径向磁悬浮轴承结构特性研究及其模型的建立

本文分析研究了径向可控磁悬浮轴承的多磁极结构对系统模型的影响，推导并建立了一种新的考虑耦合作用的数学模型。     

水润滑赛龙轴承及其润滑性能综述

赛龙以其抗冲击、耐泥砂、耐磨损、承载力高而逐渐成为一种新兴的水润滑轴承材料。本文简单介绍了水润滑赛龙轴承材料的分类，论述了水润滑赛龙轴承的发展现状以及其结构、特性和优点，并阐述了水润滑赛龙轴承的研究现状和推广应用前景。     

Fault diagnosis as an aid to process machine reliability

Identification of the reasons for failures of process plant machines is the first step in obtaining increased reliability. Weibull analysis of the service life obtained from maintenance records requires a minimum of only five incidents and provides an insight into the failure mechanism. Two examples are given where Weibull analysis of maintenance records helped identify the cause of failure and was instrumental in achieving enhanced reliability of process plant machines.     

星载激光通信终端轴承预紧力及加载结构研究

星载激光通信终端通过方位、俯仰轴系的运动实现目标跟踪。轴系回转精度是二维转台实现良好工作的前提。通过对角接触球轴承模拟分析,确定卫星发射以及在轨运行时转台轴承的最优预紧力大小,通过轴承预加载结构实现轴承从高预紧状态过渡到轴承低预紧状态,解决了传统固定式预紧力不能同时满足两种工况的难题,即发射时大预紧力满足高刚度与基频,在轨运行时低预紧力以降低平均摩擦,扭矩噪音以及轴承接触应力。     

高速切削机床主轴轴承的研究与发展

基于高速切削中高速机床主轴用轴承的运动机理，本文着重从润滑、密封、预紧等方面阐述了滚动轴承的研究与发展，并明确了其与工程应用的关系。     

Experimental investigation of porous bearings under different lubricant and lubricating conditions

The performance of porous bearing under different lubricants and lubricating conditions was experimentally investigated in this study. In order to carry out the experiments, a new test rig was designed to determine the tribological properties of based sintered bronze journal bearings that were manufactured by powder metallurgy (P/M) techniques. To determine the effects of lubricating conditions with and without oil supplement (OS) on the tribological characteristics of these bearings under static loading and periodic loadings, some experiments were carried out using different lubricants. In the tests, pure base oil (SAE 20W50), two fully formulated commercial engine oils (SAE20W50) and lubricating oils with commercial additive concentration ratio of3% were used. The worn surfaces of test bearings were examined using optical microscopy. Experimental results showed that the change in friction coefficient was more stable and in smaller magnitude under static loading than that of periodic loading. In addition, the friction coefficient and the wear rate conducted with base oil resulted in higher values than those of fully formulated oils with and without OS lubricating conditions. The experimental results obtained in this study indicated that the correct selection of lubricant and suitable running conditions were very important on the tribological characteristics of porous bearings.     

片状转子磁悬浮控制系统的研究

转子轴向尺寸大幅缩小后形状趋于片状,轴向转动惯量与径向转动惯量之比增大,称为片状转子。片状转子磁悬浮轴承系统因陀螺效应而存在耦合,随着转子转速的升高,耦合现象也随之加强。针对片状转子的数学模型,基于交叉反馈算法,推算了轴向三控制点间的交叉反馈系数,对系统进行Simulink仿真,仿真结果表明以此算法为基础开发的控制系统能够完全消除因陀螺效应产生的耦合作用。实验对比了分散控制系统和交叉反馈解耦控制系统下控制电流和位移的幅值。交叉反馈控制系统下的控制电流和位移有明显减小。     

In-Situ,On-Demand Lubrication System for Space Mechanisms

Many of today's spaceraft have long mission lifetimes. Whatever the lubrication method selected, the initial lubricant charge is required to last the entire mission. Fluid lubricant losses are mainly due to evaporation, tribo-degradation, and oil creep out of the tribological regions.

In the past, several techniques were developed to maintain the appropriate amount of oil in the system. They were based on oil reservoirs (cartridges, impregnated porous parts), barrier films, and labyrinth seals. Nevertheless, all these systems have had limited success or have not established a proven record for space missions.

The system reported here provides to the ball-race contact fresh lubricant in-situ and on demand when the ball bearing is close to failure. The lubricant is stored in a porous cartridge attached to the inner or the outer ring of a ball bearing. The oil is released by heating the cartridge to eject oil, taking advantage of the greater thermal expansion of the oil compared to the porous network. The heating may be activated by torque increases that signal the depletion of oil in the contact. The low surface tension of the oil compared to the ball bearing material is utilized and the close proximity of the cartridge to the moving balls allows the lubricant to reach the ball-race contacts. This oil re-supply system avoided a mechanism failure, reduced torque to an acceptable level, and extended the life of the component.     

The Application of Nearly Embarrassingly Parallel Computation in the Optimization of Fluid-Film Lubrication©

The combination of powerful, yet inexpensive PCs and readily available open sources for parallel computation marks a new era of easy access to massive computation for the tribology community. The study demonstrates the applicability of embarrassingly parallel computation in the optimization of air-lubricated porous bearings with four design variables. To achieve high speedup without increasing the coding complexity, the master computer implements the lattice method to allocate the near-the-same computational load in the master-slave cluster. The effect of master capability on the cluster performance is also presented. The results are compared with that of an unparallelized simplex method and indicate a significant reduction in execution time due to parallelism. In a simulated analysis, a high speedup can also be obtained in dealing with a problem with many design variables. This study provides the framework for optimization of applications with complex tribological models to be solved with minimum execution time.     

Tribochemical Surface Reaction and Lubricating Oil Film

A radioactive tracer technique was used to investigate a tribo-chemical surface reaction obtained by a thrust collar type friction Machine. Radioactive dibenzyl disulfide labeled with sulfur-35 was used as an additive. Steel and copper disks were used as friction specimens.

Radioactive copper sulfide on the friction surface was quantitatively measured with a G-M tube, and a kinetical analysis of the reaction was carried out.

The friction coefficient decreased linearly depending on the amount of surface produced on the friction surface. This dependency was accompanied by adsorption of dibenzyl disulfide, which made a more effective lubricating oil film and was enhanced by the sulfide on the friction surface.

The results of kinetical analysis were explained effectively by considering the oil film behavior related to the adsorptive action of the surface sulfide.