Investigation of ductile damage during surface mechanical attrition treatment for TWIP steels using a dislocation density based viscoplasticity and damage models

It is now well-known that the over-treatment during surface mechanical treatments such as shot peening can generate damage in the near surface region. In the present article, the damage evolution during impact loading is numerically investigated. For this purpose, a dislocation density based viscoplastic constitutive model coupled with damage is proposed. The mechanical behavior of twinning induced plasticity (TWIP) steels is described by a dislocation density based viscoplastic model, also including the kinetic of twinning. It allows investigating the strain hardening behavior of TWIP steels. To predict the damage evolution in these ductile steels, the Gurson-Tvergaard-Needleman (GTN) yield criterion is combined with the dislocation density based model. A user-defined subroutine is developed to implement this model in ABAQUS. 3D numerical simulations of single impact are then performed to investigate the impacting process, as well as the damage evolution due to high strain rate impact.