AN ANISOTROPIC EXTENSION FOR A THERMOVISCOPLASTIC GTN DUCTILE DAMAGE MODEL

Abstract

In this work, a thermoviscoplastic GTN ductile damage model is extended to account for anisotropic plastic behavior. The novel feature of the proposed model is the enrichment of a GTN model, with the Hill's yield criterion accounting for hardening, softening, strain-rate effect, plastic work heating, thermal diffusion, and void shearing mechanism. The anisotropy is introduced by changing the equivalent stress definition, which provides greater flexibility to the model. The resultant modifications in the yield criterion and in the damage evolution equations are described. Two numerical problems involving plates subjected to tension loading that leads to ductile damage and eventual fracture are presented and discussed in order to validate the present approach. A mixed finite element formulation is adopted together with the fully damaged zone technique to represent the ductile fracture. Results obtained through computational simulations highlight the effect of the anisotropic parameters on mechanical behavior in terms of the global stress-strain curve and the local evolution of plastic strains, porosity and temperature. We conclude that the proposed anisotropic model is simple to implement yet provides more flexibility in capturing complex ductile fracture processes.