The effect of warm water surface treatments on the fatigue life in shear of aluminum joints

The effect of warm water treatment on the fatigue life of 2024 T3 aluminum alloy adhesively bonded with FM73 epoxy adhesive was investigated. As expected, the fatigue life was shown to depend on the surface preparation of the bonds. Fatiguing the specimens in wet conditions led to a slightly shorter life than under dry conditions. There was a correlation between performance in the wedge test and fatigue life for these bonded systems. Warm water treatment of the aluminum leads to an improvement in both of these properties. The improvement in fatigue life can be attributed to a significant improvement in the wetting of the surface by the adhesive. This moves the failure surface away from the surface into the bulk of the adhesive.