In situ pressure measurements in an elastohydrodynamically lubricated point contact using Raman microspectrometry. Comparison with numerical calculations

摘要

Raman microspectrometry has been applied to in situ pressure measurements in an elastohydrodynamically lubricated (EHL) point contact. An experimental set-up coupling a Raman spectrometer and an elastohydrodynamic ball on disc test rig has been developed. Pressure profiles and maps have been recorded under pure rolling conditions for a wide range of applied loads, rolling speeds and lubricant temperatures. The measured pressure profiles are compared quantitatively with numerical solutions of the isothermal EHL point contact problem. The good agreement obtained allows a validation of both the measurement method and the experimental set-up. Discrepancies between the experimental and the numerical profiles observed at high rolling speeds are attributed to inlet shear heating of the lubricant. The corresponding temperature rise is estimated. The evolution of the film thickness with speed is studied and the transition from isothermal to thermal regime is pointed out.