Relative fatigue life prediction for elliptical contact problem based on mixed plasto-elastohydrodynamic lubrication analysis with 3D real surface roughness

Plastic deformation and pitting failures often occur in gas turbine bearings due to heavy loads, surface roughness and long service time at the interface between ball and raceway. The gas turbine bearing is a typical elliptical-contact friction pair, in this article, a numerical solution procedure is developed for the predictions of plastic deformation and relative fatigue life m based on the simulation of three-dimensional (3D) mixed plasto-elastohydrodynamic lubrication (PEHL) in elliptical contacts, whose results have been verified by comparing the predicted stress, film pressure and thickness with those from the semi-analytic method (SAM). The effects of machined surface roughness and the plastic deformation on the mixed PEHL lubrication characteristics, surface/subsurface stresses and relative fatigue life are studied. The results show that plastic deformation may significantly reduce the surface and subsurface stress concentrations caused by excessive elastic properties and micro asperity contact, and prolong the relative fatigue life for bearings.