Numerical Modeling of Stress-State Dependent Damage Evolution and Ductile Fracture of Austenitic Stainless Steel

In this study, a stress-state-dependent elastoplastic-damage coupled constitutive model was developed and implemented into a commercial FEA program to predict the plastic behavior and fracture of 304L stainless steel. Damage evolution was experimentally quantified using unloading–reloading tensile tests, and Bonora’s damage model was applied to describe this evolution. The uncoupled damage model accurately captured the force–displacement response of smooth tensile specimens but exhibited up to an 8 % discrepancy in predicting the maximum load for notched specimens. In contrast, the coupled damage model, which accounted for stress triaxiality-dependent damage evolution, reduced this discrepancy to just 1.8 %. This study demonstrates that 304L stainless steel sheets exhibit a true stress–strain relationship that depends on stress triaxiality, and disregarding this factor can lead to notable differences in fracture predictions.