Quantitative Comparisons Between Measured and Solved EHL Dimples in Point Contacts

Using a mineral bright stock oil as lubricant, the dimple phenomena in the circular EHL contacts composed of a glass disk and a steel ball were investigated experimentally with the optical interferometry technique. The traction coefficient was also measured. The experimental results were compared quantitatively with the numerical results of the corresponding thermal Newtonian EHL solutions. The comparisons show that the Newtonian thermal EHL theory can explain very well the relationship between the dimple phenomena and the slide-roll ratio, but cannot predict accurately the depth of the dimple and the magnitude of the traction coefficient. It has also been found that the Newtonian flow model overestimates the effect of the temperature-viscosity wedge and consequently, a non-Newtonian flow model may be necessary for a better understanding of the EHL dimple phenomena.