基于振动信号的精密轴系状态监测及早期缺陷诊断

针对某执行机构用精密轴系磨损的监测及诊断问题,提出一种基于变分模态分解及能量分布的故障诊断方法,在对轴承振动信号进行变分模态分解的基础上,分析了各阶有限带宽模态函数分量的功率谱能量分布情况,并根据试验数据和分析结果确定轴承振动信号功率谱能量分布阶次可以作为轴承磨损的诊断指标,最后通过搭建的轴承组件振动状态监测系统验证了该方法的有效性。     

微速差双转子系统振动信号分离法研究

为了有效地对旋转机械进行现场动平衡，降低机器异常振动，需要准确得到不平衡量大小和相位。采用常规的解“拍”方法分离具有内外双转子系统的振动信号是十分困难的，尤其是转子间存在微小速差的情况。研究采用基准信号作触发，分别对内外转子进行同步采样，提出了一种不用解“拍”就可直接获取各转子振幅和相位的信号分离法。结合DSP技术，该方法成功地应用于双校正面双转子系统的现场整机动平衡。     

基于多通道振动信号的港机车轮轴承故障诊断

提出一种基于多通道振动信号的港机台车车轮轴承故障诊断的方法。通过分析港机台车车轮轴承的特殊性,阐述现有轴承故障诊断方法以及存在的问题,并指出了基于多通道振动信号分析方法的优势。描述了系统信号采集硬件构架,充分发挥现代计算机的高速运算,大容量存储能力,利用多进程并发,采用模块化思想,搭建了分析系统用户界面软件。通过时域、频域、功率谱、静态参数等多种信号分析方法对振动信号进行分析,实现对轴承的故障诊断。实时监测和离线分析大量现场数据结果表明,该故障诊断系统诊断方便,无需停工,成功率高,符合港机台车车轮轴承故障在线诊断要求。     

双转子系统内转子不同心频谱特性分析

采用Timoshenko梁建立双转子系统的有限元模型,再根据三弯矩方程计算内转子不同心引起的附加轴承载荷,将轴承载荷引入双转子动力学方程,最终建立内转子不同心的双转子系统动力学模型.采用Newmark-β法求解系统动力学方程,分析不同心对转子系统振动频谱的影响.搭建了双转子试验台对仿真结果进行验证.研究表明:内转子轴承的不同心将导致轴承载荷随标高量线性变化,轴承载荷会使内转子产生静态变形.不同心状态下的不平衡响应除引起内、外转子倍频振动外,还激起了多阶正向进动和反向进动的固有频率,导致双转子系统振动频谱更加复杂.     

航空发动机双转子系统碰摩故障振动特性研究

航空发动机转子系统的振动对飞机的飞行安全具有重要影响。文中针对某型航空发动机无中介轴承的双转子系统的结构特征,采用集中质量法建立了双转子-轴承-机匣耦合的动力学模型,分别对内外转子碰摩故障进行了仿真,通过轴心轨迹图、时域波形图、频谱图、庞加莱图分析了双转子系统耦合振动响应特性,提取了内外转子碰摩故障特征。研究成果可以为航空发动机振动状态监测和故障诊断系统提供理论支持。     

膜片联轴器耦合的不对中转子-轴承系统的不平衡响应分析

转子系统的不平衡是旋转机械最为常见的故障之一，它影响转子系统的振动品质。考虑了转子系统不平衡力的作用，建立了膜片联轴器耦合的转子-轴承系统的运动微分方程；并以膜片联轴器耦合的双跨转子-轴承系统为研究对象，分析了不对中状态下转子系统的不平衡稳态响应，重点讨论了两跨转子各结点之间的振幅差异，结果表明膜片联轴器具有显著的隔振效果。     

旋转式能量回收装置转速测量方法研究

海水淡化旋转式能量回收装置的转子转速最能直接体现装置的运转状态,但转子被外筒体完全包裹,转子转速无法直接测量。为此,对旋转式能量回收装置振动频率与转子转频进行了分析,提出了一种基于振动信号的旋转式能量回收装置转子转速测量方法。首先,通过实验采集了不同流量下装置的振动和转速数据,并且对装置振动频率与转子转频进行了分析,发现了装置振动主要频率与转子8倍转频有良好的对应关系,建立了振动主频与转子转频的关系式;然后,在此基础上研究了从振动信号中获取转频信息的信号处理与转频计算方法,包括使用小波变换消除振动信号中的基线漂移,利用包络法进行了信号解调以凸显转频信息,为了准确地计算旋转式能量回收装置转子的转速,通过振动能量估计了转频的范围;最后,为了对该转速测量方法的准确性进行验证,在实验平台上对其进行了实验。研究结果表明：在装置平稳运转状态下,该方法测量转速最大误差率为2.55%,在非平稳运转状态下的最大误差率为4.58%,能够满足在线、准确地测量旋转式能量回收装置转子转速的要求。     

车用增压器浮动轴承外间隙的试验

介绍了检验车用增压器动态特性的方法、测试系统、试验结果与分析。辨识了转子振动信号谱图中各个主要成分的物理意义，发现了浮动轴承的动态特性，即特频及其变化规律，确认了浮动轴承外间隙对转子振动有很大的附加影响。根据特频与基频对照，选择不同外间隙的浮动轴承进行试验，找出了降低浮动轴承外间隙对转子振动附加影响的途径。     

多级离心泵转子—轴承碰摩故障诊断

针对某电厂高压多级离心泵在首次启动运转时,对泵进出口压力、轴承温度、振动信号等工艺量参数实时监测,并运用频谱分析技术对其振动信号进行时域、频域分析,在大约运转40分钟时间,诊断给出该水泵转子与轴承系统可能存在局部碰摩现象,为防止故障加剧,因此立即停车解体检查,其与分析结果完全吻合,有效地阻止了转子-轴承局部碰摩而引发诸如叶轮口环、轴套磨损等其他的故障,对泵组的安全稳定运行起到了关键性作用,此诊断分析方法对类似振动故障识别具有一定的参考价值和指导意义。     

尺寸误差对转子系统摩擦功率影响的实验研究

针对滑动轴承转子系统存在的尺寸误差,设计加工了滑动轴承系统实验平台,开发了基于LabVIEW软件平台的非线性动力学特性分析系统,描述了相应信号处理、模块设计的工作原理,分析了轴承宽度,轴承直径和轴颈直径的尺寸误差对摩擦功率损失的影响,并进行相应的能量损失实验研究。实验结果表明各种尺寸变化对系统会产生不同程度的影响,验证了尺寸误差对转子轴承系统摩擦功率的影响实验与理论结果的一致性。为转子系统参数及其公差设计,降低能耗,提供了理论依据。     

磁悬浮轴承-转子系统的机电耦合动力学模型

对磁悬浮轴承 -刚性转子系统建立了完整的机电耦合动力学模型 ,其中除了人们通常所考虑的陀螺效应外 ,着重考虑和增加了推力磁轴承对转子横向振动的耦合效应和由于轴颈倾斜所引起的径向磁轴承之间的耦合效应 ,以及控制系统的电学微分方程和传感器与磁轴承非共点安装对系统性能所带来的耦合影响。该模型可用于五自由度磁悬浮轴承 -刚性转子系统的机电耦合动力学性能研究     

液下硫磺泵的转子动力学分析

为减少长轴液下硫磺泵转子系统的振动,基于转子动力学对液下硫磺泵进行研究,以转子体、轴承、轴承座以及联轴器构成转子系统,运用ANSYS模拟转子系统的临界转速、转子不平衡引起的同步振动响应。结果表明:转子系统在第一阶临界转速下运行,为刚性转子;在前四阶临界转速下,轴承处的变形都较小;在加载了不平衡量的谐响应分析中,轴承与叶轮都在前四阶固有频率下产生共振现象,两叶轮振幅接近,各轴承最大振幅也远小于标准要求。液下泵转子系统的动力学研究对预防转子破坏引起的故障具有重要意义。     

转子系统振动信号的小波分析原理与应用研究

分析了小波变换对非平稳信号的时频局部细化分解原理,指出小波分析工程应用的核心是对信号子频带信息的深层利用。通过对滑动轴承支承的转子系统正常及轴颈发生瞬态碰摩两种状态信号小波分解结果的利用,对子频带信息的能量特征量和小波域信息熵相对变化率进行了计算。结果表明,小波域能量比和信息熵相对变化率可以准确地探测与定位系统内轴颈瞬态碰摩故障,具有量化系统异常变化程度的能力。     

磁悬浮硬盘转子机电耦合动力学分析

为研究磁悬浮硬盘转子的动力学特性,建立了一种基于状态空间的统一的动力学模型,同时将磁力轴承为弹簧阻尼支承系统建立简化的转子动力学模型,通过两种模型的计算结果分析,机、电、磁、控制相互耦合的作用,对磁悬浮硬盘转子系统的特征值有较大的影响。     

Dynamic characteristics of spindle with water-lubricated hydrostatic bearings for ultra-precision machine tools

A key component of ultra-precision machine tools is the spindle. The motivation for this study was to improve machining accuracies in precision cutting and grinding by pursuing improvements in the spindle characteristics by designing a sophisticated spindle with water-lubricated hydrostatic bearings. The static bearing stiffness of the developed spindle was investigated in previous studies. In addition to the static bearing stiffness, the dynamic characteristics regarding bearing stiffness also affect significantly on the machining results. In this study, dynamic characteristics of the developed spindle with water-lubricated hydrostatic bearings were investigated via simulations and experiments. Not only bearing dynamics but also rotor dynamics were considered in this study.In the simulation studies, the spindle dynamic characteristics were analysed based on the transfer matrix method. A spindle rotor supported with hydrostatic bearings was represented by discrete sections of the rotor. The mathematical model of transverse linear vibrations of the spindle rotor was derived with distributed parameters for these discretized rotor sections. As a result of the analysis on the amplitude-frequency characteristic, radial displacements of the rotor due to bearing displacement and bending deformation were defined. Then, the frequency characteristics were represented with Nyquist plots. Resonant frequencies and amplitudes formation in the transverse vibration of the rotor were determined. The influence of rotor bending deformations on spindle compliance was assessed. Furthermore, the study examined the influences of the supply pressure of the lubricating fluid, radial clearance and journal diameter of the hydrostatic bearings on the amplitude of the rotor vibration, and the resonance frequency of the system.Furthermore, the dynamic characteristics of the spindle were examined experimentally. The simulation results were in good agreement with the actual spindle dynamics obtained experimentally. The influence of the structural parameters of the rotor and the operating parameters of the bearings on the spindle dynamic characteristics was also determined. It was verified that the amplitude of the vibration of the rotor overhang part was dominantly affected not by bearing stiffness but by bending stiffness of the bearing journal of the front bearing and the length of the rotor overhang.Then it was verified that the resultant displacement of the rotor in the radial direction due to the influence of the bearing characteristics and the structural effect of the rotor is significantly small. Practical recommendations to improve the spindle design in terms of the dynamic characteristics of the spindle with water-lubricated hydrostatic bearings were also derived.     

一种可控滑动轴承-转子系统性能计算方法*

针对可控滑动轴承油膜性能计算困难问题,提出一种考虑基础参振的滑动轴承性能计算的动网格模型,阐述网格更新原理,给出可控滑动轴承所支撑转子系统轴心轨迹的计算方法。在滑动轴承-转子-基础系统的性能计算时,该方法保证油膜径向网格线和轴颈表面垂直,能减小轴承油膜性能计算的累计误差。通过不平衡载荷条件下的转子轴心静平衡位置计算结果与油膜力数据库方法、经典数据进行对比,验证了该模型的正确性,并利用该方法分析受正弦位移激励的滑动轴承-刚性转子系统的工频振动情况。结果表明：选择合适相位和幅值的正弦位移激励来控制轴承座,可减小转子系统的不平衡振动。这为基于超磁致伸缩材料的轴承、基于压电陶瓷材料的轴承、柔性铰链可倾瓦轴承等可控轴承-转子系统的性能计算提供了一种新方法。     

Dynamics modeling and modal experimental study of high speed motorized spindle

This paper presents a dynamical model of high speed motorized spindles in free state and work state. In the free state, the housing is modeled as a rotor with equivalent masses including bearing pedestals, motor stator and rear end cover. As a consequence, a double rotor dynamics can be modeled for high speed motorized spindles by a bearing element which connects the housing and bearing pedestals. In the work state, the housing is fixed and the system becomes a bearing-rotor dynamical model. An excitation-measurement test in the free state is designed to analyze the cross spectral density and auto spectral density of input and output signals. Then the frequency response function of system and coherence function of input and output signals which are used to analyze the inherent characteristics of the double- rotor model can be obtained. The other vibration test in the work state is designed to research the dynamical supporting characteristics of bearings and the effects from bearings on the inherent characteristics of the system. The good agreement between the experimental data and theoretical results indicates that the dynamical model in two states is capable of accurately predicting the dynamic behavior of high speed motorized spindles.     

基于1 1／2维谱的滚动轴承故障诊断

提出了基于１１／２维谱的滚动轴承故障诊断新方法。１１／２维谱保留了信号的相位信息且能够有效抑制噪声。用１１／２维谱分析滚动轴承振动信号,可以提取由于二次相位耦合产生的非线性特征,识别故障模式。试验结果表明,这种方法能有效地诊断滚动轴承故障,且对初期故障很敏感。     

STUDY ON THE COUPLED ELECTROMECHANICAL DYNAMICS OF ROTOR SYSTEM EQUIPPED WITH MAGNETIC BEARINGS

The influences of thrust magnetic bearing and journal tilt on dynamic characteristics of rotor system are studied mainly. The outcome shows that the influences of coupling effects of thrust magnetic bearing and tilt of journal on critical rotational speeds of system are very large, and the stability of system reduces greatly. That shows it is important that the influence of coupling effects of thrust and radial magnetic bearings due to the rotor tilting must be considered in the study of rotor-magnetic bearings system dynamic characteristics, and also shows it is important that the rotor is mounted and debugged in ideal alignment of magnetic bearings.