Bulletproof properties and failure mechanism of para-aromatic polyamide fiber/epoxy resin composite

In order to investigate the bulletproof performance and failure mechanism of para-aromatic polyamide fiber/epoxy resin(EP) composite, the lead core projectiles were employed to penetrate composite target. The type of reinforcement was para-aromatic polyamide fiber, whereas the resin was EP; Nano-SiO₂and polyvinyl butyral (PVB) worked as modifier. Unidirectional (UD) composites were fabricated using hot pressing process. The effects of single-layer fiber areal density, the structure of UD sheet, shooting angle and resin modification on the ballistic properties were discussed. The final fracture morphologies were observed by the stereomicroscopy. The failure mechanisms of composite target subjected to the ballistic impact were analyzed. The results show that para-aromatic polyamide fiber/EP composite exhibits excellent bulletproof performance. As the increasing of single-layer fiber areal density, the bulletproof performance of composite increases with fluctuations. Moreover, the bulletproof performances of 4 layer sheets with 0°/90°/0°/90° layer sequence(4UD) structures are superior to those of 2 layer sheets with 0°/90° layer sequence(2UD) structures. When shooting with a angle, the higher penetration layer ratio and smaller back face sign-ature (BFS) ratio are found. PVB improves the bulletproof performance. It can be concluded that the energy absorptions are significantly influenced by the tensile deformation of fiber, the delamination of sheet and the matrix resin cracking.