... existing in the literature for estimating the RCF lives, the current model considers microcrack initiation, coalescence, and propagation stages. The proposed model relates the fatigue life to a damage parameter D , which is a measure of the gradual material degradation under cyclic loading...

... contacts. Crack initiation as well as propagation stages are modeled using damaged material zones in a unified framework. The spalling phenomenon is found to occur through microcrack initiation below the surface where multiple microcracks coalesce and subsequent cracks propagate to the surface...