The Role of Thermoelastic Effects in the Scuffing Failure of Rolling/Sliding EHD Contacts

Abstract : A two-dimensional numerical solution of the thermal Reynolds', elasticity, and energy equations resulted in predictions of the flow velocities and temperatures within the lubricant film between a crown roller and a rotating shaft. The results showed a good agreement with previously measured experimental data on the surface temperatures in an EHD contact and on the resulting frictional torques for both rolling and sliding. A pressure and temperature dependent viscosity was assumed for the synthetic paraffinic hydrocarbon used in the experiments. This model allowed an evaluation of the relative importance of the generation, viscous dissipation, and compression terms in the energy equation at different stations along the mid-film line of contact. Based on the insight about the relative importance of terms as found in the numerical simulation, convenient expressions were developed for an approximate method of predicting the mid-film temperature and sliding friction force. The influence of thermal expansion of the contact between a crowned surface in sliding contact with a rotating cylindrical surface was included in a model of thermoelastic instability to predict the onset of scuffing failure. The simplified approach assumed a heat balance between the generation from friction and the heat conducted into the cylinders.