• Title, Summary, Keyword: Magneto-rheological Fluid

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Surface Tension of Magneto-Rheological Fluids

  • Rahimi, Shai;Weihs, Daniel
    • Journal of Magnetics
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    • v.21 no.2
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    • pp.261-265
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    • 2016
  • Surface tension is a major factor in the thermodynamics as well as fluid properties of Magneto-Rheological Fluids (MRF). We measured the surface tension of an MRF using two different methods. A wettability characterization based on contact angles measurements for the fluid interacting with two different surfaces was conducted. A hydrocarbon based commercial MRF with more than 80% solid weight, placed on quartz and poly-tetra-fluoroethylene (PTFE) surfaces was used. We measured the fluids' surface tension value by means of contact angles measurements and by the falling drop method.

Design of A Rotary MR Damper (로터리 MR댐퍼의 설계)

  • Lee, Jong-Seok;Lee, Ji-Ung;Baek, Woon-Kyung
    • Proceedings of the KSME Conference
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    • pp.945-950
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    • 2007
  • This paper presents the design study of a rotary MRF(Magneto-Rheological Fluid) damper that can be conveniently used in the joints to control the damping torques. The basic design concept is to determine the geometric design variables allowing the magnetic flux to flow across the same sectional areas under volume constraint condition. The effects of each design variables for generating the torques were investigated by magnetic field analyses.

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항공기 엔진용 유체 마운트의 성능해석

  • An, Yeong-Gong;Ahmadian, Mehdi;Morishita, Shin
    • 유체기계공업학회:학술대회논문집
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    • pp.220-227
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    • 1998
  • This paper evaluate the performance of a Magneto-Rheological (MR) fluid mount. The mount incorporates MR fluid in a conventional fluid mount to open and closed the inertia track between the fluid chambers of the mount. It is shown that such switching of the inertia track improves the mount's isolation effect, by eliminating the large transmissibility peak that commonly exists at frequencies higher than the notch frequency for conventional fluid mounts. The switching frequencies of the MR mount is evaluated, based on the parameters of the mount. A simple control scheme for switching the mount between the open and closed states is proposed, and the performance of the controlled mount is compared with conventional mounts. A sensitivity analysis is conducted to evaluate the effect of parameter errors in estimating the switching frequencies and mount performance. The results show that the switching frequencies can be accurately determined from mount parameters that are easily measured or estimated.

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Torsional Vibration Damper Using Magneto-Rheological Fluid (MR 유체를 이용한 비틀림진동 감쇠기)

  • 안영공;신동춘;양보석;김동조
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.313-317
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    • 2001
  • Magneto-Rheological fluid (MR fluid) is known as a class of functional fluid with controllable apparent viscosity of the fluid by the applied magnetic field strength. Extensive researches with the functional fluids have been done on applications of the fluid to mechanical components such as suspension, absorber, engine mount, clutch, break, valve, etc. In this study, a new torsional damper using MR fluid is proposed, and the response property of the damper was theoretically investigated. The present damper is quit effective for reducing the driveline vibration in a wide range of the engine speed.

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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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Electromagnetic Design Methodology for MR Fluid Actuator (MR 유체 작동기의 전자기적 설계 방법)

  • Nam Yun-Joo;Moon Young-Jin;Lee Yuk-Hyung;Park Myeong-Kwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.10
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    • pp.1305-1313
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    • 2006
  • This paper presents an electromagnetic design methodology for the magneto-rheological (MR) fluid actuator. In order to improve the performance of the MR fluid actuator, the magnetic circuit including the MR fluid, the ferromagnetic material for flux path and the electromagnetic coil should be well designed, thereby the magnetic field intensity can be effectively supplied to the MR fluid. First of all, in order to improve the static characteristic, the length of the flux path is decreased by removing the unnecessary bulk of the yoke. Next, in order to improve the dynamic and hysteretic characteristics, the magnetic reluctance of the ferromagnetic material is increased by minimizing the cross section through which the flux passes. The effectiveness of the proposed design methodology is verified by the magnetic analysis and a series of basic experiments.

Performance Comparison Between ER and MR Clutches with Same Gap Size (동일한 간극을 갖고 있는 ER 및 MR 클러치의 성능 비교)

  • Hong, Sung-Ryong;Choi, Seung-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.6
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    • pp.1055-1064
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    • 1999
  • In this wort ER(electro-rheological) clutch and MR(magneto-rheological) clutch are devised and their performance characteristics such as response time and controllability are compared. As a first step, field-dependent yield stresses of ER and MR fluids are distilled in shear mode. For reasonable comparison between two clutches, a nondimensional design model is established by choosing same design parameters of gap size and number. Following the manufacturing of two clutches, field-dependent torque level, response time to step input, mechanical Power generation to electric power consumption are experimentally measured and compared. In addition, in order to investigate torque controllability of the clutches a sliding mode controller is formulated and experimentally realized. Control bandwidths of two clutches are identified and tracking control responses for desired torque trajectories are presented.

A Study on Tribological Properties of Magneto-Rheological Fluid (MRF) in Polishing Process (연마공정에서 MR 유체의 트라이볼로지적 성질에 대한 연구)

  • Lee S.O.;Jang K.I.;Min B.K.;Lee S.J.;Seok J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.497-498
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    • 2006
  • Tribological properties of a Magneto-Rheological(MR) fluid in a polishing process are studied. For this polishing process, abrasive wear model is proposed as a function of shear force, normal force and actual mean velocity of MR particles at workpiece surface. Experimental conditions are changed by varying the gap distance between workpiece and tool and the rotational speed of tool. From the experimental results, a modified Stribeck curve is obtained, and the friction coefficient turns out to have linear relationship with a modified Sommerfeld number. The validity of the wear model is supported by additional experiments performed for measuring material removal rates.

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Modeling and Vibration Control of Small-sized Magneto-rheological Damper (소형 MR 댐퍼의 모델링 및 진동제어)

  • Lee, Jong-Woo;Seong, Min-Sang;Woo, Je-Kwan;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.344-349
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    • 2012
  • This paper presents a new small-sized damper featuring magneto-rheological (MR) fluid which can be applied to vibration control system. The proposed MR damper consists of cylinder, piston, a couple of bearings, oil-seals and magnetic circuit which has two coils. In this damper, approximately 5cc of MR fluid is used. The damping force of the MR damper is designed to be followed by linear shear-mode Bingham-plastic model. In order to verify the performance of the MR damper, an experimental apparatus is established. In the experimental test, the damping force of the MR damper is measured with respect to time, displacement and velocity. In addition, the time response of MR damper is measured when 1A of step current is applied. Finally, The proposed small MR damper is applied to vibration control. In this process, a simple 1-DOF system is modeled and controlled using PID controller.

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Modeling and Vibration Control of Small-sized Magneto-rheological Damper (소형 MR 댐퍼의 모델링 및 진동제어)

  • Lee, Jong-Woo;Seong, Min-Sang;Woo, Je-Kwan;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.11
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    • pp.1121-1127
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    • 2012
  • This paper presents a new small-sized damper featuring magneto-rheological(MR) fluid which can be applied to vibration control system. The proposed MR damper consists of cylinder, piston, a couple of bearings, oil-seals and magnetic circuit which has two coils. In this damper, approximately 5cc of MR fluid is used. The damping force of the MR damper is designed to be followed by linear shear-mode Bingham-plastic model. In order to verify the performance of the MR damper, an experimental apparatus is established. In the experimental test, the damping force of the MR damper is measured with respect to time, displacement and velocity. In addition, the time response of MR damper is measured when 1A of step current is applied. Finally, the proposed small MR damper is applied to vibration control. In this process, a simple 1-DOF system is modeled and controlled using PID controller.