This paper uses three lubrication models to explore the differential phenomenon in the status of thin film lubrication (TFL). According to the viscous adsorption theory, the modified Reynolds equation for thin film elastohydrodynamic lubrication (TFEHL) is derived. In this theory, the film thickness between lubricated surfaces is simplified as three fixed layers across the film, and the viscosity and density of the lubricant vary with pressure in each layer. Under certain conditions, such as a rough or concentrated contact of a nominally flat surface, films may be of nanometer scale. The thin film elastohydrodynamic lubrication (EHL) analysis is performed on a surface forces (SF) model which includes van der waals and solvation forces. The results show that the proposed TFEHL model can reasonably calculate the film thickness and the average relative viscosity under thin film EHL. The adsorption layer thickness and the viscosity influence significantly the lubrication characteristics of the contact conjunction. The differences in pressure distribution and film shape between surface forces model and classical EHL model were obvious, especially in the Hertzian contact area. The solvation force has the greatest influence on pressure distribution.

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The pure squeeze magneto-elastohydrodynamic lubrication (MEHL) motion of circular contacts with an electrically conducting fluid in the presence of a transverse magnetic field is explored under constant load condition. The differences between classical elastohydrodynamic lubrication and MEHL are discussed. The results reveal that the effect of an externally applied magnetic field is equivalent to enhancing effective lubricant viscosity. Therefore, as the Hartmann number increases, the enhancing effect becomes more obvious. Furthermore, the transient pressure profiles, film shapes, normal squeeze velocities, and effective viscosity during the pure squeeze process under various operating conditions are discussed.

This paper presents a novel experiment method to investigate the microscopic mechanism of the oil film under the pure squeeze elastohydrodynamic lubrication (EHL) motion. An optical EHL squeeze tester is used to measure the interference fringe patterns of the contact region. In order to show the dimple thickness clearly, the grayscale interferometry method is employed to obtain the film thickness map. In addition, the effects of squeeze speed, load, and lubricant viscosity on the dimple film thickness are explored under a quasi-static condition.

This paper analyzes theoretically the contact length derived from elastic-plastic mechanics and microcontact theory with the aim of improving the traditional method of predicting roughness factor though experiments. The accuracy of the analysis is verified through experiments. It transpires from the theoretical model that the contact length between a grinding wheel and a workpiece increases with decreasing curvature radius of peak, increasing hardness of the workpiece as well as increasing depth of cut. It is also revealed that the contact length is directly proportional to the square of 0.32 of the hardness, approximately, whilst the square root of surface roughness and the density of peak of the grinding wheel show less influence on the contact length. The analysis method has reduced the variation between predicted and experimental values than that of the old methods. These results will be beneficial in analysing and designing the product quality of grinding.