Ballistic Impact Response of Tri-Metallic Armour to Nonrigid NATO FMJ M80 Projectiles

Abstract

Enhancing protection against high-velocity projectile impacts is a prominent area of research. Monolithic metallic plates are preferred for armour due to their high ductility and resistance capabilities. Upsurge of terrorism demands impact mitigation applications in the defence sector igniting interest for lower weight composite systems, especially multi-metal systems. So far, a limited attention has been given to the ballistics performance of multi-metal systems. This research investigates the ballistic performance of multi-metal systems consist high strength alloys of steel (SS), aluminium (Al) and titanium (Ti) subjected to high velocity projectile impacts. Investigations were carried out to study the projectile residual velocity, back-face pressure (BFP), back-face signature (BFS) and fracture mechanisms observed on metal layers. Ballistic tests were conducted using 7.62×51 mm NATO projectiles fired at different velocities. A parametric study was carried out to determine the tri-metallic configurations with the same areal density as 6 mm SS and defeat an NIJ Level III threat. The effect of adding Ti on the ballistic performance was investigated for the first time in relation to projectile residual velocity and BFP. Furthermore, BFP and BFS of the targets were specifically studied to introduce behind armour blunt trauma (BABT) protection against hard metal armours, for the first time as well. An analytical framework to determine the projectile residual velocity of perforated tri-metallic targets and BFP of non-perforated targets was developed. It was found that the residual velocity generally decreased with the increase in Ti layer thickness of all studied combinations. Results show that the proposed multi-metal systems have the potential to produce a lightweight armour with superior ballistic performance in comparison to existing monolithic armour.