A lubricated wear model for determining wear surface geometry on journal-bearing surfaces

Abstract

In this study, the friction fatigue mechanism is employed to describe the quantitative information concerning characterization of the steady-state wear process in journal bearings, which combined with the load sharing notion in mixed lubrication. For this approach, the asperity stress cycle number is estimated by combining the statistical dynamic contact model with the mixed elasto-hydrodynamic lubrication (EHL) simulation model. The maximum shear stress theory is applied together with the subsurface stress distribution of contact asperities to predict the average volume of wear fragment for asperity. Quantitative analysis of steady-state wear profiles for the bearing reveals that the maximum wear depth appears at both ends of the bearing. With the increase of running time, the wear gradually extends to the bearing centre, and the wear rate rapidly decreases to a certain value and then tends to be stable. With this lubricated wear model, the influences of surface roughness, external load, and shaft speed are also discussed. The proposed wear simulation method is based on the interdisciplinary theory, which includes the description of surface micro-morphology (Gaussian rough surfaces), the friction fatigue theory for explaining the generation of wear debris, and the coupling effect of wear and lubrication that is expressed by considering the wear surface geometry in oil film thickness equation. Additionally, the simulation results and available experiment data are compared to demonstrate the fatigue wear modeling scheme.