Inhibition of interlaminar damage in CFRP laminates by inserting non-woven carbon fiber interlaminar reinforced tissue

Carbon fiber-reinforced plastics (CFRPs) are known for their high strength and stiffness, essential in high-performance applications. However, in complex structures with fiber discontinuities, such as tapered sections and bolt holes, CFRP laminates are prone to interlaminar damage due to low interlaminar toughness. This study aimed to enhance CFRP interlaminar fracture toughness by inserting non-woven carbon-fiber-reinforced layers. Two non-woven tissues were used: resin-impregnated conventional carbon fiber and resin-free recycled carbon fiber. Evaluations of modes I and II interlaminar fracture toughness revealed that laminates with non-woven inserts had fracture toughness values two to three times higher than pristine CFRP. Non-woven tissues of varying lengths were embedded at ply discontinuities, and tensile tests were conducted to assess their effectiveness. Results confirmed that both non-woven tissues significantly improved interlaminar toughness and effectively suppressed delamination, attributed to high fiber content and complex crack paths, enhancing energy absorption and mechanical performance in CFRP laminates.