Comparative Impact Response, Damage, and Healing Performance of CFRP Laminates with Different Thicknesses and Reinforcement Architectures

Carbon-fiber-reinforced polymer (CFRP) laminates can exhibit different low-velocity impact responses and post-impact performance depending on laminate configuration. This study compares three self-healing CFRP configurations manufactured from CompPair HealTech® materials: 1.45 and 3.30 mm unidirectional (UD) laminates and a 2.66 mm woven laminate. Low-velocity impact tests were performed at 5 and 10 J. Internal damage was qualitatively examined using visual inspection and X-ray phase-contrast imaging (XPCI), while post-impact performance and recovery were assessed by compression-after-impact (CAI) testing before and after thermal healing. The 1.45 mm UD laminate exhibited the largest displacement and lowest maximum impact force, whereas the 3.30 mm UD laminate showed the highest force and smallest displacement, with the woven laminate exhibiting an intermediate response. Despite its greater impact stiffness, the 3.30 mm UD laminate showed the largest relative reduction in residual compressive strength after 10 J, with strength retention decreasing from approximately 98% after 5 J to 64% after 10 J. The 1.45 mm UD and woven laminates retained 89% and 88% after 5 J and 82% and 72% after 10 J, respectively. After healing, the 1.45 mm UD and woven laminates recovered to approximately 99% of their virgin strengths after 5 J. After 10 J, strength retention reached 91%, 79%, and 81% for the 1.45 mm UD, 3.30 mm UD, and woven laminates, with corresponding healing efficiencies of 49%, 42%, and 31%, respectively. XPCI revealed configuration-dependent internal damage patterns that became more pronounced at 10 J. Overall, the investigated laminate configurations exhibited distinct impact responses, internal damage patterns, residual strengths, and levels of mechanical recovery after healing.