Integrating Numerical and experimental analyses for the realization of pre-detection of delayed fractures on punched surfaces of ultra-high-strength steel sheets

A key challenge encountered in finite element (FE) punching simulations is accurately capturing the arrest or delay in crack propagation during punch penetration. Conventional methods relying on element deletion demonstrate inadequacies in representing crack arrest, particularly complicating the simulation of the punched surface states in scenarios with minute clearances. This study introduces a novel approach for fracture representation in FE punching simulations, wherein cracks were integrated as perimeter lines during the remeshing process. Utilizing observation-driven crack propagation paths and arrest behaviors, we analyzed the residual stress on punched surfaces under minimal clearance conditions. Results indicate that for 22MnB5 hot-stamped steel, the residual stresses within the interior side of the burnished region can exceed 1 GPa in cases with a 10-μm clearance.