In this study, experimental and numerical investigations were carried out in order to compare the performances of composite and metallic patches for repairing aircraft structures. In the experimental part, an accelerating aging of the composite was realized by the immersion of the composite patch in distilled water. The fatigue lives of notched plates repaired with aged composite patch, non-aged composite patch and aluminum patch were measured.

In this study, we analyzed the fatigue behavior of a V-notch crack in an aluminum alloy 7075-T6 plate repaired with bonded composite patch under constant and stepped variable amplitude loading. The effect of adhesive disbond on the repair performance was analyzed. The obtained results confirm the need of repairing cracks at their early creation for a maximum repair performance and showed that the increases in the disbond width and the stress ratio have a large negative effect on the repair efficiency.

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