Influence of Surface Roughnesson the Mixed Elastohydrodynamic Lubrication Performance of Gear Contact Area

Most practical engineering rough surfaces approximately follow non-Gaussian distributions. Surface roughness characteristics play an important role in gear lubrication performance. An elastohydrodynamic lubrication (EHL) model for involute gears was developed by simplifying the contact between meshing tooth surfaces of spur or helical gears as a three-dimensional infinite line-contact model. By using the proposed model and non-Gaussian random roughness surfaces generated by numerical method with given parameters based on FFT, the meshing process of spur and helical gears was analyzed. The film thickness, contact area ratio and contact load ratio of contacting points were obtained as well.The results show that a small skewness improved the lubrication state under sufficient oil conditions; instead, while for a oil starvation, the lubrication status became worse when the skewness decreased. However, in all cases, a greater kurtosis provided a better lubrication state.