Simulation And Experimental Study On The Influence Of Surface Texture Parameters On Lubrication Performance

Reasonable surface texture design can significantly improve the tribological properties of sliding friction pairs.However,the textured topography studied at present is relatively simple,and the synergistic effect between the textures of array arrangement is not clear,especially the studies considering cavitation effect are rather scarce.Therefore,in this thesis,numerical simulation and experimental methods were used to study the morphology parameters and distribution patterns of surface texture under the condition of cavitation effect.In numerical simulation,a three-dimensional micro-texture calculation model considering cavitation effect was established.CFD method was used to simulate the oil film bearing capacity,friction coefficient and pressure distribution under different texture depth,area density and surface shape.Different texture arrays were designed to study the influence of different distribution patterns on the oil film bearing capacity.In terms of experiment,cavitation images were collected by using a visual experimental bench to study the growth characteristics of texture-induced cavitation bubbles and the influence of different surface textures on cavitation bubbles.Meanwhile,the tribological properties of the textured array were measured to verify the rationality of the simulation study,and the friction reduction mechanism of the textured array was further analyzed.The results show that cavitation is one of the main reasons for the micro-texture to improve the oil film bearing capacity,which can not be ignored in the simulation study.With the increase of texture depth(area density),the bearing capacity of oil film first increases and then decreases,and the friction coefficient first decreases and then increases,which means the texture has the optimal depth and area density.With the increase of the slip velocity of the upper wall,the optimal depth of the texture tend to decrease while the optimal area density tend to stabilize.The surface shape of texture with confluence can improve the bearing capacity of oil film,and the higher the speed,the more obvious the effect of improving lubrication.The texture array whose distribution mode is monosymmetric orientation is most beneficial to the improvement of oil film bearing capacity,and the bearing capacity is the best when the tilt Angle is 26.6°.The experimental results are consistent with the simulation results.The friction coefficient of the monosymmetric orientation texture array is reduced by 29.4% compared with that of the sample without texture,and the main reason for the friction reduction of the micro-texture array is the increase of the oil film thickness.In addition,it is found in the experiment that the textureinduced cavitation bubbles have a growth process that gradually increases to a steady state.The composition of the bubbles is mainly the air precipitated from the lubricating oil,and the surface shape of the texture will affect the morphology of the cavitation bubbles.