Prediction of fretting fatigue lifetime of dovetail joints using a Modified Theory of Critical Distances

Dovetail joints are widely used in mechanical systems and aerospace applications. Under cyclic loading conditions, they are susceptible to fretting fatigue, which can lead to premature failure. Therefore, improving the accuracy of lifetime prediction under fretting fatigue is crucial. In dovetail joints, fretting conditions result in a complex stress-strain distribution on the contact surface, affecting the applicability of different failure criteria. This study examines the stress states across various models and evaluates the suitability of each criterion accordingly. The accuracy of crack initiation angle prediction for two types of dovetail joints is improved. The maximum principal stress serves as a reference for extreme stress, while the stress gradient describes the rate of change in stress. The combination of stress gradient and maximum principal stress provides a more comprehensive representation of stress distribution. The traditional Theory of Critical Distances (TCD) is unable to effectively address the complex stress distribution in stress concentration areas. To overcome this limitation, a Modified TCD (MTCD) is proposed, integrating the effects of stress gradients and maximum principal stress into the original TCD framework. The MTCD method significantly improves the accuracy of predicting the initiation lifetime of both dovetail joints compared to the traditional TCD method. This study not only enhances the understanding of fretting fatigue behavior in dovetail joints but also provides a reliable predictive tool for evaluating more complex models of dovetail joints.