PA无纺布增韧CFRP层合板的层间断裂韧性及机理OA

Carbon fiber-reinforced polymer(CFRP)laminates externally bonded to structures are a common method for bridge repair and strengthening.However,issues such as susceptibility to delamination and easy crack propagation reduce structural reliability.A hot-pressing process was employed to fabricate CFRP lami-nates with interlayer toughening by polyamide(PA)nonwoven fabrics of different areal densities(15,20,30,and 40 g/m2).The Mode Ⅰ interlaminar fracture toughness(GⅠC)and Mode Ⅱ interlaminar fracture toughness(GⅡC)were tested to analyze the interlaminar toughening effect and mechanism of the PA nonwoven fabric.The results show that the PA nonwoven fabric significantly improves the interlaminar fracture tough-ness.Compared with the untoughened specimens,the GⅠC values of interlaminar fracture toughness increase by 163％,251％,388％,and 476％for areal densities of 15,20,30,and 40 g/m2,respectively.While the GⅡC values increase by 146％,169％,204％,and 204％,respectively.The untoughened specimens exhibit simple delamination failure,while the bridging effect in toughened specimens alters the damage pattern.Fur-thermore,the Mode Ⅱ fractures in the 30 and 40 g/m2 PA nonwoven fabric experience flexural failure.The PA nonwoven fabric exhibits excellent toughening effectiveness and maintains thermal stability at the hot-pressing temperature of 168℃.Complicate the crack propagation path through a three-dimensional interac-tive network,coupled with a large amount of energy dissipation via fiber bridging,pull-out,and fractur.Ad-ditionally,the interfacial bonding between the PA nonwoven fabric and the resin shifts the crack propagation path from the carbon fiber-resin interface to the PA fiber-resin interface.