Effect of cyclic hygrothermal aging on mechanical behaviours of adhesive bonded aluminum joints

Abstract

This paper focuses on the effect of cyclic hygrothermal aging on the mechanical behavior of the adhesive bonded aluminum joints. The adhesive joint specimens were immerged in the temperature/relative humidity set at 80 °C/95％ and −40 °C/30％ for cycle experiments for un–aged, 20, 40, and 60 cycles, respectively. Joint bonding angles were set to 0°, 15°, 30°, 45°, 60°, 75° and 90°. The stress modes of the adhesive joints were directly related to the bonding angles. It revealed that the hygrothermal aging significantly decreased the ultimate failure strength and stiffness of adhesive joints. The failure strength decreased with the increase of aging cycles. Besides, for the tensile–shear combined loading, the environmental degradation was much more obvious. The joint failure displacement values increased obviously after hygrothermal aging than that of un–aged. With the increase of aging cycles, the failure displacement of 75° and 90° joints increased more obviously than that of 0°, 15°, 30°, 45° and 60° joints. Moreover, Fourier Transform Infrared (FTIR), Energy Dispersive X-ray Spectrometer (EDS), Scanning electron microscope (SEM) and Differential scanning calorimetry (DSC) was used to analyze the characteristic of adhesive.