Structural Evolution and Microstructural Features of the Hydrodynamically Penetrating Copper Jet of a Shaped Charge

Abstract

Shaped charges are unique and very effective warhead technology mostly applied to the rocket propelled grenades (RPGs) along with other applications (e.g. perforation of rocky formations in mining, rock drilling and other geological technics etc.). RPG's armour piercing and perforation performances originate from an explosively induced formation of a stretching metallic jet with very high velocities (hypervelocity). The hydrodynamic penetration mechanism of the stretching quasi-solid metallic jet is extremely complex and has not been fully understood. Both the jet with spout-like form and the target (i.e. RHA armour steel) behave hydrodynamically (i.e. incompressible fluid) and yet both solid strangely. The present study, as part of a large-scale customized R&D project, is stopping the penetration of the stretching jet of a RPG rocket within an "add-on" armour system. A series of experimental detonations and explosion of shaped charge munitions was conducted to elucidate the microstructural evolution and microstructural features of the metallic copper jet. Penetrating metallic spout-like jet forms were stopped and apprehended/caught within the inner layers of highly succesful composite based "add-on" armour designs. Structural evolution and microstructural analysis of the penetrating metallic jet were investigated to understand this extraordinary "solid-but behaving like fluid (quasi-solid)" metallic copper jet material. The findings obtained in this study suggest that the effective way of stopping the lethal effects of this weapon could be managed by diverting and/or twisting its linear stretching and penetration pathway.