Influence of fragmentation on the capacity of aluminum alloy plates subjected to ballistic impact

Abstract

In this paper, the perforation resistance of 20 mm thick aluminum plates subjected to moderate velocity impacts is examined experimentally and numerically. Plates made of four different tempers of aluminum alloy AA6070 were struck by ogive-nosed and blunt-nosed cylindrical projectiles with a diameter of 20 mm. We show that for this alloy material strength is not the decisive factor for the plates' resistance against perforation, but that a combination of ductility and strength, which inhibits fragmentation of the target plate, might be more important. Interpreting the results with previously obtained experimental data in mind sheds new light upon the role fragmentation plays for the capacity of metal plates undergoing impact loading. Increasing the material strength increases the probability of fragment ejection, which is unfavorable for the capacity. A novel 3D node-splitting technique which is available in the finite element code IMPETUS Afea Solver was employed to describe possible fragmentation and debris ejection in the numerical simulations. By using the node-splitting approach instead of element erosion, an improvement in the qualitative description of fracture for the least ductile tempers can be obtained without compromising the predicted component behavior for the more ductile tempers.