A method for investigating the pure squeeze action in an isothermal elastohydrodynamically lubrication (EHL) problem, i.e., circular contacts lubricated with couple stress fluid, was developed. A constant load condition was used in the calculations. The initial conditions such as pressure profiles, normal squeeze velocities, and film shapes were obtained from the classical hydrodynamic lubrication theory at a specified large central film thickness. The coupled transient modified Reynolds, elasticity deformation, and load equilibrium equations are solved simultaneously. The simulation results reveal that the effect of the couple stress is equivalent to enhancing the lubricant viscosity, thus enlarging the film thickness. The effect of couple stress in thin film lubrication varies with film size. That is, the thinner the lubricating film is, the more obvious the effect of couple stress is. For larger characteristic length, materials parameter, and load, the central pressure, central film thickness, and rigid separation are larger than those of smaller characteristic length under the same load. The time needed to achieve maximum central pressure and the Hertzian pressure increases with increasing characteristic length.

Surface texture plays an important role in improving the tribological properties of materials. In this paper, the effect of different shapes (i.e., triangle, square, hexagon, round) on the tribological performance of cross-grooved texture was investigated. First, the mixed lubrication condition was used for the pin-on-disc rotating sliding tests. Then, the stress distribution of the four textures was analyzed to better explain the experimental results. Overall, the hexagon-textured specimens exhibited lower friction coefficients than the other shape-textured specimens under the examined conditions. Simulation results indicate that the contact stress can be reduced on the surface of hexagon-textured specimens, and this leads to a better oil film for lubrication. Furthermore, the hydrodynamic lubrication stood out with the increase of speeds to 250 rpm. However, as the test loads further increased, the film thickness decreased, resulting in the increase in the asperity contact areas, which dropped the above advantage of hexagon-textured specimens. This study would be beneficial for the texturing tribological and lubrication design.

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.

In recent years, the China’s rapid economic development and living standards of people have been improved, and the usage of clothing, food, housing, and transportation has increased. However, due to the prevalence of sports injuries and their high frequency of incidence, sports injury incidents do occur from time to time. Sports injury will not only affect the normal training of athletes and sports enthusiasts but also adversely affect their health. An estimation model of sports injury is designed based on an improved recursive neural network algorithm to reduce the incidence of sports injury in the process of physical exercise so that athletes and sports enthusiasts can reduce sports injury, which is conducive to physical health and sports health.