A finite strain micromechanical-based constitutive model: Application to porous polycrystal

A finite strain micromechanical-based constitutive model is developed for multi-phase polycrystal to characterize the interplay among strain hardening, texture evolution, and stress-strain relation. The phases are regarded as ellipsoidal inhomogeneities within the polycrystalline matrix, which can be considered as an aggregation of different orientated grains. At the grain level, the crystal plasticity model is applied to physically describe the inelastic deformation results from crystallographic slipping. At the polycrystalline level, an algorithmic finite strain self-consistent model is proposed to associate the strain and rotation rate at the grain level with the corresponding terms of the polycrystalline matrix rigorously. At the representative volume element level, the phases with different properties are investigated by extending the Mori-Tanaka model at finite strain. The algorithmic self-consistent model is validated by comparing the calculated normalized stress-strain curves and textures with those obtained by the model adopting extended Taylor hypothesis and the experimental data of stainless steel. Moreover, the grain and polycrystalline level behaviors calculated by the algorithmic self-consistent model are compared to those derived from the full-field model. The effects of void and elastic particles on overall mechanical behavior are analyzed by the extended Mori-Tanaka model, which is then verified by predicting the mechanical behavior of sintered nano-silver stub columns under stress-controlled compression loads.