Investigation on the Evolution of Subsequent Yield Surface of Pure Aluminum Under Changing Loading Paths Considering Microstructure Effects

The anisotropy behavior is one of the most important key issues in the simulation of sheet metal forming, which can highly affect the prediction accuracy of metal forming behavior, especially under complex loading paths. In this study, the initial and subsequent yield surfaces of the pure aluminum material are numerically investigated through the representative volume element (RVE) methodology. The crystal plasticity theory is chosen to represent the microscopic elastoplastic behavior of pure aluminum, and its polycrystalline geometrical model is built by the Voronoi algorithm. Together with user material subroutine, the initial and subsequent yield surfaces evolution of pure aluminum under different loading paths is simulated in commercial software ABAQUS/Implicit. Through the investigation, the great influence of the microtexture on the obtained inhomogeneous stress distribution of RVE model can be presented. Meanwhile, the effect of the loading directions and the predeformation is also investigated and discussed. The shape of the subsequent yield surface is also strongly dependent on both the yield definition and direction of preloading, and the high anisotropy phenomena appear corresponding to different yield definitions. At the same time, the pole figures at different forming stages are given, and the evolution of polycrystalline texture is analyzed and predicted. It can be concluded that some strong relationship between the texture evolution, the inhomogeneous stress field, and the subsequent yield surface evolution is proved and discussed. This study provides a good methodology to study the yield surface evolution of aluminum together with the crystal plasticity theory, with considering the evolution of the microtexture evolution during the plastic deformation of the metal.