Extension of GISSMO Damage Model based on Lode Angle Dependence

This paper presents the extension and validation of the damage model GISSMO (Generalized Incremental Stress State dependant damage MOdel). The damage model is extended for 3D usage by utilization of Lode angle parameter. The fracture strain is defined in the stress triaxiality and Lode angle parameter space as a surface. The fracture strain definition is introduced as a table definition. The stress triaxiality and Lode angle parameter space is covered with proper specimens and load conditions. The validation is done for dual phase steel DP600. Round specimens, flat-grooved plane strain specimens with different notches and Nakazima biaxial specimens are used to get information for the Lode angle parameter values 1, 0 and -1, respectively. Additionally butterfly and flat tension specimens are used in order to cover intermediate stress states. The focus of the paper is the introduction of a calibration approach using numerical simulation and comparison with experimental results of specimens. The simulations were performed using LS-DYNA and an extended version of the GISSMO model.