On the order of plates providing the maximum ballistic limit velocity of a layered armor

The high-velocity impact of a three-dimensional rigid sharp impactor penetrating into a ductile layered armor is studied using a simplified model for an impactor-armor interaction. The goal of the study is to determine the order of the plates in the armor that provides the maximum ballistic limit velocity. It is found that the ratio of the distortion pressure to the density of the plate is the parameter that determines the order of the plates in the multi-layered armor that provides the maximum ballistic limit velocity, namely, the plates must be placed in the order of increasing this parameter, regardless of their thickness. The right order of the plates can be of prime importance if the values of this parameter vary strongly for different plates. Numerical simulation is performed in order to verify the theoretical findings and to obtain a quantitative estimate for the increase in the ballistic limit that results from changing the order of the plates in the armor. (C) 1999 Elsevier Science Ltd. All rights reserved.