On the influence of fracture criterion in projectile impact of steel plates

Perforation tests presented in a previous study on 12-mm-thick circular high-strength steel plates are numerically evaluated using the non-linear finite element code LS-DYNA. In the present study, the influence of fracture criterion in numerical simulations of the perforation process has been studied for three different steel alloys. The five-parameter Johnson–Cook fracture criterion, which is calibrated based on several relatively simple tensile tests, is found to give both qualitatively and quantitatively good results for this kind of impact problem. However, this study will also show that a one-parameter fracture criterion where only one simple material test is required for calibration, is found to give similar results as the Johnson–Cook criterion. The study indicates that the ballistic limit can be quantitatively well predicted independent of the chosen fracture criterion, but qualitatively some differences are seen during the perforation process.