• Title, Summary, Keyword: Magneto-rheological Fluid

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Response Property of Multi-directional Mount Using Magneto-Rheological Fluid (MR유체를 이용한 다방향 제진형 마운트의 응답특성)

  • 안영공;신동춘;양보석;이일영;김동조
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.7
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    • pp.517-523
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    • 2003
  • This paper presents response property of the squeeze mode type mount using Magneto-Rheological fluid (MR fluid) . The MR mount for the isolation of multi-directional vibrations was constructed in this study. Both the mechanism and shape of the mount are the same as squeeze film dampers for a rotor system. In the present work, the performance of the mount was experimentally Investigated according to the magnetic field strength. The experimental results present that the MR mount can effectively reduce the vibration in a wide range of frequency by controlling the applied electromagnetic filed strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents In this study.

Vibration control of mechanical systems using semi-active MR-damper

  • Maiti, Dipak K.;Shyju, P.P.;Vijayaraju, K.
    • Smart Structures and Systems
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    • v.2 no.1
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    • pp.61-80
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    • 2006
  • The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.

Analysis of Magneto-rheological Fluid Based Semi-active Squeeze Film Damper and its Application to Unbalance Response Control of Rotor (자기유변유체를 이용한 반능동형 스퀴즈 필름 댐퍼의 해석 및 회전체 불균형 응답 제어)

  • Kim, Keun-Joo;Lee, Chong-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.3
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    • pp.354-363
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    • 2005
  • Squeeze film dampers (SFDs) have been commonly used to effectively enhance the dynamic behavior of the rotating shaft supported by rolling element bearings. However, due to the recent trends of high operating speed, high load capacity and light weight in rotating machinery, it is becoming increasingly important to change the dynamic characteristics of rotating machines in operation so that the excessive vibrations, which may occurparticularly when passing through critical speeds or unstable regions, can be avoided. Semi-active type SFDs using magneto-rheological fluid (MR fluid), which responds to an applied magnetic field with a change in rheological behavior, are introduced in order to find its applications to rotating machinery as an effective device attenuating unbalance responses. In this paper, a semi-active SFD using MR fluid is designed, tested, and identified to investigate the capability of changing its dynamic properties such as damping and stiffness.In order to apply the MR-SFD to the vibration attenuation of a rotor, a systematic approach for determining the damper's optimal location is investigated, and also, a control algorithm that could improve the unbalance response characteristics of a flexible rotor is proposed and its control performance is validated with a numerical example.

Identification of Negative Stiffness Effects in Magneto-Rheological Fluid based Squeeze Film Damper (자기유변유체를 이용한 스퀴즈 필름 댐퍼에서의 부강성 효과 규명)

  • 김근주;김정훈;이종원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.739-744
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    • 2001
  • In order to investigate the stability of magneto-rheological fluid based squeeze film damper (MR-SFD), its negative stiffness effect, which arises from magnetization of MR-SFD, is identified theoretically and experimentally. The analytical model of MR-SFD includes the magnetic circuit as well as the displacement stiffness associated with the squeeze mode of MRF. Extensive experiments are carried out to measure the magnetic attraction forces generated in the MR-SFD, with the excitation frequency and the eccentricity of the journal varied, which are controlled by an active magnetic bearing. The simulation and experimental results are found to be in good agreement. It is concluded that the negative stiffness effect dominates only in the low frequency region because its effect diminishes in the high frequency region due to the eddy-current loss.

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Design of Magneto-rheological Fluid Based Device (자기유변유체를 이용한 공학 장치의 설계)

  • Kim, Jeong-Hoon;Lee, Chong-Won;Jung, Byung-Bo;Park, Young-Jin;Cao, Guangzhong
    • Proceedings of the KSME Conference
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    • pp.544-549
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    • 2001
  • The effect of power supply voltage on the performance limits in a laboratory Magneto-rheological fluid based device was identified by experiments. It suggests that the frequency range of motion for control be limited by the voltage attenuation due to the coil inductance and the maximum power supply voltage set for practical use of MRF devices. In this work, the magnetic and electrical characteristics of MRF device are investigated and a design procedure is formulated to achieve the desired performance for a given power supply.

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A Study on the Development of a Hydraulic Damper using Semi-Active Viscous Damping (반능동 점성감쇠를 이용한 유체댐퍼 개발에 관한 연구)

  • 전종균;김현식
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.1 no.2
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    • pp.15-20
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    • 2000
  • In this paper, hydraulic damper was studied to solve vibration problems of bridge, structures and several mechanic parts rising magnetic fluid. The damper was modeled using Magneto Rheological fluid and MR damper was manufactured on the basis of design drawing. To investigate the efficacy of magneto rheological phenomenon. experiments were performed on the several design parameters using Universal Testing Machine(UTM). Damping efficacy were examined by frequencies. displacement and electric currents through experiments.

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A New Type Speaker Utilizing a Magneto-rheological Fluid Diaphragm (자기유변유체 다이어프램을 이용한 새로운 타입의 스피커)

  • Park, Jhin Ha;Yoon, Ji Young;Kim, Seon Hye;Lee, Tae Hoon;Lee, Soo Hyuk;Choi, Seung Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.27 no.2
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    • pp.182-188
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    • 2017
  • In this work, a new type speaker which features various resonant frequencies is proposed utilizing a magneto-rheological (MR) fluid and its performance is evaluated in terms of the change of the field-dependent sound pressure level. In order to achieve this goal, a whole concept of the speaker system is firstly discussed and subsequently a controllable diaphragm is made using MR fluid whose rheological properties such as viscosity are controllable by the magnitude of magnetic field. Then, the proposed speaker system consisting of the inner structure and the squeeze mode type of MR diaphragm is established in an anechoic room The effectiveness of the proposed speaker system is experimentally evaluated at two different conditions; with and without the magnetic field. It is shown from experimental tests that the sound pressure level at different sound source can be controlled which is not able to achieve using one conventional speaker system.

Design of a Magneto-Rheological Fluid Clutch for Machine Tool Application (공작기계 적용을 위한 MR 클러치 설계)

  • Kim, Ock Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.8 no.1
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    • pp.57-63
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    • 2009
  • Magneto-Rheological(MR) fluid composes of a base fluid and ferromagnetic particles less than tens of micrometer size dispersed in the fluid. It is called as a smart material because its rheological properties are changable by a magnetic field. Its important applications are active devices such as controllable dampers and controllable clutches. The merit of those products is that their functional characteristics are controllable such that they enable active control strategies. This paper proposes an idea for machine tool applications of the MR fluid clutch as a safety device for power transmission. FEM has been used for magnetic field analyses and the results are compared with some former experiments. Some design syntheses of the MR clutches are suggested and hopefully considered that it may be an effective safety device for power transmission of machine tools.

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Analysis of Magneto-rheological Fluid based Semi-active Squeeze Film Damper and Its Application to Unbalance Response Control of Rotor (자기유변유체를 이용한 반능동형 스퀴즈 필름 댐퍼의 해석 및 회전체 불균형 응답 제어)

  • Kim, Keun-Joo;Lee, Chong-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1005-1011
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    • 2004
  • Squeeze film dampers (SFDs) have been commonly used to effectively enhance the dynamic behavior of the rotating shaft supported by rolling element bearings. However, due to the recent trends of high operating speed, high load capacity and light weight in rotating machinery, it is becoming increasingly important to change the dynamic characteristics of rotating machines in operation so that the excessive vibrations, which may occur particularly when passing through critical speeds or unstable regions, can be avoided. Semi-active type SFDs using magneto-rheological fluid (MR fluid), which responds to an applied magnetic field with a change in rheoloaical behavior, are introduced in order to find its applications to rotating machinery as an effective device attenuating unbalance responses. In this paper, a semi-active SFD using MR fluid is designed, tested and identified by means of linear analysis to investigate the capability of changing its dynamic properties such as damping and stiffness. Furthermore, the proposed device is applied to a rotor system to investigate its potential capability for vibration attenuation: an efficient method for selecting the optimal location of the proposed damper is introduced and control algorithm that could improve the unbalance response properties of a flexible rotor is also proposed.

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Sliding Mode Control for Improving Performance of Mount with MR(Magneto-Rheological) Fluid (MR마운트 진동제어 성능 향상을 위한 슬라이딩 모드 제어)

  • Ahn, Young Kong;Kim, Sung-Ha;Jeong, Seok-Kwon
    • Journal of Power System Engineering
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    • v.21 no.4
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    • pp.18-25
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    • 2017
  • This paper deals with vibration control of a small mount with MR(Magneto-Rheological) fluid as a functional fluid mount for precision equipment of automobiles. Damping and stiffness coefficients of the mount with MR fluid are changed by variations of the applied magnetic field strength. We present the robust control scheme, based on a conventional sliding mode control theory, for the design of a stable controller that is capable of vibration control due to various disturbances such as impact and periodic excitations, and is insensitive to dynamic properties of the mount. We got stable controller by using Lyapunov stability theory. The controller is then realized by using a semi-active control condition in simulations. Chattering problem of the sliding mode control is eliminated by saturation function instead of signum function. The sliding mode control with Lyapunov stability theory is superior to passive and Sky-Hook control in performance.