Modelling of ductile fracture in stainless steel combining porous plasticity and phase-field models

For a correct representation of ductile fracture, it is crucial to consider triaxiality effects and micromechanical processes in the material. Based on Aldakheel et al. (2018), we propose a phase-field model for ductile fracture in conjunction with porous plasticity according to the Gurson-Tvergaard-Needleman model, where the driving force is modified to include a threshold value composed of the critical and failure porosity. The phase-field is considered as a regularisation of void coalescence and replaces the local effective porosity in the porous plasticity model. The coupled model is applied to 13Cr steel, a realistic material for applications subject to large deformations and ductile fracture. New experimental data for the high-strength stainless steel is obtained from various experimental tests covering different stress states and is used to validate explicit dynamic simulations. The implementation offers the possibility of viscous regularisation and adaptation to experimental results, with this work including a study of the viscosity parameter to ensure a good approximation to the quasi-static fracture evolution.