Some Results of Theoretical Study of Plastic Deformation and Texture Formation in Polycrystals PDF Download
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Author: Krzysztof Wierzbanowski
Publisher:
ISBN:
Category : Dislocations in crystals
Languages : en
Pages : 166
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Book Description
Author: Krzysztof Wierzbanowski
Publisher:
ISBN:
Category : Dislocations in crystals
Languages : en
Pages : 166
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Book Description
Author: Franz Roters
Publisher: John Wiley & Sons
ISBN: 3527642099
Category : Technology & Engineering
Languages : en
Pages : 188
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Book Description
Written by the leading experts in computational materials science, this handy reference concisely reviews the most important aspects of plasticity modeling: constitutive laws, phase transformations, texture methods, continuum approaches and damage mechanisms. As a result, it provides the knowledge needed to avoid failures in critical systems udner mechanical load. With its various application examples to micro- and macrostructure mechanics, this is an invaluable resource for mechanical engineers as well as for researchers wanting to improve on this method and extend its outreach.
Author: U. F. Kocks
Publisher:
ISBN: 9780521465168
Category : Science
Languages : en
Pages : 676
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Book Description
A successful book covering an important area of materials science, now available in paperback.
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.
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.
Author: Hans Rudolf Wenk
Publisher: Elsevier
ISBN: 1483289346
Category : Science
Languages : en
Pages : 631
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Book Description
This volume provides an introduction to the texture analysis of deformed materials and explores methods of determining and interpreting the preferred orientation of crystals in deformed polycrystalline aggregates.**The book reviews: 1) the techniques, procedures, and theoretical basis for the accumulation and analysis of orientation data; 2)the processes by which polycrystals deform and the microstructural mechanisms responsible for the development of the preferred orientation; 3) the textures in specific systems and application of principles to the solution of specific problems.**With a combination of metallurgic and geologic applications, Preferred Orientation in Deformed Metals and Rocks: An Introduction to Modern Texture Analysis will be an important source book for students and researchers in materials science, solid state physics, structural geology, and geophysics.**FROM THE PREFACE: Determination and interpretation of the preferred orientation of crystals in deformed polycrystalline aggregates (in this volume also referred to as texture) has been of longstanding concern to both materials scientists and geologists. A similar theoretical background--such as the dislocation theory of crystal plasticity--has been the basis of understanding flow in metals and rocks; and similar determinative techniques--including microscopy and x-ray diffraction--have been used to study textures and microstructures. Whereas many of the fundamental principles have been established early this century by scientists such as Jeffery, Sachs, Sander, Schmid, Schmidt, and Taylor, only in recent years has knowledge reached a level that provides a quantitative framework which has replaced a largely phenomenological approach. This is expressed in the sudden new emphasis on textural studies, as documented by the large number of recent publications.**This volume contains material to serve as an introduction for those who wish to enter this field as well as reviews for those who are already engaged in advanced research....**The book is divided into three parts. The first (Chapters 2*b17) deals with techniques, procedures, and theoretical bases for the accumulation and analysis of orientation data. The second (Chapters 8*b112) introduces processes by which polycrystals deform and the microstructural mechanisms responsible for the development of the preferred orientation. All those chapters emphasize basic principles and apply to metals as well as to minerals. The third part (Chapters 13*b126) illustrates textures in specific systems and the application of the principles set out in the earlier chapters to the solution of specific problems. Readers of these chapters will quickly become aware that metals have been more exhaustively studied than minerals; but they will also realize that, because of their structural symmetry, metals are in general much simpler than rocks and that the intepretation of metal textures is less involved. An extensive list of relevant references provides access to much of the original literature on textures....
Author: J. Gittus
Publisher: Springer Science & Business Media
ISBN: 9400941811
Category : Technology & Engineering
Languages : en
Pages : 424
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Book Description
The scientific work of Jean Mandel has been exceptionally rich in the area of the mechanics of solids; the subjects which he has treated have been extremely diverse, from the theory of plasticity, buckling, soil mechanics, visco-elasticity, the theory of reduced models, and thermo dynamics, to percolation in porous media. But throughout this com prehensive work Jean Mandel has always maintained his interest in forming connections between the properties of materials (strength, deformability, viscosity) and the properties of their basic constituents. What is sometimes referred to in materials science as the transition from the microscopic to the macroscopic has for him been a very constant direction of research, which he never ceased to encourage in the Laboratoire de Mecanique des Solides of which he was the director. It is known that in the plasticity of metals permanent deformations must be sought in intercrystalline slip and more generally in disloca tions and the various microstructural defects. Before deformation of polycrystals is tackled, it is necessary to understand the mechanisms which take place within the crystal: the different systems of slip which may be activated and also the elementary mechanisms of twinning. Jean Mandel has shown how to make the transition from the behaviour of the single crystal to that of the polycrystal and has given the relation ships between the overall permanent deformation of the polycrystal and the plastic deformation of the single crystal.
Author: Bernard Budianski
Publisher:
ISBN:
Category : Crystals
Languages : en
Pages : 134
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Book Description
Plastic strain is considered a consequence of slipping on some of the 12 slip systems of facecentered-cubic single crystals. The polycrystal is assumed to be macroscopically homogeneous and initially isotropic -- that is, the crystal orientations, sizes, shapes and locations are random and uncorrelated. The rotations of the grains during deformation are neglected, and the average plastic strain in grains of a given orientation is calculated on the basis of the assumption that the grains under consideration are spherical and elastically isotropic. (Author).
Author: Gang Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 332
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Book Description
Author: Wojciech Truszkowski
Publisher: Springer Science & Business Media
ISBN: 9401596921
Category : Science
Languages : en
Pages : 156
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Book Description
The reader shall find in the offered monograph a systematic presentation of scientific effects in the field of anisotropy studies reached by the author and his collaborators in the period of recent four decades: published and discussed in a number of papers and conference contributions. The central construction line of discussion is to be sought in the full and comprehensive analysis of ret:) function defining the anisotropy coefficient varying during the tensile test. No doubt, this function can be considered as a nutshell carrier ofcomprehensive information about the essential features influencing the directionality of the studied material's plasticity. The function also provides the basis to elaborate methods used in the determination of such characteristics. In the historical presentation of literature in the field of plastic anisotropy, the original input was offered by W.M. Baldwin Jr., already in 1946, who observed the differentiated strain rates in three mutually perpendicular directions of the sample subjected to static tensile test. In the following years, further and expanded analysis of the problem was undertaken by Lankford, Hill, Gensamer, Jackson, Low and Smith.
