• 제목, 요약, 키워드: Magneto-rheological Fluid

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MR유체를 이용한 미세 채널구조물의 표면연마 (Surface polishing of Micro channel using Magneto-Rheological fluid)

  • 이승환;김욱배;민병권;이상조
    • 한국정밀공학회:학술대회논문집
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    • pp.1873-1876
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    • 2003
  • Magneto-rheological polishing is a new technology used in precision polishing. It utilizes magneto-rheological fluid. nonmagnetic polishing abrasive, aqueous carrier fluids in magnetic field to remove material from a part surface. Silicon micro channel as work piece is fixed in the slurry which is made of MR fluid and CeO$_2$(10 vol%) abrasive particles. And permanent magnet rotate in the slurry to transfers magnetic force to abrasive particles by increasing yield strength of MR fluid. so, the obtained bottom surface roughness of micro channel by experiment reduced to Ra 0.010 $\mu\textrm{m}$ Rmax 0.103 $\mu\textrm{m}$ and finwall surface roughness of micro channel reduced to Ra 0.018 $\mu\textrm{m}$ Rmax 0.468 $\mu\textrm{m}$. At optimum conditions of variables, the workpiece as silicon micro channel have about 24 times smaller surface roughness than before polishing.

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자기점성유체 댐퍼의 자기장 및 유동 해석에 따른 성능비교 (Comparison of Performances refer to Magnetic and Fluid Analysis of Magneto-Rheological Flow Damper)

  • 송준한;손성완;이규섭;전종균
    • 한국소음진동공학회:학술대회논문집
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    • pp.98-102
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    • 2009
  • The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. To manufacture the magneto-rheological fluid damper that uses such characteristics of the fluid, a flow analysis of the inner damper was conducted to forecast the damper's capacity. In addition, using the finite element method software, analysis on the characteristics of electromagnetic field around the coil operation unit inside the damper. Based on the result of the analysis, a single core damper and a double core damper were built and tested for their dynamic function. Based on the result of the experiment, the propriety of the flow analysis was demonstrated, and the proposed model was verified.

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자기유변탄성체 액츄에이터의 마찰특성 연구 (A Study of Friction Characteristics in Magneto-Rheological Elastomer)

  • 이득원;이철희;김철현;조원오
    • Tribology and Lubricants
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    • v.27 no.4
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    • pp.213-217
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    • 2011
  • In this study, friction characteristics using elastomeric actuator with Magneto-rheological (MR) materials are identified. Typically, Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. MR fluid has been applied to various industry fields such as to brake, clutch, damper, engine mount and etc. However, MR fluid has been used under the sealed condition to prevent leaking issues. In order to overcome these problems, MR elastomer that has same property as MR fluid has been developed and studied. MR elastomer mainly consists of polymer material such as natural rubber or silicon rubber with particles that can be polarized with magnetic field. And it is called as a smart material since its stiffness and damping characteristics can be changed. In this study, MR elastomer is produced and pin-on-disc tests are carried out to identify the friction characteristics of the material. Several test conditions are applied to evaluate the feasibility to use as a smart actuator in the field of vibration control.

Design of Magneto-Rheological Fluid Based Device

  • 김정훈;이종운;정병보;박용진
    • Journal of Mechanical Science and Technology
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    • v.15 no.11
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    • pp.1517-1523
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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 is limited by the voltage attenuation due to the coil inductance and the maximum power supply voltage set for practical use of an MRF devices. In this work, the magnetic and electrical characteristics of the MRF device are investigated and a design procedure is formulated to achieve the desired performance for a given power supply.

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낙하 충격 실험을 통한 자기유변탄성체의 충격 흡수 성능 평가 (The Evaluation of Shock Absorption Performance of Magneto-Rheological Elastomer Through the Drop Impact Test)

  • 정경식;이철희
    • 한국소음진동공학회:학술대회논문집
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    • pp.92-93
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    • 2013
  • In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

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

  • 안영공;양보석;신동춘;김동조
    • 한국소음진동공학회:학술대회논문집
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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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반능동형 MR유체 마운트의 성능제어 (Control Performance for Semi-active Mount Featuring Magneto-Rheological Fluid)

  • 김옥삼;박우철;이현창
    • 동력기계공학회지
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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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자기 유변 유체를 이용한 반능동 감쇠기의 개발 (Development of Semi-active Damper by Magneto-Rheological Fluid)

  • 정병보;권순우;김상화;박영진
    • 유변학
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    • v.11 no.2
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    • pp.105-111
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    • 1999
  • 감쇠기는 기계 시스템에서 에너지를 소모하는데 사용되는 요소이다. 이러한 감쇠기에는 수동 감쇠기, 능동 감쇠기, 반능동 감쇠기 등의 종류가 있다. 반능동 감쇠기는 수동 감쇠기에 비해서 더 좋은 성능을 내면서 능동 감쇠기보다는 더 작은 동력원을 필요로 하는 장치로 상황에 따라서 그 감쇠력 특성을 변화 시킬 수 있다. 본 논문은, 자기 유변 유체를 이용한 반능동 감쇠기의 개발에 관한 것이다. 자기 유변 유체는 가제어성 유체의 일종으로 인가 자기장에 대해서 그 유동학적 성질이 변하며 높은 항복응력, 낮은 점성계수, 불순물에 대한 안정성과 넓은 사용 온도 범위 등의 장점을 가진 재료이다. 이를 이용할 경우 간단한 구조로 반능동 감쇠기를 설계할 수 있을 뿐만 아니라 빠른 응답성 등의 효과도 기대할 수 있다. 본 연구에서는 자기 유변 유체를 이용하여 설계·제작된 몇 가지 종류의 감쇠기들을 통하여 그 응용 방법과 범위 그리고 응용 시 수반되는 문제점 등을 제시하였다.

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

  • 이동길;안영공;정석권;양보석
    • 한국소음진동공학회:학술대회논문집
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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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자기점성유체를 이용한 가변감쇠 마운트의 모델화 (A Modeling of a Variable-damping Mount Using Magneto-Rheological Fluid)

  • 안영공;양보석;삼하신
    • 소음진동
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    • v.11 no.1
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    • pp.141-146
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    • 2001
  • 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 1-20 (m in diameter are dispersed in a liquid such as mineral oil or silicone oil, at the concentration of 20 - 40 vol%. Electro magnetic coil is installed at the bottom of a variable-damping mount filled with MR fluid, and performance of the mount 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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