Theoretical and Experimental Investigations on EHL Point Contacts with Different Entrainment Velocity Directions

Abstract

Film thickness prediction plays an important role in evaluating the performance and durability of machine elements under elastohydrodynamic lubrication (EHL). However, current formulae may not be appropriate for general conditions occurring in real contacts. This study investigates the effect of different lubricant entrainment velocity angles on film thickness distribution. For this purpose, a steady-state isothermal EHL model is used under a wide range of parameter sets including varying sum velocity, contact pressure, and sum velocity angle. Considerable differences in the trend of the central film thickness with respect to the lubricant entrainment velocity angle for low and high loaded contacts are shown. The results are compared with experimental measurements by means of an optical ball-on-disc tribometer and a twin-disc machine using capacitance method. Good agreement between numerical results and experimental measurements was found.

KEY WORDS:

• Elastohydrodynamic Lubrication
• Film Thickness
• Velocity Directions
• Numerical Analysis
• Capacitance Method
• Optical Interferometry

ACKNOWLEDGEMENTS

The authors express their thanks for financial support from the European Social Fund and the state budget of the Czech Republic (No. CZ.1.07/2.3.00/20.0126). The authors also thank the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, HO 1339/34-1) for their kind sponsorship of this research.