Crack repair of aluminium components using glass fibre reinforced polymer composite patches: Effect of patch thickness on tensile behaviour

Crack propagation in metallic structures is a critical issue in industries such as aerospace, oil and gas, and automotive, where conventional repair methods such as welding or part replacement are often costly and time-consuming. This study investigates the effectiveness of Glass Fibre Reinforced Polymer (GFRP) composite patches for repairing cracked aluminium sheets. Centre- and edge-notched specimens with crack lengths of 5, 10, and 15 mm were fabricated and repaired using hand lay-up GFRP patches of varying thicknesses (two and four layers). Tensile tests were performed according to ASTM E8 to evaluate the mechanical performance of repaired specimens compared with unrepaired samples. The results demonstrated that composite patches significantly improved the load-carrying capacity of cracked specimens, with thicker patches providing higher strength recovery. Specifically, specimens with four-layer GFRP patches produced the highest maximum stresses of 152.44 MPa and 184.67 MPa for edge and centre cracks of 5 mm, respectively, compared with substantially lower strengths in unrepaired samples. An increase in patch thickness led to greater tensile-strength recovery; however, this improvement must be weighed against weight considerations, particularly in weight-sensitive applications such as aerospace structures.