Simulations of the penetration of limestone targets by ogive-nose 4340 steel projectiles

In this paper we extend Forrestalʹs semi-empirical penetration method for limestone targets to account for pitch, yaw and projectile deformation. This is achieved using a combined analytical and computational technique we have developed to calculate permanent projectile deformation without erosion. With this technique we use an explicit transient dynamic finite element code to model the projectile, and an analytical forcing function based on the dynamic expansion of a spherical cavity derived from Forrestalʹs depth of penetration equation to represent the target. Additionally, this work extends the forcing function methodology by introducing a successive layering technique to account for the loss of confinement due to entrance cratering effects. Results from simulations are compared with the corresponding experimental results and shown to be in good agreement. Furthermore, it is shown that in many of the events the projectile goes through significantly more deformation than what is observed from its post-test configuration.