Experimental analysis of the fatigue life of repaired cracked plate in aluminum alloy 7075 with bonded composite patch

• The cracks must be repaired at the early initiation.
• The disbond risk must be taken into account in the repair design.
• The repair efficiency is improved with decreasing load blocks.

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. The latter is low for increasing loading blocks but significantly high for decreasing blocks.