Development of a contact compliance method to detect the crack propagation under fretting

Partial slip fretting conditions are classically known to favor contact crack nucleation and crack propagation. Considered as a plague for modern industries, numerous theoretical researches have been conducted during the past two decades to predict such fretting damage. However, a review of last few years critically outlines the need of precise and in-situ experiments to qualify and quantify the given models. To palliate such aspect, an original approach which consists in following the contact stiffness evolution as an indicator of the fretting cracking phenomena, has been developed. Applied for an aluminium/steel contact, it demonstrates that the incipient crack propagation is related to a discontinuous decrease of the contact stiffness. Based on this online analysis, a fretting cracking endurance parameter has been extrapolated to develop fast and low cost fretting cracking endurance chart. A FEM analysis has been performed in an attempt to formalize the given experiments.