Yaw-induced transitions in ballistic limit and fracture mechanisms in steel plate perforation

This study investigates how the yaw angle influences the ballistic limit velocity and the associated fracture mechanisms in steel plates. Three-dimensional simulations were carried out for blunt cylindrical projectiles with diameter of 7.62 mm, length of 22.86 mm, and mass of 8.16 grams, impacting 4340 steel plates with 10 mm thickness. The results show a non-monotonic dependence of the ballistic limit on yaw: the resistance increases with angle, reaches a pronounced maximum between 60° and 75°, where the ballistic limit nearly doubles compared with normal impact, and decreases for larger angles. The analysis also reveals a transition in fracture mechanism occurring between 45° and 60°, marking the shift from ductile hole enlargement to shear-dominated plugging. These findings demonstrate that yaw is a governing parameter in the dynamic fracture of ductile plates, linking global ballistic resistance to local stress states and advancing the physical understanding of protective structures subjected to oblique and yawed impacts.