The third dimensionless parameter in the penetration dynamics of rigid projectiles

The present paper defines a third dimensionless parameter, i. e., the damping function ξ, besides the impact function I and geometry function N of a projectile introduced early, in the penetration dynamics of rigid projectiles. It only depends on the interaction of the projectile and the target materials and is independent of the projectile geometry. A general penetration drag, which contains the terms of damping effect and the dummy mass of the projectile induced by the deceleration effect, is adopted in the formulation. Dimensionless formula for the depth of penetration (DOP) is obtained with only three parameters I, N and ξ for general convex shapes of various hard projectiles. Different geometry parameters are also presented for some common shapes of warheads. Theoretical predictions for DOP dependent/independent of the damping function ξ, show good agreement with the published test data for different projectiles and impact velocities as well as different targets.