A combined approach to study and model the effect of viscous heating in small porous, self lubricating journal bearings

Friction torque is one of the key performance parameters of journal bearings and it is strongly influenced by the temperature dependent lubricant viscosity. In small bearings, this temperature cannot be measured directly. Therefore, a combined experimental, numerical and analytical approach is used to determine the lubricant temperature for the application in instationary Stribeck measurements. The thermal model proposed returns temperature and it is verified by FE simulations. Based on friction measurements with a Newtonian reference oil and friction models, the change in temperature is detected in a second independent way as viscosity changes with temperature. Results are presented in function of speed, clearances and for both porous and nonporous bearings. Half-frequency whirling and its effect on friction was detected.