Constant deceleration approaches for penetration analysis of rigid projectile into concrete: Revisited

Abstract

A new approach of constant deceleration penetration into concrete targets has been presented recently. It is based on observations from two-dimensional numerical simulations of penetration into aluminum targets, showing a rather constant deceleration during the tunneling stage, which leads to conjecturing a general simple constant deceleration approach to represent constant resistance during penetration. This approach has been extended to concrete materials despite their entirely different behavior. This article reviews the one-stage constant deceleration approach and compares it with test data and with analytical and numerical models. This study clearly shows that concrete penetration cannot be presented by the proposed constant deceleration approach. The constant deceleration approach assigns constant deceleration to the projectile from its impact with the target and ignores the entrance stage. This study shows that a two-stage simplified approach shows superior results compared to the one-stage approach. Experimental studies with instrumented projectiles show that although at low-strength concrete the deceleration variation with time is moderate, its variation with time at higher strength concrete is significant. The variable deceleration–time records are confirmed by theoretical models using the material constitutive relationships. It has been found that the proposed constant deceleration is merely a calibration constant to the measured penetration depth and does not represent a physical deceleration of the penetrating projectile. It is concluded that there cannot exist a simplified approach with a constant deceleration or even an arbitrarily predefined another shape of the deceleration curve that may properly represent different penetration scenarios in concrete targets.