Load spreading and penetration resistance of layered structures—a numerical study

The objectives of this study were to gain insight into the penetration resistance of layered structures, and to examine the effects of layer damage and imperfect interfaces on load spreading and projectile defeat capabilities of the layers. To investigate the overall penetration process instead of just the terminal state, we examined the time history of the energy transfer between the projectile and the target, and between the layer and the substrate. Under idealized conditions, without layer damage or an imperfect interface, a target with a single thick high-strength, high-wave-speed layer offers the best penetration resistance. The high impedance and strength of the layer enhance the projectile defeat capability of the target; more impact energy is dissipated in the projectile and less energy is delivered to the target. The high wave speed of the layer allows the impact load and energy imparted to the target to be absorbed more quickly and distributed widely in the substrate. Both layer damage and an imperfect interface degrade the targetʹs capability to defeat the projectile and to spread the load. However, the former has a more detrimental effect than the latter.