Damage simulation and experimental analysis of the repaired composite laminates with mortise‐and‐tenon‐lap joint

Abstract In this paper, a mortise‐and‐tenon structural design was introduced into composite maintenance to create a new type of joint between the repair patches and the parent structure, where both the patches and the structure were carbon fiber composites. Effects of different joints, including step‐lap and mortise‐and‐tenon‐lap joints, on the bending failure of the repaired composites were simulated and then verified through experiments. Results showed that compared with the traditional step‐lap method, the mortise‐and‐tenon connection changed the direction of damage extension from a simple single path to complex multiple paths, which effectively inhibited the damage expansion and enhanced the structural damage tolerance. Therefore, the flexural strength of the repair with the new joint was improved by 19.9%. However, the mortise‐and‐tenon‐lap joint resulted in a poor moisture‐heat resistance of the repaired structure. Interestingly, although the flexural strength of the mortise‐and‐tenon repair decreased by 10.45% after the hygrothermal treatment, it was still higher than that of the step‐lap repair without hygrothermal treatment. Highlights A novel joint, mortise‐and‐tenon, was introduced into composite maintenance. Damage extended along multiple paths in the new joint and was inhibited. Flexural strength of the repair was higher than that of traditional step‐lap repair.