Effect of air gap and order of plates on ballistic resistance of two layered armor

The high velocity normal impact of a three-dimensional rigid conical impact or penetrating into a two-layered ductile armor with an air gap is studied using a simplified model for an impactor-armor interaction. The goal of the study is to investigate analytically the dependence of the ballistic resis tance of the armor on the order of the plates in the armor and on the width of an air gap between the plates. It is found that the ratio between the v alues of a single parameter depending on the material properties of the pla tes determines this dependence in both cases. This parameter characterizes the properties of the material of the plate; for the most widely used model s of impactor-armor interaction, it is the ratio of the distortion pressure to the density of the plate. (C) 1999 Elsevier Science B.V. All rights res erved.