Energy absorption and ballistic limit of targets struck by heavy projectile

Impact on composite structures was a critical topic with great importance in the recent past. In this paper, impact on Glass/epoxy laminates by a 558.6 gms mild steel cylindroconical projectile, in the range of 30 - 100m/s, was studied. Composite panels consisting of 3 and 5 layers of 3 types of glass reinforcement with different combinations were prepared viz.3 layers of WRM/epoxy, CSM/epoxy, Glass Fabric/epoxy, WRM/CSM/epoxy, WRM/Fabric/epoxy and CSM/Fabric/epoxy laminates. Tests were conducted to determine the ballistic limit as well as energy absorption for different initial velocity of the projectile using a piston type, gas gun launcher. A mathematical model based on the energy balance principle was proposed to predict the ballistic limit. The WRM/ epoxy laminates showed higher energy absorption capability and better ballistic limit whereas CSM/Epoxy showed the least of all. Increase in energy absorption was noted up to a certain limit and then decreases slightly for all the 6 types of panels. The delamination area increased with increase in initial velocity up to ballistic limit and a small decrement was observed from thereon. The ballistic limit determined experimentally was compared with the proposed model and showed good agreement with the experimental value.