磁流变阻尼器优化设计与性能分析

利用磁流变液这种智能材料的力学性能 ,制作了一种双出杆磁流变阻尼器。文中主要讨论了磁流变阻尼器结构设计、磁路设计的基本原理 ,并讨论了结构参数对磁流变阻尼器性能的影响 ,最后优化设计了磁流变阻尼器的结构参数 ,给出了磁流变阻尼器结构参数的匹配关系     

磁流变减振器原理

这里分析了一种磁流变减振器的原理,用粘度模型描述了磁流变液随外加磁场变化的流变特性,得到的阻尼力方程为这种减振器的设计提供了理论基础。研究结果表明:随着外加磁场的增加,磁流变液的表观粘度增加,减振器产生的阻尼力增大。     

Friction behavior of magnetorheological fluids with different material types and magnetic field strength

Magnetorheological (MR) fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic field, which is known as MR effect, resulting in variation of stiffness, shear modulus, damping and tribological characteristics of MR fluid. As MR effect depends on the density of particles in the fluid or the strength of a magnetic field, the experiments are conducted to evaluate the friction property under reciprocating motion by changing the types of MR fluid and the strength of a magnetic field. The material of aluminum, brass, and steel are chosen for specimen as they are the most common material in mechanical applications. The surfaces of specimen are also observed by optical microscope before and after experiments to compare the surfaces with test conditions. The comparing results show that the friction coefficient increases as the strength of a magnetic field increases in regardless of types of MR fluid or the material. Also the density of particle in MR fluid affects the friction characteristic. The results from this research can be used to improve the performance of mechanical applications using MR fluid.     

磁流变阻尼器阻尼性能研究

为了研究新型可控流体磁流变液的特性以及利用以磁流变液为流体的阻尼器的阻尼特性，本文对磁流变液的重要组成部分——磁性微颗粒进行了介绍．并讨论了描述磁流变液的流变模型。在分析现有磁流变阻尼器结构的基础上．提出了一种改进的阻尼器结构。最后对改进结构测试了其性能，分析了影响其性能的各种因素，并提出了目前尚待解决的主要问题。     

冲击载荷作用下磁流变阻尼器的建模与分析

以某12．7 mm机枪的磁流变(MR)后坐阻尼器为研究对象,基于Herschel-Bulkley本构模型,建立了该MR后坐阻尼器的轴对称一维层流模型。运用ANSYS软件,对该阻尼器的MR阀进行了磁场有限元分析,求得了环状间隙间MR流体的磁通密度。将MR流体流动模型和MR阀有限元结果相结合,建立了不同磁场作用下阻尼力随活塞速度的变化规律,利用这些规律对该阻尼器的落锤撞击试验和实弹射击试验进行了数值仿真。理论与试验结果的对比指出,在低磁场作用的情况下,理论与试验结果具有较好的一致性。     

基于多孔泡沫金属材料的简易磁流变阻尼器可行性研究

针对磁流变液阻尼器价格昂贵及不易密封且易失效的问题,提出以多孔泡沫金属材料为载体,解决上述应用的瓶颈问题的新理念。介绍基于多孔泡沫金属材料的简易磁流变液阻尼器的概念设计,并对其可行性进行初步研究,初步研究结果表明多孔泡沫金属可以储存磁流变液,同时磁流变液在磁场作用下可以从泡沫金属溢出并实现阻尼功能。     

基于有限元仿真的磁流变阻尼器性能研究

对双线圈活塞式磁流变阻尼器结构和工作原理进行分析,应用ANSYS软件对阻尼器磁场有限元仿真,证明励磁线圈电流异向时磁场的利用效率更高,并且建立电流异向时阻尼间隙磁感应强度和电流的函数表达式,结合阻尼力模型和磁流变液的材料特性,得出阻尼力关于电流值和活塞运动速度的理论关系。通过阻尼器台架试验,对理论关系进行验证,结果表明:理论值准确的描述了阻尼力变化规律。为磁流变阻尼器设计及改进提供方法。     

磁流变减振器磁场特性分析及试验研究

设计了磁流变减振器磁芯磁路,建立了磁路的仿真模型,仿真研究了磁路的磁场特性,用实验的方法对仿真模型进行了验证和修正;在此基础上,建立了整个磁流变减振器的仿真模型,仿真研究了其磁场分布规律及不同参数下阻尼孔附近的磁通密度.研究结果表明,磁芯直径、工作缸壁厚、阻尼通道长度和线圈电流是影响磁场特性的主要因素,合理选择磁路结构参数可使其性能得到最大发挥.设计并制造出一种车辆单筒充气式磁流变减振器,对其进行了台架试验,得到不同电流下的减振器示功特性图,研究发现,通过调节减振器励磁线圈中的电流获得不同强度的磁场,在磁场作用下,磁流变液粘度发生变化,从而改变减振器的阻尼特性,减振器的饱和工作电流约为2A.试验验证了磁路设计的正确性,并为实现车辆磁流变半主动空气悬架控制研究奠定了基础.     

A 3D model for magnetorheological fluid that considers neighboring particle interactions in 2D skewed magnetic fields

Magnetorheological (MR) fluid is used as the working medium in MR finishing. The viscosity of the MR fluid, which determines the shear acting on the workpiece surface stress, can be controlled by the intensity of the applied external magnetic field, and is thus an important design parameter in the finishing process. Most previous studies have used a shear stress value obtained experimentally under a limited set of conditions. Although a recent theoretical model that predicts the shear stress in an external vertical magnetic field has been developed, it treats the energy variation with respect to the strain and the intensity of the magnetic field only among the adjoining particles in a chain. Because that model assumes no multiparticle interactions, it is not well suited to a case in which the magnetic field is more than one dimension such as in MR finishing. In this study, a new three-dimensional model is proposed by expanding the one-dimensional model and considering multiparticle interactions. The proposed model assumes that each particle is surrounded by the 26 neighboring particles, and the total internal energy is estimated by calculating the magnetic dipole interactions among the particles. Therefore, the proposed model considers not only the particle-to-particle energy variations, but also the chain-to-chain energy variations. The behavior of MR fluid is evaluated using the proposed model in a two-dimensional skewed magnetic field.     

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。     

圆盘式磁流变离合器特性分析

磁流变离合器是通过磁流变液的剪切应力传递转矩的器件.介绍了一种园盘式磁流变离合器的工作原理,用Bingham 模型描述了磁流变液随外加磁场变化的流变特性,基于Navior-Stokes方程,分析了磁流变液在两圆盘间的流动,得到了离合器传递的转矩和输出角速度的方程,为离合器的设计奠定了理论基础.研究结果表明:离合器传递的转矩和输出角速度可由外加磁场连续控制.     

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。     

磁流变液装置及其在机械工程中的应用

磁流变液是一种在磁场作用下,其流变学性能可作出迅速响应,且易于控制的新型智能材料。基于磁流变液的装置包括阻尼器、制动器、离合器、抛光装置和液压阀等,有很大的潜在发展前景,有些已在汽车、健身设备和抛光机械等工程领域取得商品化应用。本文在分析磁流变液装置工作模式的基础上,对近十年来磁流变液装置（尤其是阻尼器）以及这些装置在机械工程领域的应用进行了分类和全面综述,并对其应用前景进行了展望。     

磁流变液特性及其装置在工程领域中的应用

磁流变液是一种在外加磁场作用下流变特性发生急剧变化的新型智能材料。介绍磁流变液的主要特性及其工作模式、近年来磁流变液装置在工程领域尤其在机械工程中的应用,以及国内外磁流变液的发展现状。     

小位移挤压式磁流变阻尼器的实验研究

设计了小位移、大阻尼力特性的挤压式磁流变阻尼器,并进行了相应的实验研究,包括示功特性和阻尼特性,以及所选用的重庆仪表材料研究所磁流变液MRF-01K的饱和磁场强度.实验结果表明,随着电流的增加,减振器示功图曲线包围面积逐渐增大,耗能增加,减振效果增强,其与激振器的激振频率关系不大;由阻尼特性曲线可知,阻尼器的输出力既与阻尼器电流有关,又与激振器频率有关,频率越大,电流越大,输出的力越大.     

挤压式磁流变液阻尼器--转子系统的动力学特性与控制

用磁流变液代替常规挤压油膜阻尼器的润滑油,可制成阻尼特性受磁场控制的挤压油膜阻尼器,用于转子系统的振动控制。依据Bingham模型推导了磁流变液挤压油膜的雷诺方程及其解的表达式,给出了油膜流速、压力分布、油膜反力和阻尼器内磁拉力等的计算公式;以磁流变液阻尼器—刚性转子系统为例,理论分析了挤压油膜的力学特性和转子系统的不平衡响应特性;设计和制造了一种用于转子振动控制的挤压式磁流变液阻尼器;试验研究了支承在该阻尼器上的单盘偏置柔性转子系统的不平衡响应特性和控制方法。研究表明,磁拉力可降低一阶临界转速和临界振幅;油膜反力可降低转子系统在无阻尼临界转速处的振幅,并使一阶有阻尼临界转速增大;通过开关控制能使阻尼器具有最佳的减振效果,使转子振幅在全转速区达到最小。     

Rheological measurement of redispersibility and settling to analyze the effect of surfactants on MR particles

The smart materials such as magnetorheological (MR) fluids are gaining wide popularity due to their superior control abilities. These abilities are strongly dependent about the stability of the MR fluid which needs to be sustained for the useful life of the system. In the present research work, experimental studies focusing on aggregation, redispersibility and settling of carbonyl iron-based MR fluids have been conducted to analyze the effect of surfactants on controlling settling and redispersibility. The experimental investigations were conducted by preparation of nine MR fluids samples using three types of surfactants (oleic acid, citric acid and tetramethylammonium hydroxide) and three different carrier fluids (water, silicone oil and DTE light mineral oil). The samples were prepared by mixing on rotational machine for 24 h and the homogeneity of the samples was visually inspected. The shear stress and viscosity variation of the homogenous mixture with respect to shear rate was obtained using magnetic rheometer. A new method is presented for measuring the settling of homogenous mixtures by measurement of the change in the magnetic field strength due to settlement of particles. The effect of surfactant type and its quantity on the stability of MR fluid is explored and the results of settling and redispersibility have been presented.     

Variable stiffness and damping magnetorheological isolator

This paper presents the development and characterization of a magnetorheological (MR) fluid-based variable stiffness and damping isolator. The prototype of the MR fluid isolator is fabricated, and its dynamic behavior is measured under various applied magnetic fields. The parameters of the model under various magnetic fields are identified, and the dynamic performance of the isolator is evaluated in simulation. Experimental results indicate that both the stiffness and damping capability of the developed MR isolator can be controlled by an external magnetic field.     

新型磁流变阻尼器设计及磁场有限元分析

磁流变液是一种新型的智能材料,在外加磁场作用下其流变学特性如屈服强度能够在毫秒级时间内发生连续可逆的变化.利用磁流变液的这种特殊性能,针对力觉再现技术的要求,设计了一种新型的磁流变阻尼器结构.详细阐述了该阻尼器的工作原理和力矩模型,并完成了有限元模型的建立.运用磁场有限元分析软件Ansoft对阻尼器进行了磁场强度检验并进行了相应的结构改进.仿真结果表明该阻尼器设计结构合理,为磁流变阻尼器的准确设计提供了保证.     

Study on damping properties of magnetorheological damper

To research the properties of a new kind of smart controllable MR (magnetorheological) fluid, in this paper, the rheological models are discussed. On the basis of analyzing the structural forms of MR dampers, an improved structure of the MR damper is introduced; the properties of the novel MR damper are then tested. The experimental results reveal that the Herschel-Bulkley model predicts the force-velocity well; the damping properties of the ameliorated structure of the MR damper have improved; when the excitation is a trigonal signal, the MR damper reveals a thinning effect at high velocity; and when the excitation is a sinusoidal signal, the MR damper reveals a nonlinear hysteretic property between the damping force and relative velocity. Finally, the main unsolved problems have been put forward. __________ Translated from Ningxia Engineering Technology, 2005, 24 (4) (in Chinese)