Effect of fragment shape on the impact damage of carbon/aluminum laminated shell structure

Carbon fiber-reinforced composite materials are widely used in the aerospace area as protective frame against collision. The effect of fragment shape on the impact damage in carbon fiber reinforced aluminum laminates (CRALL) fabricated by carbon fiber reinforced plastic (CFRP) layers combined with aluminum alloy 2024-T3 layers was studied. The 2.48 mm thickness CRALL 2/1 layup and 4.16 mm thickness CRALL 3/2 layup were designed and investigated. The 30 g mass fragments with a flat, hemispherical or conical shape were launched up to 68~238 m/s by the air gun to impact and penetrate these composite targets normally. Experimental results on the 0°/90° CFRP and CRALLs reveal that the fracture modes, ballistic limits and energy absorption are significantly affected by the fragment shape. With the with the increase thickness of CRALLs, the influence of the projectile shapes on fracture modes will be diminished. Due to the strain rate hardening effect, the 4.16 mm thickness CRALL3/2 targets performed higher ballistic limits and better specific energy absorption ability than 4 mm 0°/90° laminated CFRP in all three shapes fragments.