Prediction of fretting crack propagation based on a short crack methodology

Fretting tests have been conducted to determine the maximum crack extension under partial slip conditions, as a function of the applied tangential force amplitude. An analytical model representing a fretting-induced slant crack has been implemented and combined with the Kitagawa-Takahashi short crack methodology. This approach provides reasonable qualitative agreement between experimental and predicted maximum fretting crack lengths, supporting previous results concerning the prediction of the fretting–fatigue endurance. It is, however, observed that the model is systematically conservative. A discussion of the appropriate fundamental parameters when dealing with steep stress gradients such as those present in fretting, and which are difficult to interpret in the context of the Kitagawa-Takahashi method, is presented. It is shown that an inverse procedure identifies the required fundamental parameters. Hence, a specific fretting long crack transition length for the low carbon steel studied can be extrapolated. It is also shown that the maximum crack length evolution under plain fretting wear test conditions can be used to calibrate fretting fatigue predictions.