Constant kinetic energy impacts of scale size kE projectiles at ordnance and hypervelocity

Abstract

Summary This paper presents scale size firings of tungsten alloy KE penetrators into RHA and ceramic targets at constant impact energy. Experiments were carried out mainly at 1.55 and 2.15 km/s but additional data and hydrocode simulations cover a wider velocity range. Semi-infinite RHA and 100 mm thick RHA targets at normal incidence were used, in addition to 40 mm thick RHA at 60 degrees obliquity. The Al2O3 ceramic target was at normal incidence and used a thick lateral confinement, and an RHA backing to measure residual depth of penetration. Behind armour effects (BAE) measurements were made using the finite thickness targets. The semi-infinite RHA experiments show the expected peak in performance at about 2200 m/s and an analytical equation was in good agreement to experiment. The hypervelocity penetrator eroded slightly less than the ordnance velocity case against finite thickness RHA. The mass efficiency of the ceramic target increased from 1.65 at 1.55 km/s to 1.93 at 2.15 km/s but there was still an improvement of 25 % in penetration at the higher velocity. Simulations of the experiments used the GRIM2D and 3D hydrocode and an Armstrong-Zerilli material model and generally gave good agreement. Penetration simulations with a simplified Johnson-Holmquist ceramic model compare well with experiments at the two velocities. Further simulations indicate an optimum velocity at 2500 m/s. The higher velocity impacts produced more behind armour debris, with the fragment number approximately in proportion to the square of the impact velocity.