Penetration and Perforation Thresholds of <scp>GnPs</scp> Reinforced Carbon/Glass Fiber Epoxy Hybrid Composites

ABSTRACT Composite materials have found extensive application in advanced sectors, including aerospace, defense, and automotive technologies, thanks to their outstanding mechanical properties. However, their high sensitivity to impact loads remains a major limitation. Low‐energy impacts may lead to internal damages like delamination, matrix cracking, and fiber breakage, while exceeding a certain energy threshold results in penetration and perforation. Low penetration and perforation thresholds in structural composite components pose significant risks to safety and operational performance. Therefore, enhancing not only impact resistance but also penetration and perforation thresholds is crucial for the reliable use of composite materials. This study investigates the penetration and perforation behavior of 12‐layered neat and graphene nanoplatelets (GnPs) reinforced composite laminates, including carbon fiber (CFRP), glass fiber (GFRP), and hybrid fiber reinforced polymer (HFRP) systems with various stacking sequences. The laminates were fabricated using the vacuum bagging method. Low‐velocity impact tests were performed at energy levels ranging from 15 J up to the perforation threshold. The energy profiling method was employed to assess the penetration and perforation thresholds, and the damage mechanisms were examined progressively. Results showed that GnPs reinforcement, fiber hybridization, and stacking sequence modifications increased both thresholds while reducing damage at the same impact energy level.