2024 Volume 19 Issue 1 Pages 87-94
It is possible to calculate the oil film thickness and the pressure distribution on the Hertzian contact surface of bearings, gears, traction drives, etc. by the EHL theory by Dowson et al.. For these calculations, it is important to determine the high pressure viscosity and high pressure density of lubricant. In a previous report, I constructed a theory of the relationship between viscosity, temperature and pressure. And the van der Waals type viscosity equation was derived. Similarly, in this study, I constructed a theory of the relationship between density, temperature and pressure. As a result, it was found from the dimensional analysis that 1/3 power of density (line density) was negatively proportional to temperature. This linear equation was found to be a van der Waals type line density equation which consists of three eigen constants: absolute zero line density ρt=01/3, line density constant 1/G and pressure constant H/G. Furthermore, the pressure constant H/G of the line density equation is equivalent to the PR of the liquid state equation and the pressure constant C/B of the van der Waals type viscosity equation. And I report the results of estimating the high pressure density of various lubricants by the line density equation.
