An engineering-applicable stress-life model for dovetail joints incorporating leading-edge stress gradient and micro-slip effects

This study focuses on TC4 titanium alloy dovetail joints and proposes a life assessment method that incorporates both stress gradient and fretting slip effects. The research begins with the design of specialized fretting fatigue test specimens to investigate the coupled phenomena of fretting fatigue and wear. Numerical simulations based on the dovetail contact configuration are then conducted to thoroughly analyze the stress distribution characteristics and their dynamic variations at the contact leading edge. To address the unique stress distribution features at the contact leading edge, the study develops a simplified method for rapid determination of the critical distance with gradient modification. This leads to the establishment of a stress-life model that simultaneously considers both the stress gradient and micro-slip amplitude at the contact leading edge. In addition, compared with the elastoplastic analysis, this life prediction model also has good accuracy under pure elastic finite element analysis, which is very convenient for engineering application. The proposed model demonstrates several advantages, including minimal fitting parameters, clear physical interpretation of fretting damage parameters, and improved prediction accuracy. Experimental validation shows that 90% of the predicted results fall within a 1.5x scatter band, significantly enhancing the accuracy of fretting fatigue life prediction and engineering applicability for dovetail joints.