The Damage Mechanism Route to Better Armor Materials

This paper describes the mechanisms by which brittle materials are penetrated by impacting projectiles, links ballistic performance to fracture behavior, and in turn to microstructure, and suggests a route unexplored previously for achieving better armor materials. Fracture patterns on cross sections through partially penetrated glass and ceramic targets show that deep penetration proceeds by the crushing and subsequent flow of fragments away from the projectile path. Preliminary finite element simulations indicate the likely positive effect of increasing frictional flow resistance of fragments. Tests are envisioned for measuring crush and fragment flow behavior, showing the effects of microstructural variables, guiding mathematical models, and hence leading to a capability to design computationally improved armor materials and structures.