基于油膜厚度测量的纹理表面润滑中气穴效应的研究

By the microfabrication techniques, many types of surface texture can be manufactured on one or both sides of friction pairs to improve the lubricating property. By now, the design of surface texture is almost based on the engineering experience or the friction measurement. Due to the lack of direct measurement of film thickness, there is no consistency conclusion on some lubrication mechanisms, such as the local hydrodynamic effect and the cavitation effect. Recently, the reported research results indicate that the influence of cavitation on the lubricating property of surface texture in microscale, can not be ignored. For example, the inlet suction mechanism put forward by Fowell holds that cavitation enhances the entrainment of lubricant. By optical measurement of oil film thickness in this project, cavitation in the conformal contact with surface texture will be studied in the following lines: (1) A piezoelectric actuator is used to position the film thickness at high precision, and the load is measured in the presence of cavitation so that the inlet suction mechanism can be validated; (2) Several factors that are related to the existence of cavitation are identified; (3) By comparison between the measured film thickness and the numerical result, proper ranges of bulk modulus of the lubricant and the cavitation pressure are clarified; (4) The JFO (Jakobsson-Floberg-Olsson) model is proved to deal with these problems. The development of this project will help to promote the research of lubrication mechanism with surface texture. The results of this research are very important for the lubrication design of precision machineries and micro systems.

微细制造技术能够在摩擦表面构筑各种纹理以增强润滑。目前表面纹理的设计多基于工程经验和摩擦力的测量。由于缺乏膜厚的直接测量，对某些润滑机制尚无一致性结论，包括纹理的局部流体动压效应及气穴效应。近年来，研究发现气穴对微尺度下表面纹理中的润滑性能产生了不可忽视的影响，例如Fowell提出的入口吸入机制强调气穴区的作用，认为负压增强了润滑油的卷吸作用。本项目借助润滑油膜的光学测量，对面接触表面纹理润滑中的气穴效应进行研究：1）利用压电陶瓷促动器实现膜厚的精准定位，对接触区油膜承载力进行测量，验证入口吸入机制；2）明确表面纹理润滑中影响气穴的几个关键因素；3）通过比较膜厚测量值与数值计算结果，确定润滑油的弹性体积模量和空化区负压值的合理变化范围；4）验证JFO理论模型的合理性。本项目的开展将有助于推动表面纹理润滑机制的深入研究，为精密机械和微系统的润滑设计提供必要的试验依据和理论支持。

微细制造技术能够在摩擦表面构筑各种纹理以增强润滑。目前表面纹理的设计多基于工程经验和摩擦力的测量。由于缺乏膜厚的直接测量，对某些润滑机制尚无一致性结论，包括纹理的局部流体动压效应及气穴效应。近年来，研究发现气穴对微尺度下表面纹理中的润滑性能产生了不可忽视的影响，例如Fowell提出的入口吸入机制强调气穴区的作用，认为负压增强了润滑油的卷吸作用。本项目借助润滑油膜的光学测量，对面接触表面纹理润滑中的气穴效应进行了系统研究：1）利用光学反馈测量系统作为系统实现膜厚的精准定位，对接触区油膜承载力进行测量，可定性验证入口吸入机制；2）明确了表面纹理润滑中影响气穴的几个关键因素：表面形貌，润滑油和卷吸速度等；3）通过比较膜厚测量值与数值计算结果，确定了润滑油的弹性体积模量和空化区负压值的合理变化范围；4）通过分别测量4种凹槽表面和4种表面纹理的微型滑块与玻璃盘间油膜厚度，研究了气穴对表面织构润滑性能的影响；利用Visual Fortran和商业软件Fluent对实验结果进行了数值分析，研究结果验证了JFO理论模型的合理性。本项目的开展将有助于推动表面纹理润滑机制的深入研究，为精密机械和微系统的润滑设计提供必要的试验依据和理论支持。