Experimental study on anti-penetration mechanism of bolted composite protective structure with limited span under impact of low-velocity projectile

Analysis on Deflection of Projectile Penetrating into Composite Concrete Targets

“…The process of action of projectiles and diamond-shaped moving target involves complex deformation and damage of materials, and in order to simplify the problem, the degree of energy dissipation or change in the state of motion of the object before and after the impact can be described by the impact recovery coefficient [32,33]. Here, the impact recovery factor e is defined as the ratio of the separation velocity of an object after impact to the approaching velocity before impact, and expressed as:…”

“…In the last few decades, extensive penetration experiments have been carried out to improve our understanding of the problem of a concrete target penetrated by a rigid projectile and enhance our capacity to predict the ballistic performance of the projectile within the concrete target and further understand its penetration mechanism [25][26][27][28][29][30][31]. The related experimental research indicates that the projectile may undergo great changes in attitude and trajectory during penetration in the case of normal penetration with angle of attack, as the position of the part of the projectile subjected to non-axisymmetric force relative to the center of mass changes [32][33][34][35][36][37]. Based on this fact, the deflection mechanism of the projectile can be utilized to design the protective structures for better anti-penetration performance, considering that the alteration of the attitude and trajectory of the projectile during projectile-target interaction can result in prolonged penetration path, weakened penetration ability, and thus reduced penetration depth, so that the damage to the target plate can be prevented [38][39][40][41][42].…”