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Metals have a crystalline structure and the plastic flow in these materials occurred in the special crystalline planes and special crystalline directs that occurs in the planes. This mechanism is related to metals plastic deformation in the microscopic level. In this mechanism, non homogenous microstructure and the effect of crystalline direction play a major rule in the material behavior. Crystal plasticity constitutive equations are used for investigation of the crystalline direction effect and material texture. Voronoi method is used for simulating the non homogenous microstructure in plastic deformation. In this study, the elastic modulus parameters obtained by molecular dynamic simulations. Finally, the plastic deformation of Fe metal is simulated with finite element method that good agreement was observed with the experimental data.

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Grains in polycrystalline texture have anisotropic deformation nature. This cause material to show completely different behavior at meso and micro scale than they do at macro scale. To be specific, deformation at these scales is heterogeneous and cannot be modeled using constitutive equation in continuum plasticity. In this paper, in order to investigate deformation behavior of 316L stainless steel at micro scale a crystal plasticity finite element (CPFE) modeling system has been developed. The crystal plasticity equations were implemented in the ABAQUS/Implicit FE code through a user-defined material subroutine, UMAT. Verification was done through comparing the CPFE result against those obtained through implementing crystal plasticity formulation in MATLAB software. Comparison show good agreement between the analytical and CFFE result. Afterward, three dimensional simulation of tensile test on Stainless Steel type 316L is carried out using CPFE method and continuum macro mechanic FE. Deformation characteristic and localization behavior of single grain specimen at tensile test has been captured and predicted using CPFE method; on the other hand, macro mechanic finite element is unable of predicting localization and evolution of lattice at micro and meso scale. At the last part, a set of CPFE analysis are conducted on representative volume elements with 10 Grain and 5 set of different grain orientations. Results show a scattering in plastic part of stress-strain response of material with switching from one set of grain orientation to another set. It has been found that the material behavior at these scales is highly direction dependent.

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Increasing usage of metals in engineering structures has made the metal forming process become superior in the solid mechanic researches. Meanwhile, the physical theories are of high significance due to the individual features. The crystal plasticity theory is one of these theories. This theory predicts the texture evolution and deformation of these materials by modeling the plastic deformation mechanisms of crystal material’s micro-structure (such as metals). Connecting with micro-structure enables this theory to predict the anisotropy of single crystals, and also the prediction of some phenomena in polycrystals which are aggregate of single crystals, is possible. Presenting a suitable work hardening model which contains the anisotropy behaviors of single-crystals is very important. In this paper, at first, the principles of crystal plasticity are explained, and then by evaluating several experimental results and the most commonly used work hardening models, a new work hardening model will be presented. This model adapts better with experimental results, compared to the previous models. The scope of this research is specifically for crystal materials with FCC structure, nevertheless, some part of this research is applicable to the other structures.

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