Research On Sliding Surface Micro-Circlation Bionic Lubrication Effect And Local Failure Mechanism

The gap between the engineering sliding surface and the smooth surface is constant, which may not form the wedge shape to meet the sufficient and necessary condition for sliding surface generate the hyrodynamic lubrication. And its lubrication state depends on the surface texture distribution such as Abbott support area curve. Therefore, the biomimetic grid-textured surface is designed based on the bionic principle and its geometry parameters affected on the lubrication characteristic is investigated. The micro lubrication pressure is used to compensate for the macro lubrication without hydrodynamic phenomena. The results reveal that micro circulation lubrication in local area and its failure mechanism. The research project has been supported financially by National Natural Science Foundation and National Ministry of Education Doctoral Foundation of China.The research designed various grid-textured surfaces and the microfabrication technique was taken as the research object to fabricate the surface in this dissertation. The mathmatic model was used to represent its topography.In order to research the miro-hydrodynamic lubrication effects of the bionic grid surface. The flow visualization hydrodynamic lubrication experiment was carried out for each of various different geometry parameter of grid textured. The film thickness and friction coefficient and lubricant flow characteristic were tested. Then a simulation model is developed to analyze the mirco-circulation phenomenon. It reveals that the grid-textured surface helps build up micro-pressure at the intersection points of each rhombus cell. The pressure peaks help improve the lubrication of frictional pairs. It deduces that the mutual effect between the working condition and bionic grid textured surface and the hydrodynamic lubrication form condition.A phenomenon of a local failure mechanism for grid texture surface’s micro-hydrodynamic elastic lubrication is caused by the lubrication discontinuous of the bionic grid surface. The Hertz theory and material relationship were used to descript the elastic deformation of the friction surface, based on the theory analytical of the micro roughness’s elastic contact model. Then the micro circulation elastic lubrication of the fractal surface was further established. It reveals that the effective between the surface topograph and the lubrication property. And the self-lubricating composite was adopted to solve out the local failure affected by the physic properties. The research shows that the method can significantly reveal the failure machinsim of the hydrodynamic lubrication by the coupled effects of porosity and surface fractal dimension. This model can provide a basis design theoretical for design of the sliding friction material and suface grid texture.In order to study the local failure mechanism during the mirco circulation lubrication sliding process, the work research on the deformation and unstability of micro elastic region. A fractal rough surfaces sliding contact model has been developed, which takes into account temperature rise and distribution. The finite-element method and thermal conduct theory are employed as the analytical methods. The model is used to analyze the local failure of the surface generated by typical rough surfaces and investigate the factors of thermal effects on the tribological performance of surface asperities. The results yield insight into the local failure mechanism and working condition (especially the high load and high velocity). The research provides a basis theoretical for lubrication failure of the friction surface on the sliding process under the extremly working condition.In order to investigate the lubrication state affected by the grid-textured, the study provides set of optimal design model based on the geometry parameters as dimensionless length, depth and angle of the grid textured surface. Effect of the grid textured surface on frictional performance was investigated by it. The results show that micro-cycle grid texture sliding surface can decrease friction coefficient effectively, and the geometry parameters have couple effects on the lubrication characteristic. The theoretical approach established providing a rudimental method for optimizing the design of grid textured surface.