Dynamic analysis of a rigid rotor supported by three-pad hydrostatic squeeze film damper lubricated with ferrofluid

This work describes an analytical study on the dynamic behaviour of a three-pad hydrostatic journal bearing lubricated with ferrofluids. Each pad is fed with an external pressure through a capillary restrictor-type hydraulic resistance. Ferrofluid or magnetic fluid is a colloidal dispersion of magnetic nano-particles in a carrier liquid. In this study, a non-linear method was performed using Jenkins model in order to investigate the effect of ferrofluids lubrication on the vibrations amplitude and the transmitted forces of hydrostatic squeeze film dampers. The results presented in this paper showed that the ferrofluid lubrication is useful in controlling the bearing vibrations and transmitted forces. The results illustrated in this work are expected to be quite useful to the bearing designers.     

液体静压主轴油膜滑移现象的分析及试验研究

针对液体静压主轴运动过程中动态特性问题,研究微尺度下油膜滑移对轴承承载力,刚度及动态刚度的影响。把微尺度下发生的速度滑移引入到油膜性能方程中,结合液体静压主轴系统平衡方程推导出了主轴系统承载力、刚度及动态刚度表达式,研究了油膜初期主轴静动态性能及油膜动刚度特性。从仿真结果中得到油膜滑移的发生使得承载力及刚度增大,最大刚度对应油膜厚度减小。最后刚度检测试验间接得出了实际主轴系统油膜流动过程中,存在油膜微滑移现象。本项研究为液体静压主轴微尺度下油膜滑移现象及性能的研究探索了一条新途径。     

大功率船用柴油机主轴承负荷与润滑性能的数值分析

主轴承是柴油机的主要摩擦副之一,其工作时的润滑状态直接影响船舶柴油机整机的工作性能。特别是在大功率低中速船用柴油机中,主轴承连续工作时间更长,负荷更大,工况更加恶劣,难以形成良好的动压润滑。因此,论文以9缸G32大功率船用柴油机为例,对各段主轴承的轴承载荷,轴心轨迹,最小油膜厚度进行了计算分析,为判断各道主轴承的润滑情况,精确预测轴承性能,以及判断轴系是否存在异常工作情况提供了依据。     

Calculation of oil‐film thickness in journal bearings running at varying rotational speeds

There are many methods of calculating the properties of lubricated hydrodynamic sliding bearings running at variable loads, but, in some cases, sliding bearings of heavy‐duty machines run under constant load and at variable speeds; this can lead to reduced film thickness in the bearing and boundary lubrication. The minimum oilfilm thickness in such a bearing needs to be calculated so that the proper lubricant viscosity can be selected to reduce solid‐solid contact during machine operation. In this study, a method is presented for calculating the film thickness of sliding bearings operating with alternating rotational directions. The results of the calculations show that the squeeze effect can develop enough load‐carrying capacity to prevent solid‐solid contact between the rubbing surfaces during operation, provided the change of direction of rotation is quick enough.     

Load‐carrying capacity of lubricated and dry sliding elements

The factors influencing the load‐carrying capacity of tribological contacts are reviewed. The load‐carrying capacity depends in part on the lubrication regime, and hydrodynamic, hydrostatic, and elastohydrodynamic lubrication are discussed. In some circumstances, lubrication is not possible. The parameters of dry rubbing are described, and approaches to the design and operation of dry bearings are discussed, particularly the choice of suitable non‐metallic materials for use in the wear couple.