Experimental Characterizations of the Fracture Data of a Third Generation Advanced High Strength Steel

The simulation of a crash event in the design stage of a vehicle facilitates the optimization of crashworthiness and significantly reduces the design cost and time. The development of a fracture material card used in crash simulation is heavily dependent on laboratory testing data. In this paper, the experimental characterization process to generate fracture data for fracture model calibration is discussed. A third-generation advanced high strength steel (AHSS), namely the XG3^TM steel, is selected as the example material. For fracture model calibration, fracture locus and load-displacement data are obtained using mechanical testing coupled with digital image correlation (DIC) technique. Test coupons with designed geometries are deformed under different deformation modes including shear, uniaxial tension, plane strain and biaxial stretch conditions. Mini-shear, sub-sized tensile, and Marciniak cup tests are employed to achieve these strain conditions. The gage length sensitivity is analyzed under uniaxial tension and equi-biaxial stretch conditions as references for the mesh regularization in the generalized incremental stress state dependent damage model (GISSMO). The experimental practices discussed in this study are used to generate a complete fracture data package of sheet metals, which is successfully applied in the GISSMO model calibration of the XG3^TM steel.