求解阶梯形超静定梁弯曲的传递矩阵法

介绍了求解梁弯曲时的传递矩阵法。首先将梁分成单元，然后对单元进行受力分析和变形分析，得出了梁受弯时的一般解。最后利用该解构成传递矩阵。这里介绍的传递矩阵法采用矩阵形式表达，不论是静定问题还是超静定问题，都使用同样的程序进行计算，非常适合上机计算。     

水轮发电机组轴系临界转速及弯曲变形计算的解析法

采用求解弹性梁横向振动微分方程的传递矩阵方法来计算水电机组轴系的临界转速及弯曲变形。     

圆轴扭转的传递矩阵法

介绍了圆轴扭转时的传递矩阵法。首先将圆轴分成单元，然后对单元进行受力分析和变形分析，得出了圆轴受扭时的一般解。最后利用该解构成传递矩阵。这里介绍的传递矩阵法采用矩阵形式表达，不管是静定问题还是超静定问题，都使用同样的程序进行计算，非常适合上机计算。     

转子摩擦热稳定灵敏度的研究

动静摩擦产生热弯曲易导致转子失稳。文中 发生摩擦热弯曲的转子－轴承系统的传递矩阵,利用传递矩阵对参数偏导数矩阵的递推公式得到了热稳定特征值对参数的灵敏度计算格式。     

水电站厂房结构有限元整体求解中的过渡单元研究

研究了水电站厂房结构有限元整体求解时大体积混凝土与梁、柱等杆系结构连接的过渡单元。文中介绍的方法简单，便于工程技术人员接受，也便于编制计算机程序。特别当现有程序中已有杆件单元刚度矩阵程序时，则过渡单元的程序十分容易实现。     

大容量高速电机转子截面突变处刚度特性及等效模型

转子梁单元模型因计算效率高等优点在大容量高速电机转子动力学优化设计中被广泛应用,其对转子截面突变处的力学连续性假设使得弯曲刚度被过高估计,工程上采用了过渡轴段的等效模型但仍存在较大误差,对此,基于欧拉梁和铁木辛柯梁理论对阶梯转子的刚度特性进行分析,并通过与实体单元结果对比,细化过渡轴段模型参数,实现基于修正梁模型的转子弯曲刚度的精确计算。计算结果证明所建模型兼顾了转子实体单元有限元模型的高计算精度和梁单元模型的高计算效率的优点。     

斜齿轮–平行轴转子系统模态耦合特性分析

以一个两对斜齿轮耦合的三平行轴转子系统为研究对象,考虑静态传递误差、齿轮几何偏心的影响建立了全自由度通用齿轮啮合动力学模型,并考虑转子系统的影响,建立了平行轴系齿轮转子系统有限元模型,其中转子系统采用梁单元来模拟,齿轮之间的耦合作用通过啮合刚度矩阵和阻尼矩阵来模拟。通过修改啮合刚度矩阵研究了无耦合、单轴弯扭轴摆耦合、轴系弯弯耦合、轴系扭扭耦合、轴系弯扭耦合、轴系弯扭轴摆耦合的系统模态变化规律,采用模态应变能确定了系统各阶主导模态,研究结果可为齿轮及转子系统设计提供参考。     

利用Euler梁模型计算汽轮机叶片静频和动频的传递矩阵法

根据在定常轴向力作用下,均匀梁的横向振动方程,推导了其固有振动特 连续质量传递矩阵模型。通过对模型的修正,获得了在分布轴向力作用下梁振支睡传递矩阵模型,并使用该模型计算了在不同分布轴向力作用下悬 固有频率以及４３２型叶片的频和动频,结果表明悬臂梁的固有频率以及４３２型叶片的静频和动频,结果表明此方法不仅能精确地计算在分布轴向力作用下梁结构的振动特性还能比较准确地计算叶片的静态和动态振动特性。     

在动坐标系复平面上计算转子支承系统带油膜阻尼的不平衡响应

提出在动坐标系中复数平面上用传递矩阵法计算带油膜阻尼的转子支承系统的稳态不平衡响应及传递特性的方法，推导了在动坐标系中复数平面上的单元传递矩阵及其具体算法，它还考虑了挤压油膜阻尼器等的油膜刚度、油膜阻尼及其非线性特性对不平衡响应和传递特性的影响。以实际计算某燃气轮机为算例，得出了稳态不平衡响应和非线性双稳态曲线等。     

用五面体（6、15节点）单元和六面体单元计算焊接结构的应力场（Ⅰ）

三维有限元理论，构造了五面体６节点和１５节点单元的形函数，并建立了它们的单元刚度矩阵，将这两种不同节点的五面体单元和六面体８—２１节点单元结合可以计算焊接结构的应力场，并开发了相应的程序，文中计算了工字梁焊接结构的应力场，通过与电测实验结果的比较表明：本文建立的五面体单元和六面体单元匹配可以有效地用于焊接结构的应力场计算．     

Modeling the pull‐in behavior of electrostatically actuated micro beams by an approximate finite element method

We establish the deflection functions of electrostatically actuated micro beams by an approximate finite element method (AFEM), in which the beam and the electrostatic load are discretized. The beam is replaced with a series of beam elements by traditional FEM. Using the total differential of the distributed electrostatic force, we represent such a force with the nodal forces on the beam elements. We calculate the deformation curve of the beam by gradually loading voltage in small increments, and pull‐in behavior is identified when the convergence of the deflection iteration cannot be achieved after voltage increment. The proposed method considers the effect of deformation on stiffness by establishing a new equivalent stiffness matrix for each voltage step based on of the results of previous steps. Through this approach, we prevent the approximate errors of the stiffness matrix from accumulating. The AFEM results on micro beams with different geometries indicate good agreement with those obtained by other studies and those derived using commercial FE software. Copyright © 2013 John Wiley & Sons, Ltd.     

基于非对称模型的发电机转子-轴承系统动力特性分析

该文在旋转坐标下建立了发电机非对称转子 -轴承系统的数学模型 ,推导了非对称转子、轮盘和轴承的传递矩阵。针对传统传递矩阵法存在的对多自由度非对称转子 -轴承系统的数值不稳定问题 ,该文在构造系统非对称部件的传递矩阵时 ,引入了Riccati变换 ,使之适合于复杂实际非对称转子动力特性的求解。将这种方法应用于某 6 5 0MW核电发电机转子 轴承系统的动力特性计算 ,计算结果与实验结果吻合的较好 ,证明该方法能解决传统方法不能解决的实际非对称转子 轴承系统动力特性 (临界转速、不平衡响应和稳定性等 )的计算问题 ,为非对称电机转子的设计提供了更准确的计算方法。     

Adaptive robust boundary control of coupled bending‐torsional vibration of beams with only one axis of symmetry

In control design for vibration of beams in literature, the beam section is considered to have two axes of symmetry so that the bending and torsional vibrations are uncoupled; thus, the bending vibration is controlled independently without twisting the beam. However, if the cross section of a beam has only one axis of symmetry, the bending and torsional vibrations become coupled and the beam will undergo twisting in addition to bending. This paper addresses Lyapunov‐based boundary control of coupled bending‐torsional vibration of beams with only one axis of symmetry. The control strategy is based on applying a transverse force and a torque at the free end of the beam. The control design is directly based on the system partial differential equations (PDEs) so that spillover instabilities that are a result of model truncation are avoided. Three cases are investigated. Firstly, it is shown that when exogenous disturbances do not affect the beam, a linear boundary control law can exponentially stabilize the coupled bending‐torsional vibration. Secondly, a nonlinear robust boundary control is established that exponentially stabilizes the beam in the presence of boundary and spatially distributed disturbances. Thirdly, to rule out the need for prior knowledge of disturbances upper‐bound, the proposed robust control is redesigned to achieve an adaptive robust control that stabilizes the beam in the presence of disturbances with unknown upper‐bound. The efficacy of the proposed controls is illustrated by simulation results. Copyright © 2016 John Wiley & Sons, Ltd.     

Return ratio and sensitivity computation for multivariable control systems and feedback-stabilized multiple amplifier active circuits

A method is presented for determining the sensitivities of multivariable control systems and feedback-stabilized multiple-amplifier active circuits. The derivation is based on the inverse transfer matrix, from which the return difference matrix with respect to a particular set of elements is obtainable directly for properly-chosen variables. When the sensitivities are determined with respect to the gain elements and all local loop transmissions are high, the local return differences can be substituted by the corresponding negative return ratios, which simplifies the resulting relationships greatly if no interaction exists between the various gain elements. A related problem occurs with feedback circuits, for which the desirable stabilizing looptransmissions cannot be identified by inspection. In this case, the return difference matrix yields the formal answer. Two practical examples are given.     

大推力推挽纵振弯纵复合直线超声电机

提出一种大功率夹心式纵弯复合直线超声电机。电机定子主体结构由2个小端相连的指数形变幅杆组成,并在连接处设有驱动足。纵弯振动叠加并在驱动足处产生具有驱动作用的椭圆轨迹。在经典变幅杆理论和变幅杆弯振的传递矩阵分析法的基础上,利用有限差分法,分析各结构参数变化对纵弯谐振频率变化的灵敏度,选取敏感度最大的参数作为设计变量,将电机的纵弯频率简并至27.476kHz。有限元仿真和阻抗特性测试结果与理论计算结果吻合。讨论分析了纵弯振动间的耦合作用并提出带耦合环节的等效电路模型拓扑结构,并利用单相驱动实验验证模型的正确性。电机样机的最大速度为1280mm/s,最大推力为45N。     

Matrix-reactance frequency converters using an low frequency transfer matrix modulation method

This paper deals with three-phase matrix-reactance frequency converters (MRFCs). Their topologies are based on unipolar PWM AC matrix-reactance choppers (MRCs). In the discussed MRFCs the voltage matrix converter (MC) or current MC is used for electrical energy transfer instead of the source or load synchronous connected switches. As a result both a frequency change and the buck-boost voltage conversion are possible. It is important that electrical energy storage in the passive elements used in MRFCs is equal to zero in an AC voltage period; therefore these converters can be treated as ones without DC storage. The main purpose of this paper is to carry out a comprehensive comparison of basic properties of MRFCs using an low frequency (LF) transfer matrix modulation method, which are the FCs with the voltage gain greater than one. Presented in this paper are the results of steady and transient states analysis of the MRFCs using an low frequency (LF) transfer matrix. A two-frequency complex function method is applied for solving non-stationary averaged state space equations. Furthermore, theoretical results are verified against some simulation and experimental test results of a c.a. 1 kVA laboratory model of the MRFC based on MRC with buck-boost topology.     

基于曲梁理论的弧形钢闸门纵向主梁正应力计算

弧形钢闸门纵向主梁实为曲梁,其截面正应力仍沿用直梁理论进行计算。本文从曲梁挠曲线微分方程出发提出了一种基于曲梁理论的计算方法。通过对应力计算中结构特征系数公式的推导,提出了弧门箱形截面纵向主梁偏心距e的计算方法,分析了曲率对曲梁截面弯曲正应力分布的影响,并对曲梁理论和直梁理论计算结果进行详尽的误差分析。分别运用曲梁理论及直梁理论对工程实例进行计算,直梁理论相对有限元方法计算结果的误差达到14.23%,而曲梁理论相对有限元方法计算结果的误差仅为2.23%,可见基于曲梁理论的计算精度显著优于直梁理论,采用基于曲梁理论的计算方法更加安全可靠。本文方法可为相关工程设计提供参考和理论依据。