The Influence of Surface Texturing on the Frictional Behaviour in Starved Lubricated Parallel Sliding Contacts (original) (raw)
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In industrial applications, a starved lubrication condition may occur, leading to a reduction in film thickness; by modifying the surface geometry, the tribological performance of the contact is enhanced. In this paper, the influence of surface texturing as a method for reducing the friction on the film thickness in parallel sliding surfaces for starved lubricated contacts is investigated. The results in this study have shown that surface texturing can improve film formation for starved lubricated contacts and, respectively, the load carrying capacity. The effect of starvation on several texturing patterns with several texturing properties was investigated and the film thickness for these conditions was studied. With the numerical algorithm developed and taking cavitation into consideration, the effect of shape, depth, size, and texture pitch on the film thickness was studied.
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Considering the influence of wall slip on fluid flow is important for many engineering topics involving liquid-solid interfacial phenomena, such as flow through porous media, liquid coatings and lubrication. Boundary slip can act as a method to reduce friction in lubricated contacts. Furthermore, surface texturing can also play a positive role to enhance the film thickness. Therefore, combination of these two methods can be beneficial in order to improve the tribological performance of lubricated contacts. Although, in recent years the study of frictional behaviour of surface with boundary slip is getting more attention, the combination of these two methods of surfaces properties modification is interesting to investigate. For the no-slip boundary condition, the first layer of fluid molecules has the same velocity as the contacting solid surface and this condition has been widely applied in the field of fluid mechanics. In lubricated contacts with boundary slip, the first layer of the lubricant molecules move with a different velocity from that of the solid surface. In this article, the frictional behaviour of boundary slip in parallel sliding lubricated contacts for textured surfaces is investigated. This study shows that boundary slip has a significant influence on the film thickness in case of textured surfaces. Furthermore, it is possible to increase the film thickness, and enhance the frictional behaviour by modifying the boundary slip parameters.
The Influence of Surface Texturing on the Film Thickness in Parallel Sliding Surfaces
In many industrial applications, a modification of the surface geometry can enhance the tribological behavior of contacts to a favorable condition. In this paper, the effect of surface texturing on the film thickness in parallel sliding surfaces is investigated. It is shown that surface texturing can improve film formation and as a result the load carrying capacity. With the numerical model developed and by considering cavitation, the effect of shape, depth, size and textured area fraction on the film thickness is studied. Further, the optimum size for the most beneficial texturing pattern with respect to film thickness is discussed.
Effectiveness and design of surface texturing for different lubrication regimes
Meccanica, 2012
The aim of the present research work was to investigate the possibilities of designing surface texturing for different lubrication regimes and to evaluate its effectiveness, especially under starved, boundary and mixed lubrication regimes. This was achieved by combining an experimental tribological investigation with a surface-roughness analysis, a 2D FEM simulation and fluid dynamic modelling. The tribological investigation under unidirectional and reciprocating sliding was focused on the effect of the laser-texturing parameters-including the dimple depth and size, the dimple area density and the contact size-on the coefficient of friction under different lubrication regimes, achieved by varying the sliding speed, the normal load and the lubricant viscosity. The results of this investigation show that under starved lubrication conditions the textures resist sliding, resulting in increased friction, as was also indicated by the FEM simulation. Only when a very
Effect of Surface Texture on the Sliding Pair Lubrication Efficiency
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The paper presents certain problems related to the lubrication of textured surfaces. It was noted that for a specific load, the lubrication effectiveness will depend on the shape, size and mutual distribution of the texture’s elements. Proposals for determining the lubrication irregularity parameters were presented for textures with a rectangular mesh and round recesses. The experimental part presents the laser texturing methodology, tribological testing methodology and preliminary test results where the significant role of the relationship between the trajectory of motion and the texture mesh was demonstrated.
Role of Surface Texture on Friction under Boundary Lubricated Conditions
Tribology Online, 2008
Ensuring effective lubrication between sliding surfaces is one of the challenges in the field of tribology. In addition to the conventional parameters like speed, load, contact geometry and material parameters, the surface texture also influences the coefficient of friction. In the present investigation, the effect of surface texture on coefficient of friction under boundary lubricated condition was studied by sliding Al-4Mg alloy pins against EN8 steel discs of various surface textures using pin-on-disc machine. Both isotropic and directional textures were generated on the surfaces of the discs. Scanning Electron Microscopy and optical profilometer studies were carried out on the contact surfaces of both the pins and discs before and after the experiments. The result showed that the coefficient of friction varied considerably with surface textures. In addition, maximum value coefficient of friction was observed when pins slid perpendicular to the unidirectional texture and minimum when pins slid on random texture. Backscattered scanning electron micrographs revealed the transfer of iron from the disc to the pins and it was highest when pins slid perpendicular to the unidirectional texture and least for the random texture. However, no transfer layer of Al-Mg alloy was observed on the steel disc.