导　　师： 黄平

学科专业： 080203

授予学位： 博士

作　　者： ;

机构地区： 华南理工大学

摘　　要： 弹流润滑摩擦副接触区内部及摩擦副间油膜压力、温升和接触区亚表层的应力测量是弹流润滑领域的基础问题，研究表明虽然弹流润滑的理论建模及数值模拟分析水平已经达到了很完善的水平，建立的理论模型能计算出弹流润滑的膜厚、压力及温升分布，但弹流润滑实验测量问题尚未完全解决，弹流润滑接触区的油膜压力、温升和接触区亚表层的应力分布尚无理想的测量方法。结合当前光弹性测试技术发展，作者首次提出了用光弹性方法进行弹流润滑油膜压力分布、温升和接触区亚表层压力分布测量研究。研究成果对进一步阐明弹流油膜承载机制，揭示摩擦副的失效机理，对摩擦学设计、摩擦材料的制备及润滑设计的性能评价具有重要的指导意义。 通过对目前的弹流润滑膜厚测量技术的优缺点进行逐一分析，对弹流润滑的压力和温度测量技术进行综述，指出目前的弹流润滑测试技术主要是膜厚测量技术，而弹流润滑压力测试技术存在不足。颈缩现象和二次压力峰是弹流润滑的重要特征，而通过实验测量颈缩和二次压力峰也是弹流实验的一大难点，经过众多弹流研究科学家的努力，多年来尚无特别完善的实验测量方法。本文首次提出应用光弹技术，利用光弹性材料制作摩擦副，进行弹流润滑压力测量。主要研究工作包括以下几点： 1/)通过对光弹应力分析理论基础的介绍，分析光弹性理论中条纹级数与入射光波长的关系，结合弹流润滑接触区的压力分布及尺度特点，从理论上证明了可以应用光弹性技术来测量弹流润滑压力。 2/)搭建了弹流润滑光弹测量实验台，并通过实验台进行了弹流润滑压力的测量，实验结果初步证实了通过光弹性进行弹流润滑压力测试实验的可行性。分析了此实验台存在的不足，对实验台进行了结构、加载方式、光源等改进，通过对比白炽灯、荧光灯及LED照明光源的实验效果，确定了采用荧光灯为实验台的照明光源，并引入了菲涅尔透镜作为准直镜。 3/)对不同工作压力和滑动、滚动速度状态的润滑压力分布进行了试验，并对实验结果进行了分析对比。光弹性实验结果的应力条纹需要进行定级，而弹流润滑应力区的条纹级数通常较高。尽管进行条纹定级的方法很多，但是人工神经网络在进行光弹条纹定级方面有着独特的优势。通过人工神经网络对弹流润滑光弹实验结果进行了条纹的定级。 4/)光弹技术应用于弹流润滑测量实验结果为应力差，为进一步分析，需要进行主应力的分离。光弹应力分离方法包括数值法、实验方法和混合法等三大类，数值法主要是剪应力差及基于LAME-MAXWELL方程的应力分离法、解补偿方程法；实验方法有：钻孔法、斜射法、条带法和条纹涂层法及划线法；混合法主要是基于求等和线法的各类方法和近期出现的数字散斑相关法和红外热成像法。通过分析各种光弹应力分离技术的优缺点，指出目前大部分的光弹应力分离技术均无法直接应用于光弹性弹流润滑压力测量实验，只有红外热成像技术可以较方便地进行弹流润滑光弹实验主应力的分离。 5/)最后研究了基于红外成像技术的热应力分析原理，总结了由红外热成像信号到实验试样内部应力和的相关计算公式的推导。搭建了基于红外成像技术的弹流润滑时变热分析实验系统，采用光弹实验进行纯滑动摩擦方式，进行了石蜡油、二甲基硅油和润滑脂三种不同粘度系数的润滑剂润滑下的动载摩擦热测量实验，获得了不同载荷和滑动线速度实验条件下的摩擦区表面及亚表层温升数据。 通过对比分析实验结果，可以认为实验结果正确地反映了载荷对温升的影响趋势，证明了基于红外热成像仪的弹流润滑热应力分析是可行的。 Measurements of the pressure distribution of EHL film, the temperature rise and thestresses in the friction pair are the fundamental issues for EHL study. There have beenenormous progresses both in the theoretical modeling and numerical research since the firstsolution to elastohydrodynamic lubrication problem bring out. Maps of film thickness,pressure and temperature can be obtained by solving numerical model simultaneously orseparately. But the pressure measurement problem is not been solved completely, becausethere is no ideal solution to acquire the transient pressure distribution of EHL film and innerfriction pair and the temperature rise. By combining the development of photoelastic measurement technical the applicantpropose to adopt photoelastic experimental technology to measure the pressure distribution ofEHL film and inner friction pair. Merits and disadvantages of EHL film thickness measurement technique was analyzed，as well as EHL pressure and temperature measurement technology. The above analysisdemonstrates that the main EHL experiment technique is film thickness measurement ratherthan pressure measurement. Although film thickness reduction and pressure spike in lubricantexit region is key feature of EHL contact, it is difficult to obtain it experimentally. Despite thetremendous effort of EHL scientist it still far from perfect EHL pressure measurement method.In order to measure EHL pressure, photoelasticity was purposed by apply experiment samplemade by photoelastic materials. The main innovative work complete in this paper include asfollows: 1/) Through analysis of the theoretical basis of photoelastic stress analysis, fringe orderand the wavelength of incident light, combined with the characteristics of pressuredistribution and scale of EHL contact area, it is theoretically proved that the feasibility ofapplication of photoelastic technique to measure the elastohydrodynamic lubrication pressure. 2/) The Photoelastic Measurement Experiment platform of elastohydrodynamiclubrication has built. The Measurement of elastohydrodynamic lubrication pressure wasconducted and the result proved the experiment method practicable. In order to overcome theshortcoming of the first stage experiment rig, the structure, load mode and light source havebeen improved. By comparing the result of filament lamp, fluorescent light and LED lightsource, fluorescent light source was adopt as experiment rig light source. Fresnel lens isintroduced as a collimating lens. 3/) Experiments of EHL pressure distributions under various speeds and loads have beenconducted and the result been analysis. Fringe order identify is the key issue of photoelastic result analysis. Although there are multiple methods to label the fringe order, artificial neuralnetwork has prominent potential in high order fringe process. Thus an artificial neuralnetwork has been built to analysis the experiment result. 4/) The photoelastic experiment results in fringe map are related to the principal stressdifference and usually they need to be separated for further analysis. There are three kinds ofmethods to separate the principal stresses. They are the numerical method, experiment methodand hybrid method. The numerical method is mainly based on the difference of shear stress,and the stress separation solution is based on LAME-MAXWELL equation and thecompensation equation. The experimental method includes drilling process, oblique incidencemethod, stripe coating technic and slitting. The hybrid approach can supply isopach such asthe digital speckle correlation method and the infrared thermal imaging technique. Throughthe analysis of the advantages and disadvantages of various photoelastic stress separationtechnology, the present paper points out that the infrared thermal imaging technology can bemore easily separated the photoelastic experiment stress of elastohydrodynamic lubrication. 5/) Finally, the principles of the infrared imaging technology of thermal stresses have beenstudied and summarized and the formulas are dealed with the signal from infra imagers forthe sum of the principal stresses. A time varying EHL experimental system based on the infraimager has been built up. An experiment with photoelastic sample in pure slide line contactand lubricated by paraffin oil, polydimethyl siloxane fluid and grease is carried out. The resultdemonstrates that the different slide speed and load pressure correctly lead to temperaturerising differently.

关 键 词： 弹流润滑实验 光弹性 压力测量 红外应力测量

分 类 号： [TH117.2]

领　　域： [机械工程]