CY型液下泵转子系统动态优化设计

对CY型液下泵转子系统进行动态优化设计。采用有限元法作动力分析,对其进行优化设计,即以动柔度为目标函数,考虑共振频率禁区、强迫振动、转子的强度和刚度以及尺寸边界约束,用数学规划与逆摄动相结合的优化方法求解,并采用了灵敏度分析和回归分析等技巧。以CY液下泵转子系统为例,重分析2～3次。     

基于ADAMS的双半内圈角接触球轴承动态性能分析

在双半内圈角接触球轴承拟动力学分析的基础上,结合保持架的弹性变形,利用ADAMS系统开发了该轴承参数化刚柔耦合仿真分析模块,分析了轴承各元件间作用力和保持架侧壁上某节点的当量应力随时间的变化情况,并对比了柔性保持架与刚性保持架的动态特性,结果表明:保持架的弹性变形对轴承的动态性能影响很大。     

高速机床主轴用陶瓷球轴承动态性能试验分析

对高速磨床主轴用陶瓷球轴承B7005C／HQ1P4在不同转速、载荷及润滑条件下的运转特性进行试验，结果表明：电主轴在80000r／min的转速下仍能正常运转；在起始温度、转速、润滑及冷却相同的条件下，陶瓷球轴承较钢制轴承摩擦力矩小、温升低；在润滑不充分的情况下，陶瓷轴承具有良好的运转特性。     

高速机床主轴用陶瓷球轴承动态性能研究

随着数控机床的迅猛发展，主轴轴承朝着高转速、高精度、高刚度、高可靠性、长寿命方向发展，许多新技术、新材料开始在轴承制造业中使用，混合陶瓷球轴承就是机床高速化的产物。通过分析计算和试验验证来对陶瓷球轴承的动态性能进行研究，可为陶瓷球轴承的设计计算提供可靠依据。     

基于ANSYS的大型异步电机转子系统动态特性分析

采用有限元分析软件ANSYS建立了大型异步电机YKS1000-4TH转子系统的集中质量-梁单元有限元模型和三维有限元模型.采用Qr damped法对两种模型进行了模态分析,求得系统的前3阶固有频率和振型,并计算出相应的主轴临界转速.最后改变油膜支承刚度,分析系统临界转速随油膜刚度的变化规律,为大型异步电机转子系统的设计提供了理论依据.     

发动机转子-滚动轴承系统的振动性能研究

针对发动机转子 滚动轴承系统建立了有限元模型,将弹性轴段、刚性圆盘和弹性支承的动力方程集结后得到系统振动方程,分析计算了支承刚度对系统固有频率的影响。将转子不平衡惯性力和轴承支反力作为激励,求解了系统的稳定响应,得出了合理设计支承刚度和阻尼,可以改善转子系统的振动特性的结论。通过转子系统模拟实验,对该结论进行了验证。     

基于LS-DYNA的深沟球轴承结构参数影响动态性能的研究

本文基于LS-DYNA创建轴承动力学仿真模型,以6309深沟球轴承为研究对象,考察了该轴承在国标测试工况下结构参数对轴承动态性能的影响规律。首先,研究内圈、保持架的线速度仿真结果并和理论计算结果对比,误差较低,证明了模型的准确性。其次,研究了相同沟曲率、不同游隙对轴承振动趋势的影响,结果表明随着径向游隙的增大轴承的振动加速度逐渐减小。最后,研究了相同游隙、不同沟曲率对轴承结构振动的影响,结果提出了对于内、外圈沟曲率不同组合,轴承振动值较低的优选参考区域。     

电磁轴承柔性转子系统动态响应分析

给出了基于多输入多输出(M IMO)系统建模方法的电磁轴承柔性转子系统动态响应优化算法,通过数值仿真实例搜索得到系统最佳工作点。对电磁轴承柔性转子系统动态响应为目标函数的寻优规划的凸凹性进行了判定,对寻优结果作了鲁棒性分析,据此对寻优结果的可靠性给出了定量结论。计算与分析结果表明:电磁轴承柔性转子系统动态响应寻优规划为非凸规划,通过本文提出的优化仿真方法得到的系统最佳工作点为局部最优解且逼近全局最优解。     

深沟球轴承中球的自转规律研究

建立航空发动机高低压转子系统中深沟球轴承的拟静力学模型,运用Newton-Raphson法进行求解,分析载荷和转速对深沟球轴承内部载荷分布和球自转规律的影响。结果表明：深沟球轴承在转速不高时,径向力的改变对钢球自转角速度的影响不明显,而在转速较高时,随着径向力的增加,钢球自转速度逐渐增大;随着径向力的增加,承载区最外侧钢球的自转角速度比承载区内侧钢球的自转角速度增幅大;随着转速的增加,钢球的自转角速度增加。     

A novel nonlinear model of rotor/bearing/seal system and numerical analysis

A novel nonlinear model of rotor/bearing/seal system based on the Hamilton principle is proposed for steam turbine systems in power plants. The Musznyska model and unsteady bearing oil-film force model were applied to describe the nonlinear steam excitation force and oil-film force. The Runge-Kutta method was used to solve the motion equation of the rotor/seal/bearing system. The dynamic characteristics of the rotor/bearing/seal system were analyzed with bifurcation diagrams, time-history diagrams, trajectory diagrams, Poincare maps and frequency spectrums. The numerical analysis indicates that the seal force and the oil-film force influence the nonlinear dynamic characteristics of the rotor system. With the increase of rotation speed, the rotor system exhibits rich forms of periodic, double-periodic, multi-periodic, quasi-periodic and chaotic motion. The combined impact of steam excitation force and bearing oil-film force may cause a severe vibration which seriously affects the safety and stability of the rotor. The presented model provides a theoretic foundation for further research on the ultra-supercritical steam turbines.     

The dynamic behavior of a rotor system with a slant crack on the shaft

For a Jeffcott rotor system with a 45° slant crack on the shaft, the motion equations are established with four directions, i.e. two transversal directions, one torsional direction and one longitudinal direction. It can be seen from the deducing process of the stiffness with the strain energy release approach that there are coupling stiffnesses of bending–torsion, bending–tension and torsion–tension for the slant-cracked shaft and only bending–tension for the transverse-cracked one. The paper shows that besides the coupling stiffnesses, there is bending–torsion coupling caused by the eccentricity. All these couplings affect the responses of the slant-cracked shaft and the transverse-cracked one. Comparing responses of a cracked shaft with an open crack model and those with a breathing crack model finds that there are the same prominent characteristic frequencies for these two kinds of shafts, even though the cracked shaft with a breathing crack model behaves much more non-linear than that with an open crack model. Therefore, almost all studies in this paper adopt the open crack model since it needs taking much longer time to compute responses of a breathing cracked shaft than that of an open cracked shaft. Analyses of steady responses indicate that the combined frequencies of the rotating speed and the torsional excitation in the transversal response and the frequency of the torsional excitation in the longitudinal response can be used to detect the slant crack on the shaft of the rotor system.     

Effects of rotor misalignment in airgap on dynamic response of

Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins which takes place through the motor airgap. When relative misalignment of a rotor in the airgap is introduced during assembly, the dynamic characteristics of the motor system are affected. The rotor-motor system used in a washing machine is modeled using FETM and magnetic forces in a BLDC motor with radial rotor eccentricity are determined analytically. The transient whirl responses of a rotor system supported on two roller bearings with relative misalignment in the motor airgap are investigated by considering mechanical and magnetic coupling effects. Results show that rotor misalignment in the airgap considerably affects the vibration of the rotor-motor system.     

Nonlinear dynamic characteristics of geared rotor bearing systems with dynamic backlash and friction

Effects of the friction and dynamic backlash on the multi-degree of freedom nonlinear dynamic gear transmission system, which incorporate time varying stiffness, are investigated. Firstly, the relationship between gear central distance error and backlash is deduced and the dynamic backlash is defined, subsequently a multi-degree of freedom nonlinear dynamic gear transmission system is developed with dynamic backlash, friction and time varying stiffness. The nonlinear dynamic system is solved by the Runge-Kutta method. The results show that the friction force may enlarge the displacement magnitude and affect the high frequency parts significantly in frequency domain at low speed. But the RMS of the steady response is reduced on the effect of friction. The difference between the constant backlash and the dynamic backlash models is also discussed. The system may enter into previous chaotic motion due to the effect of dynamic backlash. Finally, no impact motion, single-side impact motion and double-side impact motion are also predicted in the new dynamic backlash model.     

Effectiveness of Impact-Synchronous Time Averaging in determination of dynamic characteristics of a rotor dynamic system

Dynamic characteristics of rotor dynamic systems, namely natural frequencies, damping and mode shape, vary with rotation speed due to gyroscopic effect. To consider such effect, modal analysis is required to be performed while in operation. However, to generate the frequency response functions, it is not viable to perform data reduction in frequency domain as noise and harmonics excited by rotating forces dominate the spectrum and hide the natural frequencies. The full set of dynamic characteristics is difficult to obtain. A novel technique, referred to as Impact-Synchronous Time Averaging (ISTA), is developed in this study to screen out the noise and harmonics.     

滑动轴承转子系统非线性动力学稳定性研究

采用多尺度法研究了滑动轴承刚性平衡转子系统临界点的稳定性。研究发现，滑动轴承在其线性失稳转速上发生Hopf分岔，系统是发生超临界Hopf分岔还是亚临界Hopf分岔取决于系统参数的设计。给出了通用的公式和程序，为滑动轴承的非线性动力学设计及性能预测提供了有利的工具。     

Vibration response of rigid rotor in unloaded rolling element bearing

Rolling element bearings appear in nearly 90% of all rotating machinery. Their dynamic performance is often the limiting factor in the performance of the machines that use them. The specific construction of a bearing has a decisive influence on its dynamic behaviour. The paper defines a new vibration model of a rigid rotor supported by rolling element bearings. By application of the defined model, the parametric analysis of the influence of internal radial clearance value and number of rolling elements influence on rigid rotor vibrations in unloaded rolling element bearing was performed. The defined vibration model and parametric analysis were verified experimentally. The results of experimental analysis are also presented in this paper.     

Design and test of a solid material damper for a rotor bearing system

For a rotor bearing system operating at high speed, a solid material flexible damped support called here a solid material damper has been designed and tested. The properties of the damper can be selected and adjusted to provide the necessary damping levels to get the vibration of the rotor under control. This is especially useful for a flexible rotor running in the vicinity of a critical speed or over the threshold speed obtained from calculations on the basis of linearized hydrodynamic forces. The damper was fabricated and installed and its ability to restrain effectively the rotor from vibration was demonstrated by means of an operating test.     

可变阻抗滑动轴承的动力系数计算

本文讨论了具有两个动力缓冲器的可变阻抗滑动轴承的动力学系数及其计算方法，建立了基于Ｒｅｙｎｏｌｄｓ方程和流量连续性原理的油膜压力分布理论模型，并提出了这种轴承油膜的线性动力学系数计算的压力扰动法。理论分析结果表明这种轴承可以在运行条件下有效地改变其油膜的动力特性，为这种轴承的实际应用提供了必要的理论基础。     

转子系统的动态优化设计研究

大型旋转机械的转子系统是整个机组的重要的组成部分。在分析转子、轴承、支承系统振动的基础上,建立整个转子系统的振动模型以及集中质量转子系统力学模型。同时对转子系统进行了以多阶振型为目标、多阶临界转速及动力响应为约束变量的优化设计工作,对优化设计方法从数学建模到优化分析,再采用ANSYS计算作了系统的详述。通过设计使转子系统的动态性能在图纸设计阶段就得到预测和优化,使产品的性能趋于最佳。