考虑弹性变形的不同综合曲率下的滑动副油膜计算

本文介绍了考虑滑动副中较软元件弹性变形及贫油状态的滑动副承载能力计算,其中变形计算采用了半无限体法,并参照联邦德国Bernd Schaude著作采用了简化的处理方法,大大简化了计算过程,且便于利用油压分布计算中的差分格式。为了保证计算精度,减少计算时间,采用了合理划分网格,合理选定计算顺序和设法加速收敛等措施。     

用耦合分析法研究内燃机活塞环-气缸套传热润滑摩擦问题

在以往对活塞环-气缸套润滑摩擦性能的研究中,大都忽略了活塞组-气缸套间的导热,或者将导热过程简化,这与该摩擦副的实际润滑摩擦状况相去甚远.把柴油机缸内燃气、活塞、活塞环、润滑油膜、气缸套、冷却介质作为一个耦合体,考虑各部件间及相应物理场间的耦合关系,采用耦合分析法建立了活塞环-气缸套的三维非稳态热混合润滑摩擦模型.该模型以三维瞬态热传导模型、动压润滑模型和润滑油膜传热模型为基础,并考虑了润滑油的黏温变化、燃烧室燃气泄漏、表面粗糙度、油膜破裂位置以及气缸套圆周方向上的非轴对称性等影响因素.采用上述模型,对6110型柴油机活塞环-气缸套摩擦副进行了传热、润滑、摩擦耦合分析,得到了活塞组-气缸套的温度场,并用试验证实了耦合模型的正确性;与此同时,得出了润滑油膜的温度、黏度、最小油膜厚度和摩擦热随曲轴转角和活塞环周向高度的分布曲线.     

我国地域经济差异与人口迁移研究

改革开放后的区域经济差异持续扩大是促动我国人口迁移空前活跃的主要因素,而日趋活跃的人口迁移亦对区域经济差异产生均衡作用。本文通过测算我国1985-2000年各省区在人口迁移前后“人口—GDP”的基尼系数变化,验证了人口迁移对区域经济发展不均衡的减缓作用。在此基础上,测算区域经济达到均衡状态下的各省区理论人口和人口迁移潜力,并重点分析了县一级行政地域的理论人口和人口迁移潜力分布。     

A high shear rate, high pressure microviscometer

The development of a high shear rate, high pressure microviscometer is described. This viscometer was developed specifically to examine a highly loaded, dynamic contact generated in a small volume of fluid. The viscometer was used to examine the fluid film formed by the mechanism of elastohydrodynamic lubrication in the presence of an SAE 50 oil. A complete numerical analysis of the resulting elastohydrodynamic contact was performed.     

The effect of nitrogen and sulphur compounds on extreme pressure lubrication

This paper reports the synthesis of hydroxyheptadecyl-substituted-1,3,4-thiadiazoles and mercapto-1,2,4-triazoles and the evaluation of extreme pressure activity of their admixtures (0.5% and 1% w/ v) with a paraffinic oil in a four-ball test. Alloy steel bearing balls of 12.7 mm diameter were used as test specimens. All the additives exhibited good activity in reducing wear and increasing the values of mean Hertz load (MHL) and flash temperature parameter (FTP) as compared to the base fluid. The presence of p-methoxy- and p-chloro- groups in the thiadiazole and mercapto triazole rings has been found to enhance the activity of these additives. Scanning Auger Electron Spectroscopy surface studies were conducted to analyse the additive-metal interaction.     

Kinetics and mechanism of iodide-film growth on lead-effect of short-circuiting and higher-valent dopant

The effect of a higher-valent dopant like Sb on the iodination rate of lead under normal and short-circuit conditions in iodine pressure of 0.615–6.578 kPa and in the temperature range of 423–523 K has been investigated. Like pure Pb, Sb-doped Pb also follows the parabolic law of film growth. The isothermal parabolic rate constants are found to be enhanced due to the presence of Sb. The iodine-vapor-pressure dependence of the isothermal parabolic rate constant has been observed to be k_ppI ₂ ^1/2 . This has been explained on the consideration of electron-hole migration across the film as the rate-limiting step. The activation energy for iodination of Sb-doped Pb under normal condition is estimated to be 64 kJ · mol^–1 in an iodine pressure of 0.615 kPa. The rate of iodide-film growth has been found to increase considerably under a short-circuit mode of experiments. Such observations have been explained with the concept of ion migration as the rate-limiting step for the film-growth process. The iodine pressure dependence of rate constants under short-circuit conditions is observed to be k_pI ₂ ^1/3 , associated with an activation energy value of 51 kJ mol^–1. The effect of putting additional resistances in series to the short-circuit Pt path during iodination of Sb-doped Pb is found to be similar to that observed for pure Pb. Results of the present study have been explained considering the prevalence of Schottky-Wagner type of point defects in the lead-iodide film. Wagner's electrochemical potential gradient has been confirmed to be the main driving force for the film-growth process. Iodide films have been characterized by SEM, EDS, EPMA, XRD, and AES analyses to substantiate the kinetics results.     

超固体润滑及其在微机械电子系统中的应用前景

介绍了超固体润滑的概念 ,综述了超固体润滑的研究现状和近年来的研究成果 ,通过对微机械电子系统摩擦学问题的讨论 ,分析了超固体润滑在微机械电子系统中应用的前景 ,阐述了超固体润滑技术在微机械电子系统中应用的发展趋势     

速度、油量对滚动直线导轨副摩擦力的影响

利用Stribeck曲线和Hamrock Dowson的最小油膜厚度计算公式,分析速度与润滑油量和摩擦力的关系。分析结果表明：在一定工况下,当速度由小到大变化时,滚动直线导轨副的润滑状态会经历边界润滑、混合润滑和弹流润滑3个阶段,摩擦力先减小后增大;润滑油量越多,直线导轨副在相对较好的润滑状态下工作,摩擦力就越小。通过滚动直线导轨副综合性能试验台,研究速度与润滑油量对滚动直线导轨副摩擦力的影响。结果表明：在高速运行下,速度对摩擦力影响较大;同时在注油量不断增加至注满的过程中,摩擦力大小先急剧变小,然后摩擦力曲线变化趋于平缓,此时的供油量即为最合适的润滑油量。     

表面织构创新设计的研究回顾及展望

近十年来,作为一种可以显著提高界面性能的方法,表面织构已成为国内外界面科学领域的一个研究热点。微细加工技术的进步,使得通过精确控制织构的形状和尺度,优化其界面性能成为可能;仿生技术的发展为表面织构设计提供了源泉;对表面织构作用机制的深化理解促使了其应用领域的扩展。目前,表面织构的应用已涉及减摩、抗磨、增摩、减振、抗粘附、抗蠕爬等多个领域。TRIZ理论认为实现发明创新的基本原理和规律是客观存在的。人们如果掌握这些原理和规律,就可以能动地进行设计和创新,其结果具有预测性和可控性。对表面织构的研究进展进行了综述,从TRIZ理论的角度进行了归纳和总结,并通过TRIZ理论对表面织构研究的发展趋势进行了展望。