APPARENT TARGET STRENGTH IN LONG-ROD PENETRATION

We investigate the apparent enhancement of target strength in the stea dy-slate Tale model of long-rod penetration. Computing the effective a rea over which the target behaves as a fluid provides a satisfactory e xplanation of the measured effective one-dimensional target strength. Expressing the effective target strength as R-t = aY(1), we postulate that a = A(e)/A(p), where Y-t is the nominal strength; A(e) is the eff ective target fluid cross-sectional area and A(p) the true projectile cross-sectional area. For the case of a rod and projectile of the same material, we use the Tate model together with the Birkhoff jet model to show a approximate to 4 is likely. Simultaneously satisfying Newton 's Second Law and the Tate model yields a = 4 for purely fluid behavio r, i.e. at high penetrator velocities. By explicitly including strengt h terms in both Bernoulli's Law and Newton's Second Law, we derive a m ore general strength multiplier. This multiplier is a Function of the penetrator velocity as well as the density and strength of both the pe netrator and target. At the velocity threshold for steady-slate erodin g-rod penetration, a = 2 + 2 root 1-Y-p/Y-t, where Y-p is the projecti le strength. (C) 1997 Published by Elsevier Science Ltd.