For the third generation ultra-high strength steel DP980, six kinds of characteristic tensile specimens were designed to obtain different stress states and ultimate strains under different strain paths, and the failure model GISSMO was developed. Then, the simulation calibration of specimen level was completed, and the grid size correction coefficient was obtained based on the benchmarking of unidirectional tensile specimens. Furthermore, the bending damage of cap-shaped beam was calculated by theoretical derivation, and the bending radius was determined. In addition, the quasi static three-point bending experiment and dynamic axial collapse experiment of cap-shaped beam were designed, based on the developed failure model GISSMO, the bending simulation of cap-shaped beam was completed by DYNA to obtain the initial damage value after bending. Finally, the simulation benchmarking was completed by introducing the initial damage. The results show that the simulation results of failure model GISSMO are more consistent with the experimental results after considering initial damage, which indicates that the forming initial damage must be considered when the larger machining initial damage occurs.