Investigation and optimisation of cracked aluminium alloy plate restored for fatigue loading application

Abstract

Crack propagation could be catastrophic, and it needs the urgent attention of the user. A cracked structure needs to be repaired or replaced at the earliest. Costs associated with the complete replacement of the part paves the way for the former option, especially in the aircraft industry. Composite materials have good directional properties in the strength and toughness compared to the conventional materials like metals, alloys and plastics. In this study carbon fibre reinforced polymer (CFRP) has been used to repair the inclined crack in aluminium alloy plate having 1.6 mm thickness. Repaired aluminium alloy specimens were subjected to fatigue load to investigate the effectiveness of CFRP. By using the ply drop technique, the strength of the damaged structure has been restored. Various options have been evaluated by conducting the design of experiment. A peeling off tendency of the CFRP patch was observed during the study. To suppress this peeling off tendency, interfacial shear stress between CFRP and the aluminium was studied more intensely rather than the fracture toughness parameters. To select the optimum configuration MCDM optimisation techniques were used and numerical solutions were validated by lab experiments.

Analysis of Inclined Crack in Aluminium Alloy Plate Subjected to Three-Point Bending Load Repaired with Carbon Fiber Reinforced Polymer

“…Alternating or fatigue type of load is the most critical load and the parts fail at much lower stress level in this type of loading than the other types of load. CFRP repair proved to be the best one for the fatigue loading also [21]. For pressure vessels full-encircle bonded repairs by composite materials have been allowed in the US since 1991.…”