磁性液体阻尼减振实验台的设计和实验分析

为了测试磁性液体阻尼器的有效性和各种参数对阻尼器减振效果的影响,设计一种阻尼器模型,并根据阻尼器的工作原理设计一套满足频率低、位移小、加速度小等条件的实验台,根据实验要求,在实验台上对磁性液体阻尼器进行实验.结果表明:实验台可实现频率范围为0.74～5.75 Hz的振动;与没有安装阻尼器相比,弹性悬臂梁在安装阻尼器后振幅完全衰减的振动时间缩短约65％;安装阻尼器后的悬臂梁对数衰减率随频率大小的变化规律是先增大后减小,然后再增大;安装阻尼器后的悬臂梁对数衰减率随着振幅的增大而增大;磁性液体阻尼器对于不同长度悬臂梁的振动都起到了很好的减振作用,当悬臂梁的长度为0.7m时,磁性液体阻尼器的减振效果最好;磁性液体阻尼器对于不同初始振幅的悬臂梁振动都具有良好的减振效果.     

基于ADAMS的载重汽车半主动悬架磁流变减振系统研究

为改善车辆悬架系统的刚度和阻尼特性,通过分析载重汽车半主动悬架系统的运动,建立了半主动悬架磁流变减振器阻尼力设计模型,确定了磁流变阻尼器的结构参数、控制策略,应用ADAMS软件仿真分析了磁流变连续可变阻尼半主动悬架的动力学响应。仿真结果表明,磁流变阻尼器具有很好的阻尼减振效应。利用磁流变液体的表观黏度随外加磁场变化阻尼可变的特性,控制半主动悬架的刚度和阻尼规律,实现了载重汽车的自适应减振,有效改善了车辆的行驶平顺性及操纵稳定性。     

磁流变液阻尼器振动控制测试系统的设计

设计了用于测试磁流变液阻尼器减振效果的半主动控制系统,利用压电式加速度传感器、数据采集卡和伺服电动机,通过数字PID的控制方式控制电动机转速和磁流变液阻尼器的活塞运动频率;利用VC++6.0软件设计了数据采集和控制程序,并对某结构进行了振动控制的实验研究,实验结果表明:设计的振动控制测试系统能使结构的振幅减小明显,减振效果良好。     

半主动TMD控制双跨轴系过临界振动的研究

针对多轴串联机械通过临界转速时振动过大的问题,对调谐质量阻尼器在双跨轴系振动控制中的应用进行了研究。并基于转子结构,设计了具有对称结构的笼式半主动调谐质量阻尼器用于控制轴系振动;搭建了双跨转子实验台,在不改变转子轴系原有支撑形式上,在两根轴上分别安装了调谐质量阻尼器,对调谐质量阻尼器对轴系各跨转子振动的影响规律进行了实验研究。研究结果表明,不可控调谐质量阻尼器可以有效抑制安装所在轴临界转速附近的振动,对相邻轴影响较小,但会引起新共振峰。根据此实验结果通过开关控制策略实现调谐质量阻尼器半主动控制,说明半主动调谐质量阻尼器可以在不停机的情况下,抑制转子轴系通过各阶临界转速时的振动,避免失谐。     

半主动直接输出反馈变结构控制电流变阻尼器减振研究

针对多层结构电流变阻尼器减振系统运动状态难以完全实时测量、扰动存在不确定性、系统参数容易出现摄动以及阻尼器连续可调的特点,提出了半主动直接输出反馈变结构控制策略,根据滑模运动方程稳定的Hurwitz判据选择滑模梯度参数,实现控制与扰动完全解耦;饱和非线性环节使阻尼器阻尼力不超调;阻尼力对主结构做负功控制规则保证主结构最佳减振。仿真分析表明,电流变阻尼器减振控制系统效果明显,不仅对扰动具有自适应性,而且对系统参数摄动也具有很强的鲁棒性。     

化工厂管道振动原因分析及控制

某塑料厂出料管路振动严重,为解决这一问题,采取有限元分析方法,计算了管系结构固有频率、气柱固有频率和瞬态冲击响应,再经过现场测量,结合理论计算结果,确定了管道振动原因,得出了相应的减振措施,并研究液压阻尼器和调谐质量阻尼器的选型和设计方法。对采取减振措施后的管路重新进行测量,结果表明改造措施有效,减振效果非常明显,达到了预期的减振效果。     

基于磁流变阻尼器的半主动悬挂控制实验研究

将磁流变阻尼器应用于半主动悬挂系统。建立了基于磁流变半主动悬挂系统的二自由度1/2车体的履带车辆振动模型。应用LQR最优控制理论,提出了一种基于磁流变阻尼器的履带车辆半主动控制策略,并在振动实验台上进行了半主动控制实验,模拟了车辆通过正弦路面的情形,结果表明,应用该控制策略能得到良好的减振效果。     

汽车悬架控制系统研究动态与展望

综述汽车悬架控制系统的基本类型，半主动控制和主动控制的控制策略。由于智能阻尼装置具有机械结构简单，动态范围大，能耗低等特点，是一种非常有前途的半主动减振装置。介绍电流变液体及磁流变液体和装置的主要特点与优点，并给出智能阻尼器的模型。着重论述几种控制方法在汽车悬架控制系统中的应用，探讨今后的研究方向和发展趋势。     

航海船舶多维振动半主动控制研究

本文采用基于并联机构和磁流变阻尼器的半主动控制多维减振装置，实现对船舶航行中面临的多维振动半主动控制。对减振装置进行结构设计、系统控制模型分析和控制算法研究，并制作样机进行实验研究。样机实验结果表明，该半主动控制多维减振装置能实现船舶多维减振，且减振效果优于被动控制多维减振。     

磁流变并联减振系统半主动控制及实验

采用典型三平移并联机构3-PRRP(4r)作为主体机构,选择MR(磁流变)阻尼器替代并联机构的驱动副,建立三平移并联多维减振系统;利用Lagrange方程建立多维减振系统的数学模型,以支路速度、加速度作为反馈信号,对机构动平台进行控制;根据MR阻尼器阻尼力的产生原则,设计了自适应模糊控制器。在此基础上,建立了实验样机及减振测控系统,对系统进行减振控制实验。实验结果表明,该半主动多维减振装置结构简单、可靠性好、所采取的控制算法有效,具有良好的多维减振效果。     

采用半主动TMD的建筑结构振动控制研究

为了改善在建筑结构中采用调频质量阻尼器（简称TMD）进行抗震时抗震效果不稳定和抑制频带窄等缺点，研究了变阻尼半主动调频质量阻尼器（简称STMD）。为了使阻尼变化容易实现，在设计激励力时采用了阶跃函数方式；同时还考虑到变动阻尼应在一定范围内进行的特点，提出了含约束的结构振动半主动控制方案；在控制策略方面，考虑到地震的随机性，引入了广义预测控制方法。从实例分析可知，采用STMD可以使设计质量、刚度和阻尼值分别下降约30％，90％，90％。计算仿真结果表明，采用STMD的抗震效果比TMD要好得多。     

A road-adaptive control law for semi-active suspensions

This paper presents a road-adaptive control law for semi-active vehicle suspensions. In semi-active suspensions, damping coefficients are controlled so as to make the actual damper force as close to the desired damper force as possible at any time instance. The proposed control law consists of a road-adaptive sky-hook damping algorithm and a Road Detection Algorithm (RDA). This approach leads to the sprung mass and unsprung mass velocity feedback control law with time varying gains. The gains are tuned by the RDA. To evaluate the performance enhancement brought about by the proposed control law, the performance of a semi-active suspension with the proposed control law is compared to those of the sky-hook controlled semi-active suspension and a passive suspension. The controller has been implemented experimentally on a quarter car test rig and a semi-active damper with a 19 damping rates has been used to generate the desired semi-active force. The proposed control law provides adequate damping for the wheel hop frequency and improved performance compared to that of the sky-hook control law.     

飞机起落架磁流变减摆器的设计流程

随着对半主动控制材料磁流变液研究的不断深入,磁流变液阻尼器装置的应用变得更加广泛。为了设计出性能更优越的磁流变液减摆器装置,根据磁流变液阻尼器的一般设计方法,对磁流变减摆器的设计流程进行了研究,总结并提练出一套完整详细的设计流程,按照这套设计流程做了一个算例进行实验验证。通过对实验结果的分析,理论设计的最大出力与初始阻尼力及仿真计算结果与实验结果十分接近,尤其在高频率高振幅时,由实验数据处理得到的示功图也很光滑,表明设计出来的减摆器具有很好的耗能特性,验证了磁流变液减摆器设计流程的可行性。     

应用于空间大型光机结构中的黏滞液体阻尼器

针对大型光机结构的结构特性,为抑制宽频噪声对结构指向稳定度及精度的影响,设计了一种可以在全频段提供高阻尼低轴向刚度的液体阻尼器。首先,对液体阻尼器的参数设计理论进行了分析;其次,通过微振动一体化集成仿真分析了引入液体阻尼器对整机的影响,由分析结果可知,在内外框架之间安装阻尼器,可以达到抑制宽频噪声的目的,一般情况下光轴指向精度(Line of Sight)可以改善50%以上,同时对结构特性改变较小;最后,设计了测试系统,对阻尼器参数的特性进行了实验研究,可知该液体阻尼器的阻尼系数随频率升高降低,在低频时可以达到18 574 N·s/m, 300 Hz时阻尼系数在300 N·s/m以上,轴向刚度约为28 659 N/m,随频率变化基本保持不变。结果表明:试验测试结果与仿真结果相符,液体阻尼器的刚度及阻尼参数的设计都达到了技术要求,根据仿真与试验的分析验证了阻尼器对大型光机结构振动抑制的有效性。     

Finite Difference Solution of Response Time Delay of Magneto-rhelological Damper

Magneto-rhelological(MR) dampers are devices that employ rheological fluids to modify their mechanical properties. Their mechanical simplicity, high dynamic range, lower power requirements, large force capacity, robustness and safe manner of operation in cases of failure have made them attractive devices for semi-active real-time control in civil, aerospace and automotive applications. Time response characteristic is one of the most important technical performances of MR dampers, and response time directly affects the control frequency, application range and the actual effect of MR dampers. In this study, one kind of finite difference solution for predicting the response time of magneto-rheological dampers from "off-state" to "on-state" is put forward. A laminar flow model is used to describe the flow in the MR valve, and a bi-viscous fluid flow model is utilized to describe the relationship of shear stress and shear rate of MR fluid. An explicit difference format is used to discretize the Novior-Stoks equation, and stability condition of this algorithm is built by Von-Neumann stability criterion. The pressure gradient along the flow duct is solved by a dichotomy algorithm with iteration, and the changing curve of the damping force versus time of MR damper is obtained as well. According to the abovementioned numerical algorithm, the damping forces versus time curves from "off-state" to "on-state" of a cylindrical piston type MR damper are computed. Moreover, the MR damper is installed in a material test system(MTS), the magnetic field in the wire circles of the MR damper is "triggered" when the MR damper is imposed to do a constant speed motion, and the damping force curves are recorded. The comparison between numerical results and experimental results indicates that this finite difference algorithm can be used to estimate the response time delay of MR dampers.     

On a combination of ground-hook controllers for semi-active tuned mass dampers

This study proposes a semi-active on-off damping controller that is a mix of three conventional ground-hook controllers for semi-active tuned mass damper systems. Three conventional ground-hook controllers are shown to be effective only in a certain frequency range. By taking advantage of all three ground-hook controllers, the mixed controller shows its better performance. More-over, we found an analytical solution of the harmonic vibration of the semi-active controlled system. The accuracy of the analytical solution and the superior performance of the proposed controller are verified by the numerical simulations.     

Modified liquid column damper for vibration control of structures

A modified version of the traditional tuned liquid column damper (TLCD) absorber is proposed as a passive vibration control device for structures vibrating at low frequencies. This new version, denoted as tuned liquid column ball damper (TLCBD), is equipped with a coated steel ball, in place of the orifice in TLCD, immersed inside the horizontal column of the damper. The current study examines the performance of TLCBD for a harmonic excitation which is a simplified model for the vortex shedding forces on structures in the cross wind direction. A parametric study to investigate the effect of the ball size and absorber mass on the suppression capacity is carried out. The absorber damping characteristics is identified experimentally using a single point laser vibrometer system and the measured damping factor is used in the mathematical model. Intensive numerical simulations were conduced and the results are compared with the traditional TLCD with optimum parameters. The results revealed an improvement of the vibration suppression capability of the proposed version that exceeds around 66% reduction.     

双调谐液体柱形阻尼器及其基本动力性能

借鉴被动调谐质量阻尼器(tuned mass damper,简称TMD)和调谐液体柱形阻尼器(tuned liquid column damper,简称TLCD)各自的优缺点,结合土木工程结构减震装置的经济性和适用性,提出了一种双调谐液体柱形阻尼器(doubly tuned liquid column damper,简称DTLCD),建立了简谐激励作用下单自由度DTLCD控制体系(DTLCD-SDOF)的运动方程,推导了其动力反应放大系数。提出了针对DTLCD的调优策略及优化评价函数,通过相关算法获得DTLCD-SDOF系统的参数优化程序,并利用该程序得到了DTLCD的最优参数。具体分析了不同参数对DTLCD共振峰值和调频宽度的影响,并对阻尼器阻尼参数或受控结构频率发生变化后DTLCD的鲁棒性进行了评价。对DTLCD,TMD,TLCD及DTMD的有效性和鲁棒性进行了对比分析。理论与数值研究结果表明,DTLCD的控制效果明显优于TMD和TLCD,与DTMD效果相同,并且在主结构频率的摄动方面拥有更佳的鲁棒性。事实证明,DTMD比TMD和TLCD更具工程适用性。     

Design and analysis of a new magneto rheological damper for washing machine

In this article, a new magneto rheological (MR) sponge damper is proposed for suppression of vibrations in a washing machine. The article presents design optimization of geometric parameters of MR sponge damper (MRSD) using the finite element analysis (FEA) and first order derivative techniques for a washing machine. The article explains the hysteresis behavior and the relationship of damping force with input current for the proposed MRSD. Moreover, the characteristics of the MRSD such as energy dissipation and equivalent damping coefficient are investigated experimentally in terms of input current and excitation amplitude. The passive dampers installed in washing machine are ineffective in reducing unwanted vibrations at resonant frequencies due to real time unbalanced mass. For this purpose, a test setup is established in order to compare the performance of passive dampers with the proposed MRSDs in a washing machine. It is noticed that MRSDs reduce average vibrations of 75.61 % in a low frequency band, whereas in a high frequency band, the MRSDs lessen average vibrations of 30.57 % in a washing machine. In order to determine the performance of proposed design MRSD, a detailed comparison of the performance parameters, such as total damping force, passive force, maximum average vibrations after suppression by MR dampers, maximum current and power ratings is provided with the existing designs of MR damper for washing machine from the literature.