Solution agreement between dry contacts and lubrication system at ultra-low speed

The Reynolds equation has been widely applied in lubrication analyses, but the extent and limit of its application have not been fully explored. Great efforts have been made so that the solution convergence speed and accuracy are significantly improved. However, while the working conditions are severe, such as extremely heavy load, low speed, and low viscosity due to temperature increase, the lubricant film thickness becomes very thin and surface contact may occur. As a consequence, the lubrication solution becomes difficult. Contact and thin-film or mixed lubrication under severe conditions are of great importance, as many components operate in such regimes. This article investigates the solution evolution of the Reynolds equation as the entraining velocity decreases, using the unified mixed elastohydrodynamic lubrication (EHL) model presented by Hu and Zhu. By comparing the ultra-low speed solution of the Reynolds equation with that of dry contact analysis, it is found that the solution of the Reynolds equation finally converges to those of the corresponding dry contact under otherwise the same operating conditions. The results manifest that with the unified solution approach the Reynolds equation system can be used to handle the situation of dry contact and mixed lubrication, in which both hydrodynamic lubrication and surface contact coexist.