The Simulation Of Materials Processing With Crystal Plasticity FEM

Generally,in engineering practice, the analysis of mechanical properties of metals or alloys of polycrystalline aggregates is conducted with the assumption that materials are continuous, homogeneous and isotropic from point of view of statistics, which is proven valid and meet the needs of strength design in engineering by macroscopic material tests. However, the assumption in macroscopic statistics will meet its’bottle necking’in explaining the underlining microscopic mechanism in severely plastic deformation, fatigue damage and destruction of materials.It is helpful to introduce the theory of the meso-plasticity,which can help us creat a better understanding of the meso-plastic anisotropy behavior of polycrystalline material has great influence on material processing process and product quality. Therefore, the study has both theoretical and practical applications.In this paper, the underlining microscopic mechanism of polycrystalline material in severely plastic deformation is studied exploratorily. Its main contents are as follows:(1) On the basis of the crystal plasticity constitutive relation and its numerical value principle which has been published in previous papers, the old programs are rewritten into user-defined material subroutines in FORTRAN,the new program is debugged and applied to the finite element analysis on polycrystalline material.(2) Based on geometric principle of Voronoi diagram.Matlab and Python are both used to realize the precise model and simplified model of polycrystalline material containing2d and3d on ABAQUS platform.Two models are contrasted through tensile simulations, the results shows that Voronoi polycrystal model does a fine job of describing the overall appearance and shape of the polycrystalline grains,which can fully satisfy the needs of the present study.(3) To the precise model and simplified model, do tensile simulations, analysis the location accuracy of them, compare the advantages and disadvantages, and discuss the grain number and meshing impact on simulation accuracy.The results shows that precise model has some advantages in describing the stresses, but simplified model has computational advantages. In the aspect of simulation precision, the polycrystal model contains about100grain, each grain is composed of100-200units, can be calculated more accurately in describing the complex deformation of each grain in the polycrystal. (4) The rolling deformation of polycrystalline copper with different initial orientation has been simulated. Results show that, the initial orientation and distribution of polycrystalline models have important influence on rolling deformation process evolution, and the deformation of the grains in the polycrystalline model and the stress and strain fields are not uniform but associated with the orientation, size, and shape of the grain and the interactions of the grains surrounded.Orientation of each grain has a certain degree of concentration after rolling in polycrystal model. Simulation result agrees with the results of tests and shows the material evolution ot the deformation in th the rolling process,which provides some references to the material plastic processing.