solder Alloy Under Cyclic Stress Control." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32862.

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A damage coupling viscoplastic model is developed to predict fatigue life of solder alloy 63Sn-37Pb under stress control. The viscoplastic flow rule chosen employs a hyperbolic sine function. A damage evolution equation is formulated based on three distinct material deformation behaviors: (i) stress rate independent damage evolution; (ii) stress rate dependent cyclic damage evolution; and (iii) stress rate dependent ductile damage evolution. The cyclic stress testing with different stress waveforms was first conducted to investigate their progressive viscoplastic deformations of the solder alloy. The investigation reveals that the material constants used in the model can be adequately determined from the results of standard creep tests. The constitutive model is validated by comparing the predicted and measured ratchetting results of the solder alloy under different forms of stress cycling. The proposed model is found to be capable of satisfactorily describing the viscoplastic deformation and ratchetting failure behaviors of the solder alloy under the conditions of the cyclic stress loading.
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Neilsen, Mike, Wei-Yang Lu, Bill Olsson, and Terry Hinnerichs. "A Viscoplastic Constitutive Model for Polyurethane Foams." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14551.

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A series of experiments was recently performed to characterize the mechanical response of several different rigid polyurethane foams to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Based on these experiments, a foam plasticity model that captures volumetric and deviatoric plasticity was developed. This model has a yield surface that is an ellipsoid about the hydrostat. These polymeric foams were also found to be very strain-rate and temperature dependent. Thus, a new viscoplastic foam model was developed to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This paper includes a description of recent experiments and experimental findings. Next, development of a foam plasticity model and a viscoplastic foam model is described. Finite element simulations with the new models are compared with experimental results to show behavior that can and cannot be captured with these models.
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Zhang, Ran, Gang Zhao, Wei Wang, Xiaoxiao Du, and Mayi Guo. "NURBS-based Isogeometric Analysis for Small Deformation of Viscoplastic and Creep Problems." In CAD'20. CAD Solutions LLC, 2020. http://dx.doi.org/10.14733/cadconfp.2020.116-120.

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9

Dienemann, Lara L., Anil Saigal, and Michael A. Zimmerman. "Elastic-Viscoplastic Mechanics of Lithium in a Standard Dry Room." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23894.

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Abstract In electrochemical-mechanical modeling of solid-state batteries, there is a lack of understanding of the mechanical parameters and mode of deformation of lithium metal. Understanding these characteristics is crucial for predicting the propagation of lithium dendrites through the electrolyte — a key element of battery safety. Past theories have assumed linear elastic as well as elastic-plastic deformation of lithium. However, recent experiments show that the primary mode of deformation is creep. This study replicates the temperature dependent mechanical experiments but inside an industrial dry room, where battery cells are manufactured at high volume. Furthermore, this work conducts time dependent studies — also inside the dry room — to gain insight of the large deformation theories of lithium metal. The results confirm the activation energy, which dictates the creep mechanism, is correlated to core diffusion rather than lattice diffusion.
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Hartl, Darren, George Chatzigeorgiou, and Dimitris Lagoudas. "Three-Dimensional Modeling of Rate-Dependent Deformation in Shape Memory Alloys at High Temperatures." In ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1468.

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Active structures composed of Shape Memory Alloys (SMAs) and High Temperature SMAs (HTSMAs) continue to be developed for applications that benefit from solid-state actuation. The need to account for the response of these materials under non-conventional loading paths that include elevated temperature conditions has become important. Conventional SMAs are exposed to such temperatures during processing, including final shape-setting. HTSMAs, by virtue of their title, are exposed to such high temperatures during transformation. This work addresses new developments in the constitutive modeling and numerical analysis pertaining to irrecoverable inelasticity in SMAs at high temperatures, where this behavior becomes rate-dependent. The description of such behavior requires the development of a theoretical framework able to capture the coupling between the rate-independent transformation and the rate-dependent creep. The proposed phase transformation-viscoplastic model is based on continuum thermodynamics; here the elastic relations, the inelastic evolution equations, and the transformation criteria are summarized. The evolution equation for the viscoplastic strain is non-homogeneous in time, and thus rate-dependency results. The viscoplastic parameters are generally assumed to exhibit a strong dependence on temperature. The rate-independent and rate-dependent constitutive equations that comprise the full 3-D model are numerically integrated using a scheme that accounts for both transformation and viscoplastic deformation in a coupled manner. The implementation allows for 3-D analysis of SMA bodies using an FEA framework that includes Abaqus and an associated user material subroutine. Example analyses are discussed, including shape-setting in a conventional SMA and experimentally validated structural analysis of an HTSMA specimen.
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