Analysis on minimum oil film thickness of EHL elliptical contacts by using multilevel methods

HAMROCK and DOWSON have developed a simplified expression for influences of ellipticity parameter, dimensionless speed, load, and material parameters on minimum film thickness. However, EHRET shows that his numerical results by using multilevel method have a large difference as compared with the simplified expression under point contact (a ball on a plate configuration). This paper developed a new simplified expression. The influence of the ellipticity parameter, the dimensionless speed, load, and material parameters on minimum film thickness was investigated from low pressure level (0.35 GPa) to high pressure level (3.43 GPa). The ellipticity parameter was varied from one to eight. The dimensionless speed parameter was varied over a large range. The dimensionless load parameter was varied over a range of four orders of magnitude. Conditions corresponding to the use of solid materials of bronze, steel, and silicon nitride and lubrications of paraffinic and naphthenic mineral oils were considered for the dimensionless material parameter. Four hundred different cases were calculated for the new simplified expression.