The Explosively Formed Projectile (EFP) as a Standoff Sea Mine Neutralization Device

Abstract

There are many methods that can be used for the clearance of underwater ammunition; for example, sea mines. In all such techniques, the primary aim is to defuse underwater ammunition without detonation. Explosively formed projectiles (EFPs) have great potential to cleanly and safely defuse underwater ammunition. Underwater simulations and experiments were conducted to highlight the use of EFPs for safe destruction of sea mines. The copper liner configuration was used to study the penetration performance of the EFPs in water. ANSYS AUTODYN-2D hydrocode was used to simulate copper EFP penetration, passage, and impact with a target immersed in water. Simulation results were obtained by making use of Lagrangian and Euler formulations. The results indicated that the velocity of an EFP reduces sharply as it enters the water. However, the velocity of an EFP is stable in the later part of its flight through the water. The results further indicated that after covering five cone diameters (CDs) in water, the velocity of the EFP was reduced below critical and it failed to perforate an aluminum target plate of 5 mm thickness. Nevertheless, it perforated the target plate at 4 CDs in water. A known quantity of high explosive sandwiched between two plates, just like explosive reactive armor (ERA), was used as a target to simulate the sea mine. Flash X-ray was also used to record the flight and penetration of the EFP through the target plate. Simulation results matched reasonably well with the experimental results.