On the Evolution of Texture and Yield Loci in Finite Plastic Deformation of F.C.C. Polycrystals with the Taylor Model PDF Download
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Author: Gang Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 332
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Author: Gang Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 332
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Author: Vlado A. Lubarda
Publisher: CRC Press
ISBN: 1420040782
Category : Science
Languages : en
Pages : 665
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Book Description
Understanding the elastoplastic deformation of metals and geomaterials, including the constitutive description of the materials and analysis of structure undergoing plastic deformation, is an essential part of the background required by mechanical, civil, and geotechnical engineers as well as materials scientists. However, most books address the su
Author:
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Category : Dissertations, Academic
Languages : en
Pages : 780
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Author: Dorel Banabic
Publisher: Springer
ISBN: 3319440705
Category : Technology & Engineering
Languages : en
Pages : 416
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Book Description
This book gives a unified presentation of the research performed in the field of multiscale modelling in sheet metal forming over the course of more than thirty years by the members of six teams from internationally acclaimed universities. The first chapter is devoted to the presentation of some recent phenomenological yield criteria (BBC 2005 and BBC 2008) developed at the CERTETA center from the Technical University of Cluj-Napoca. An overview on the crystallographic texture and plastic anisotropy is presented in Chapter 2. Chapter 3 is dedicated to multiscale modelling of plastic anisotropy. The authors describe a new hierarchical multi-scale framework that allows taking into account the evolution of plastic anisotropy during sheet forming processes. Chapter 4 is focused on modelling the evolution of voids in porous metals with applications to forming limit curves and ductile fracture. The chapter details the steps needed for the development of dissipation functions and Gurson-type models for non-quadratic anisotropic plasticity criteria like BBC 2005 and those based on linear transformations. Chapter 5 describes advanced models for the prediction of forming limit curves developed by the authors. Chapter 6 is devoted to anisotropic damage in elasto-plastic materials with structural defects. Finally, Chapter 7 deals with modelling of the Portevin-Le Chatelier (PLC) effect. This volume contains contributions from leading researchers from the Technical University of Cluj-Napoca, Romania, the Catholic University of Leuven, Belgium, Clausthal University of Technology, Germany, Amirkabir University of Technology, Iran, the University of Bucharest, Romania, and the Institute of Mathematics of the Romanian Academy, Romania. It will prove useful to postgraduate students, researchers and engineers who are interested in the mechanical modeling and numerical simulation of sheet metal forming processes.
Author: Cristian Teodosiu
Publisher: Springer
ISBN: 370912672X
Category : Technology & Engineering
Languages : en
Pages : 300
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Book Description
The book gives a comprehensive view of the present ability to take into account the microstructure and texture evolution in building up engineering models of the plastic behaviour of polycrystalline materials at large strains. It is designed for postgraduate students, research engineers and academics that are interested in using advanced models of the mechanical behaviour of polycrystalline materials.
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ISBN:
Category :
Languages : en
Pages : 67
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Book Description
Large deformation uniaxial compression and fixed-end torsion (simple shear) experiments were conducted on annealed OFHC Copper to obtain its stress- strain behavior. This material behavior was also predicted using the Taylor-type rate dependent polycrystal model by Asaro and Needleman. Simulations of the experiments were conducted in personal computers, using a recently developed, highly efficient, fully implicit, time integration scheme by Kalidindi et al. In the initial phase of the simulation, the evolution of the constituent single crystal slip system deformation resistance was estimated using the experimentally determined compressive stress-strain behavior of the polycrystal. With this crystal constituent behavior, the stress-strain behavior of the polycrystal for simple shear was computed.
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ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 864
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Category : Metallurgy
Languages : en
Pages : 1628
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Author: Eloisa Zepeda-Alarcon
Publisher:
ISBN:
Category :
Languages : en
Pages : 175
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Book Description
The vast majority of rocks that constitute the Earth are composed of multiple mineral phases and complicated deformation conditions are found everywhere, yet little is known about plastic deformation of polyphase polycrystalline rocks, especially with low symmetry phases and highly contrasting mechanical properties. In particular, plastic deformation of mantle rocks is of interest for its connection to geophysical processes, such as mantle convection, slab subduction and upwelling plumes. Seismic observations show regions in the mantle where seismic waves encounter large scale anisotropy of the rocks they propagate in. Although there are many possible reasons for this large scale anisotropic signature of these particular regions, in the upper mantle it has been connected to the development of crystallographic preferred orientation, hereafter called texture, of the mineral olivine due to plastic deformation produced by specific geodynamical processes. Studies have also connected measured seismic anisotropy to texture in the minerals that compose the core mantle boundary region, in the mantle transition zone and in the core of the Earth. Deformation of lower mantle minerals is still poorly understood. Although large convective cells, upwhelling plumes and subducted slabs are expected, the bulk of the lower mantle remains seismically isotropic. The lower mantle is mainly composed of the mineral bridgmanite and ferropericlase, with a small volume fraction of Ca-Si-perovskite. Understanding plastic deformation of the bridgmanite and ferropericlase mineral aggregate can provide valuable information to better understand lower mantle dynamics, and to explain seismic observations. The objective of this dissertation is to explore plastic deformation of bridgmanite and periclase polycrystalline aggregates from both modeling and experimental approaches. In particular to understand the influence of microstructure in texture development and the role of deformation heterogeneities at the local grain scale. A finite element framework is used in Chapter 2 to explore plastic deformation by dislocation glide of a virtual two phase polycrystal with a random microstructure. Aggregates are deformed up to 20% strain under uniaxial compression and two different simulations where performed using the FEpX code, one where the yield strength of both phases is the same, and the second where the yield strength of the bridgmanite phase is 8 times higher than the periclase. This approach enabled the investigation of the effects of yield strength contrast in the mechanical response of the phases under uniaxial compression. Trends in texture development, plastic deformation rates and intragranular misorientation distributions are analyzed. Single phase bridgmanite and single phase periclase simulations were also performed for comparison with their two phase counterparts. It is found that both the bridgmanite and periclase phase develop weak texture in both the single and two phase simulations. Distributions of the plastic deformation rate show that as the yield strength contrast is increased in the two phase simulations, heterogeneities in the distribution of the plastic deformation rate across the bulk of the sample increase drastically. However, a wider distribution of the plastic deformation rate is observed in the single phase bridgmanite simulation, than in the two phase simulation where both phases have the same yield strength. This indicates that deformation heterogeneities in bridgmanite are mainly due to the high anisotropy of its single phase mechanical properties. Misorientation of each element in a grain with respect to the grain average orientation is calculated and statistical trends of the grains of the bridgmanite phase and the periclase phase are analyzed separately and compared. While misorientation distributions for the bridgmanite phase remain very similar across the different simulations, misorientation distributions of the periclase phase become much wider and with a larger mean misorientation as the yield strength contrast is increased. In addition, the distribution of misorientations in the periclase phase when deformed on its own is the narrowest of them all, indicating that deformation heterogeneities in the periclase phase are introduced by deforming in the two phase scenario with a harder phase. Slip system activity calculations show most of the deformation by dislocation slip is carried by the periclase phase in the two phase simulation with large yield strength contrast. A fast Fourier transform formulation implemented in the VPFFT code is used in Chapter 3 to study the effects of microstructure in texture development of a two phase polycrystalline aggregate composed of 75% bridgmanite and 25% periclase, and also single phase simulations for comparison. Using this approach, it is also found that bridgmanite and periclase develop weak texture, even when deformed as single phase aggregates. Furthermore, it is observed that there is little microstructure dependence of the texture and strain rate distributions for a microstructure where periclase is at the cores of bridgmanite grains, one where grains of both phases are randomly distributed across the aggregate and one where periclase grains are at triple junctions of the bridgmanite grains. A microstructure where periclase grains is percolating around bridgmanite grains is found to be the outlier of this study, it develops very strong texture in the bridgmanite phase and presents sharper distributions of the strain rate in this phase than the other tested microstructures, indicating a microstructure dependance of the deformation of bridgmanite in this case. Since grains are discretized into smaller elements, statistical trends in the distribution of strain rates of regions at grain boundaries and regions in interior of grains can be compared. It is found that in two phase simulations, regions at grains boundaries in grains of the periclase phase develop the widest distribution of strain rate values, suggesting that deformation heterogeneities are mainly concentrated in these regions. High pressure diamond anvil cell experiments were performed on the bridgmanite + periclase two phase system to explore texture development at high pressure due to dislocation slip. Diamond anvil cell experiments were performed in synchrotron x-ray sources, where 2D diffraction patterns are collected and samples are laser heated to induce phase transformations at high pressures. The sample grains sizes that were previously possible to analyze using the traditional Rietveld technique were limited to grain sizes that produced smooth powder diffraction patters in order to analyze intensity variations along Debye rings and determine the texture developed in the sample. Recently the high pressure diamond anvil cell community has adopted a more novel multigrain data collection and analysis technique, where diffraction images with sharp diffraction spots originating from multiple grains can be indexed and clusters in orientation space are searched to correlate multiple diffraction spots with the particular grain they originate from. Applying this data collection technique presents challenges in the diamond anvil cell, in particular when non hydrostatic conditions are desired for texture development studies. The small rotation angle accessible to the diamond anvil cell, peak overlap due to plastic deformation in the grains and low intensity of diffraction spots due to weakly diffracting materials are some of the challenges encountered in these experiments. An overview of the implementation of this data collection and analysis technique to the diamond anvil cell for texture studies, together with some preliminary results, is presented in Chapter 4.
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Category : Dissertation abstracts
Languages : en
Pages : 896
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