Interfacial damage mechanism and in-situ repair of thermoplastic composites with embedded metal mesh layer

An integrated structural-functional design of glass fiber reinforced polypropylene (PP) thermoplastic composites is proposed, in which a metal mesh is embedded as an induction heating element to enable efficient in-situ repair via magnetic induction. End-notched flexure (ENF) and low-velocity impact (LVI) tests were conducted to evaluate the crack propagation resistance and impact performance before and after repair. Internal damage before and after repair was comparatively analyzed through ultrasonic C-scan imaging, X-ray computed tomography, and scanning electron microscopy (SEM). The results show that internal thermal conduction facilitates matrix remelting and reflowing during the induction repair process, leading to the densification of the structure and an enhancement of the interlaminar fracture toughness by up to 74.13%. The repaired specimens also retained 87.75% of their original peak load under a high-energy impact of 40 J, indicating a substantial repair of impact performance. Moreover, the repair method primarily enhanced matrix properties while exhibiting limited repair of fiber damage. This design strategy combines mechanical reinforcement with in-situ repair capability, offering a feasible and promising approach for the high-efficiency in-situ repair of glass-fiber reinforced thermoplastic composites in engineering applications.