• Title, Summary, Keyword: MR fluid

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Performance of Squeeze Film Damper Using Magneto-Rheological Fluid (MR유체를 이용한 스퀴즈필름 댐퍼의 응답특성)

  • 안영공;양보석;신동춘;김동조
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.67-70
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    • 2002
  • This paper presents the property of the Squeeze Film Damper (SFD) using Magneto-Rheological fluid (MR fluid). The damping property of a SFD for a flexible rotor system varied according to vibration mode. MR fluid is known as a functional fluid with controllable apparent viscosity of the fluid by applied magnetic field strength. When the MR fluid is applied in the SFD, the SFD using MR fluid can effectively reduce vibrations of the flexible rotor in a wide range of rotating speed by control of the applied magnetic field strength. To investigate in detail the SFD using MR fluid, the SFD to support one mass was constructed and its performance was experimentally investigated in the present study. The damping property of the SFD using MR fluid has viscous damping by Newtonian fluid, but not Coulomb friction by Bingham fluid. Therefore, The system damped by the SFD can be considered as a linear system.

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Control Performance for Semi-active Mount Featuring Magneto-Rheological Fluid (반능동형 MR유체 마운트의 성능제어)

  • Kim, O.S.;Park, W.C.;Lee, H.C.
    • Journal of Power System Engineering
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    • v.8 no.2
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    • pp.53-58
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    • 2004
  • In this paper, the semi active mount featuring Magneto rheological fluid(MR Fluid) is proposed. MR fluid is suspension of micro sized magnetizable particles in a fluid medium, and its apparent viscosity can be varied by the applied strength of magnetic field. When the controllable MR fluid is applied to mechanical devices, the devices provide simple, rapid response interfaces between electronic controls and mechanical systems. The MR fluid is applied in the conventional fluid mount for improving its performance of the mount's isolation effect. A appropriate size of the MR mount is designed and manufactured on the basis of Bingham model of MR fluid. In addition, the field dependent damping forces of MR mount are evaluated with respect to the input frequency variation.

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A Modeling of a Variable-damping Mount Using MR Fluid (MR 유체를 이용한 가변 감쇠 마운트의 모델화)

  • Ahn, Young-Kong;Tsuchiya, Takashi;Yang, Bo-Suk;Morishita, Shin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1338-1343
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    • 2000
  • This paper deals with an application of Magneto-Rheological (MR) fluid to a small size mount for precision equipment of automobiles. MR fluid is known as a class of functional fluids with controllable apparent viscosity of fluid by the applied magnetic field strength. A typical MR fluid is a suspension where pure iron particles of $1{\sim}20mm$ in diameter are dispersed in a liquid such as mineral oil or silicone oil, at the concentration of $20{\sim}40$ vol%. Electro magnetic coil is installed at the bottom of a variable-damping mount filled with MR fluid, and its performance was investigated experimentally. Furthermore, the properties of the MR Mount on experimental Study were explained analytically by mechanical model of the MR mount.

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A study on the force control of a servo actuator with built-in MR Valve (MR 밸브 내장형 서보 액추에이터의 힘 제어에 관한 연구)

  • Ahn K.K.;Song J.Y.;Kim J.S.;Ahn Y.K.;Park J.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.1
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    • pp.1-6
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    • 2006
  • A servo actuator with a valve using MR (Magneto-Rheological) fluid is proposed for fluid control systems. The MR fluid is well known as a functional fluid whose apparent viscosity is controlled by the applied magnetic field strength. The pressure in the MR cylinder can be controlled by the applied magnetic field strength. Good points of the MR cylinder are more simple, compact and reliable structure than a conventional oil hydraulic cylinder. The experimental results show that the MR cylinder could be used as a servo actuator.

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A Sliding Mode Control for an Engine Mount Using Magneto-Rheological Fluid (MR유체를 이용한 엔진마운트의 슬라이딩모드제어)

  • 이동길;안영공;정석권;양보석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1144-1149
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    • 2001
  • In this paper, a sliding mode controller of a fluid engine mount using MR (Magneto-Rheological) fluid was discussed When the MR fluid is applied to a fluid mount, resistance of MR fluid can be controlled by electro-magnetic valve installed in the inertia track. Since the rheological property of the MR fluid shows a function of shear rate, the damping characteristics of the mount will be change according to the frequency. Changing an applied magnetic field to the valve changes the property of the mount, such as the resistance of the MR fluid, the notch and the resonant frequencies due to the fluid passing, quantity of the fluid passing, the effective piston area of the volumetric damping and stiffness. Therefore, the fluid mount using MR fluid can be regarded as a variable structure system The sliding mode control known well as a particular type of variable structure control was introduced in this study. The sliding mode control, which has inherent robustness, is also expected to improve the control performance in the engine mount The sliding mode controller for the mount formatted by taking into account the response property with a time constant to MR fluid and the variable mount property. The motion equations of the fluid mount are derived from Newton's law of motion and used in numerical simulation. Numerical simulations illustrate the effectiveness of the sliding mode controller.

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A study on the novel linear actuator using MR fluid

  • Song, Joo-Young;Ahn, Kyoung-Kwan;Ahn, Young-Kong
    • 제어로봇시스템학회:학술대회논문집
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    • pp.296-300
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    • 2004
  • A new MR cylinder with built-in valves using MR fluid (MR valve) is proposed for fluid power control systems. The MR or Magneto-Rheololgical fluid is a newly developed functional fluid whose obvious viscosity is controlled by the applied magnetic field intensity. The MR cylinder is composed of cylinder with small clearance and piston with electromagnet. The differential pressure is controlled by the applied magnetic field intensity. It has the characteristics of simple, compact and reliable structure. The size of MR cylinder and piston has ${\varphi}$60mm${\times}$259mm and ${\varphi}$58mm${\times}$136.5mm in face size respectively and 0.8mm in gap length. Through experiments on the static characteristics, it is found that the differential pressure is controlled by the applied magnetic field intensity under little influence of the flow rate, which corresponds to a pressure control valve. Effectiveness of the MR cylinder is demonstrated through the position control of one link MR manipulator.

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A study on material removal characteristics of MR fluid jet polishing system through flow analysis (유동해석을 통한 MR fluid jet polishing 시스템의 재료제거 특성 분석)

  • Sin, Bong-Cheol;Lim, Dong-Wook;Lee, Jung-Won
    • Journal of the Korea Society of Die & Mold Engineering
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    • v.13 no.3
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    • pp.12-18
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    • 2019
  • Fluid jet polishing is a method of jetting a fluid to polish a concave or free-form surface. However, the fluid jet method is difficult to form a stable polishing spot because of the lack of concentration. In order to solve this problem, MR fluid jet polishing system using an abrasive mixed with an MR fluid whose viscosity changes according to the intensity of a magnetic field is under study. MR fluid jet polishing is not easy to formulate for precise optimal conditions and material removal due to numerous fluid compositions and process conditions. Therefore, in this paper, quantitative data on the factors that have significant influence on the machining conditions are presented using various simulations and the correlation studies are conducted. In order to verify applicability of the fabricated MR fluid jet polishing system by nozzle diameter, the flow pattern and velocity distribution of MR fluid and polishing slurry of MR fluid jet polishing were analyzed by flow analysis and shear stress due to magnetic field changes was analyzed. The MR fluid of the MR fluid jet polishing and the flow pattern and velocity distribution of the polishing slurry were analyzed according to the nozzle diameter and the effects of nozzle diameter on the polishing effect were discussed. The analysis showed that the maximum shear stress was 0.45 mm at the diameter of 0.5 mm, 0.73 mm at 1.0 mm, and 1.24 mm at 1.5 mm. The cross-sectional shape is symmetrical and smooth W-shape is generated, which is consistent with typical fluid spray polishing result. Therefore, it was confirmed that the high-quality surface polishing process can be stably performed using the developed system.

Path Control of MR Fluid Jet Polishing System for the Polishing of an Aspherical Lens Mold Core (비구면 렌즈 몰드 코어 연마를 위한 MR Fluid Jet Polishing System의 경로 제어에 관한 연구)

  • Kim, K. B.;Cho, M. W.;Ha, S. J.;Cho, Y. K.;Song, K. H.;Yang, J. K.;Cai, Y.;Lee, J. W.
    • Transactions of Materials Processing
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    • v.24 no.6
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    • pp.431-436
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    • 2015
  • MR fluid can change viscosity in the presence of a magnetic field. A characteristic of MR fluid is reduced scattering during jetting. For these reasons a MR fluid jet polishing system can be used for ultra-precision polishing. In the current paper, the polishing path was calculated considering the aspherical lens profile equation and the experimental conditions for the MR fluid jet polishing system. Then the polishing of an aspherical lens mold core using the MR fluid jet polishing system with the calculated path control was made and the results were compared before and after polishing.

Polishing Characteristics of a Mold Core Material in MR Fluid Jet Polishing (MR Fluid Jet Polishing 시스템을 이용한 금형코어재료 연마특성에 관한 연구)

  • Lee, J.W.;Ha, S.J.;Cho, Y.G.;Cho, M.W.;Lee, K.H.;Je, T.J.
    • Transactions of Materials Processing
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    • v.22 no.2
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    • pp.74-79
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    • 2013
  • The ultra-precision polishing method using MR fluid has come into the spotlight for polishing metals and optical materials. The MR fluid jet polishing process can be controlled using a change of viscosity by an imposed magnetic field. The MR fluid used for polishing process is a mixture of CI particles, DI water, $Na_2CO_3$ and glycerin. The efficiency of polishing depends on parameters such as polishing time, magnetic field, stand-off distance, pressure, etc. In this paper, the MR fluid jet polishing was used to polish nickel and brass mold materials, which is used to fabricate backlight units for 3-D optical devices in mobile display industries. In MR jet polishing, ferromagnetic materials like nickel can decrease the polishing efficiency by interaction with the cohesiveness of the MR fluid more than non-ferromagnetic materials like copper. A series of tests with different polishing times showed that the surface roughness of brass (Ra=1.84 nm) was lower than that of nickel (Ra=2.31 nm) after polishing for 20 minutes.

Development of Flow Control Valve Using MR Fluid (MR유체를 이용한 유량제어 밸브)

  • Lee, Hyung-Don;Bae, Hyung-Sub;Lee, Yuk-Hyung;Park, Myeong-Kwan
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.9
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    • pp.888-891
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    • 2011
  • This paper presents development of flow control valve using MR fluid. Generally, since the apparent viscosity of MR fluids is adjusted by applying magnetic fields, the MR valves can control high level fluid power without any mechanical moving parts. In this paper, flow control valve using MR fluid on the behavior of the magnetic field influence on the numerical analysis of more accurate electromagnetic parameters were obtained, even if when magnetic field apply inside of surrounding MR fluid from electromagnet, more realistic designing way analysis of characteristic of whole magnetic field distribution is suggested by surrounding magnetic material. Also, comparison of flow rate inlet and outlet, behavior of MR fluid in experiments proposed. A new type of flow control valve using MR fluid is proposed by analysis of behavior of MR fluid in experiments.