Purpose This paper aims to use the method of curve splicing to combine the slip zone and the no-slip zone to further improve the lubrication performance of the liquid film. The combination of the slip zone and the no-slip zone of an existing heterogeneous surface is still a single line stitching method so that a very large residual space at the surface of the friction pairs remains present, necessitating further improvement of the joining scheme between the slip zone and the no-slip zone in heterogeneous surfaces. Design/methodology/approach A set of discrete sinusoids is used as the splicing track for both the slip zone and the no-slip zone, the starting point and amplitude of the curve are introduced as the simulation variables and the effects of these variables on the bearing capacity and friction coefficient of the liquid film are comprehensively analyzed. Findings The results show that the method of selecting the sinusoidal curve as the slip zone and the no-slip zone trajectory, which is based on the existing method of linear stitching, can further enhance the bearing capacity and reduce the friction coefficient of the liquid film. Originality/value This method can further enhance the bearing capacity and reduce the friction coefficient of the liquid film.
This paper explores the synergy mechanisms that are associated with the coexistence of multiple textures, to improve the precision control of a hydraulic servo cylinder. Based on the classical Reynolds equation, it establishes a single-texture and a nine-texture model to compare and study the synergy of surface textures. The film thickness is obtained under different working conditions for 1 N. Based on this parameter, it compares the simulation results from the two models with the experimental results to determine if the friction coefficient is reduced when multiple textures exist. When multiple textures exist, the inlet pressures of the central texture increase, but the peak pressure and cavitation pressure decrease. The synergy of the textures acts as an 'average pressure' and causes the pressure to decrease, which directly decreases the shear force. As the area ratio of the texture increases, the beneficial effect from the synergy gradually increases and then decreases, which implies that there is an optimum area ratio. The depth of the texture was 10 μm and the optimum depth-to-diameter ratio was 0.009. When the speed increases for a light load, the oil film thickness increases. However, this phenomenon does not substantially change the synergistic effect.
The problem of shaft axial motion which significantly affects the lubrication performance has been a common phenomenon in journal bearing systems. The existing work involved in the solution of shaft axial motion is also very rare. In this study, we choose to examine the flow between sliding pair in which regard we present a unique heterogeneous surface consisting of a slip zone and a no-slip zone. The results reveal the following points: 1) By appropriately arranging the slip zone to change the angle between the borderline and the moving direction of the upper plate, it is possible to control the direction of the lateral traction in which the liquid film acts on the upper plate. 2) Exponent of the power function of the borderline and aspect ratio of the computational domain are large or small are not conducive to increasing the effect of lateral traction. For the object of this study, the final results of the optimization are shown that the lateral traction can account for 20% of the resistance.
A numerical solution for line contact elastohydrodynamic lubrication (EHL) occurring on the rough surface of heterogeneous materials with a group of particles is presented in this study. e film thickness disturbance caused by particles and roughness is considered into the solution system, and the film pressure between the contact gap generated by the particles and the surface roughness is obtained through a unified Reynold equation system. e inclusions buried in the matrix are made equivalent to areas with the same material as that of the matrix through Eshelby's equivalent inclusion method and the roughness is characterized by related functions. e results present the effects of different rough topographies combined with the related parameters of the particles on the EHL performance, and the minimum film thickness distribution under different loads, running speeds, and initial viscosities are also investigated. e results show that the roughness morphology and the particles can affect the behavior of the EHL, the traction force on a square rough surface is smaller, and the soft particles have more advantages for improving the EHL performance.
Reducing friction and wear in contact pairs is a formidable challenge in engineering applications. In this study, the influence of different particle distribution parameters on the flow field for elastohydrodynamic lubrication (EHL) friction pairs is analyzed using a multigrid method. In particular, the effects of the particle distribution density and location on the tribological properties are examined. A general Reynolds equation for an arbitrary non-Newtonian fluid is used to account for the non-Newtonian properties in the contact area. An inclusion-EHL model is established by coupling the flow field with the elastic field of heterogeneous particles below the contact surface, which are subject to eigenstrains. The results illustrate that the distribution density of the particles causes fluctuations in the film pressure and thickness and that the spacing ratio and position of the symmetry center have serious effects on the traction force. It is also found that the traction force can be effectively reduced by using a reasonable set of particle distribution parameters.
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