The role of granular buoyant force of projectile in determining the penetration depth

Abstract

This research develops a new formulation for final penetration depth of projectile on granular material. Although several relevant researches exist to estimate final penetration depths of blunt projectiles, estimation of final penetration depth of sharp projectiles is still difficult. Direct application of the formulation of blunt projectile cannot be applicable for sharp projectile. It is possible to employ heuristic and empirical formulations to predict the penetration depth of projectiles. Through several experimental studies, this research, however, finds out that buoyant force of sharp projectiles can be included in the existing formula for the final penetration depth of blunt projectiles. In order to verify the hypothesis, first of all several experiments with cylinder and ball were carried out to validate the existing theory. After sharp projectiles are experimented, the effect of the buoyant force is formulated as initial penetration depth. By adding this initial penetration depth determined by balancing between the buoyant force and weight, it is possible to adjust the existing formula for sharp projectiles. To show the validity of the present formulation, several cone shape projectiles are modeled and tested.