Integrated experimental screening of bonded composites patch repair schemes to notched aluminum-alloy panels based on static and fatigue strength concepts

This paper seeks to outline an experimental screening procedure for a bonded composites patch repair scheme for cracked aluminum-alloy panels based on static and fatigue strength concepts. The materials used in this investigation comprised LY12 aluminum-alloy as a substrate, SY-24C as the adhesive system and T300/3234, G803/3242 and SW220/2322 fibre/epoxy prepregs as the patch materials. Static and fatigue behaviour of the specimens with serious patch materials and thicknesses was investigated experimentally. The experiments showed that the effects of repair of a notched panel with an asymmetric composite patch on the static strength and fatigue life of the repaired panel vary depending on the thicknesses of the patch and the fibre/epoxy prepreg materials. Because of the reduction of stress concentration caused by repairing, there is an improvement in the residual strength of the repaired specimens; thus the tensile residual strengths of repaired specimens are greater than those of un-repaired notched specimens.