Ballistic limit predictions for perforation of multi-layered aluminium armour targets by rigid, nose-pointed projectiles

Abstract

We have developed a heuristic, closed-form model for estimating the ballistic performance of layered, in-contact aluminium targets that are penetrated by a rigid projectile through ductile hole growth. The model uses an estimated material resistance for each layer, based on the specific cavitation energy concept. Weighting of the material resistance by the corresponding layer thickness leads to the effective (or average) target resistance of the in-contact layers, which we termed as the target stack resistance. For in-contact layers, we propose that the resistance of each layer is influenced by its relative position in the stack. The in-contact plates that are subsequent to the layer that is being penetrated (the backing layers), provide additional support (a reinforcement effect) and by that increase the resistance to ductile hole growth in the penetrated layer. A campaign of ballistic experiments and numerical simulations is performed to compare the performance of monolithic and in-contact layered 6061-T651 aluminium targets against 7.62 mm APM2 projectiles. The developed model is compared with the experimental and numerical results and is found to provide good agreement. An unexpected prediction of the model is verified by numerical simulations.