涡轮膨胀机止推轴承—转子系统的振动分析

为了确保涡轮膨胀机止推轴承在受到瞬时冲击时不致发生损坏事故，研究了止推轴承－转子系统的轴向瞬态过程，计算了止推轴承的线性油膜刚度系数和阻尼系数，并对线性和非线性两种情况下的轴向瞬态响应作了分析与比较，为止推轴承－转子系统的可靠性评估提供了科学依据。     

滑动油膜轴承动态特性系数的迭代识别法

本文主要研究油膜轴承动态特性系数的现场识别方法,针对现场识别无法施加人工激振、测点较少,转子不平衡量未知,测点偏离轴承中心等实际限制条件,文中提出一种迭代识别法,直接利用转子不平衡响应(位移时间历程)来识别实际工况下油膜轴承的动态特性系数,最后通过计算机仿真算例分析,取得了满意的结果.     

挤压油膜阻尼在储能飞轮转子支承系统中应用研究

在飞轮储能系统实验研究中,利用永磁轴承-螺旋槽流体动压锥轴承的混合支承,并采用了挤压油膜阻尼为转子支承系统提供阻尼。基于流体润滑理论的雷诺方程和长轴承近似理论,推导出一端封闭、一端开口边界的挤压油膜的压力分布近似解析解,得到等效油膜刚度和阻尼系数。最后对比分析了飞轮转子支承系统不平衡响应的计算与试验结果。     

狭缝节流气体静压轴颈—止推轴承静脉特性分析

在气体静压轴颈－止推轴承的离散化过程中，采用有限元方法，利用加权余量法将其二阶偏微分方程降低一阶，使利用三角单元线性插值函数成为可能，简化了压力分布方程式的计算，给出了轴承的静态特性，分析了结构工艺尺寸、狭缝宽度和轴承间隙等因素对径向和轴向承载性能的影响，揭示了轴颈和止推轴承之间的相互影响规律，并且研究了轴承内部气膜压力分布的规律，最后，通过实测值对计算结果进行了验证。     

轴承非线性油膜力的一种变分近似解

基于自由边值理论和凸集上的变分方法，提出一种求解当轴颈大扰动时实际轴承瞬态油膜力的近似公式。公式中引入一个参数来模拟油膜破裂自由边界（雷诺边界条件），则凸集上的泛函极值问题就转换为求此参数的代数极值问题。对椭圆轴承在轴颈作大范围扰动情况下的计算结果表明，这一方法达到了很高的精度，可用于转子－轴承系统的非线性动力分析，能大量降低数值计算瞬态油膜力所需的计算量。     

推力轴承各耦合动特性系数对转子横向振动状态的贡献

系统地研究了推力轴承各耦合动特性系数对转子横向振动状态的贡献。计算结果表明，推力轴承对转子横向振动状态的影响主要由推力盘摆动而产生的耦合动特性系数所决定，而由平动所产生的耦合动特性系数对转子振动状态影响的贡献很小，可以忽略。     

考虑密封的悬臂转子系统的裂纹故障分析

以双盘悬臂立式转子-轴承系统为研究对象，建立了系统运动微分方程，并用数值方法分析了在非线性密封力和非线性油膜力作用下的裂纹转子的动力学特性。分析表明，在一定深度裂纹下，转子系统响应随不同角频率比表现出复杂的非线性现象，出现了周期k运动、拟周期运动和混沌运动等多种运动形式。在一定角速度时，工作在远离临界角速度区的转子系统对裂纹非常敏感，而工作在近临界角速度区的转子系统对裂纹不是特别敏感，但是裂纹对它的运动状态影响较大。该研究结果为该类转子-轴承系统的安全运行与故障诊断提供了一定的理论参考。     

狭缝节流气体静压轴颈-止推轴承静态特性分析

在气体静压轴颈 -止推轴承的离散化过程中 ,采用有限元方法 ,利用加权余量法将其二阶偏微分方程降低一阶 ,使利用三角单元线性插值函数成为可能 ,简化了压力分布方程式的计算 ,给出了轴承的静态特性 ,分析了结构工艺尺寸、狭缝宽度和轴承间隙等因素对径向和轴向承载性能的影响 ,揭示了轴颈和止推轴承之间的相互影响规律 ,并且研究了轴承内部气膜压力分布的规律 .最后 ,通过实测值对计算结果进行了验证     

油膜支承转子系统动静件碰摩特征分析

以支承在油膜轴承上的Jeffcott转子为对象，分析了油膜力对碰摩转子动力学行为的影响。通过与刚支情形对比，发现油膜力是耦合作用于碰摩转子系统，有时能够抑制振动，有时却加剧振动。因此实际转子碰摩故障诊断过程中，必须在充分考虑支承情况的基础上建立合理的非线性动力学模型，才能为实际转子系统的碰摩故障分析提供必要的理论依据。     

带有两端支座松动故障的转子系统的振动分析

应用现代非线性动力学理论，分析了带有两端支座松动故障的转子-轴承系统的复杂运动现象。模拟结果表明：带有两端支座松动故障的转子-轴承系统运动在未到共振区时以周期运动为主，在过共振区后，运动形式以拟周期和混沌为主，两个松动支座的振动在一定程度上相互抑制。同时，当支座发生松动时，轴颈的轴心轨迹以及支座的Poincare截面图和相轨迹都呈现出特殊的形状，并且这些形状又随松动支座的振幅是否达到最大间隙值而有所不同。上述结论可望为转子-轴承系统的松动故障的研究及故障诊断提供理论参考。     

有限长滑动轴承非线性油膜力的近似解法

本文中提出了一种求解有限长径向滑动轴承非线性油膜力的近似解析方法.在滑动轴承-转子系统非线性动力行为分析中,油膜力计算模型通常采用"π"油膜假设,但是,实际工况中油膜的存在区域并非是"π"区域,运行时油膜中出现气穴,破裂成条纹状(即具有Reynolds边界条件).本文中的近似解析方法采用Reynolds边界条件,基于变分原理,运用分离变量法求解油膜的压力分布,其中油膜压力的周向分离函数通过无限长轴承的油膜压力分布获得,油膜的破裂终止位置角通过连续条件确定,轴向分离函数运用变分原理并结合周向函数求得.计算结果表明:本文中提出的方法和有限元方法的结果吻合得很好.在此基础上,分析了一些轴承参数对油膜压力分布的影响.     

Dynamic response of a rub-impact rotor system under axial thrust

A model of a rigid rotor system under axial thrust with rotor-to-stator is developed based on the classic impact theory and is analyzed by the Lagrangian dynamics. The rubbing condition is modeled using the elastic impact-contact idealization, which consists of normal and tangential forces at the rotor-to-stator contact point. Mass eccentricity and rotating speed are used as control parameters to simulate the response of rotor system. The motions of periodic, quasi-periodic and chaotic are found in the rotor system response. Mass eccentricity plays an important role in creating chaotic phenomena.     

推力轴承瞬态启动油膜热不稳定性的线性分析

以简化推力轴承为对象 ,理论上证明了推力轴承运行时存在热不稳定性 ,采用小扰动分析法得到了油膜温度的扰动方程 ,应用简正模态分析法推导了无量纲热不稳定性准则数以及推力轴承运行的热不稳定性准则 .     

滑动轴承非线性油膜力的神经网络模型

在已有的滑动轴承非线性油膜力数据库基础上 ,将轴承的位置和速度参数加以综合 ,利用变量状态空间变换将分段的油膜力数据转换成连续的数据空间 ,建立非线性油膜力连续型数据库和相应的网络模型 .以圆轴承 -转子系统为例 ,分别采用有限差分法、数据库法和 BP网络模型计算了轴承系统的非线性油膜力和轴心轨迹 .结果表明 ,网络模型计算结果与基于数值方法的结果较为吻合 ,可以显著地提高轴承系统的计算效率     

轴向磁悬浮轴承的力学特性分析

介绍了五自由度电磁轴承系统中轴向磁悬浮轴承的各种可能受力情况,及其位移传感器的安装位置在分析上述情况时的作用;同时讨论了轴向磁悬浮轴承对径向轴承的影响,分析了一般情况下径向位移传感器的安装位置对轴向和径向轴承间静态和动态力耦合以及系统稳定性的影响。分析结果表明位移传感器的安装位置对电磁轴承系统的稳定性分析有着重要的影响,也是分析设计此类轴承必须考虑的因素之一。     

Bearing Load Measurement in a Hydropower Unit Using Strain Gauges Installed Inside Pivot Pin

To determine a machine’s mechanical condition it is of importance to know the radial bearing forces in the machine. Radial forces are caused by magnetic pull forces in the generator, clamped shafts, mass unbalance and flow properties around the turbine. Measuring the shaft displacement in the bearing or the bearing housing acceleration is not sufficient for status determination of a vertical hydropower unit. It is the magnitude and frequencies of the radial forces in combination with structure properties which give information as to whether a measured value is harmful or not. This paper presents an alternative method for measurement of radial bearing load in a hydropower unit. The method presented in this paper is based on strain measurements on pivot pins. The pivot pins are placed behind the bearing pad and the radial loads acting on the pad propagate through the pivot pin. New pivot pins were purchased and equipped with strain gauges. The new pivot pins were calibrated and a transfer function between applied load and measured output voltage was identified for each pivot pin. After calibration the pivot pins were installed in a vertical hydropower unit. Measurements were performed for several different operating modes of the hydropower unit. To verify that the measured load levels were of right order of magnitude, the radial bearing loads were calculated from numerical simulations of bearing properties and shaft eccentricity measurements. The two methods for determining bearing load showed almost the same results. This indicates that either method can be used to determine bearing load.     

Lubrication of a rotating circular thrust bearing with a casson lubricant

Lubricants today are subjected to increasing mechanical shearing forces. This has resulted in an increasing interest in materials having variable viscosity. The problem of rotating circular thrust bearing is investigated with Casson fluid as a shear thinning lubricant. The pressure and load capacity of the thrust bearing is calculated when the feeding is done from the centre of the plates to the periphery. Also, moment of friction acting on the plates is calculated for different values of Casson number and for various values of ratio of inside to outside radius. It has been found that there is a decrease in the value of load capacity of the Casson lubricant. Also, it has been observed that there is an appreciable increase in the values of moment of friction for Casson fluid.     

可倾瓦径向滑动轴承支承的转子系统瞬态响应计算

研究了可倾瓦径向滑动轴承支承的转子系统瞬态响应的计算方法,提出了可倾瓦径向滑动轴承非线性滑膜力计算的数据库方法,将可倾瓦与轴颈的结构和运动参数归结到三个参数中,建立了起可倾瓦的非线性油膜力数据库,通过精确插值到每一运动参数组合下轴承提代的油力和轴瓦上所受的油膜力矩。     

Dynamic modeling and analysis of a spur planetary gear involving tooth wedging and bearing clearance nonlinearity

Tooth wedging, also known as tight mesh, occurs when a gear tooth comes into contact on the drive-side and back-side simultaneously. Tooth wedging risks bearing failures from elevated forces. This work studies the nonlinear tooth wedging behavior and its correlation with planet bearing forces by analyzing the dynamic response of an example planetary gear. This planetary gear is representative of a wind turbine geartrain. A two-dimensional lumped-parameter model is extended to include tooth separation, back-side contact, tooth wedging, and bearing clearances. The results show significant impact of tooth wedging on planet bearing forces for a wide range of operating speeds. To develop a physical understanding of the tooth wedging mechanism, connections between planet bearing forces and tooth forces are studied by investigating physical forces and displacements acting throughout the planetary gear. A method to predict tooth wedging based on geometric interactions is developed and verified. The major causes of tooth wedging relate directly to translational vibrations caused by gravity forces and the presence of clearance-type nonlinearities in the form of backlash and bearing clearance.