Patch repair of pin-connected composites with cracks and examination of post-repair strength

Due to the increasing use of fiber-reinforced composite plates instead of traditional materials, pin connection application is widely used in their assembly. During this use, crack damage occurs in composites. The crack damage that occurs significantly limits the life of the structure. For this reason, instead of completely changing the material, a more suitable method, repair, was used to eliminate the effect of crack damage in the study. In this study, the damage behavior of carbon fiber-reinforced composite plates containing cracks under pin load was experimentally investigated. First, test samples were cut from composite plates and pin holes were drilled in them. The samples were subjected to tensile tests with pins from these holes. Then, two different crack types were created in the holes in the direction of tension and perpendicular to the direction of tension and were subjected to tensile tests with pins in this way. Thus, the effect of the cracks formed in the hole was obtained. Finally, a patch piece was cut from the same composite plate and the cracks were repaired with this patch on one and two sides using adhesive. Then, a pin hole was drilled in the repaired sample again and it was subjected to tensile tests. As a result; the results of the crack-free, cracked and crack-repaired pin samples were compared. It was observed that double-sided repair showed much superior performance compared to single-sided repair. It was observed that the damage type changed with the change of crack length in double-sided repair and that the critical transition length changed. However, it was determined that the damage load was independent of the crack length.