Repair of aircraft structures using composite patches bonded through induction heating

In this study, we investigated the use of composite patches to repair aluminum alloy double-lap joints. The carbon composite patches were cured using induction curing or oven curing. Joints were repaired using precured or cocured composite patches. The bond strengths of the different joints were compared. We also investigated whether the incorporation of carbon nanotubes (CNTs) in the adhesive bondline affected bond strength. We found that the induction-cured samples exhibited bond strengths similar to those of the corresponding oven-cured samples; this was true for both the baseline and the CNT-reinforced samples. Further, the samples processed using cocured patches exhibited higher bond strengths than did the corresponding samples processed using precured patches. In the case of both the precured and the cocured patch samples, the dispersion of 0.5 wt% CNTs in the adhesive bondline increased the bond strength slightly. The effect of the two different types of patches placed on top of the aluminum substrate on the rate of temperature increase by induction curing was shown experimentally, and, numerical simulations were performed to verify the experimental results. The results from this study show that the induction curing and co-curing method may be regarded as a sound and efficient method for composite patch bonding repair.