Optimizing Control for Rotor Vibration with Magnetorheological Fluid Damper

The aim of this work is to analyze and design a control system for vibration reduction in a rotor system using a shear mode magnetorheological fluid(MRF)damper.A dynamic model of the MRF damper-rotor system was built and simulated in Matlab/Simulink to analyze the rotor vibration characteristics and the vibration reduction effect of the MRF damper.Based on the numerical simulation analysis,an optimizing control strategy using pattern search method was proposed and designed.The control system was constructed on a test rotor bench and experiment validations on the effectiveness of the proposed control strategy were conducted.Experimental results show that rotor vibration caused by unbalance can be well controlled whether in resonance region(70%)or in non-resonance region(30%).An irregular vibration amplitude jump can be suppressed with the optimization strategy.Furthermore,it is found that the rapidity of transient response and efficiency of optimizing technique depend on the pattern search step.The presented strategies and control system can be extended to multi-span(more than two or three spans)rotor system.It provides a powerful technical support for the extension and application in target and control for shafting vibration.

Optimizing control of a two-span rotor system with magnetorheological fluid dampers

A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled （ first critical speed region 37% , second critical speed region 42% ）. To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.

First order sensitivity analysis of magnetorheological fluid damper based on the output damping force

With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various parameters on damping force characteristics. A mathematical model of the output damping force on the MRF damper is established by the mechanism modeling method,a first order output sensitivity equation is deduced and the expression of the first order output sensitivity function is obtained. The first-order sensitivity functions of ten design parameters are solved,and the influence degree of system parameters change on the output force of MRF damper is analyzed by comparing the sensitivity index of the parameters. Two sensitivities of vibration velocity and control current are obtained through experiment to prove the other parameters sensitivity analysis conclusion by analogy verification,which provides guidance for the structure optimization design of MRF damper.

Research on the dynamic performance of ship isolator system that use magnetorheological dampers

Isolator systems on ships should ideally be able to simultaneously reduce low frequency vibration response and high frequency shock response. Conventional isolator systems are unable to do so To solve the problem, a new style isolator system was created. This isolator system consists of a steel coil spring component and a magnetorheological （MR） damper component working in parallel. Experiments on this isolator system were carried out, including tests of vibration reduction and shock resistance. The vibration load frequencies were set from 1-15 Hz, and force amplitudes from 2.94-11.76kN. The maximum shock input acceleration was 20 g, and impulse width was lores. Both the vibration and shock loads were applied using MTS Systems Corporation＇s hydraulic actuators. The experimental results indicated that the isolator system performs well on system vibration response, with resonance humps of the vibration response obviously reduced after using the MR damper. For the shock experiment, the attenuation of shock response was much faster with increased MR damping. The MR damper＇s effect on shock moments was very different from its performance in vibration mode. The correlation between MR force and control current was not as evident as it was during vibration loads.

Autoregressive trispectrum and its slices analysis of magnetorheological damping device

A combined magnetorheological damper combined with rubber spring and magnetorheological damper is addressed.This type of damping device has inherited the merits of rubber spring and the magnetorheological damper.The test damping device is made up of combined magnetorheological damper,amplitude controller,signal collecting device,computer software for dynamic analysis,etc.When a zeromean and non-Gaussian white noise interfere with the device,a time series autoregressive(AR) model is conducted by using the sampled experimental data.Trispectrum and its slices analysis are emerging as a new powerful technique in signal processing,which is put forward for investigating the dynamic characteristics of the magnetorheological vibrant device.The present of trispectrum and its slices analysis change with the variation of controllable working magnetic field of the damper correspondingly.It is indicated that AR trispectrum and its slices analysis methods are feasible and effective for investigation of magnetorheological vibrant device.

两结构联系体系MRFD半主动控制系统优化设计

本文对用磁流变流体阻尼器 (MRFD)联系两结构的半主动控制系统进行了优化设计 ,提出了一种权矩阵的选取方法 ,并通过仿真分析表明 ,在两个子结构层间设置磁流变流体阻尼器 (MRFD)可以使这种两结构半主动控制体系的总体动力响应显著降低 。

基于MRFD的爆炸冲击隔震体系及其半主动控制

为有效减少爆炸冲击荷载对防护工程内人员及设备等的伤害,利用磁流变液阻尼器(MRFD)能够提供连续可调库伦阻尼力的特点,建立了基于MRFD的爆炸冲击隔震体系。对该体系进行了几种基于瞬时最优主动控制算法的半主动控制数值仿真分析,结果表明:选用合适的半主动控制算法及恰当的控制参数,利用MRFD进行冲击隔震,能有效控制结构在爆炸冲击荷载作用下的加速度反应。

Research on low-frequency mechanical characteristics of the MR dampers in ship isolators

A new isolator composed of a steel rope spring and a magneto-rheological(MR) damper was designed and a study on low-frequency mechanical characteristics of MR dampers in isolators was carried out.It used the characteristics of the MR damper,such as fast response,controllable damping,small energy consumption,wide dynamic scope,and great adaptation.The relationships between MR damping forces and influencing factors were analyzed based on experimental data.The results show that damping force is not only related to structural dimensions,but also closely related to controllable current and vibration frequency.Finally,the empirical formula for damping forces was corrected,and the relationship between correction coefficients and factors analyzed.

A Blast Shock Isolation System with MRFD and Its Semi-Active Control Analysis

To effectively reduce the damage to people and devices in civil defense engineering subjected to blast shock, a blast shock isolation system with magnetorheological fluid dampers (MRFD) is proposed. MRFD can provide continuously adjustable Coulomb friction and has many advantages for semi-active control. Numerical simulation of this isolation system is finished using Matlab simulink toolbox. General semi-active control algorithms are consided based on instantaneous optimal active control algorithm. And the results indicate that the shock isolation system can work efficiently, decreasing about 93% of the peak acceleration of the isolation floor.

一种新型引磁式磁流变阻尼器研究

针对特定结构限制下磁流变阻尼器工作性能的优化问题,在传统磁流变阻尼器的基础上设计了一种新型引磁式磁流变阻尼器,建立了磁场与流场耦合动力学模型;以输出阻尼力和动态可调系数为优目标函数,基于多目标遗传算法对该型磁流变阻尼器内部活塞进行了优化;建立了多物理场耦合模型并进行了仿真和冲击试验。仿真结果表明:在相同外形尺寸条件下,新型磁流变阻尼器的有效阻尼通道长度为64 mm,相比普通磁流变阻尼器提高了60%;新型磁流变阻尼器的力学特性与动态可调性更加优越,当施加2.0 A电流、活塞运动速度为0.09 m/s时,新型磁流变阻尼器的输出阻尼力为55.9 kN,相比普通磁流变阻尼器(32.4 kN)提高了72.5%;施加不同大小电流时新型磁流变阻尼器的峰值压力与吸能容量均明显高于普通磁流变阻尼器。冲击试验结果表明:当施加2.0 A的电流、冲击速度为2.45 m/s时,相比普通磁流变阻尼器,其峰值压力达到11.64 MPa、峰值压力提高约41%。峰值压力试验结果与仿真结果对比表明:仿真结果和试验结果的趋势是一致的,其相对误差在0.1之内,表明了仿真模型的有效性。

基于最小二乘法和BP神经网络的磁流变阻尼器H-B模型参数辨识方法

针对Bingham模型磁流变阻尼器由于剪切稀化效应带来的阻尼力计算误差,在理论和仿真分析的基础上,提出一种最小二乘法和BP神经网络相结合的方法,对磁流变阻尼器H-B模型进行参数辨识,获得各参数与电流的关系,从而对磁流变阻尼器的阻尼力进行准确计算。最后通过磁流变阻尼器实验对理论方法进行验证。结果表明:借助于磁流变阻尼器的仿真分析,最小二乘法和BP神经网络相结合的磁流变阻尼器H-B模型参数辨识方法精确度高、吻合性好,验证了参数辨识结果的通用性及准确性。

单筒式磁流变减振器阻尼力计算方法研究

磁流变减振器具有结构简单、响应时间短、阻尼力大且连续可调等一系列优点,是目前研究的热点。然而在磁流变减振器的阻尼力计算及半主动控制理论等方面仍然存在许多问题。针对这些问题,设计一种单筒式磁流变减振器,并提出一种单筒式磁流变减振器阻尼力计算方法。首先建立了单筒式磁流变减振器阻尼力模型;其次,建立了单筒式磁流变减振器磁域模型,利用仿真软件得出磁场分布;最后通过实验得出铁心进、出口磁通密度与线圈电流间的关系。结果表明,流道进、出口处的磁通密度与线圈电流成线性变化规律,阻尼力随线圈电流的增加呈现先增大后减小的变化规律。在不通电流时,阻尼力随铁心运动速度的增加而增大;通入电流后,阻尼力受铁心速度的影响很小;阻尼力随铁心与缸筒间隙的变大而明显减小,并且随着间隙的增加,铁心运动速度对阻尼力的影响也减小。

全通道内置阀式磁流变阻尼器的设计及性能分析

针对磁流变假肢中磁流变阻尼器体积大、输出阻尼力较小的问题,设计了一种全通道内置阀式磁流变阻尼器。首先,通过布置导磁楔形环和隔磁环,引导磁力线穿过全部液流通道,并进行了阻尼器磁路分析和输出阻尼力数学模型的推导;其次,利用ANSYS软件进行了阻尼器电磁场仿真;再次,采用多目标遗传算法优化阻尼器的结构参数,并仿真对比了优化前后阻尼器的平均磁感应强度和输出阻尼力;最后,加工了结构参数优化前后的阻尼器样机,并对其进行了动力学性能测试与分析。结果表明:优化后阻尼器活塞头的体积减小了24.4%,最大输出阻尼力提高了24 N;当电流为2 A时,优化前最大输出阻尼力仿真值为295.38 N,测试值为309.76 N,误差为4.6%;优化后最大输出阻尼力仿真值为307.77 N,测试值为333.76 N,误差为7.6%。所设计的全通道内置阀式磁流变阻尼器体积较小,输出阻尼力较大,液流通道的空间利用率较高。研究结果可为磁流变假肢中磁流变阻尼器的设计提供参考。

基于下肢假肢的阶梯式变间隙磁流变阻尼器设计

针对下肢假肢步态变化时所需阻尼力大小不同的问题,提出一种基于下肢假肢的新型阶梯式变间隙磁流变阻尼器(MRD)。基于Bingham力学模型设计MRD的两级阻尼间隙宽度及主要结构尺寸,通过ANSYS Maxwell分析其内部磁场分布,采用Simulink仿真输出阻尼力。结果表明:阶梯式变间隙MRD步行时的工作间隙为1.6 mm,最大阻尼力为902.7N;跑步等其他复杂步态时的工作间隙为0.6 mm,最大阻尼力为2033.7 N,满足不同步态的阻尼力要求,且该MRD的最大工作电流为0.4 A,极大降低了阻尼器功耗。所提出的阶梯式变间隙MRD具有阻尼力分级输出、可调范围大、能耗低的优点,可代替阻尼间隙固定的传统MRD应用于假肢系统。

磁流变阻尼器力学模型的研究现状

磁流变液是一种流变特性会随施加的磁场强度大小和方向而变化的粘性流体,磁流变阻尼器是一种智能减振器,其阻尼力会随输入电流的大小而变化,其得到了国内外相关专家的广泛研究和应用。先回顾前磁流变阻尼器力学模型的研究情况,并对各种模型进行对比分析,最后讨论了目前磁流变阻尼器研究中还有待解决的问题。

磁流变阻尼器对斜拉索减振效果的试验研究

采用磁流变阻尼器作为被动控制器件 ,以钱江三桥南岸 15 4 m长的斜拉索为试验对象 ,通过阶跃激励的方法获得斜拉索振动的自由衰减信号。对采集到的信号进行小波分解、希尔伯特变换识别系统的等效阻尼比。据此来判断磁流变阻尼器在施加不同电压情况下对索前三阶模态振动的减振效果 ,并与油阻尼器的制振效果进行比较。试验结果表明磁流变阻尼器作为被动控制器件时制振效果明显 ,优于油阻尼器且控制的频域范围要比油阻尼器的广 ;当供电失效时也可满足索减振的要求。索的各阶共振峰频率在安装 MR阻尼器后发生稍许漂移。

汽车磁流变减振器设计准则探讨

提出了微型汽车磁流变减振器的设计准则 ,建立了磁流变减振器的理论分析模型来预估减振器阻尼力的大小。测试结果表明 ,减振器的阻尼力由粘性阻尼力和磁场阻尼力组成 ,随着磁场强度的增加 ,减振器的阻尼力也增大 ,基本上符合理论预估值 ,说明所建立的理论分析模型是可行的。

汽车半主动悬架系统研究进展

基于系统工程理论 ,论述了汽车半主动悬架系统的研究和动态 ,分析了目前电 磁流变液减振液的研究及减振器开发现状。在分析了一些较为成功的半主动悬架控制策略的基础上 ,论述了经典控制、线性最优控制、自适应控制和智能控制方法在半主动悬架系统中的应用前景 ,提出了基于天棚阻尼控制理论、模糊控制理论和自适应控制理论为主线的复合控制策略。此外 ,提出了基于磁流变液减振器的半主动悬架系统研究与开发的整体思路 ,探讨了值得研究的若干理论和应用问题。

单出杆汽车磁流变减振器设计与试验

在分析磁流变减振器工作模式基础上,结合汽车减振器的工作要求,分别完成了混合模式和流动模式磁流变减振器的结构设计,建立了两种模式下的数学模型并进行了相关的仿真研究,设计出了产品并进行了试验研究。比较分析发现,二者阻尼力在低速时差异不大,但是在高速时差异较大。从工程实现和控制角度看,混合工作模式可以减少阻尼孔的堵塞并具有较大的可控倍数,其性能要明显优于流动模式减振器。通过试验证明,建立的模型、提出的设计思路和方法符合工程要求。

磁流变液温度特性研究

主要配制了温度稳定性能优异的磁流变液,并分析温度对磁流变液悬浮相、载液和添加剂的影响,研究了磁流变液的粘度-温度特性,该磁流变液在20～100℃温度范围内粘度稳定性能优良。测试了该磁流变液的阻尼器在不同温度下施加不同电流时的阻尼力特性,并初步探讨了磁流变液阻尼力的温度衰减性能。