An elastoviscoplastic model for porous single crystals at finite strains and its assessment based on unit cell simulations

An elastoviscoplastic model is formulated at finite strains for porous single crystals. The model extends the yield function developed by Han et al. (2013) for porous single crystals at infinitesimal strains to finite strains, incorporating the evolution of void volume fraction and strain hardening of single crystal matrix. The model is assessed through three-dimensional unit cell finite element simulations based on periodic homogenisation and loading paths with prescribed constant stress triaxiality. The unit cell simulations are performed for face-centered cubic crystals with various crystallographic orientations, stress triaxialities and initial void volume fractions, showing the competitive influence of the stress triaxiality and the crystallographic orientation on the effective behaviour and the void volume evolution. The proposed model captures the hierarchy of porous single crystal responses with respect to crystal orientation and void volume fraction. It represents a remarkable compromise between description of unit cell behaviour and tractability in the computation of structural components.