采用虚设振幅逆解法估算弹性阻尼支承最佳参数

施加于转子－轴承系统的弹性阻尼支承，在设计参数选择合理的情况下可以明显改善系统的固有或强迫振动响应特性。本文采用虚设振幅逆解法计算弹性阻尼支承最佳参数。该方法既具有理论上的合理性，又便于工程设计采用，特别适用于结构复杂的系统设计。文中就单质量转子系统采用该方法估算最佳支承参数以控制系统不平衡响应进行了计算和分析。结果表明，按照虚设振幅逆解法所设计的弹性阻尼支承，在参数匹配得当时，对于改善系统的制振性和减小传递力是极为有效的。     

挤压油膜阻尼器对滑动轴承-转子系统的影响

建立了转子-挤压油膜阻尼器-滑动轴承系统的动力学计算模型,分析了挤压油膜阻尼器对滑动轴承-转子系统的强迫振动的影响、挤压油膜阻尼器的刚度和阻尼搭配关系以及转子-挤压油膜阻尼器-滑动轴承系统的自由振动稳定性问题。研究结果表明,合理的外弹性支承可以使系统的振幅得到有效控制,而且也提高了系统的稳定性;如要减小系统的振幅可以通过一个低的支承刚度和一个合适的阻尼来实现。在小的支撑刚度的情况下,存在一个很宽的支承阻尼域,此域可以获得低幅值的不平衡响应。     

转子系统强迫振动自校正控制

给出了用于转子系统强迫振动主动控制的自适应控制方案,它主要由可控径向轴承和自校正控制器两部分组成。可控轴承为系统的执行元件,自校正算法则由多步递推预报器和控制器组成,通过在线测量转子系统输入输出值,调整油腔压力而使强迫振动振幅减小。仿真计算表明自适应控制适用于转子系统强迫振动控制,转子不平衡引起的振动幅值可有效地减小。     

基于弹性支承的磁悬浮轴承转子系统振动控制

为寻找抑制磁悬浮轴承转子系统振动的有效方法,基于有限元分析软件ANSYS对转子系统附加外弹性支承前后的动态特性进行仿真对比分析,同时搭建磁悬浮轴承转子试验台进行试验验证。仿真及试验均表明,通过引入合适的外弹性支承结构,可以有效抑制系统振幅。     

利用弹性支承改善滚动轴承的振动特性

本文研究了弹性支承滚动轴承系统的非线性振动问题，着重分析了利用弹性支承改善滚动轴承振动特性的原理和方法。首先建立了弹性支承滚动轴承的力学模型；然后，根据这一模型对系统进行了振动计算；通过对所得到的最大振幅及轴承动压力的分析，得出了弹性支承可以减小滚动轴承非线性振动的结论；最后，对弹性支承的一个应用实例作了简要说明。     

基于反共振不平衡转子-轴承系统的振动控制

基于反共振原理和弹性支承法，研究了不平衡转子－轴承系统弹性振动控制方法。给出了不平衡转子－轴承系统抑制轴承弹性振动的设计公式，并设计了一种弹性支承元件。弹性支承的实验研究结果表明，弹性支承转子系统优于其它支承形式的转子系统。     

磁流变液阻尼器-柔性转子系统振动特性与控制的再研究

对先前提出的理论分析模型进行适当改进，用新模型对支承在磁流变液阻尼器上的单盘悬臂柔性转子系统的振动特性和控制技术进行再研究。研究表明，随着磁流变液阻尼器的库仑阻尼力的增大，系统在无阻尼临界转速处振幅明显下降，但在两阶临界转速之间的一定转速区振幅增加；同时，随着库仑阻尼力的增加，阻尼器轴承处的振幅在几乎所有转速时都被减小，甚至在某些转速区间该轴承被“锁住”，而且轴承能够振动的区间越来越窄。这说明转子系统从一个弹性支承系统逐步转化为一个准刚性支承系统，阻尼器支承的有效刚度越来越大，使得一阶有阻尼临界转速逐渐提高，并逐渐接近刚支临界转速。根据这些特性，提出通过开关控制抑止转子通过两阶临界转速过程中的振动，并使转子振幅在全转速区达到最小。仿真结果表明，系统能平稳通过两阶临界转速。     

轴承载荷对转子系统各支承的耦合振动分析

以多支承转子 轴承 弹性基础系统为研究对象,对多支承转子系统某支承处轴承载荷变化引起不同支承点处轴及轴承的耦合振动响应进行了研究。首先,建立了多支承转子系统支承间的耦合振动模型,并进行了仿真和试验,耦合振动模型考虑了每个支承处的油膜耦合效应,通过轴承载荷敏感度矩阵得到各支承耦合力;然后,利用龙格库塔法对油膜刚度为定刚度和动刚度两种情况下的转子系统进行了数值分析及仿真;最后,在8支承转子试验台上进行试验,采取改变某一支承处的位移来得到轴承载荷的变化,并提取各支承处的振动信号。结果表明,轴承位置在稳态和瞬态两种情况下改变时振动响应明显不同,油膜刚度为动刚度的分析结果更为合理。     

固体材料外弹性阻尼支承的研究

本文提出了一种轴承-转子系统的新型外弹性阻尼支承——固体材料外弹性阻尼支承的设计,介绍了性能测试方法。通过所研制的该支承与实际转子结合的运行试验,全面考察了实际应用时对系统稳定性的影响。结果表明,该支承能够有效地抑制系统的强迫振动和控制系统线性意义下失稳以后的振动强度。     

变支承磁悬浮转子超临界运行仿真研究

针对工业中转子系统在跨越一阶临界转速时,振动幅度过大及失稳的问题,通过对转子系统平稳跨越一阶临界转速方法的归纳和研究,提出了一种基于主动控制下的磁悬浮轴承—转子系统变支承跨越一阶临界转速的方法。首先建立了主动控制下的变支承磁悬浮转子系统数学模型,并分析了两支承转子系统和三支承转子系统跨越一阶临界转速时的响应特性;然后利用ADAMS和Matlab联合仿真了主动控制下的变支承磁悬浮转子系统跨越一阶临界转速时的振动特性。仿真研究结果表明:变支承磁悬浮转子系统在超临界运行时具有良好的减振效果,与传统两支承转子系统相比,其最大振幅减小了52.6%。     

激励幅值慢变转子系统的动力学研究

建立了激励幅值慢变转子系统的动力学模型,利用渐近法对其动力学行为进行解析研究,得到了用显式形式表示的近似解析解,给出了系统响应的时域波形图和轴心轨迹图,分析了激励频率和系统阻尼对最大轴心位移的影响。结果表明:激励幅值慢变转子系统的振幅会产生相应的慢变波动,此类转子系统为多周期运动,周期数取决于激励频率和幅值慢变系数组合关系,且振动周期具有参数慢变敏感性等。     

用谐波平衡法分析齿轮耦合的转子－轴承系统的动力特性

在齿轮耦合的转子－轴承系统中,有多种因素使系统产生非线性振动。,有多种因素使系统产生非线性振动。在考虑齿轮时变啮合刚度和齿面间摩擦力的情况下,使用谐波平衡法,研究了系统的动力特性,并用数值解对其结果进行了校对。研究发现,由于齿轮时变啮合刚度和齿面摩擦力的影响,即使没有不平衡质量引起的激励,系统也会产生振动;即使是单频激励,系统也会产生多频响应。     

The vibrations of a textile machine rotor with nonlinear characteristics

In this paper the free vibrations of a textile machine rotor which rotates with constant angular velocity are considered. The rotor consists of a weightless shaft and a disc with variable mass. The force in the shaft is assumed to be nonlinear. Mass of the disc is varying due to the winding up of the textile band. Severe vibrations occur due to the mass varying. When the nonlinearity is small and the variation of the mass is a function of “slow time,” the vibrations can be denoted not only numerically but also analytically by use of the multiple scales method. The results are compared.     

转子在线自动平衡研究

研究了转子在工作转速下实现在线自动平衡的方法。以电磁执行器作为施力装置,运用傅里叶分析和线性系统的叠加原理,对不停车的情况下转子不平衡振动的识别和抑制的算法进行了推导,并在一滚珠轴承支承的转子系统上进行了试验研究。结果证明该方法和装置能够使旋转工作频率下转子的不平衡振动大大减小。     

Stability analysis of a rotor bearing system due to surface waviness and number of balls

In the paper, the stability analysis of a rigid rotor supported by ball bearings has been studied. In the analytical formulation, the contacts between balls and races are considered as nonlinear springs, whose stiffnesses are obtained by using Hertzian elastic contact deformation theory. The implicit type numerical integration technique Newmark-β with Newton–Raphson method is used to solve the nonlinear differential equations iteratively. The effects of surface waviness and the varying number of balls on stability of rotor bearing system are observed. All results presented in form of fast fourier transformations show that the vibration characteristics of the rotor and its bearings change, when the bearings operate in different regions of their nonlinear load deflection characteristics. From the analysis, it is implied that the number of balls and number of waves in the ball bearing are two important governing parameters affecting its dynamic behavior.     

Unbalance Response of a Super-Critical Rotor Supported by Foil Bearings—Comparison with Test Results©

This article compares theoretical and experimental results on the unbalance response of a super-critical rotor supported by two kinds of gas foil bearings. Analysis of the super-critical rotor is performed with viscoelastic foil bearings (VEFB) and conventional bump foil bearings and compared with early published experimental data. The vibration orbits obtained by theoretical investigation on the viscoelastic foil bearings (VEFB) and the conventional bump foil bearings are compared with the experimental vibration orbits of the super-critical rotor supported by both foil bearings. A numerical analysis program can calculate the static and dynamic characteristics of the elastically supported gas foil bearing using the measured stiffness and damping of the elastic foundation. After the stiffness and damping of both foil bearings are calculated using the perturbation method, vibration orbits of the flexible rotor modeled by the finite element method are calculated. Vibration orbits calculated by numerical analysis agree well with experimental data when the vibration amplitude is small and the rotating speed is below the bending critical speed. The numerical results also show that the enhanced structural damping of the elastic foundation reduces vibration near the bending critical speed.     

Free vibration of a Jeffcott rotor with pure cubic non-linear elastic property of the shaft

The paper considers the free vibration of a Jeffcott rotor whose shaft has a strong non-linear elastic property. The mathematical model of the Jeffcott rotor is a second-order non-linear differential equation with a complex deflection function. An analytic procedure based on the Krylov–Bogolubov method is developed to solve this differential equation. Two different types of initial conditions are considered. The obtained solution describes the oscillatory motion of the rotor center. The influence of the damping, hydrodynamic and gyroscopic force and the variation of the mass of the rotor on the vibrations of the rotor is then analyzed.     

液体动静压球轴承轴心运动轨迹研究

为研究外载荷对轴承转子系统稳定性的影响,以小孔节流的液体动静压球轴承转子系统为研究对象,建立液体动静压球轴承转子系统动力学模型。通过求解轴承润滑数学模型获得非线性油膜力,分析转子所受到的外载荷,采用欧拉算法预测出轴心下一个时刻位移、速度和加速度,并分析转子系统质量、不平衡载荷和阶跃载荷对转子回转精度的影响。结果表明：随着转子系统质量的增加,所需平衡的油膜力增加,轴心振动幅度增加,从而导致转子回转精度降低;相对于不考虑不平衡载荷,考虑不平衡载荷后其振动形态为椭圆且振动幅值增大,减小不平衡值将减小振幅并提高旋转精度;随着阶跃载荷的增加,达到平衡所需的时间也增加。     

Free vibration of SDOF systems with arbitrary time-varying coefficients

A new analytical approach for determining the exact solutions for free vibration of single-degree-of-freedom (SDOF) systems with non-periodically time-varying coefficients (mass and stiffness) is presented herein. In this paper, the function for describing the variation of mass of a SDOF system with time is an arbitrary one, and the variation of the stiffness is expressed as a functional relation with the mass function and vice versa. Using appropriate functional transform, the governing differential equation for the title problem is reduced to a Bessel’s equation or other analytically solvable equations. Exact solutions for free vibration of SDOF systems with non-periodically varying coefficients are obtained for six important cases. In order to simplify the free vibration analysis of a SDOF system with multi-step time-varying coefficients, the fundamental solutions that satisfy the normalization conditions are constructed based on the exact solutions derived. It is more convenient to determine the displacement response of the SDOF system by using the fundamental solutions and a recurrence formula developed in this paper. Numerical example shows that the proposed procedure is a simple, efficient and exact method.