Self consistent intragranular ductile damage modelling in large plasticity for FCC polycrystalline materials

Abstract

This work deals with micromechanical modelling of ductile damage and its effects on the inelastic behaviour of FCC polycrystalline metallic materials such as the evolution of their crystallographic textures. The constitutive equations are written in the framework of rate-dependent polycrystalline plasticity. A strong coupling between plasticity and damage is ensured through a ductile damage variable, which has been introduced at the Crystallographic Slip System (CSS) scale of each FCC grain to describe the material degradation through initiation, growth and coalescence of microdefects inside the aggregate neglecting thermally activated intergranular (or creep) damage. Both the theoretical and numerical (FEA) aspects of the micromechanical coupled model are presented. The model is implemented into a general purpose finite element code in order to analyse the effects of both texture evolution and ductile damage initiation inside the favourably oriented CSSs. The identification of the material parameters is based on experimental results obtained on copper specimens. The ability of the proposed model to predict the plastic strain localization, the induced textural evolution, as well as the effect of the ductile damage occurrence and its evolution until the final macroscopic fracture are investigated.