Influence of fibre orientation parallel to impact direction on the impact response of unidirectional glass/epoxy composite: Experimental investigation on confinement and hybridisation

In a high-velocity impact phenomenon, the damage is localised, and for thick composite laminates, most of the projectile's kinetic energy is absorbed through out-of-plane compression and shear mechanisms. In conventional composite laminate, as the fibre orientations are in the in-plane of laminate, the out-of-plane compression and out-of-plane shear of laminate are utilised. In composites, the out-of-plane compressive strength is significantly lower than the in-plane (fibre direction) strength. The present study investigates the impact response of unidirectional (UD) glass/epoxy composite targets with fibres oriented parallel to the impact direction. The lack of research on the impact behaviour of unidirectional glass/epoxy composites with fibre orientation parallel to the impact direction demands further experimentation and understanding of failure mechanisms. In this study, firstly, the impact response of UD glass/epoxy composites with fibres oriented parallel to the impact direction (GFID) was investigated and compared with conventional cross-ply (GFCP) and quasi-isotropic (GFQI) glass/epoxy laminates. Secondly, to address the issues of GFID splitting on impact, GFID was confined in both the hoop and normal-to-binder directions. Thirdly, the impact response of various hybrid GFID with and without confinement with GFCP as backing was evaluated. GFID under out-of-plane punch load fails by splitting, and its compressive participation depends on the impact velocity. GFID under the hoop and normal-to-binder direction confinement showed better specific impact energy absorption relative to pure GFID. The experimental results show that GFID wounds with carbon fibre used as a facing with GFCP as a backing provide better impact resistance at HVI conditions than conventional laminates of the same thickness. These findings suggest that the combination of GFID and GFCP targets can be used to have better impact resistance in various applications.