Size and Scale Effects in Fretting Fatigue Thresholds

Abstract

Components subject to fretting experience a peculiar combination of loading conditions, where contact and classical fatigue interact intricately to produce failure. As a consequence, the prediction of fretting fatigue limit curves poses a challenge, in part due to the large number of parameters governing the phenomenon. This poses an obstacle to formulating efficient predictive approaches.

We demonstrate that these difficulties can be overcome successfully by means of a combination of experimental and computational approaches. Our analysis relies on various experimental data from Hertzian and ’flat and rounded’ contact pad specimens and different calculation procedures developed previously, which resulted in fretting threshold curves for specific loading conditions. The derivation of such thresholds is however rather lengthy, so that for the purposes of formulating design rules a more efficient ’master curve’ approach is proposed.

This paper presents comprehensive results on the application of an efficient and concise functional description of the fretting fatigue threshold curves based on the use of a ’multi-scaling power law’. The predictions encompass all of the results obtained for different loading conditions by the stress-based approach and by short crack arrest methodology.