Oblique Perforation of Targets by Small Armour-Piercing Projectiles

Abstract

In order to simplify the analysis of results, most investigations of oblique impact have restricted the range of target properties so that only one failure mode is obtained. The present work attempts to show the influence of failure mode on oblique impact by using targets having a wide range of strengths. Experiments are described in which the critical angle to defeat 0.30-calibre APM2 projectiles at two impact velocities and two target thicknesses is obtained for steel targets ranging in hardness from 270 to 735 HV. The data are used to investigate the effect of oblique impact on areal density, and it is found that softer targets (less than about 450 HV) give greater improvement in areal density with angling. The mode of target failure is related to the penetration resistance/hardness relationship. It is found that the angling of targets raises the hardness at which adiabatic shear begins to cause a reduction in penetration resistance in steels with hardness, from about 350 HV to around 430 HV. This effect appears to be associated with the changing geometry of penetration, due to the dynamics of oblique impact suppressing the onset of a concentrated shear.