Experimental Investigations on the Effects of Thermal Residual Stresses on the Efficiency of Repaired Panels with Glass/Epoxy Composite Patch

The aim of this experimental investigation is to study the effect of various curing temperatures on crack-front shape and crack growth life of centrally cracked aluminium panels in mode-I condition with single-side glass/epoxy composite patches. The aluminium panels are made of Al 2024-T3 with the thicknesses of 2.29 mm. Unidirectional four layers lay-up perpendicular to the initial crack length were used for the patches of all specimens and the adhesive was Araldite LY564. The cyclic remote stress of 118 MPa with the R-ratio of 0.05 was applied for all models. The experiments were performed for different curing temperatures of room temperature, 50oC, 80oC, 100oC and 120oC. It is shown that the fatigue crack growth life of the repaired panels with curing temperatures of 100oC and 120oC is considerably smaller than those obtained for specimens cured at room temperature and 50oC.