The Black Adder EFP bomb is an Explosively Formed Projectile that is designed to penetrate armour and knock out vehicles. It consists of a liner and high explosives. The EFP is then shaped into either a jet or a slug, depending on the shape of the liner. A jet gives maximum penetration and is usually used in armour piercing munitions, while a slug can be less effective.
The formation process of the EFP is analyzed using numerical simulation and an X-ray system. The X-ray system allows the EFP to be photographed at specific points in time after the high explosive detonation. This allows the copper liner to be tracked and shaped by computer. The data from the X-ray photos are then compared with the numerical results to evaluate the accuracy of the simulation.
As the EFP travels, it stretches and fractures. When the tip copper metal reaches its metal tensile stress limit, it breaks, leaving behind a metal precursor penetrator and a coating layer. The metal precursor penetrator is then pushed outward to form the coated projectile.
The different shapes of the EFP are due to differences in the size and geometry of the copper liner. A study of three kinds of liners shows that the thickness of the edge and curvature radius influence the formation behavior. The EFP formed by the liner with the thinnest edge thickness has a forward-folded configuration, while the one with uniform thickness has a backward-folded configuration.