Influence of temperature and humidity on the fatigue behaviour of adhesively bonded CFRP/aluminium alloy joints

Abstract

ABSTRACT To further promote the use of composite bonded structures in engineering applications, it is necessary to understand the change law of the fatigue performance in the long-term server process. This paper investigated the effect of temperature and humidity on the fatigue behaviour of adhesively bonded CFRP/aluminium alloy joints using an experimental method. The quasi-static tensile and fatigue tests of CFRP/aluminium alloy butt joints were carried out at 20 °C, 40 °C, 60 °C and 80 °C, as well as at different ageing times of the 60 °C/95% RH hygrothermal environment. The results demonstrate that with increasing test temperature, the fatigue performance of the adhesive joints decreases substantially, especially when the temperature is close to or higher than Tg of the adhesive (similar to the static failure strength). In the 60 °C/95% RH environment, the fatigue performance of the joint decreases as the ageing time increases, and the fatigue strength decreases more obviously in the early ageing stage. In the single logarithmic coordinate system, the S-N curves at different temperatures/ageing times both conform to the linear law. The function of the stress-temperature/ageing time-number of the cycles to failure was established to help understand the influence law of the environment on the fatigue characteristics of joints and provide a reference for the prediction of the fatigue performance of adhesively bonded joints exposed to a hygrothermal environment.