Physics of behind armor debris threat reduction

Abstract Liners behind steel targets are frequently applied to increase the survivability of occupants of an armored vehicle. The purpose of a liner is to decrease the effects of behind armor debris (BAD). The performance of a liner can be expressed by its ability to decrease the number of effective fragments and to reduce the emission angle of the BAD cloud. The goal of the presented study was to investigate the behavior of different liners perforated by a 70 mm caliber-shaped charge. In the experimental part of the study 25 liner configurations were tested. Not only the liner material was varied, but also the structure of the liner: mono layer or multiple layer systems, respectively. It is found that the BAD cloud can be substantially reduced by suitable liner configurations, when sufficient extra weight per area is allowable. This finding is specific for the studied shaped charge threat. In a series of numerical simulations we achieved additional insight into the mechanisms determining the performance of a liner. The principle mechanisms are termed retardation, retraction, substitution, contraction and dissipation. While not all of these effects are relevant for the shaped charge threat, and some depend trivially on the weight per area, there are also effects that can be controlled by the strength and compressibility of the liner material.