电/磁流变技术在机械工程中的应用(上)

电／磁流变液（ERF／MRF）是在电／磁场作用下，其流变学性能可迅速响应，且易于控制的新型智能材料。基于电／磁流变技术的装置包括阻尼器、制动器、离合器、抛光装置和液压阀等，都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。在分析电／磁流变液装置工作模式的基础上，对近十年来电／磁流变液装置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，对其存在的问题及应用前景进行了展望。     

电/磁流变技术在机械工程中的应用(下)

电／磁流变液（ERF／MRF）是在电／磁场作用下，其流变学性能可迅速响应，且易于控制的新型智能材料。基于电／磁流变技术的装置包括阻尼器、制动器、离合器、抛光装置和液压阀等，都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。本文在分析电／磁流变液装置工作模式的基础上，对近十年来电／磁流变液装置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，对其存在的问题及应用前景进行了展望。     

基于混合模式的磁流变阻尼器的工作原理

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，本文讨论了磁流变液的流变特性，在分析磁流变液装置基本工作模式的基础上，论述了一种流动模式和剪切模式共同作用的混合模式的磁流变阻尼器的工作原理。论证了这种新型阻尼器的阻尼力能十分灵敏的实现阻尼的目的，在车辆和工程领域具有广阔的应用前景．     

基于混合模式的磁流变阻尼器的工作原理

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。该文讨论了磁流变液的流变特性，在分析磁流变液装置基本工作模式的基础上，论述了一种流动模式和剪切模式共同作用的混合模式的磁流变阻尼器的工作原理。论证了这种新型阻尼器的阻尼力能十分灵敏的实现阻尼的目的，在车辆和工程领域具有广阔的应用前景。     

基于混合模式的磁流变阻尼器的工作原理

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.本文讨论了磁流变液的流变特性,在分析磁流变液装置基本工作模式的基础上,论述了一种流动模式和剪切模式共同作用的混合模式的磁流变阻尼器的工作原理.论证了这种新型阻尼器的阻尼力能十分灵敏的实现阻尼的目的,在车辆和工程领域具有广阔的应用前景.     

磁流变阻尼器的动态性能试验研究

介绍磁流变阻尼器的工作原理和结构,并对其进行了动态性能试验研究。试验结果表明磁流变阻尼器是一种优秀的阻尼系数可调的半主动减振装置,可以提供一定范围稳定可调的阻尼力;基于试验数据探讨了磁流变阻尼器的力学模型,在反映磁流变液剪切稀化(稠化)特性的Herschel—Bulkley模型的基础上得出修正的双粘性滞回本构模型。     

ERF/MRF装置在机械工程中的应用 (Ⅱ)

在分析电／磁流变液装置工作模式的基础上，对近10年来电／磁流变液装置及这些装置在机械工程领域的应用进行分类和全面综述。对其研究存在的问题及应用前景进行了展望。     

ERF/MRF装置在机械工程中的应用(上)

在分析电／磁流变液装置工作模式的基础上，对近10年来电／磁流变液装置以及这些装置在机械工程领域的应用进行分类和全面综述，对其研究存在的问题及应用前景进行了展望。     

基于磁流变抛光技术的实验装置研究

在介绍了磁流变抛光的基本原理的基础上,对磁流变抛光的实验装置进行了分类设计,从工件与抛光盘的相对位置和磁流变液的注入形式考虑,分别通过平置式、倒置式和正置式,使抛光装置与不同机床进行整合,实现了模块化设计理念.同时对不同的整合方案进行了比较,得出合理的设计方案.     

多孔泡沫金属磁流变液阻尼器设计及力学性能研究

磁流变液阻尼器的力学性能直接决定了其应用范围。目前的磁流变液阻尼器主要集中于大阻尼力的减振,而对于阻尼力范围较小的应用较少。对此,根据多孔泡沫金属材料的特性,论文设计了一种多孔泡沫金属磁流变液阻尼器,分析了其工作原理,并利用搭建的性能测试系统对其力学性能影响因素进行了研究。结果表明:该多孔泡沫金属阻尼器可用于小阻尼力方面的减振,而且其他条件相同时,采用泡沫金属铜产生的阻尼力比采用泡沫金属镍的阻尼力大,为磁流变技术的推广应用提供了新思路。     

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.     

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。     

Comparative Study on Wear Characteristics between Flow Mode and Shear Mode Magnetorheological Dampers

This comparative study experimentally examines the wear characteristics of magnetorheological (MR) dampers operated in flow mode and shear mode. First, electromagnetic coil structures are designed for two different MR dampers to maximize the field-dependent damping force. Two MR dampers are also designed to have the same volume of MR fluid for reasonable comparison. After identifying the field-dependent damping force at the initial state, the two dampers are operated up to 60,000 cycles using a reciprocating-type wear durability tester. The field-dependent damping forces are then evaluated before and after operation. The wear properties of the MR fluid are investigated using scanning electron microscope (SEM) images that show the changes in the MR fluid particles' size and shape. The surface roughness of the MR damper's piston areas are also measured. In addition, the effects of the permeability of the piston sleeve materials on the wear properties are investigated by selecting three different sleeve materials that have different permeability values: 0.2% carbon steel (S20C), 0.45% carbon steel (S45C), and tool die casting steel (STD-11). The surface roughness of each case is tested and the atomic spectrum is investigated after long operation using energy-dispersive X-ray spectroscopy (EDS) inside the piston. The experimental results obtained from this work indicate that the motion of the operating mode significantly affects the wear characteristics of the MR fluid itself as well as the magnetic effective areas of the MR dampers.     

Application of smart passive damping system using MR damper to highway bridge structure

Magnetorheological (i.e., MR) dampers are one of the most prospective semiactive control devices for civil engineering applications to earthquake hazard mitigation, because they have many advantages such as small power requirement, reliability, and low price to manufacture. A smart passive system based on an MR damper system without including a power supply, controller, and sensors consists of an MR damper and an electromagnetic induction (i.e., EMI) system that uses a permanent magnet and a coil. The electromotive force induced by movement of a structure can control MR damper effectively without any external power supply and control algorithm. This smart passive control system is implemented to verify the effectiveness for seismic protection of benchmark structural control problem for the seismically excited highway bridge, which is based on the newly constructed 91/5 highway over-crossing in Southern California. The results of the numerical simulations show that the presented control system can be beneficial in reducing seismic responses of benchmark bridge structure.     

Design and experimental analysis of new industrial vibration dampers

Vibration dampers are the first line of defense against shock and impacts sustained by mechanical and structural systems. Consequently, for decades, new impact damping technologies have been developed and applied in several engineering fields to attenuate undesired vibrations. Linear particle chain (LPC) impact dampers are the latest category of impact dampers being developed for the mitigation of unwanted vibrations in many systems. However, the challenges associated with prototyping such devices made their application in practical systems very limited. This paper proposes five innovative designs for the LPC impact dampers satisfying a wide range of industry needs in terms of efficiency, cost, and sustainability. The proposed designs are fabricated and tested under the same conditions to assess their efficiency in attenuating the vibration of a simple structure. Each design showed consistent behavior, but some designs outperformed others depending on the geometry, physical characteristics, and type of structure. The detailed design, experimental study, and time response comparisons are presented here to provide an initial study towards the development of practical sustainable LPC vibration dampers for real engineering applications.     

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。     

The experimental identification of magnetorheological dampers and evaluation of their controllers

Magnetorheological (MR) fluid dampers are semi-active control devices that have been applied over a wide range of practical vibration control applications. This paper concerns the experimental identification of the dynamic behaviour of an MR damper and the use of the identified parameters in the control of such a damper. Feed-forward and recurrent neural networks are used to model both the direct and inverse dynamics of the damper. Training and validation of the proposed neural networks are achieved by using the data generated through dynamic tests with the damper mounted on a tensile testing machine. The validation test results clearly show that the proposed neural networks can reliably represent both the direct and inverse dynamic behaviours of an MR damper. The effect of the cylinder's surface temperature on both the direct and inverse dynamics of the damper is studied, and the neural network model is shown to be reasonably robust against significant temperature variation. The inverse recurrent neural network model is introduced as a damper controller and experimentally evaluated against alternative controllers proposed in the literature. The results reveal that the neural-based damper controller offers superior damper control. This observation and the added advantages of low-power requirement, extended service life of the damper and the minimal use of sensors, indicate that a neural-based damper controller potentially offers the most cost-effective vibration control solution among the controllers investigated.     

气囊抛光技术及其研究现状

气囊抛光能够获得稳定的材料去除特性和高质量的抛光表面。回顾了气囊抛光的工作原理、特点和发展现状,对气囊抛光的关键技术进行了比较分析,包括抛光工具,进动抛光,脉动抛光,磁流体抛光,驻留时间,边缘控制和过程控制,抛光轨迹规划,磨粒场及气囊抛光应用等。研究结果表明,气囊抛光是一种值得关注的自由曲面高效精密抛光方法。