CRYSTAL PLASTICITY NUMERICAL ANALYSIS ON YIELD AND SUBSEQUENT YIELD OF POLYCRYSTALLINE COPPER UNDER COMBINED TENSION-TORSION LOADING

Combined tension-torsion test under pre-tension and pre-torsion deformation, the yield characteristics of polycrystalline copper in grain scale was investigated by crystal plasticity theory associated with polycrystalline aggregate model. Through a sub-model method, the cross-scale analyses of mechanical behavior of polycrystalline copper by the calculations using a representative volume element (RVE) and a. specimen under tension and torsion were carried out. Based on the research on the shape and the evolution of a. subsequent yield surface, the effects of different loading paths and yield definitions on the subsequent yield surface were explored. The heterogeneous statistical analysis of the polycrystalline copper under different loading paths was also performed. And further more, the effects of loading history on the subsequent yield surface, and on the micro heterogeneous distribution were estimated. The numerical results show that the shape of the subsequent yield surface and the appearance of yield surface corner are related to the pre-loading direction and the different yield definitions, the heterogeneous deformation in polycrystal under different loading paths is very various. The results by the analysis based on crystal plasticity calculation combined with the sub-model method are compared with experimental results and they are in reasonable agreement.