Validation of GISSMO Model for Fracture Prediction of a Third-Generation Advanced High-Strength Steel 2018-01-0107

Advanced high-strength steels (AHSS), due to their significantly higher strength than the conventional high-strength steels, are increasingly used in the automotive industry to meet future safety and fuel economy requirements. Unlike conventional steels, the properties of AHSS can vary significantly due to the different steelmaking processes and their fracture behaviors should be characterized. In crash analysis, a fracture model is often integrated in the simulations to predict fracture during crash events. In this article, crash simulations including a fracture criterion are conducted for a third-generation AHSS, that is, 980GEN3. A generalized incremental stress state dependent damage model (GISSMO) in LS-DYNA is employed to evaluate the fracture predictability in the crash simulations. The fracture strains of the 980GEN3 steel are experimentally characterized under various deformation modes encompassing shear, uniaxial tension, bending, plane strain, and balanced biaxial stretch conditions. The GISSMO parameters are determined and calibrated using fracture tests at these deformation modes for the 980GEN3 steel. Validation simulations are performed on three-point bending component crash tests and good correlations are achieved. The validated GISSMO card for the 980GEN3 steel can be used in crash simulations of automotive structures.