Penetration of Fine Foundry Sand by Rigid Projectiles

In another paper [1], the authors presented an approach to penetration of a particulate target. This theory is based on the friction that the particles of target material present to the entire penetrator surface, including its shank. The shank of the penetrator affords a very large surface area compared to that of the nose. Even modest friction acting on the shank can provide a fairly large retarding force. Normal pressure acting on the projectile is assumed to be velocity-squared dependant, as indicated by a number of methods, including cavity expansion modeling [2]. Penetration of sand and soil has been considered by numerous investigators, e.g. [3–5]. These investigations did not directly address the frictional component of the net resisting force acting on the penetrator. A series of laboratory scale penetrations tests were performed. Data from these tests was used to evaluate the parameters in the model. Fine foundry sand is a high-density medium (1960 kg/m³) with a small amount of friction. This contrasts the target used by the authors in [1], which had a sizable amount of friction. Results from the theory are in excellent agreement with the experiments with velocities as high as 630 m/sec.