面接触油膜润滑测量系统

介绍了一种能够实现面接触油膜润滑测量的试验系统,该系统以静止的刚性滑块和旋转的透明玻璃盘组成润滑副。滑块的定位采用柔性并联机构,可进行面接触倾角的微小调节。油膜厚度测量采用多光束干涉技术。照明采用激光外部同轴照明,可有效扩大图像视场和膜厚的测量范围。利用该系统测量了恒倾角面接触薄膜润滑的膜厚特性和摩擦力特性,结果与已有理论有较好的一致性。     

Measurement of Sub-Nanometer Lubricant Films Using Ultra-Thin Film Interferometry

The ultra-thin film interferometric method of measuring the thickness of very thin films in lubricated contacts has been refined so as to be able to measure films down to 0.3nm with a standard deviation of 0.15nm. The main remaining source of measurement variation for films below 3nm thick is the surface roughness of the contacting solids. This modified technique has been applied to study the film-forming properties of three fluids, hexadecane, a dilute solution of surfactant in hexadecane, and cyclohexane. Purified hexadecane shows a very slightly enhanced oil-film thickness below 1nm. The long-chain surfactant forms a boundary film 2nm thick. Cyclohexane behaves as though it forms a surface layer about 1nm thick with viscosity three times the bulk fluid viscosity.     

基于电容法与光干涉法相结合的油膜测量方法

通过将电容法膜厚测量仪耦合在球-盘点接触光干涉试验台上,搭建油膜厚度测量装置。通过对目标球-盘接触副采取合理的导电措施以及台架绝缘设施来保证润滑油膜电信号的提取,该装置可实现相同工况下膜厚度值及其相应的电信号(如油膜分压值和电容值)。在纯滚动接触情况下,分别对油润滑和脂润滑下的油膜进行测量,得到光干涉膜厚、油膜分压值和电容值随随卷吸速度的变化规律,并分析接触副电容随膜厚的变化。结果显示,随卷吸速度的增加光干涉膜厚升高而油膜分压值和电容值减小,电容值随着膜厚的增加而逐渐降低。实验结果初步验证了该测量系统的可行性,可为后续实际接触副内润滑状态的评估提供方案。     

Measurement of the Rheology of Lubricant Films Within Elastohydrodynamic Contacts

There is growing need for a reliable model of the rheological response of lubricants in elastohydrodynamic (EHD) contacts, not only to predict behaviour in full-film EHD conditions, but also for use in modelling mixed-film lubrication. One barrier to developing such a model is that measurements of friction actually represent averaged values over the whole, lubricated contact under study. However the fluid film conditions of temperature, pressure and strain rate generally vary over such contacts, which makes it difficult to determine constitutive shear-stress equations from friction measurements. This paper examines the various different techniques used to study the origins of EHD friction and the underlying film rheology. It then describes and applies a technique for obtaining the temperature rise maps of both solid surfaces in a rolling-sliding EHD contacts and thus shear-stress and friction maps. The work shows that the shear stress of the traction fluid studied increases approximately linearly with pressure and decreases approximately linearly with temperature in the high-pressure central region of EHD contacts.     

对数母线滚子光弹流润滑的实验研究

为了研究对数母线滚子凸度量对滚子摩擦副润滑油膜的影响 ,本文在自制的有限长线接触光干涉弹流试验机上 ,测量了中载、富油润滑和纯滚动工况下对数修形圆锥滚子与玻璃盘之间的油膜形状与膜厚。实验结果表明对数母线轮廓滚子的凸度量对其端部的油膜厚度和膜形分布有较大的影响 ,在给定的工况条件下 ,存在一个使滚子轴向油膜厚度最为均匀的最佳凸度量 ,此最佳凸度量比在相同工况条件下用静弹性接触力学方法求得的最佳凸度量大     

自混合干涉微位移传感器

有许多测量微位移的光干涉方法 ,然而难以实现结构紧凑、价格低的测量系统 ,因为这些传统干涉方法都需要许多光学元器件。提出用激光自混合干涉术测量微位移 ,分析和讨论了自混合干涉信号的产生和处理方法 ,用快速傅立叶变换(FFT)相位探测技术分析自混合干涉信号 ,可提高相位测量精度。提出的传感器可以用于亚微米级位移的测量和控制 ,并给出了 PZT位移的实验结果     

干涉法测量多层透明膜系反射率

应用干涉法实现透明膜系反射率的测量。将待测膜系镀在两薄玻璃片上 ,并构成 F- P干涉仪 ,根据透射光谱的自由谱宽和干涉峰的半宽值 ,计算出膜系反射率 ,避免了光源波动对测量结果的影响。在实验中所用膜系的反射率小于 98%时 ,测量偏差小于 0 .0 0 4 %。     

波动供油条件下滚子副润滑性能分析

基于工程实际的供油条件,提出一种特殊的供油函数,对滚子副弹流润滑问题进行求解,定性模拟滚子副的特殊乏油现象,并分析供油函数中的参数与润滑油膜厚度和压力的关系.结果表明:供油油膜的波动导致滚子副接触区相应的压力、膜厚及部分油膜比例分布中也出现波动;随着乏油情况的加剧,供油波动对滚子副接触区的影响更大,使润滑效果更差;在一定的供油量下,波动供油的油膜波长越小,幅值越小,对乏油滚子副的润滑性能越有利.     

The Growth of Thin Lubricating Films of Plant Oils

The extreme conditions of high pressure and shear imposed in a lubricated sliding contact could influence tribochemical reactions that could occur over long sliding distances and time scales, possibly leading to changes in both friction and film thickness. Experiments conducted with 12 plant oils reveal for the first time, that thin lubricating films of some plant oils can grow to thicknesses much greater than what is predicted from either elastohydrodyamic theory or their adsorbed molecular heights. Some films grew as much as 25 times in thickness (unrefined canola oil), while others remained roughly unchanged (flaxseed and olive oil), or grew slightly and then collapsed during the test (safflower oil). The absence of a loss in film thickness and the viscoelastic-like behavior of the film when speeds are reduced to zero, support the view that polymerization could be the main mechanism of film growth. However, the lack of correlation between the degree of unsaturation and the film growth rate suggests that other mechanisms could also be at work.     

光反馈自混合干涉式微位移传感器

为了提高位移测量的精确度,提出了一种基于光反馈自混合干涉技术的位移测量方法.采用梯度最优算法分析和处理自混合干涉信号,达到数据理论的最佳拟合,实现微位移的精密测量,并通过设计算法对外部物体的运动轨迹进行重构.提出的传感器可用于亚微米级位移的测量和控制,并给出了PZT位移的实验结果.     

Bulk Modulus of Lubricating Oils as Predominant Factor Affecting Tractional Behavior in High-Pressure Elastohydrodynamic Contacts

The phase diagrams corresponding to transition from liquid to viscoelastic solid and that from viscoelastic solid to elastic-plastic solid of Santotrac100 (SN100), mineral oil, synthetic naphthenic oil, polybutene, and tetradecane were first made up by high-pressure density measurements and others. The bulk modulus of lubricating oils under a quasi-static condition was evaluated using a phase diagram. The results indicated that the bulk modulus of lubricating oils is closely related to the oil molecular packing parameter T _VE ?T (where T _VE is the viscoelastic solid transition temperature at pressure p, and T is the oil temperature). The constant values of the bulk modulus in the elastic-plastic range are different depending on the molecular structures of the oils. It has also been shown that SN100, mineral oil, synthetic naphthenic oil, and polybutene converted to amorphous solids at high pressures and tetradecane converted to molecular crystal. Next, the elastohydrodynamic lubrication tractions were measured by a ball-on-disk machine. The results indicated that the maximum traction coefficient is closely related to T _VE ?T. As a result, the importance of the bulk modulus as a predominant factor for traction characteristics of lubricating oil was pointed out.     

Estimation of Surface Temperatures Resulting in Disorientation of Boundary Lubricating Films

Estimation is considered of the temperature resistance of boundary lubricating layers during rubbing. A new experimental technique is proposed for evaluating the limiting temperature of lubricant disorientation on a metal surface with the use of electric current passing through the contact zone of a microtribometer. It is shown that this technique can provide more adequate modelling of rubbing conditions, in many cases, when compared with standard methods.     

用于纳米测量的扫描X射线干涉技术

介绍扫描Ｘ射线干涉仪在当前纳米测量技术中的重要意义,阐述了该技术的基本原理,全面介绍了国外在该领域的研究现状,并对影响纳米测量的扫描Ｘ射线干涉技术的主要因素进行了分析。     

Interferometry Measurement of Spin Effect on Sliding EHL

This paper describes interferometry measurement of the film profiles of sliding elastohydrodynamic lubrication (EHL) contacts with spin. In the custom-made EHL test rig, spin motion is introduced through adjusting the center offset of the ball-on-disc contact with respect to the disc rotation axis. A parameter, spin ratio S _sp, is employed to represent the spin level, which is defined as the ratio of the Hertzian contact radius to the center offset. Experimental results show that with spin the film shape is obviously skewed, and the film thicknesses at the two side lobes are no longer the same; therefore, the symmetry of the classical horseshoe film shape is lost. The film thickness dependences on entrainment speeds are significantly influenced by the spin ratio S _sp, and high spin ratios induce high speed indices. At a fixed spin ratio S _sp, with increasing sliding speeds the film thickness difference between the two side lobes becomes large, and the horseshoe film shape is more distorted. When applied loads are raised, more spin is introduced, film thickness decreases, and film shape is obviously twisted.     

基于散斑干涉的相位测量技术研究

本文对几种基于散斑干涉方法的相位测量技术进行了研究与比较,包括时间相移法、空间相移法、空间载波相移法以及空间载波傅立叶变换法,分析和比较了这些方法的优缺点,并对时间相移法和空间载波傅立叶变换法进行了试验研究。     

MoS_2基复合润滑薄膜的制备及其摩擦性能

采用磁控溅射法在不锈钢基体上制备了MoS2/Ni复合润滑薄膜,研究了添加DLC(类金刚石薄膜)中间层对于MoS2/Ni复合薄膜的影响,探讨了复合润滑薄膜的减摩机理;使用EDS与XRD测定了复合薄膜的主要成分和物相结构,使用多功能摩擦试验机测定了薄膜的摩擦因数.结果表明:复合薄膜的主要成分为MoS2和Ni;薄膜中主要晶面为平行于基面的(002)晶面;复合薄膜的摩擦因数在0.06～0.18之间变化,且在高速重载的环境下具有更低的摩擦因数和更高的摩擦稳定性;中间层的加入进一步降低了复合薄膜的摩擦因数,达到0.04左右.     

用双圆盘试验测试润滑油的高压流变性能

本文介绍了作者研制的双圆盘试验机，并测试了两种国产润滑油的弹流润滑膜的弹性特征对载荷，滚动速度及滑差的依赖性。测定的润滑膜剪切弹性膜量值覆盖了其他学者试验结果的范围。     

A Solution of the Thermohydrodynamic Problem for Exponential Lubricating Films

A solution of the Reynolds equation for finite bearings with exponential film shape and variable viscosity is presented. The field of temperatures is also investigated, by solving the Energy equation. Therefore, the uncoupling of Reynolds and Energy equations is obtained, by using a relationship between viscosity and film thickness. The solution may be used either for plane or convergent curved surfaces with a satisfactory accuracy, as shown by the diagrams of pressure and temperatures. The formulas are given in closed forms, either for adiabatic films or constant temperature boundaries, thus allowing rapid calculations. Furthermore, formulas for the overall characteristics are available, which may be directly used in bearing design.     

表面粗糙纹理对非牛顿热弹流润滑性能的影响

建立了考虑表面粗糙度的点接触热弹流润滑模型,假设滚滑工况下慢速运动的固体表面是粗糙的,而快速运动的固体表面绝对光滑.卷吸速度沿接触区短半轴方向,表面粗糙纹理以正弦函数来表征,润滑剂符合Ree-Eyring非牛顿流体粘性定律.通过完全数值求解,讨论了3种不同构成的粗糙纹理对弹流润滑性能的影响.其中2种是周期性时变问题,求解是从一个准稳态解开始逐个瞬时迭代来实现的.结果表明,粗糙纹理会使得接触区里对应处产生明显的局部高压,局部温升,油膜厚度也相应减小.而纵向粗糙度时润滑效果最差,因为具有更危险的最小膜厚值.