Modified Reynolds Equations for High Viscosity Surface Layer and Thin Film Lubrication Analysis of Tapered/Tapered Land Bearings as Models of Surface Texture

Abstract

The development of thin film lubrication theory is vital for future micro-textured lubrication technologies. Therefore, a modified Reynolds equation was derived in this research by incorporating the variable viscosity effect in a tribochemical adsorbed layer. The modified factors of the Reynolds equation were expressed as closed form functions for a one-sided viscosity function determined from the measured effective viscosity. Using the one-dimensional modified Reynolds equation, the load capacity and friction coefficients of micro-tapered/tapered land bearings as texture models were numerically investigated. By performing a parametric study with different viscosity ratios (10 and 100), taper lengths (10, 50, and 250 µm), taper angles, and land length ratios and a surface layer thickness of 10-nm, it was found that a high load capacity and an extremely low friction coefficient of less than 10–4 on the stationary surface could be achieved with a bearing gap of a few tens of nanometers. Since the surface height irregularities between the textures can be compensated for by the elastic deformation caused by high pressures, the lubrication regime in a parallel textured slider can be realized if the roughness heights on the mating surfaces are reduced to less than the bearing gap, using the running-in process.

Keywords

• modified reynolds equation
• thin film lubrication
• tribochemical layer
• high viscosity surface layer
• surface texture
• super low friction coefficient
• tapered bearing
• tapered land bearing