Numerical analysis of rough hydrodynamic bearings for various deterministic micro-asperity features

Abstract

The hydrodynamic analysis of isotropic and anisotropic Gaussian surfaces has been studied well. However, the analysis reported earlier cannot simply apply to non-Gaussian and self-affine fractal rough surfaces, which demands a thorough investigation to study the effect of non-Gaussian nature of surfaces having different deterministic asperity features. This work demonstrates the effect of non-Gaussian and fractal nature of rough surfaces on hydrodynamic bearing characteristics. The modified Reynolds equation is used in this work with consideration of cavitation. The variation of asperity pressure, hydrodynamic load, and friction force with lambda ratio (the ratio of nominal film thickness to composite roughness) for various types of non-Gaussian and fractal rough surfaces is presented and discussed in detail. It is found that skewness, kurtosis, and fractal signature significantly affect the bearing load capacity and bearing friction force. No significant effect of types micro features is observed on asperity pressure. Asperity pressure is found to decrease with an increase in lambda ratio. More negative skewness results in a decrease in asperity pressure.