First-Order Approximations of Dynamic Material Strengths for the Ballistic Perforation of Aluminum Target Plates

Perforation of aluminum alloy target plates by armor-piercing rounds have been shown to follow the cavity expansion scaling law, while fragment-simulating projectiles follow a shear-plugging scaling law. In both models, experimental compressive stress–strain data is needed to derive their respective material strength parameters, which are not always available. By comparison, modified Ludwik plasticity parameters are more widely available in existing literature for the aluminum alloys of interest in armor applications. We show that the maximum compressive strengths may be approximated using a fixed true strain value across 33 aluminum alloys. A simple linear relation is further established between the maximum compressive strength and the cavity expansion strength.