Analysis of thermal dynamic micro-EHL considering bearing assembly temperature

To investigate thermal failure of dynamic oil film in cylindrical roller bearings(CRBs), based on the temperature field of CRBs, non-Newtonian dynamic thermal elastohydrodynamic (TEHL) lubricating performance in cylindrical roller bearings was conducted. A single surface bump was coupled with longitudinal waviness on the roller surface, and a dynamic non-Newtonian finite line contact TEHL model was established considering the boundary temperature of the bearing assembly. Effects of the roller boundary temperature, the surface bump amplitude, the rotational speed, and the viscosity-pressure coefficient on thermal failure were analyzed. Comparison of lubricating performance between Newtonian and non-Newtonian fluid was made as well. Results show that, when the roller boundary temperature increases, the pressure and the oil temperature become larger, and the film thickness and frictional coefficient decrease obviously for roller to outer race contact. As the surface amplitude is large enough, or the rotational speed is low enough, phenomenon of partial contact between the roller and the outer ring may be generated due to high boundary temperature of solids. In addition, when the rotational speed is very low, the temperature of the roller surface reaches the first critical temperature of the adsorbed film, so thermal film failure may occur for roller to outer race lubrication.