Fatigue life estimation of adhesive joints at different mode mixities

ABSTRACT

Fatigue life prediction of adhesive joints is a concern when using this bonding technique in structural components where the joints are subjected to multiaxial stress states. Thus, the development of a fatigue failure criterion that accounts for the effect of mode mixity is crucial. The main aim of the present study is to develop a fatigue model to be able to predict the fatigue life of an epoxy-based adhesive loaded at different mode mixities. For this purpose, Arcan joints were manufactured and tested in pure modes (I and II), and mixed mode loading conditions. Using the obtained experimental data for pure mode loading conditions, a master S-N curve was constructed based on a proposed effective stress. According to this curve and by considering the numerical simulations, the fatigue lives of the joints under mixed mode conditions were estimated. Two different relations (Basquin and Stromeyer) were considered in this study. The influence of the number of load levels considered for the master curve was also analysed. It was found that more experimental results for the reference samples do not necessarily lead to a better estimation. Results show a good agreement between the experimental data and the predicted fatigue lives based on the proposed model.

KEYWORDS:

• Adhesive joints
• fatigue
• S-N approach
• life prediction
• mixed mode