Fatigue Life Evaluation of Press-Fitted Specimens by Using Multiaxial Fatigue Theory at Contact Edge

Abstract

In the shrink or press-fitted shafts such as railway axles, fretting can occur by cyclic stress and micro-slippage due to local movement between shaft and boss. When the fretting occurs in the press-fitted shaft, the fatigue strength remarkably decreases compared with that of without fretting. In this paper fretting fatigue life of press-fitted specimens was evaluated using multiaxial fatigue criteria based on critical plane approaches. An elastic-plastic analysis of contact stresses in a press-fitted shaft in contact with a boss was conducted by finite element method and micro-slip due to the bending load was analyzed. The number of cycles of fretting fatigue and the crack orientation were compared with the experimental results obtained by rotating bending tests. It is found that the crack initiation of fretting fatigue between shaft and boss occurs at the contact edge and the normal stress on the critical plane of contact interface was an important parameter for fretting fatigue crack initiation. Furthermore, the results indicated that a critical plane parameter could predict the orientation of crack initiation in the press-fitted shaft.