Fracture Prediction for an Advanced High-Strength Steel Sheet Using the Fully Coupled Elastoplastic Damage Model with Stress-State Dependence

In this study, the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage model. The effects of stress triaxiality and Lode angle are introduced into the damage evolution law to capture the loading-path-dependent failure. The proposed constitutive model is implemented into the finite element (FE) code ABAQUS/Explicit via the user-defined subroutine (VUMAT). Next, the identification procedure for DP780 based on the hybrid experimental-numerical method is presented in detail. The numerical results of simple tests are compared with the experiments, and obvious improvement is observed for the proposed model under various loading paths. Finally, the model is applied to predict the edge fracture during sheet blanking process. The predicted global load-displacement responses and crack paths have a good agreement with the experimental results, indicating that the model holds great potentials in simulation of metal forming processes.