| Surface textures are certain patterns machined with defined sizes, shapes and arrays on frictional surfaces. In order to research the antifriction behavior systematically and to look for the optimum parameters of surface texture in connected with the specific condition and lubrication state, the paper launched tribology properties of surface texture with different shapes, sizes and area ratios under hydrodynamic and mixed lubrication state considering the influence of surface roughness theoretically and experimentally. And more complicated including variable area ratios and double textured surface were also studied experimentally. The results have important implications on improving tribololgy theory and guiding design and application of surface texture.The tribology performance of surface texture under hydrodynamic lubrication was studied by solving the Navier-Stokes(N-S)equation by means of computational fluid dynamics (CFD) primarily, where the Fluent software was used. The importance of inertia was indicated, and it was found that there is certain relationship between amplitude of pressure variation curve and performance of surface texture. The larger the magnitude, the better of the performance of the dynamic pressure generally. In addition, it is not conducive to improving the performance of surface texture when swirl appears in fluid region. The depth of surface texture when the swirl begins to appear is corresponding with the optimal depth of surface texture. The Reynolds equation is suitable for the theoretical study on surface texture instead of the N-S equation when L/h0 is not larger than 46, while the cavatition must be considered.On the basis of the scope of application of Reynolds equation, the tribology performance of surface texture under hydrodynamic lubrication when L/h0 is not less than 46 was studied by solving Reynolds equation with Visual Fortran. Studies show that there are certain relationships between the optimal depth and diameter of surface texture, that is, the larger the optimal depth, the larger the optimal diameter; The depth to diameter ratio cannot be used as the only characterization size parameter on the effect of friction coefficient, but when the aspect ratio is between 0.005-0.01, the corresponding friction coefficient will be smaller. The design model of optimal parameters of the oval cross-section texture was developed and the correctness of the model was verified through experiment.The tribology performance of surface texture under mixed lubrication considering the surface roughness effect was investigated with the introduction of the average Reynolds equation developed by Patir and Cheng. It was found that, the optimum parameters of surface texture do not vary with the direction parameter changes; the optimum diameter of surface texture increased with the composite root-mean-square (rms), which is the same as the optimum depth whenσis not less than 0.5μm; while the optimum area ratio is not related to the composite rms. The design model of optimal parameters considering the surface roughness was developed and the correctness of the model was verified through experiment.A series of experimental research were carried on complicated including variable area ratios and double textured surface in the final part of the paper. The results show that, the texture with various area ratios has a great potential on improving the antifriction properties under the reciprocating motion, especially in the situation with heavy load and high speed, the design of which should be in accordance with the principle that the area ratio increasing from the middle to the ends of the region. While the double textured surface can not improve the properties of frictional pairs under various loads and lubrication states with rich or lean oil. |
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