一类阻尼控制半主动隔振系统的解析研究

研究了一类基于相对速度反馈的含立方刚度的单自由度非线性半主动隔振系统.通过平均法得到了系统分别在基于加速度-相对速度反馈的加速度驱动阻尼控制策略、速度-相对速度反馈的天棚阻尼控制策略和位移-相对速度反馈的地棚阻尼控制策略下主共振响应的近似解析解,并利用数值解验证了近似解析解的准确性.通过 Lyapunov 理论对不同控制策略下系统的稳定性进行了分析,讨论了系统参数对控制效果的影响.分析结果表明,对 3 种基于相对速度反馈的控制策略进行解析研究时,切换条件中的控制参数具有相同的表达式;在抑制共振响应振幅方面,基于速度-相对速度反馈的天棚阻尼控制策略在低频时的减振效果最好,而基于加速度-相对速度反馈的加速度驱动阻尼控制策略在高频时的减振效果最优;在抑制瞬态响应振幅方面,基于速度-相对速度反馈的天棚阻尼控制策略的减振效果最好.此类解析研究方法可应用到其他半主动开关控制策略中,为半主动隔振系统的控制策略研究提供了有效的方法和手段.      

基于分数阶磁流变液阻尼器模型的车辆悬架组合控制

磁流变液阻尼器的分数阶Bingham模型结构形式简单, 而且可以更好地描述系统的滞回特性. 建立了含有分数阶Bingham模型的单自由度1/4车辆悬架系统模型, 利用磁流变液阻尼器对在路面简谐激励下的非线性车辆悬架系统进行振动控制. 研究了含有分数阶Bingham模型的悬架系统在天棚阻尼半主动控制下的主共振响应, 利用平均法得到了系统的近似解析解. 求解了系统定常解的幅频响应方程, 并根据李雅普诺夫稳定性理论得到了悬架系统的稳定性条件. 通过绘制数值解和解析解的幅频响应曲线对比图, 验证了近似解析解的正确性. 利用簧载质量垂直方向的加速度均方根值分析了半主动控制对车辆乘坐舒适性的影响, 发现天棚阻尼半主动控制策略在低频激励区域反而会降低车辆的乘坐舒适性. 因此提出了一种被动控制与半主动控制相结合的组合控制策略, 并分析了半主动控制参数对振动控制效果的影响. 分析结果表明, 该组合控制策略不但能够提高车辆的乘坐舒适性, 而且能有效抑制悬架系统的主共振振动幅值.      

含分数阶Bingham模型的阻尼减振系统时滞半主动控制

针对基于磁流变液阻尼器的半主动控制系统中存在的时滞问题, 采用了一种将可控的时滞变量引入半主动控制切换条件的控制策略, 研究了考虑时滞的天棚阻尼控制切换条件对半主动阻尼减振系统的影响, 分析了含有分数阶Bingham模型的线性刚度系统在基础激励下的振动特性. 利用平均法得到了系统在含时滞半主动控制策略下主共振响应的近似解析解, 根据Lyapunov理论分析了系统的稳定性. 通过数值解验证了近似解析解的准确性, 二者具有较好的一致性. 利用近似解析解分析了固定激励频率下时滞对系统幅频响应特性的影响, 以及主共振峰值响应和共振频率随时滞变化的特性规律. 结果表明, 含时滞的半主动控制系统存在一个小时滞区间, 使得系统的振幅在主共振峰对应的频率附近低于不考虑时滞时系统的振幅, 且存在最优时滞使得系统的振幅大幅度降低; 而大时滞的引入会加剧系统的振动, 导致系统的颤振. 确定了基于分数阶Bingham模型的线性刚度系统在天棚阻尼半主动控制下的时滞选取原则, 为振动系统半主动阻尼控制中的时滞选取提供了参考.      

介电弹性作动器主动隔振模糊控制试验研究

采用模糊控制策略,开展介电弹性作动器的主动隔振性能试验研究。基于介电弹性材料的Maxwell应力模型建立了作动器的力电耦合模型,分析了作动器的非线性特性;针对隔振系统设计了Mamdani型模糊控制器,建立了控制电压信号与振动响应之间的关系;在此基础上,开展了介电弹性作动器主动隔振试验研究,并与加速度反馈控制进行了对比。试验结果表明,在相同驱动电压的情况下,基于模糊控制策略的主动隔振性能要优于加速度反馈控制,且能够显著降低由于非线性驱动力导致的倍频响应幅值,有助于提高隔振系统的稳定性。     

DYNAMIC CHARACTERISTICS OF VIBRATION ISOLATION SYSTEM WITH CUBIC STIFFNESS AND HYSTERESIS 1)

包含立方刚度和Bouc-Wen 型滞回的隔振系统具有复杂的非线性动力学特性。系统无阻尼响应模型可基于无滞回恢复力建立,利用谐波平衡法和泰勒展开求得近似解析解。系统有阻尼响应模型可利用解析/数值联合方法求解,该方法基于谐波平衡法和Levenberg-Marquardt 迭代算法,对于滞回产生的多值非光滑函数项,先计算时域响应再通过快速傅里叶变换求解谐波项系数。上述方法在含水平绞制梁的非线性隔振系统分析中得到有效应用。分析表明,在Bouc-Wen 型滞回和立方刚度的综合影响下,隔振系统呈现渐软–渐硬特性,滞回阻尼和线性阻尼都可以有效抑制共振,但前者高频隔振效果优于后者。     

磁流变阻尼器半主动控制方法的实验研究

由于磁流变阻尼器是一种高度非线性的装置,因此建立与之相适应的控制系统是半主动控制问题的关键。本文采用改进的Bingham模型建立了磁流变阻尼器的动力学特性模型,根据天棚阻尼开关控制、天棚阻尼连续控制和模糊控制三种控制方法,确立了从系统速度响应到磁流变阻尼器励磁电流之间的关系,并开发了一套半主动控制系统。在一个两自由度的简化车辆试验平台上进行半主动控制试验,对比研究了三种控制方法的控制效果。实验结果表明,在1.3Hz~2.0Hz的低频段内,开关控制的最佳减振效果为15.1%,连续控制的最佳减振效果为14.9%,模糊控制的最佳减振效果为20.1%。可见,三种控制方法都能有效的减小车体的振动,模糊控制的减振效果最佳。     

复合干摩擦的准零刚度隔振系统的亚谐共振

利用增量平均法研究了复合干摩擦阻尼器的准零刚度非线性隔振系统在外部简谐激励作用下的1/3次亚谐共振. 首先利用平均法得到了复合干摩擦的准零刚度隔振系统的主共振近似解析解, 然后在系统主共振近似解析解的基础上将系统的亚谐共振响应看作增量, 并利用平均法得到了准零刚度隔振系统的亚谐共振近似解析解. 利用李雅普诺夫方法得到了准零刚度隔振系统主共振和亚谐共振稳态解的稳定性条件, 并推导了系统1/3次亚谐共振的存在条件. 根据近似解析解分别得到了复合干摩擦的准零刚度隔振系统的主共振和亚谐共振力传递率. 利用数值解验证了准零刚度隔振系统主共振和亚谐共振近似解析解的准确性. 利用系统的近似解析解详细分析了准零刚度参数和干摩擦力对系统主共振和亚谐共振的幅频响应以及力传递特性的影响. 分析结果表明, 通过选取合适的干摩擦力参数, 可以消除准零刚度隔振系统在主共振区域的亚谐共振. 通过复合干摩擦阻尼器不但可以提高准零刚度隔振系统在低频区域的振幅抑制效果, 而且可以降低准零刚度隔振系统的起始隔振频率, 但是会增大系统在有效隔振频带内的力传递率.      

Semi-active hydro-gas suspension system for a tracked vehicle

A semi-active hydro-gas suspension is proposed for a tracked vehicle to improve ride comfort performance, without compromising the road holding and load carrying capabilities of the passive suspension. This is achieved through an active damper used in parallel with a gas spring. The suspension damper parameters are varied by a control mechanism based on sky-hook damping theory, which alters the flow characteristics. A damper prototype has been developed, tested for its flow characteristics, after which it has been integrated into an existing hydro-gas suspension system. An analytical model has been proposed from first principles rather than developing a phenomenological model based on experimental characteristics. This model is validated with experiments carried out on a suspension test rig. In order to compare the performance with the original passive system, an in-plane vehicle model is developed and the simulations clearly show that the semi-active system performance is superior to the passive system.     

Controlling the vertical shift of an isolated body based on the vibration of nonlinear systems with asymmetric damping forces

Asymmetric damping forces induce the equilibrium position of the isolated body to shift downward. Inspired by this phenomenon, this paper proposes the novel concept of shifting an isolated body based on the vibration of nonlinear systems with asymmetric damping forces. To verify the feasibility of this concept, a piecewise smooth isolation system is established. The incremental harmonic balance method is used to analyze the nonlinear vibration system and to obtain a steady-state analytical solution. The accuracy of the solution is verified by the Runge–Kutta method. Based on the analytical solution, the influences of some key parameters on the system vibration response are analyzed, revealing that the shift in the isolated body height increases with increasing excitation amplitude and damping asymmetry ratio. Additionally, this shift first increases and then decreases with increasing excitation frequency, reaching a peak near the natural frequency of the intermediate body. Finally, considering the complex structure, high energy consumption, and slow response of active suspension actuators, the proposed concept is applied to the tilt control of a vehicle. The simulation results show that the proposed methodology based on this concept can tilt a vehicle body to a certain angle in the turning direction, enabling the use of a semi-active actuator for vehicle tilt control to realize the control effect achieved by an active actuator.

     

DYNAMICAL ANALYSIS ON A KIND OF SEMI-ACTIVE SUSPENSION WITH TIME DELAY

对一类采用有限相对位移控制的含时滞单自由度半主动悬架系统进行了动力学分析.首先通过平均法得到了该系统的一阶近似解, 然后基于Lyapunov理论建立了系统的稳定性条件, 结果表明近似解的稳态幅值和稳定性条件都是时滞量的周期函数, 并且和外激励具有相同周期.通过对数值解和解析解的幅频曲线进行比较, 验证了一阶近似解析解的准确性, 并且解释了半主动控制中的高频颤振现象.研究了被动悬架系统并且和半主动悬架系统进行了比较, 证实了半主动悬架系统的优越性.最后, 探讨了一些关键的系统参数, 如控制间隙、时滞量、最小阻尼比等对半主动悬架系统稳态幅值的影响.     

高速列车磁流变半主动悬挂控制策略研究

为了提高列车运行平稳性,在经典的天棚控制和加速度控制的基础上,提出了一种新型混合控制策略,对高速列车磁流变半主动悬挂控制系统进行了仿真和实验研究.首先,对磁流变阻尼器(MRD)的力学特性测试分析,引入具有电流饱和特性的修正函数,建立了MRD的修正扩展双曲正切模型.然后,设计了面向列车平稳性的新型混合控制策略,通过分析车体加速度传递特性,比较了不同控制策略在全频域内的控制效果.此外,从相频特性的角度阐释了新型混合控制策略在全频段的控制优势.将MRD修正模型应用于悬挂控制,利用UM和Simulink软件建立了整车磁流变半主动悬挂控制系统联合仿真模型,分析不同控制策略对车辆动力学性能的影响.最后,构建了基于MRD的整车悬挂系统硬件在环实验台,通过开展硬件在环实验分析不同控制策略下的车体响应.结果表明,相比传统的控制策略,新型混合控制策略能兼顾低频段和高频段的振动控制效果,不仅可以提高列车的运行平稳性,而且不会恶化列车的运行安全性.硬件在环实验证明了新型混合控制策略的有效性,以及高速列车应用半主动控制悬挂的可行性.     

An alternative control strategy for semi-active dampers on off road vehicles

A control strategy is developed that takes into account the pitch and roll degrees of freedom on an off road wheeled vehicle in order to control discrete adjustable semi-active dampers more effectively. From the literature it was concluded that some existing semi-active control strategies were derived by employing models with either one or two degrees of freedom. If these strategies are applied to control semi-active dampers on a vehicle, each wheel station is controlled separately. The other degrees of freedom of the sprung mass, such as roll and pitch, are therefore not explicitly taken into account. The alternative control strategy determines that combination of damper states that will provide the highest acceleration opposing the movement of the sprung mass (deceleration), or the lowest acceleration in the direction of movement of the sprung mass. Simulation and experimental results indicated that the strategy that minimises the highest absolute value of the roll or the pitch acceleration performed significantly better than an existing semi-active control strategy (based on the absolute and relative damper velocities), especially when ride comfort under off-road conditions was taken into account. Four conventional dampers were modified, adding a by-pass assembly and controllable valve. The effect of using semi-active dampers on an off-road vehicle was evaluated during an extensive experimental programme, using ride comfort as basis. Results showed that the control strategy, as developed in this study, provided better responses in comparison to the passive configuration and an existing control strategy.     

索-梁组合结构主共振响应的时滞反馈控制

基于时滞加速度反馈控制策略对索-梁组合结构进行振动控制。根据Hamilton原理推导了索-梁组合结构非线性振动控制方程,运用多尺度法得到时滞反馈作用下索-梁组合结构主共振的一阶近似解,得出系统响应与控制参数的关系以及响应峰值和临界激励值与时滞参数的表达式。结果表明,主共振的响应存在多解和跳跃现象,调节控制增益和时滞值,可以有效抑制大幅振动。     

Research on linear/nonlinear viscous damping and hysteretic damping in nonlinear vibration isolation systems

A nonlinear vibration isolation system is promising to provide a high-efficient broadband isolation performance. In this paper, a generalized vibration isolation system is established with nonlinear stiffness, nonlinear viscous damping, and Bouc-Wen(BW)hysteretic damping. An approximate analytical analysis is performed based on a harmonic balance method(HBM) and an alternating frequency/time(AFT) domain technique.To evaluate the damping effect, a generalized equivalent damping ratio is defined with the stiffness-varying characteristics. A comprehensive comparison of different kinds of damping is made through numerical simulations. It is found that the damping ratio of the linear damping is related to the stiffness-varying characteristics while the damping ratios of two kinds of nonlinear damping are related to the responding amplitudes. The linear damping, hysteretic damping, and nonlinear viscous damping are suitable for the small-amplitude, medium-amplitude, and large-amplitude conditions, respectively. The hysteretic damping has an extra advantage of broadband isolation.     

Analysis of Duffing oscillator with time-delayed fractional-order PID controller

The free vibration of Duffing oscillator with time-delayed fractional-order Proportional-Integral-Derivative (FOPID) controller based on displacement feedback is studied. The second-order approximate analytical solution is obtained by KBM asymptotic method. The effects of the parameters in FOPID controller on the dynamical properties are characterized by some equivalent parameters. The correctness of the approximate analytical results is verified by the numerical results. The effects of the time-delayed FOPID controller with displacement feedback on control performances of Duffing oscillator are analyzed in detail by time response, and the stability conditions of zero solution and periodic motions are also presented. Finally, the control performances on Duffing oscillator with large damping are further analyzed. And the results show that one could take the advantage of time delay, when the parameters of time-delayed FOPID controller are chosen reasonably.     

Dynamics and control of a self-sustained electromechanical seismographs with time-varying stiffness

This paper is concerned with the nonlinear dynamics and vibration control of an electromechanical seismograph system with time-varying stiffness. The instrument consists of an electrical part coupled to mechanical one and is used to record the vibration during earthquakes. An active control method is applied to the system based on cubic velocity feedback. The electromechanical system is subjected to parametric and external excitations and modeled by a coupled nonlinear ordinary differential equations. The method of multiple scales is used to obtain approximate solutions and investigate the response of the system. The results of perturbation solution have been verified through numerical simulations, where different effects of the system parameters have been reported.     

Transient response analysis of a steel beam with vacuum packed particles

In this paper the method of semi-active damping of vibrations is presented. Free vibrations of a cantilever steel beam encapsulated in a sleeve, filled with the granular material are investigated. Various values of the partial vacuum generated in the granular structure allow to control the global dissipative properties of the discussed system. The loose grains encapsulated in the hermetic, polyvinyl chloride (PVC) envelope transform into a rigid, viscoplastic body as the jamming mechanism occurs when the underpressure is generated. Such phenomenon enables original strategies for semi-active damping. A detailed discussion related to the experimental results concerning the amplitude of vibration, damping, stiffness, and frequency of the continuous granular beam system is provided. The simplified Finite Element Model succeeded in describing the dynamic response of the structure.     

Random Vibration Control of Laminated Composite Plates with Piezoelectric Fiber Reinforced Composites

This paper presents an analysis of the active control of random vibration for laminated composite plates using piezoelectric fiber reinforced composites(PFRC). With Hamilton's principle and the Rayleigh-Ritz method, the equation of motion for the resulting electromechanical coupling system is derived. A velocity feedback control rule is employed to obtain an effective active damping in the suppression of random vibration. The power spectral density and meansquare displacements of the random vibration for laminated plates under different control gains are simulated and the validity of the present control strategy is confirmed. The effect of piezoelectric fiber orientation in the PFRC layer on the random vibration suppression is also investigated.The analytical methodology can be expanded to other kinds of random vibration.     

MR阻尼器的半主动控制研究

MR阻尼器能提供可以调节的阻尼力,适合用作减少结构地震响应的半主动控制器。本文对MR阻尼器的半主动控制进行研究,提出了状态跳跃算法,根据结构响应的大小实现MR阻尼器的状态切换,使结构响应得到有效的控制。这种控制策略简便,不需要在线计算,便于实施。由于速度响应直接影响MR阻尼器的阻尼力,建议用速度响应作为MR阻尼器进行状态切换的变量。文中给出了两个算例,进行了计算分析和比较,说明了状态跳跃控制算法的特点。     

Force and displacement transmissibility of a quasi-zero stiffness vibration isolator with geometric nonlinear damping

A geometric nonlinear damping is proposed and applied to a quasi-zero stiffness (QZS) vibration isolator with the purpose of improving the performance of low-frequency vibration isolation. The force, stiffness and damping characteristics of the system are presented first. The steady-state solutions of the QZS system are obtained based on the averaging method for both force and base excitations and further verified by numerical simulation. The force and displacement transmissibility of the QZS vibration isolator are then analysed. The results indicate that increasing the nonlinear damping can effectively suppress the force transmissibility in resonant region with the isolation performance in higher frequencies unaffected. In addition, the application of the nonlinear damping in the QZS vibration isolator can essentially eliminate the unbounded response for the base excitation. Finally, the equivalent damping ratio is defined and discussed from the viewpoint of vibration control.