Effect of Thermal Exposure on Static and Fatigue Characteristics of Adhesive-bonded Aluminum Alloys

Abstract

This study investigates the effect of thermal exposure (i.e., 80°C for 14 days) on the static and fatigue characteristics of adhesive-bonded aluminum joints. Results showed that thermal exposure reduced the quasi-static strength of the adhesive-bonded joints by up to ~16%. The thermal exposure slightly decreased the fatigue resistance of the adhesive-bonded aluminum joints at high cycle regime (>~106 cycles) but significantly degraded the fatigue resistance at low cycle regime (~103–104 cycles). The effects of thermal exposure on the properties of adhesive and interfacial bond adhesion between the adhesive and aluminum were analyzed. It was found that the thermal exposure degraded the properties of adhesive due to that adhesive was oxidized, which led to the decreases of the static strength and fatigue resistance at low cycle regime for the adhesive-bonded aluminum joints. The oxidation of adhesive decreased the content of O-H group in the adhesive, which likely reduced the hydrogen bond at the adhesive/aluminum interface. The decrease in the content of hydrogen bond weakened the bond adhesion at the adhesive/aluminum interface, and consequently slightly reduced the fatigue resistance at high cycle regime for the adhesive-bonded aluminum joints.