Mechanical properties of UV‐curable carbon fiber‐reinforced polymer composite patch: Repair evaluation of damaged aluminum alloy

Abstract

Epoxy resin composite patches reinforced by carbon fiber were prepared through ultraviolet (UV)-curing method, and the damaged aluminum alloy plates are rapidly repaired by means of adhesively bonding method. Mechanical properties of the composite patches and damaged aluminum alloy plates before and after repair were studied by experiment and numerical simulation. Results indicated that the tensile properties of carbon fiber/epoxy resin composite patches presented the tendency of first increase and then decrease with the increase of layer numbers of reinforced fiber. The composite patches with two layers fiber showed the best tensile properties, and the tensile strength and modulus reached 1.13 GPa and 27.79 GPa, respectively. However, the bending strength of composite patches decreased with the increase of layer numbers. Results of performance evaluation on the mechanical properties of damaged aluminum alloy plates repaired by the two layers carbon fiber/epoxy resin composite patches showed that the repair efficiency of tensile and bending properties of the repaired aluminum alloys reached more than 83% and 160%, respectively, compared with the undamaged aluminum alloys. Besides, results of numerical simulation showed that the stress intensity factor (SIF) of the crack tip on repaired aluminum alloy plates decreased significantly in comparison with the unrepaired aluminum alloy plates, which further revealing the reinforced mechanism of composite patches on the bending properties of repaired aluminum alloy plates. KEYWORDS finite element analysis (FEA), mechanical properties, polymer composite patches, repair materials, ultraviolet light curing 1 | INTRODUCTION The aluminum alloys are widely used in aerospace, automobile, ships, machinery manufacturing, and chemical industry because of the low density, high specific strength, and good thermal and electric conductivity. 1 Since aluminum alloy structures are unavoidably exposed to repetitive loads or humid environment frequently during its service life, the corrosion or fatigue damage generates easily on the aluminum alloy structures under the electrochemical effect. Therefore, it is urgent to rapidly and effectively repair the mechanical properties of the cracked aluminum alloy structures.Traditional methods of repair normally consist of riveting an additional reinforcement onto the damaged area. For the repair of metal structures, the hot-driven rivets have been extensively used from the end of 18th century. However, the hot riveting process also induces high stress concentrations in the metallic plates and makes the riveted connections become weak. 2 Hence, with the development of materials technology, it is necessary to find a more effective repair