Damping function in the penetration/perforation struck by 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 projectile introduced previously, in the penetration/perforation dynamics of a rigid projectile. It only depends on the interaction of projectile and target materials and is independent of projectile geometry. A general penetration resistance, which contains the terms of viscous effect and dummy mass of projectile induced by the deceleration effect, is adopted in the formulation. Dimensionless formula of depth of penetration (DOP) is conducted with only three parameters I, N and ξ for general convex shapes of various rigid projectiles. Different geometry parameters are also presented for some common shapes of projectiles. With accounting for viscous effect and dummy mass of a projectile, the normal perforations of thick metallic plates struck by sharp-nosed rigid projectiles are further studied and only I, N and ξ as well as the dimensionless target thickness χ dominate in perforation. The influence of damping function ξ on penetration/perforation has been discussed in detail. Theoretical predictions of penetration and perforation in the present manuscript show good agreement with the individual published test data of different projectiles and impact velocities as well as different targets.