A micromechanical model for inelastic ductile damage prediction in polycrystalline metals for metal forming

This paper deals with micromechanical modeling of ductile damage and its effects (coupling) on the plastic behavior of FCC polycrystalline metallic materials. The ‘fully coupled’ constitutive equations are written in the framework of rate-dependent polycrystalline plasticity where a ‘ductile’ damage variable has been introduced at a crystallographic slip system (CSS) scale in order to describe the material degradation by initiation, growth and coalescence of microdefects inside the aggregate. Both, theoretical and numerical (FEA) aspects of the proposed micromechanical coupled model are presented. The ability of the obtained model to predict the plastic strain localization, due to the ductile damage effect, in the classical tensile test is carefully analyzed. Application is also made to the fracture prediction in deep drawing of a cylindrical cup using a thin sheet. Finally, some concluding remarks and perspectives are pointed out.