Development of a microscopic damage model for low stress triaxiality

This work dealsa contribution to ductile damageof High-Strength Low-Alloy (HSLA) steel 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. A new modelisunderdevelopmentto takeintoaccounttheeffects oflowtriaxiality stresses (or loading) during shearing.