Temperature Effect on Load Distribution, Friction, and Wear of a Grease-Lubricated Spherical Roller Bearing (SRB)

Abstract

This article investigates the effect of temperature on the lubrication and wear behavior of a grease-lubricated spherical roller bearing (SRB) assuming mixed-elastohydrodynamic lubrication (mixed-EHL) where the contact load is shared between the lubricant film and contact asperities. Temperature effects on internal load distribution and elastic modulus and their subsequent effect on the wear are also analyzed. The effect of temperature is investigated, first on the film thickness and load sharing, and then on the friction and wear. If the temperature rises from ambient to 110 °C, the increase in the contact patch dimensions, due to the decrease of elastic modulus, is only approximately 1% and the decrease in mean contact pressure is approximately 2%. Moreover, the load at $\psi =0°$ decreases by approximately 4%, and the load zone increases by approximately 5%. As the temperature rises from 50 to 110 °C, the asperity portion of the contact load at $\psi =0°$ position is increased by 350%. At 50 °C, only 20% of the total traction is contributed by the contact asperity, which is 80% at 110 °C. For the temperature rise from 50 to 110 °C, the wear volume loss increases by 238% and nonlinearly, due to viscosity reduction and its effect on the reduction of film thickness. The isolated change of internal load distribution and elastic modulus due to temperature rise causes a relatively insignificant change in wear. Hence, the predominant effect of temperature rise on wear is due to a decrease in lubricant film thickness causing the asperity component of the contact load to increase.

Keywords:

• Friction coefficient
• wear
• rolling element bearing
• load sharing
• mixed lubrication
• temperature–internal load distribution
• temperature–elastic modulus

Acknowledgements

The authors gratefully acknowledge the financial support provided by the Rail Manufacturing CRC under the Axle Bearing Maintenance Optimization Project.