Threshold speed of short journal bearings considering the non-Gaussian longitudinal surface roughness

Abstract

During the actual machining process of journal surface, such as milling and fine turning, the surface roughness has strong non-Gaussianity. Thus, the effect of non-Gaussian longitudinal roughness on threshold speed of short journal bearings is investigated in this study. Introducing the parameters of kurtosis and skewness, the model of non-Gaussian surface roughness is established by modifying the Gaussian distribution. It is found that the non-Gaussianity of surface roughness cannot be neglected especially for the journal rotating with a larger eccentricity ratio, the error of Gaussian distribution surface reaches 19.33% when the eccentricity ratio equal 0.7. The increasing of kurtosis would reduce the threshold speed, while the increasing of skewness would enhance the threshold speed. For a larger eccentricity ratio, the effect of kurtosis and skewness on threshold speed is more distinctly.