A 3D printed continuous carbon fiber reinforced composite with function of self-detecting and self-healing of internal damages

Realizing the self-detecting and self-healing of internal damage is of great significance for ensuring the safe service and extending the service life of carbon fiber reinforced (CFR) composites. Here, a CFR thermoplastic composite composed of "long CFs - short CFs" was designed and prepared through a hybrid 3D printing method. Firstly, by multi-threaded laying and hybrid printing of conductive continuous CF inside the material, it shows that there is good consistency between the mechanical properties and conductive properties induced by internal damages, providing an important non-destructive detection method for the determination and danger warning of internal damages in the material. Secondly, the printed "long CFs - short CFs" combinated structure can induce a synergistic effect in the coupling between the composite and microwave. This synergistic effect can avoid the ignition of long CFs and the local melting of short CFR polymer, thereby making it possible to realize the noncontact microwave healing of local damages. The healed material significantly improves the toughness while ensuring almost initial strength. This study is of positive significance for achieving the 3D printing of multifunctional implementation of CF composites with "nondestructive detecting - accurate positioning - self-healing" of damages.