Roughness Amplitude Reduction Under Non-Newtonian EHD Lubrication Conditions

Over the last decade, the operating conditions of the Elastohydrodynamic lubricated (EHL) contact have become increasingly severe. Consequently, the average film thickness decreased and became comparable to the surface roughness. Under those conditions, the surface features can reduce the minimum film thickness and can thus increase wear. They can also increase the temperature and the pressure fluctuations, which directly affect the component life. In order to describe the roughness geometry inside an EHL contact, the amplitude reduction of harmonic waviness has been studied over the last decade. This theory currently allows a quantitative prediction of the waviness amplitude and includes the influence of wavelength and contact operating conditions. However, the model assumes a Newtonian behavior of the lubricant. The current paper contributes to the extension of the roughness amplitude reduction for EHL point contacts including non-Newtonian effects. A generalized model is derived that includes both types of behavior.