Identification of forming limits at fracture of DP600 sheet metal under linear and unloaded non-linear strain paths

The in-plane biaxial tensile test with a new cruciform specimen is used to investigate the forming limit strains at fracture of DP600 sheet metal. The experimental forming limits are determined under linear and non-linear strain paths without unloading provided by four independent dynamic actuators. The Oyane ductile fracture criterion is used to predict the experimental results under different strain paths.