Quantifying the inlet pressure and shear stress of elastohydrodynamic lubrication

Central film thickness in elastohydrodynamic lubrication is governed by lubricant properties in the low-pressure contact inlet. A relevant definition of pressure-viscosity coefficient would require knowledge of the maximum inlet pressure. The maximum inlet shear stress determines if the Newtonian assumption is valid. Using numerical simulations, the maximum inlet pressure is found, wherein changes in viscosity continue to influence film thickness. It is found to depend on operating conditions, and it ranges from 50 to 185 MPa. The maximum inlet shear stress is found to reach up to 2 MPa. Analytical formulas are offered for predicting maximum inlet pressure and shear stress. These allow for a refined definition of the pressure-viscosity coefficient, restricted to a clearly-defined contact inlet.