Investigation of thermal cycle effect prior to cyclic loading on fatigue life of interference fitted specimens and fatigue life prediction

Interference fit process, as a popular method, is used in aerospace and automotive industries to improve fatigue life of the joints. Investigating studies on interference fit process demonstrates that the effect of temperature variations has not been studied as an effective factor on fatigue life. In the present study, the effect of short time exposure to thermal cycle before cyclic loading on fatigue life of interference fitted fastener holes have been evaluated by experimental and numerical methods. So, to investigate the effect of temperature variations two different temperatures (i.e. 60°C and 120°C), aside from room temperature, were selected to accomplish this study. Fatigue tests were carried out on the specimens of Al-alloy 7075-T6 to obtain S-N curves. In relation to fatigue tests, three dimensional finite element analyses were used to explain the experimental results. The interference fit process, and subsequent thermal cycles and remote cyclic loading were simulated using Ansys package. The results obtained from the finite element analyses of the interference fit were employed to predict the fatigue life.