THE PENETRATION OF STEEL TARGETS FINITE IN RADIAL EXTENT

An experimental, analytical, and computational effort was undertaken t o examine the effect of confinement on penetration in armor-like steel targets. For the experiments, L/D 10, tungsten-alloy projectiles were fired at 1.5 km/s into 4340 steel cylindrical rounds of various diame ters. Penetration efficiencies, as measured by the depth of penetratio n normalized by the original projectile length (P/L), were determined and the results plotted as a function of normalized target diameter D- t/D, where D-t is the target diameter and D is the projectile diameter . As D-t/D changed from 20 to 5, P/L increased by 28%, although P/L wa s approximately independent of D-t/D for D-t/D greater than or similar to 15. An analytical model using a modified cavity expansion theory w as developed to estimate the resistance to penetration for targets of finite lateral extent. The analytical model shows decreasing target re sistance as D-t/D decreases below approximately 30; in particular, tar get resistance decreases rapidly for D-t/D < 20. Numerical simulations were performed and the computational predictions are in excellent agr eement with the experimental results; simulations were used to extend D-t/D between 3 and 78. Plastic strain contours are plotted to assess the extent of plastic how within the target; the results of the simula tions demonstrate that P/L. begins to increase when the extent of plas tic flow in the target reaches the radial boundary. Copyright (C) 1996 Elsevier Science Ltd.