Calculation of friction coefficient and temperature field of line contacts lubricated with a non-Newtonian fluid

摘要

In the present paper a model for the fast numerical prediction of the friction coefficient and the temperature field of such contacts is introduced. Motion and energy equations are numerically solved taking into consideration the non-Newtonianbehavior of the lubricant assuming a power law rheological model. The viscosity is calculated in every point of the film as a function of the local temperature and pressure. The introduced model relies primarily on two simplifying assumptions. First thepressure distribution is taken semi-elliptical over the entire contact area. Consequently the film shape is assumed to be parallel having a constant film thickness. For its calculation a modified version of the Sadeghi-McClung formula is presented, whichtakes into account the slip rate. Second the effect of the surface roughness is neglected, since, in the operating region considered, no asperity interactions take place. In order to examine the influence of these assumptions on the accuracy of theproposed model, calculated values of the friction coefficient were compared to measured ones, obtained from experiments carried out on a two disks test rig. This comparison showed very good correlation of the calculated with the measured coefficients offriction, justifying the introduced model.