THE EVOLUTION OF CONTACT VARIABLES DUE TO FRETTING WEAR IN PRESS-FITTED SHAFT

초록

This paper describes the effect of the evolution of contact surface profile due to fretting wear on the contact variables and fatigue crack initiation site by means of an analytical method based on experimental data in press-fitted shaft. A finite element analysis was performed to analyze the stress states of press-fitted shaft, considering the worn contact surface profiles of shaft. In addition, fatigue crack nucleation sites were evaluated by fretting fatigue damage parameter (FFDP) and multiaxial fatigue criteria based on critical approaches. It is found that the high contact pressure of a contact edge in press-fitted shaft decreases rapidly at the initial stage of total fatigue life and the position of its maximum shifts from the contact edge to the inside with increasing number of fatigue cycles. Moreover, the evolution of contact surface profile as a consequence of fretting wear is a main reason of the transition of crack nucleation sites in press-fitted shaft. Therefore, it can be concluded that the fatigue crack nucleation process on the fretted surface of press fits is strongly related to the evolution of contact surface profile by fretting wear at the initial stage of fatigue life.