非线性振动

There are various techniques for constructing analytical approximations to the nonlinear differential equation.

早期研究非线性振动的理论分析方法多局限於弱非线性振动系统，碰到强非线性振动系统就显的无能为力。

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

Its nonlinear vibration equation was presented, and the approximate solution of nonlinear vibration of elliptic paraboloid cable mesh was given by using Galerkin principle and KBM method.

建立椭圆平面双曲抛物面碳纤维索网在主体结构位移激励下的非线性振动方程，采用Galerkin原理及KBM法求得椭圆平面双曲抛物面碳纤维索网非线性振动的近似解。

Taking into account the temperature effect ,the nonlinear vibration of elliptic paraboloid cable net using carbon fiber cables under foundation displacement excitation was studieded.Then the nonlinear vibration equation was presented,whose approximate solution was given with Galerkin principle and KBM method.

在考虑温度变化的基础上，研究椭圆平面双曲抛物面碳纤维索网在基础激励下的非线性振动问题，建立了椭圆平面双曲抛物面碳纤维索网在基础位移激励下的非线性振动方程，采用Galerkin原理及KBM法求得了椭圆平面双曲抛物面碳纤维索网非线性振动的近似解。

This paper mainly consists of three parts:(1) Based on the Reddy's higher-order shear deformation plate theory and general von Kármán-type equations, put forward the governing equations of pre- and post-buckled vibration of several hybrid FGM plate forms which have not been studied adequately, triumphantly applying the perturbation technique combined with Galerkin method into equations solving, and get the comparatively simple result forms with complicated deduction at last;(2) As a new type of materials, piezoelectric fiber reinforced composite actuators were applied to optimal vibration control, interrelated informatons be depicted in this paper;(3) During the investigative cource, some factors not been considered adequently in other researches were discussed fully in the postbuckled vibration analysis, such as the temperature-dependent material coefficients, heat conduction and nonlinear vibration characteristic etc.

本文的研究工作主要包括：(1)基于Reddy高阶剪切变形板理论和广义Kármán型方程，给出了几类现有研究成果较少或没有彻底解决的FGM混合板结构的屈曲前和屈曲后振动特性研究的控制方程，成功将摄动-Galerkin混合法应用于求解过程，并给出了各控制方程相对直观且易于计算的解析解形式；(2)单向压电纤维增强复合材料(Piezoelectric Fiber Reinforced Composite，简称PFRC)是一种新型压电材料，本文将其应用到了结构振动控制研究当中，发现通过压电纤维体积含量的选择可以实现混合板结构的优化振动控制；(3)围绕几种有代表性的FGM混合板结构，讨论其屈曲后的振动特性，在分析中同时考虑热传导，材料物性参数的温度相关性，以及机/热/电荷载耦合效应对非线性振动特性的影响，最后给出了大量数值计算结果。

Now nonlineardynamical systems with parametric excitation are one of the most important systems intheory of nonlinear oscillations.

在非线性振动理论中目前最具有代表性的一类系统是含有参数激励的非线性动力系统，在这类系统中有着极其丰富和复杂的动力学行为，如分岔、分形和混沌振动等。

Under the fixed and clamped boundary conditions, a nonlinear differential oscillation equation with quadric and cubic items was presented by the Galerkin method, and a nonlinear free oscillation equation of the shallow reticulated shells with damage was solved.

基于Lematire等效应变损伤原理，计及扁球面网壳各个杆件的损伤影响，根据薄壳非线性动力学理论推导出含有损伤扁球面网壳非线性动力学方程和协调方程，在固定夹紧边界条件下，用Galerkin方法得到一个含二次和三次非线性振动微分方程，并对具有损伤扁球面网壳的非线性自由振动方程求解。

The result indicated that frequency of fish-shaped cable truss support system would decrease, resulting in increase of temperature.

算例表明，预应力鱼腹式索桁架支承体系固有频率随着温度的升高而减小，具有较强的非线性，其自振频率随着振幅发生变化，其非线性振动呈现&硬弹簧&特性，非线性自振频率高于线性振动频率。

A detailed model of non-linear parametric excitation vibration coupling the stay cable and the girder, in which the static sag as well as the geometric non-linearity are considered, is proposed in this paper. Based on several numeric examples investigated by the Galerkin method composed with the integration strategy, several kinds of factors effecting stay cable parameter vibration are studied. Another parameter vibration model by the axial excitation is presented and the corresponding nonlinear equations are derived. The smallest excitation amplitude,the transient state and steady state resonance amplitudes, and the changing characteristics of the axial force are obtained by using harmonic balance method. According to numerical examples calculated by numerical integration method, the effects of the inner damping of the stay cables are investigated.

本文创新地提出了斜拉桥拉索-桥面耦合参数振动模型，推导了索-桥耦合非线性参数振动方程组，联合Galerkin法及数值积分方法，对各种特性的拉索进行了数值求解，得出了影响拉索参数振动的各种因素；提出了斜拉索受轴向端激励参数振动模型，导出了模型的非线性振动方程，使用谐波平衡法得出了产生参数振动需要的最小激励幅值、共振时瞬态及稳态的振动幅值及索拉力的变化特性，并用数值积分方法对实际斜拉桥拉索进行了计算，分析了拉索阻尼对参数振动的影响。

Primary parametric resonance of a parametrically excited simply supported thin rectangular plate on nonlinear elastic foundation is analyzed.

分析非线性弹性地基上受参数激励小挠度矩形薄板的主参数共振问题，由冯卡门方程和伽辽金方法得到系统的非线性振动方程，它是杜分-马休型方程，应用非线性振动的多尺度法得到平均方程。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。