Dissertations / Theses on the topic 'Viscoplastic deformation'
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Tashman, Laith. "Microstructural viscoplastic continuum model for asphalt concrete." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/313.
Full textSHAHBODAGH, 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.
Full textFeng, 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.
Full textKyoto 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
Mimura, Mamoru. "ELASTO-VISCOPLASTIC CONSTITUTIVE MODELING FOR CLAY AND DEFORMATION ANALYSIS OF SOFT CLAY FOUNDATION." Kyoto University, 1991. http://hdl.handle.net/2433/74590.
Full textBorges, 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.
Full textPermanent 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.
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.
Full textIncludes 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.
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.
Full textSantos, 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.
Full textThe 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.
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.
Full textCataloged 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.
Diehl, Ted. "Modeling of elastic-viscoplastic behavior and its finite element implementation /." Online version of thesis, 1988. http://hdl.handle.net/1850/10461.
Full textMirmasoudi, Sara. "High Temperature Transient Creep Analysis of Metals." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1452693927.
Full textГараненко, Тетяна Романівна. "Розробка процесу формоутворення порожнистої лопатки з титанових сплавів для газотурбінних двигунів." Doctoral thesis, Київ, 2021. https://ela.kpi.ua/handle/123456789/40560.
Full textRusia, Devendra Kumar. "A modified viscoplastic formulation for large deformations using a bulk modulus approach." Ohio : Ohio University, 1987. http://www.ohiolink.edu/etd/view.cgi?ohiou1183058011.
Full textManivannan, Ganeshalingam Aerospace Civil & Mechanical Engineering Australian Defence Force Academy UNSW. "Viscoplastic modelling of embankments on soft soils." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace, Civil and Mechanical Engineering, 2005. http://handle.unsw.edu.au/1959.4/38743.
Full textHan, Songlin. "High temperature deformation modelling and finite element implementation for single crystal turbine blade materials." Thesis, University of Bristol, 2000. http://hdl.handle.net/1983/943aaa75-6406-4a06-9250-9b0ae85a5eae.
Full textAhmadi, Sadegh. "A New Eulerian-Based Double Continuity Model for Predicting the Evolution of Pair Correlation Statistics under Large Plastic Deformations." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2551.
Full textThomas, Anoop Ebey. "Modélisation numérique thermo-viscoplastique du procédé de forgeage des métaux par l’Approche Pseudo Inverse." Thesis, Reims, 2019. http://www.theses.fr/2019REIMS003/document.
Full textHot forging is a metal forming process used to form difficult-to-form materials as well as to achieve complex geometries. The reduction of yield stress at high temperatures and a subsequent increase in formability is the primary mechanism that drives the process. Numerical methods provide an efficient means to predict the material yield and the stress/strain states of the product at different stages of forming. Although classical methods are accurate enough to provide a suitable representation of the process, they tend to be computationally expensive. This limits its use in practical cases especially for process optimization. Pseudo Inverse Approach (PIA) developed in the context of 2D axisymmetric cold forming, provides a quick estimate of the stress and strain fields in the final product for a given initial shape. In this work, the PIA is extended to include the thermal and viscoplastic effects on the forging process as well as to the general 3D case. The results are compared with commercially available software, based on the classical approaches, to show the efficiency and the limitations of PIA. The results obtained indicate that PIA is a quite effective tool that can be used for both 2D and 3D simulations of hot forging
Leu, Wen-Long, and 呂文隆. "Viscoplastic Analysis of Wirebond Deformation During Molding." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/67227512162328679110.
Full text義守大學
材料科學與工程學系
87
Molding is a very important step during the packaging processes of microelectronics. The gold wires between the chip pads and leadframe deform under the action of flow loading of molten transfer molding compound. Significant permanent displacements of the wires, which are termed “wire sweep”, may occur if deformation is inelastic during cooling to room temperature. Since the advances of micro-electronics technology, the power of IC devices is improved as the physical dimensions shrink. This results in the smaller distance between gold wires. If the wire sweep is sufficiently large, it may cause a short circuit due to touching of adjacent wires. This phenomenon may be one of the most important problems in the IC package. In order to estimate the wire sweep, the knowledge of flow load, viscoplasticity of the wire, as well as finite element analysis are necessary. To develop viscoplasticity theory, experiments of rate change and stress relaxation of gold wires are performed at room temperature and 175ºC. Experimental results at both temperatures are employed to establish the viscosity functions and temperature-dependent elastic-viscoplastic constants of a wire, respectively. Because the flow load of the molten molding compound during cavity filling stage are quite different, C-MOLD package will therefore be applied to investigate the suitable flow load. Finally, the ABAQUS finite element package, together with the flow loading and viscoplasticity theory of the wire, are employed to estimate the wire sweep of the wire bond in DIP28L packages.
Haw, Shen Tzong, and 沈宗浩. "The Viscoplastic Behavior of Material for Finite Deformation." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/39306421890228788998.
Full textHsu, Tsung-Hwa, and 徐宗華. "Viscoplastic Deformation of Thin-Walled Tubes under Combined Bending and External Pressure." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/68078868291776837134.
Full textRomero, Pedro A. "Three-dimensional finite-deformation multiscale modeling of elasto-viscoplastic open-cell foams in the dynamic regime." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17091.
Full textSu, Xiang-Sheng, and 蘇祥盛. "Endochronic Simulation for Mechanical Behavior of 40/60 Solder Alloy under Viscoplastic and Creep Deformation at Various Temperature." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/44446560981766593116.
Full text