Combined application of patchwork and partial softening to enhance the collision resistance of the center pillar

Hot press formed parts in a fully martensitic structure limit its application in the centre pillar, which requires high collision resistance. In this study, the combined effect of the patchwork and partial softening on the collision characteristics of the centre pillar, such as impulse, absorbed energy, and intrusion displacement, were investigated both experimentally and numerically. The partial softening process was used to provide ductility, while the patchwork was attached to improve the stiffness during impact loading. The energy absorption was assessed by integrating unit element deformation during impact. When patchwork and partial softening were applied to the centre pillar simultaneously, the anti-intrusion and absorbed energy were improved remarkably by 20.0% and 20.3%, respectively. The combined application of patchwork and partial softening is a feasible alternative for enhancing the collision resistance of the centre pillar with high degree of reliability.