Numerical analysis of elastohydrodynamic lubrication with bio-based fluids

Abstract

During the last couple of decades, the level of public considerations of increasing world energy crisis and environmental issues in various industrial applications has risen, including in the application of lubricants in machine elements. In this study, a numerical approach was developed to investigate the feasibility to use vegetable oils as lubricants in application of roller element bearing, namely elastohydrodynamic lubrication (EHL), especially for the contact between the inner ring and the cylindrical roller element. This simulation solved Reynolds equation simultaneously with elastic deformation and pressure-viscosity equation to analyse EHL pressure and film thickness. In this simulation, some vegetable oils were used as lubricants and results were compared with mineral oils and synthetic oils that are available in the market. It was discovered that in the condition of W = 2.0452 x 10-05, U = 1.0 x 10-11, and T = 40oC, camellia oil was the best vegetable oil to replace mineral oil or synthetic oil because the maximum pressure working on the contacted surfaces of roller element bearing was lower than those of other vegetable oils. However, all simulated vegetable oils can be used as lubricants based on their pressure profiles and film thicknesses. The effects of some parameters, such as applied load, speed and temperature on the pressure distributions and film thickness profiles were also studied for all vegetable oils. The results demonstrated that the pressure and film thickness increased as the speed and load increased, but the increase of the temperature caused the pressure and film thickness to decrease.