Development of a microscopic damage model for low stress triaxiality

Abstract

This work deals a contribution to ductile damage of High-Strength Low-Alloy (HSLA) steel steels under low stress triaxiality. This work is based on micrographics observations and in situ shear tests to examine the evolution of microstructure in this kind of loading and to identify the damage process associated. Numerical simulations by finites elements has been performed to simulate the material behavior of nucleation mechanism and the interaction between cavities during the coalescence phase, as well as the effect of the relative position of the inclusions in the shear plane. The model used as a reference in this work is the Gurson-Tvergaard- Needleman (GTN) model. It has been recently improved in order to take into account the effects of low triaxiality during shearing. The implementation of this model in a finite element code is in progress.