BEHAVIOUR OF TARGETS SUBJECTED TO NORMAL AND OBLIQUE IMPACT BY SHARP NOSED PROJECTILES

Abstract

Three-dimensional numerical simulations have been performed to study the behaviour of ductile targets subjected to normal and oblique impact by sharp nosed projectiles. 12 mm thick Weldox 460 E steel targets were impacted by 20 mm diameter-conical nosed projectiles and 1 mm thick 1100-H12 aluminum targets were impacted by 19 mm diameter ogive nosed projectiles. In both the cases, targets were impacted at 0°, 15°, 30°, 45° and 60° obliquity or until the ricochet of projectile occurred. ABAQUS/Explicit finite element code in conjunction with Johnson-Cook elasto-viscoplastic material model was used to carry out the numerical simulations. The ballistic limit of 12 mm thick Weldox 460 E steel targets was found to be almost same up to 30° obliquity and thereafter it increased sharply. However, in the case of 1 mm thick 1100-H12 aluminum targets a consistent increase in the ballistic limit was observed with an increase in obliquity. Critical angle of projectile ricochet was found to increase with an increase in impact velocity. Both the targets failed through ductile hole enlargement. Petal formation occurred in 1 mm thick 1100-H12 aluminum targets. The size of two petals decreased and that of other two petals increased with an increase in target obliquity. At 45° obliquity, two smaller petals completely vanished. In the case of 12 mm thick Weldox 460 E steel targets failure occurred through the formation of a hole enclosed by a bulge. Petal formation was observed in 12 mm thick steel targets at 60° obliquity. Effect of projectile nose shape on the ballistic resistance was also studied. It was observed that as the nose angle of conical projectile increased the resistance of target decreased. Similarly, the caliber radius head (CRH) of ogive nosed projectile was varied and found to have significant effect on the ballistic resistance of the target.