A rate-dependent homogenization based continuum plasticity-damage (HCPD) model for dendritic cast aluminum alloys

Abstract

This paper develops a rate-dependent homogenization based continuum plasticity damage model (HCPD) model for computationally efficient analysis of ductile failure in porous ductile materials containing brittle inclusions. The HCPD model developed has the overall structure of the anisotropic Gurson–Tvergaard–Needleman (GTN) model for porous ductile materials. The material is assumed to remain orthotropic in an evolving principal material coordinate system throughout the deformation history. The rate-dependency of plastic deformation is captured through an over-stress viscoplastic model. The anisotropic viscoplasticity parameters in the HCPD model depend on morphological features of the microstructure as well as on the plastic deformation. They are calibrated from homogenization of evolving micro-variables in a representative volume element (RVE) of the microstructure. Micromechanical analyses of the RVE are performed using the rate-dependent locally enhanced Voronoi cell finite element model (LE-VCFEM) [8,26]. This work also introduces a novel rate-dependent void nucleation criterion due to inclusion and matrix cracking in the underlying microstrucure. Predictions of the rate-dependent HCPD model for a cast aluminum alloy are compared with the homogenized response obtained with LE-VCFEM micromechanical analyses of the actual microstructure with excellent agreement.