Plastic deformation and perforation of thin plates resulting from projectile impact

Abstract

The dynamic response of thin plates subjected to projectile impact was studied experimentally by measuring projectile velocity, permanent deformation, dynamic strain and displacements and by examining the growth of plastic deformation and motion of the projectile with a high speed framing camera. Most of the experimental work was performed with ½ in. diameter steel projectiles, spherical or cylindro-conical in shape, centrally striking a 2024-0 aluminum plate, 0.050 in. thick and clamped on a 14 ½ in. diameter, at normal velocities ranging from 75 to 933 ft/sec. Projectile speeds were chosen so as to produce significant plastic deformation at the lower velocities and complete perforation at the higher velocities. The circular boundary of the plastic zone was found to propagate away from the point of impact at about 8800 in./sec at all impact velocities. A simplified large deflection solution for the final central deflection of a rigid/plastic linearly work-hardening plate showed good agreement with the data and correlation between various perforation theories and experimental data was found to improve with increasing projectile velocity.