Mechanical properties and failure prediction of aluminum alloy-BFRP bonded joints under service high temperature aging

Abstract

50℃ and 80℃ high temperature aging environments were selected and the quasi-static tensile strength and shear strength of the aluminum alloy-BFRP (basalt fiber reinforced polymer composite) bonded joints aged for 0, 10, 20 and 30 days under high-temperature were measured at the loading rate of 1 mm/min with the designed testing fixture.The failure section of the joint was analyzed by macroscopical analysis.After 80℃ high temperature aging,post curing occurs in adhesive,the mechanical properties are enhanced. Chemical bond fracture occurs in BFRP, and glass transition temperature (Tg) is decreased. After aging for 30 days, the tensile strength of the joint is decreased and the shear strength is increased. After 30 days, the failure section of tensile joint appears to be stratified. Mixed failure of adhesive layer cohesion and fiber tear appears in the shear joint. After 50℃ high temperature aging, the mechanical properties of adhesive are slightly increased. The failure strength of the tensile joint changes little, and the failure mode is dominated by fiber tearing and delamination.The failure strength of shear joint is increased slightly, and the failure mode is mainly adhesive cohesive. According to the secondary stress criterion, the curves of tensile strength and shear strength were fitted.According to the response surface principle, the response surface equation of failure criterion with aging time was established to predict the crack generation and propagation of the adhesive layer of aluminum alloy-BFRP bonded structures.

Keywords

• aluminum alloy
• basalt fiber reinforced polymer composite
• adhesive joint
• high temper-ature
• failure