Finite Element Analysis Of Face-Centered Cubic Crystals Based On Crystal Plasticity Theory

With the rapid development of modern industry and the increasingly stringent demand for industrial materials,the research on the mechanical properties of metal materials has been gradually deepened.At this stage,the research has gone deep into the micro-structure.In the past 30 years,with the continuous development of finite element technology,plastic mesomechanics and finite element method have been combined to realize the simulation of crystal deformation with finite element software.In addition,electron backscatter diffraction(EBSD)has become a very important testing tool in the study of crystal micro-mechanics,and has made outstanding contributions to the study of the mechanical properties of the metallic materials crystal structure.In this paper,the crystal plasticity theory is embedded in the finite element software Abaqus,and the effects of crystal orientation on single and polycrystals are studied with the electron backscatter diffraction technique.Firstly,a finite element model based on the face-centered cubic crystal plasticity theory is established by the user subroutine in Abaqus.The experimental parameters of the copper single crystal are applied to the finite element model,then the stress-strain curves of the single crystal after tensile simulating are compared with the experimental results.The results are are almost the same,indicating that the eccentric model of the face-centered cubic crystal is in accordance with the actual engineering.If the crystal orientation in the experimental parameters changes,distribution of stress and strain in the single crystal also changes,which proves the anisotropy of the single crystal.Therefore,crystal orientation has benn as a variable,the Schmidt factor corresponding to the crystal orientation can be calculated.At last,the Schmidt factor and the crystal yield stress are negatively correlated,which has been consistent with the specific law of Schmidt and indicates that the crystal orientation will affect the mechanical properties of the single crystal..Based on the finite element model of single crystal,the voronoi function in Matlab has been used to establish a voronoi diagram,which is similar to the polycrystal microstructure and is introduced into Abaqus through script.After simulating the axial stretching process,it is found that the cumulative strains in different regions of the polycrystal are different due to the grain boundaries,which is causing the microscopic stress distribution is not uniform,and a large stress difference occurs on both sides of the grain boundary,so the damage is most likely to occur at the grain boundary.When the crystal orientation in the polycrystal has been changed,the strain accumulation region also changes.As a conclusion,the grain orientation affects the vulnerable parts of the metal material and the fatigue damage process of the metal material.At the same time,the polycrystalline micro-texture can be observed and analyzed by EBSD technology.The round bars of the sample taken by scanning the sample are prepared by extrusion,so the grains are strip-shaped according to qualitative analysis.Therefore,it can be inferred that the difference of processing technology will affect the crystal structure of the metal material.