Self-sensing and self-repairing of delamination damages of 3D printed hybrid fiber reinforced composites

The detection and repair of delamination damage are of great significance for enhancing the practicality and intelligence of printed composites. In this study, a unique microscopic conductive network was constructed using chopped and continuous carbon fibers as hybrid fiber-reinforced phases. This design improved the electrical conductivity in the layer thickness direction of 3D-printed composites by approximately 165 %. Leveraging the reinforcing effect of short carbon fibers, a self-detection method for delamination damage was developed, with its sensitivity enhanced by approximately 8 times compared to conventional methods. By utilizing the Joule heating effect of ply thickness resistance, an efficient interlaminar strengthening method was established, achieving a typical repair time of approximately 60 s. Furthermore, a self-repairing approach for delamination damage was proposed, enabling an Interlaminar Shear Strength (ILSS) recovery rate exceeding 100 %. Temperature distribution analysis via thermal cloud maps confirmed that high temperatures were concentrated in the damaged layers. In summary, without embedding sensors, heating wires, or conductive films, the intrinsic layer-thickness conductivity of hybrid fiber-reinforced composites can be utilized to achieve highly sensitive sensing and rapid, effective repair of delamination damage, offering a practical and intelligent solution for composite structures.