The prediction of friction and wear when a soft surface slides against a harder rough surface

The friction and wear caused by a single hard asperity in repeated sliding contact have been studied in our earlier publications. This paper outlines a method of combining all the contacts that occur between a soft surface and the asperities on a randomly rough hard surface and leads to predictions of the overall coefficient of friction and the wear rate of the soft surface. The hard asperities are assumed to be each capped with a spherical top of constant radius and their peak height distribution is taken to be Gaussian. Higher asperities in sliding contact may cut or plough the soft surface while lower asperities contact the soft surface elastically. Combining all the individual asperity contacts gives quantitative predictions of both friction and wear. Comparison between these and experimental results from the literature provides encouraging agreement.