转子振动的灰色Verhuslt预测优化控制研究

以灰色预测控制理论为基础，首次将非线性GM模型引入到转子振动主动控制中，并采用现代控制理论中的二次型优化原理，以控制力和响应加权最小为目标函数，设计了转子系统振动的灰色Verhuslt预测优化控制方案。将该方案应用于带电磁阻尼器转子轴承系统的转子振动控制中，仿真结果显示转子振动的灰色预测Verhuslt优化控制是有效的、可行的。     

可控挤压油膜轴承主动控制转子系统振动

本文提出了“可控挤压油膜轴承”,以主动控制转子系统的振动,设计了不同的可控挤压油膜油承方案,借稳态不平衡响应构成的二次目标函数,分析比较了它们的振动控制效果,根据这一研究,可初步得到如下结论:对于航空发动机,可控挤压油膜轴承极有希望成为一种更有效的振动控制方法。     

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。     

电磁轴承—转子系统的动态特性

本文提供了一个闭环控制电磁轴承-转子试验系统,在电磁力的控制作用下,重量为4公斤、直径为50毫米的转子完全悬浮于二个径向电磁轴承之中,转速可达3000转/分。本文还建立了此闭环控制系统的数学模型,通过数字仿真分析了其动态特性,探讨了控制器参数对转子运动的控制效果以及与电磁轴承动刚度之间的变化关系。     

磁悬浮支承转子系统动力学特性计算与分析

介绍一种磁悬浮支承条件下的柔性转子系统临界转速及稳定性计算方法,并对其步骤予以详解.该方法基于传统转子动力学中的改进的传递矩阵法,并结合磁悬浮轴承刚度阻尼系数计算的特点,编制了完整的系统临界转速和稳定性计算程序.最后通过一个计算实例及其实验结果的验证,表明了该计算方法的有效性.     

二自由度结构受迫非线性振动响应的数值计算

本文研究了由飞机尾部简化而成的二自由度结构受迫非线性振动,由于对复杂的运动方程不作进一步简化,方程中含有强非线性耦合项,首先采用数字滤波技术对系统受确定性激励的响应进行了计算;然后在数字模拟计算的基础上用嫁接的ITO积分方法对系统受随机白噪音激励的响应进行了计算。结果表明,ITO积分的综合嫁接方法有更高的计算效率,结果并表明系统的非线性耦合部分对响应有重大影响,是不能加以忽略的,本文的研究为多自由度非线性结构的响应计算提供了有用的思想和方法。     

非线性弹性支承转子系统动力特性分析

本文把非线性弹性支承简化为带变刚度、变阻尼元件的 Kelvin 模型,并用子结构传递矩阵法分析配有这类支承的转子系统的动力特性.     

外弹性支承滑动轴承—刚性转子系统非线性动力稳定性的研究

研究外弹性支承滑动轴承－刚性转子系统的动力稳定性问题。建立了弹性支承圆瓦轴承－Jeffcot转子系统的力学模型,针对滑动轴承水平转子,在油膜力非线性的情况下,采用Newmark方法计算其响应。对于一个具体的算例,通过改变其参数,确定其稳定区,并与滑膜力线性化时理论分析的结果进行了比较。     

The application of reduced space harmonic balance method for the nonlinear vibration problem in rotor dynamics

The reduced space harmonic balance method is demonstrated to find the maximum vibration responses of rotor systems. Within the reduced space SQP method, transition from the high dimensional optimization space to the desired reduced space is accomplished by resorting to the null space decomposition technique, resulting in the elimination of the harmonic balance constraints. Numerical examples of rotor systems are presented to show the applicability of the proposed methodology.     

折线型非线性振动响应计算的时域有限元分段求解

本文研究折线型非线性振动系统响应的求解,按分段线性性质建立了分段线性的时域有限元离散模型。在求解中先计算当前段的振动响应,根据转折条件判断是否存在转折点。当存在多个转折点时,以最早出现的转折点作为下一段的起始点,否则以本时间段终点作为下一段的起始点,然后进入下一段的计算。本文方法能在每一段较精确地求出转折点,并同时给出该转折点之前各结点的响应解。较有效地解决了这类问题的数值求解。文中算例给出了相当精确的计算结果,验证了本文方法的有效性。     

Magnetic field effects on the nonlinear vibration of a rotor

The nonlinear vibration of a rotor operated in a magnetic field with geometric and inertia nonlinearity is investigated. An asymmetric magnetic flux density is generated,resulting in the production of a load on the rotor since the air-gap distribution between the rotor and the stator is not uniform. This electromagnetic load is a nonlinear function of the distance between the geometric centers of the rotor and the stator. The nonlinear equation of motion is obtained by the inclusion of the nonli...     

Aeroelastic response of a coupled rotor/fuselage system in hovering and forward flight

Summary The aeroelastic response analysis of a coupled rotor/fuselage system is approached by iterative solution of the blade aeroelastic response in the non-inertial reference frame fixed on the hub, and the periodic response of the fuselage in the inertial reference frame. A model of the coupled system hinged with the flap and lag hinges, the pitching bearing which may not coincide with the hinges, and the sweeping-blade configuration is established. The moderate-deflection beam theory and the two-dimensional quasi-steady aerodynamic model are employed to model the aeroelastic blade, all the kinetic and inertial factors are taken into account in a unified manner. A five-nodes, 15-DOFs pre-twisted nonuniform beam element is developed for the discretization of the blade, three rigid-body-motion DOFs are introduced for the motion of the hinges and the bearing. The Hamilton's principle is employed to evaluate the equation of motion of the blade. The derived nonlinear ordinary differential equations with time-dependent periodic coefficients are solved by a modified quasi-linearization method, which is developed for the higher DOF periodic system. The resulting periodic forces and moments exerted on the fuselage by all the blades are evaluated every time, when the converged nonlinear periodic response of the blade is obtained under the consideration of the equilibrium of the blades. The fuselage structure is simplified to be a beam structure, the governing equation is established in the inertial reference frame and a two-nodes beam element is used to discretize the flexible fuselage. The periodic response of the fuselage is solved by a simple shooting method. The iteration of the rotor/fuselage response is continued, until the aeroelastic responses of the blade and the fuselage converge simultaneously. Both the hovering and the forward flight states can be considered. The results of a computed numerical example by the developed program are presented to verify in practice the economy of the modeling as well as the reliability and efficiency of the corresponding solving methods. Received 4 May 1998; accepted 11 August 1998     

非线性自由振动的迭代响应法

构造了一个考虑横向振动和板面内运动的三节点几何非线性等参环形板单元,采用迭代求响应的方法,研究了中心附有刚性质量块的非线性轴对称自由振动的频率,与已有的结果比较表明,本文的方法得到更为精确的数值结果。     

转子轴承系统振动响应谱的仿真研究

在转子轴承系统振动信号处理中,针对平稳信号的传统傅里叶变换精度较低、快变启动过程的非平稳信号频谱分析方法较复杂的问题,本文仿真构造了两类响应信号。通过对比给定信号参数与信号识别参数的误差研究了几种谱分析方法或过程的简便性和准确性。对转子系统振动平稳信号离散频谱分析时存在的误差进行了定量分析,利用比例插值法对误差进行校正,开发了高精度谱分析测试软件;分析了转子轴承系统快变过程非平稳振动信号的特征,探索了一种将t时空域非平稳信号转变为tn时空间域平稳信号的办法或过程,然后结合比例插值校正法对其进行频谱分析,再返回到t时空域获得某时刻的谱特征参数;构造了转子系统振动仿真信号检验了上述过程的准确性。研究结果表明:比例插值法提取的谱特征数据近乎与仿真信号设定值相等;针对本文构造的快变过程非平稳仿真信号,利用本文给出的谱分析过程产生的频率误差最大值为0.47%,幅值误差最大值为0.2%。本文的仿真研究为提出和考证新的谱分析方法提供了手段。     

Combined resonance of low pressure cylinder-generator rotor system with bending-torsion coupling

A nonlinear model of a low pressure cylinder-generator rotor system is presented to study sub-synchronous resonance and combined resonance. Analytical results are obtained by an averaging method. Transition sets and bifurcation diagrams are obtained based on the singularity theory for the two-state variable system. The bifurcation characteristics are analyzed to provide a basis for the optimal design and fault diagnosis of the rotor system. Finally, the theoretical results are verified with the numerical results.     

Active control of coupled flexural-torsional vibration in a flexible rotor-bearing system using electromagnetic actuator

Rotor-shaft systems are subject to non-uniform spin speed during start-up, coast-down or any non-stationary situation changing the spin speed suddenly, e.g., load fluctuation or sudden mass-loss like loss of a blade or a part thereof. For a flexurally and torsionally compliant rotor-shaft, the dynamics under non-uniform spin-speed shows inertial coupling among transverse and torsional coordinates through mass-unbalance and gyroscopic effect. This results into coupled transverse-torsional vibration, where torsional response consists of significant harmonic components at bisynchronous spin frequency, torsional natural frequency of the shaft, and at combination frequencies corresponding to sum and difference of spin and transverse natural frequencies and twice the transverse natural frequency of the rotor-shaft. As a result of the coupling, transverse rotor motion also influences the torsional motion. The Method of Multiple Scales (MMS) is used in this work to carry out an analysis of a simplified system to get an idea about the dominant frequencies of excitation. Results of numerical simulation are presented next to show the effectiveness and influence of actively controlling the transverse rotor motion on its torsional motion, at the dominant frequencies, with the help of non-contact electromagnetic force from an actuator. Transverse vibration control is also observed to control the torsional oscillations due to coupled nature of the problem. The Stability Limit Speed (SLS) of the system is also increased as a result of application of the active control action. Constant axial torque is observed to diminish the influence of coupling, and protect the system against torsional instability, but control action is a must to stabilize the transverse vibration of the system above SLS.     

不确定非线性结构动力响应的区间分析方法

研究多自由度非线性不确定参数系统的动力响应问题. 以区间数学为基础,将不确定 性参数用区间进行定量化,借助一阶Taylor级数,给出了近似估计非线性振动系统动力响 应范围的区间分析方法. 从数学证明和数值算例两方面,将其与概率摄动有限元法进行了比 较,结果显示区间分析方法对不确定参数先验信息具有要求较少、精度较高的优点.     

转子系统的平稳／非平稳随机地震响应分析

应用虚拟激励法结合精细时程积分计算了转子系统受平稳／非平稳随机地震激励的动力响应。采用虚拟激励分析将平稳随机激励转化为稳态简谐激励，将非平稳随机激励转化为瞬态确定性激励，即使对于非对称的油膜刚度阵和阻尼阵，算法仍然简单高效，并得到精确的结果。