In-situ and adhesive repair of continuous fiber composites using 3D printing

The development of automated repair processes for continuous carbon fiber reinforced thermoplastic (CFRTP) composites is still in its early stages. However, the emergence of 3D printing technology presents a significant opportunity for the automated repair process to evolve alongside CFRTP composites. This study aims to evaluate the 3D printing repair of continuous fiber composites (CFCs) and characterize the mechanical performance of the repaired specimens. Two methods are proposed for repairing CFRTP utilizing additive manufacturing (AM): repair by a separately 3D-printed and subsequently adhesively bonded patch and repair with 3D printing in-situ at a recess damage. To compare the performance of the proposed methods, 16 test specimens were 3D printed, consisting of 4 intact and 12 damaged samples. Among the damaged samples, 4 were used as damaged specimens, 4 were repaired with adhesively bonded patches, and the remainder were repaired by in-situ printing. Mechanical tests were conducted on all four types of specimens, and the results indicate that the 3D-printed in-situ repair of carbon-reinforced polycarbonate has both the highest strength and elastic modulus. The results show that the repair using adhesive patches and repair in-situ improves the elastic modulus of the damaged specimens by 30% and 44%, respectively. Similarly, the tensile strength of the specimens repaired by adhesive patches and in-situ printing is 20% and 28%, respectively, higher than that of the damaged samples. An analytical model was developed to predict the elastic modulus of damaged and intact specimens, and the analytically predicted stiffnesses showed good agreement with the experimental measurements. Overall, this study demonstrates the potential of 3D printing technology for repairing CFRTP composites and highlights the advantages of in-situ printing over adhesive patch repair.