Low-velocity impact response of small-angle laminated composites
Reducing delamination is essential in increasing the impact resistance of laminated composites. In this study, two methods were used to improve energy-absorption capabilities of laminated glass/epoxy composites; one was based on small fiber angle changes between adjacent laminae, and the other was based on through-thickness stitching reinforcement. Penetration thresholds were determined for small-angle laminated composites [0/θ] 6 for which θ = 0, 5, 10, and 15 deg. The small-angle laminated composites, especially [0/15] 6 , were found to have higher penetration thresholds than the conventional large-angle laminated composites, such as [0/90] 6 , due to damage progression (most notably, fiber bridging). Stitched small-angle laminated composites were also found to have higher impact resistance than unstitched specimens with the same stacking sequence. The use of small-angle composites was extended to multi-axis laminated composites, such as biaxis, triaxis, and sexiaxis laminated composites. Penetration thresholds of the multi-axis laminates were found to be very comparable with the uniaxis laminated composites, that is, [0/θ] 6 .