Finite Element Analysis Of Microstructural Mechanical Properties Of Polycrystalline Materials

The macroscopic mechanical properties of polycrystalline materials are largely determined by the microstructure of grains.In the microstructure,the individual grains are independent of each other and show anisotropic mechanical properties.The mechanical properties of the polycrystalline structure exhibit inhomogeneous changes when load is applied,but the mechanical behavior of the material is isotropic at the macroscopic scale.Due to the limitations of experimental test methods,this paper constructs a microstructure model of polycrystalline materials based on Voronoi diagram theory and investigates the relationship between the polycrystalline microstructure and its macroscopic mechanical properties using numerical homogenization methods.The main work of this paper is as follows:(1)A method for modeling the microstructure of polycrystals based on Voronoi diagram theory is proposed.By introducing Laguerre geometric weight coefficients in Voronoi diagram theory and based on UG/OPEN API secondary development technology,a method is proposed to generate geometric models directly in CAD software using spatial cutting technology.The method does not require reverse reconstruction by topological information of points,lines,surfaces and bodies,and it is easy to establish 3D grain boundary geometry models,and the established models can be directly imported to finite element simulation and analysis software such as ABAQUS,ANSYS,Hyper Works,etc.without additional model compatibility processing.(2)Prediction of macroscopic mechanical properties of polycrystalline materials based on finite element homogenization theory.In this paper,the macroscopic elastic modulus of alumina ceramic materials is predicted based on representative volume elements of material microstructure and finite element homogenization theory,and the RVE model with different grain sizes,grain orientations and boundary conditions is solved by finite elements.The accuracy of the prediction results of the numerical homogenization method is verified by comparing with the consistent description of the elastic modulus of alumina ceramic materials in a large literature.(3)Prediction of macroscopic mechanical properties of polycrystalline materials based on a non-ideal microstructure model.The existing literature lacks the description of three-dimensional solid grain boundaries and initial defects in predicting the macroscopic mechanical properties of polycrystalline materials.In this paper,threedimensional solid grain boundaries and initial damages are introduced in the microstructure model of polycrystalline materials.Through the study of non-ideal grain boundaries with different structures,it is found that the grain boundary model with fixed thickness is consistent with the mechanical properties of the actual material;through the study of different interfacial defect rates,different bulk defect rates,bulk defect sizes,and bulk defect shapes,it is concluded that the interfacial defect rates and bulk defect rates have significant effects on the macroscopic mechanical properties of polycrystalline materials.49 figures,3 tables,88 references.