• Title, Summary, Keyword: 자기유변유체

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Performance Change of Application Devices Caused by Magnetorheological Particle Corrosion (자기유변 입자 부식에 따른 응용장치의 성능 변화)

  • Han, Young-Min;Choi, Seong-Cheol
    • Journal of Digital Convergence
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    • v.14 no.12
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    • pp.193-199
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    • 2016
  • MR(magnetorheological) devices for vehicle applications requires the consistent control performance and the reliable operation. However, the corrosion of iron particles consisting the MR fluid can significantly affect on MR properties. This paper presents an effect of the MR particle corrosion on the performance of MR fluids such as shear stress magnitude which is directly concerned with control performance. As a first step, MR particles are corroded by water-calcium chloride solution. The resulting MR particles are examined by scanning electron microscope (SEM) and their molar ratios are analyzed by the energy dispersive X-ray analysis (EDAX). By dispersing the corroded MR particles into silicone oil, the corroded MR fluid is synthesized for evaluation of MR effect change. A rotational viscometer is adopted to measure shear stress magnitude. Finally, it is demonstrated how much the corrosion affect on performances by comparing the normal MR fluid to the corroded MR fluid, from which performance investigation of the MR devices containing the corroded MR particles will be studied in the second phase of this study.

Characteristics of MR Fluids with Different Working Modes (작동모드에 따른 MR유체의 특성 비교)

  • 이호근;김기선
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.2 no.2
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    • pp.107-113
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    • 2001
  • This work presents field-dependent Bingham and response characteristics of MR fluids under shear and flow modes. Two different types of magneto-viscometers are designed and manufactured for the shear and flow modes. respectively. For the MR fluid to be tested, MRF-132LD of Lord co. is employed. The field-dependent yield stress is experimentally distilled at various temperatures using the magneto-viscometers. Time responses of the MR fluids to step electric fields are also evaluated under two operating modes.

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Development of Semi-active Damper by Magneto-Rheological Fluid (자기 유변 유체를 이용한 반능동 감쇠기의 개발)

  • 정병보;권순우;김상화;박영진
    • The Korean Journal of Rheology
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    • v.11 no.2
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    • pp.105-111
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    • 1999
  • Dampers have been used to dissipate energy in mechanical systems. There are several types of dampers such as passive, active, and semi-active damper. Semi-active dampers have higher performance than passive ones and require less power to operate than active ones. Their damping characteristics can be changed properly for varying conditions. In this paper, we investigated the semi-active damper using Magneto-Rheological fluid. Magneto-Rheological fluid, which is one of controllable fluids, changes its damping and rheological characteristics from Newtonian fluid to Bingham fluid as the magnetic field is applied. It has several advantages such as high yield strength, low viscosity, robustness to impurities and wide temperature range of stability. If we designe a semi-active damper by using this material, we can not only design a simply structured damper but also expect rapid response. In this study, we propose several types of semi-active dampers which are designed and manufactured using Magneto-Rheological fluid and some problems encountered during their applications.

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Control of Rotational Angular Speed using Magneto-rheological Fluid (자기유변유체를 이용한 회전 각속력 제어)

  • 신성철;정재성;김정훈;이종원
    • The Korean Journal of Rheology
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    • v.11 no.2
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    • pp.67-72
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    • 1999
  • A magneto-rheological(MR) fluid based rotary loading and braking device is developed. The loading and braking forces of the device are accurately adjustable by controlling the yield stress of MR fluid, so that the vibration control, the precision position control and the speed control of rotating machines equipped with the device can be achieved. As an engineering application, constant rotational speed regulation is conducted using the device manufactured in laboratory, introducing PI control action not only with varying torque due to gravitation, with initial angular speed, but also with constant external torque made by hand. To do this, first, mathematical model was obtained via experiments. And then, simulation was carried out, based on the experimentally identified model. Its result was confirmed through experiment. It is identified by simulation and experimental results that PI action leads to satisfactory control performance in both cases that varying torque due to gravitation, with initial angular speed, and constant external torque are applied.

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Design Analysis and Experimental Evaluation of an MR Fluid Clutch (자기장 및 유동 해석을 이용한 자기유변 클러치의 성능 예측 및 검증)

  • Lee, U-Seop;Kim, Tae-Gyun;Heo, Nam-Geon;Jeon, Do-Yeong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.8
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    • pp.2143-2150
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    • 2000
  • An MRC(Magneto-rheological Clutch) has a great potential of application because of its good transmissibility, little wear-out and fast response to electrical control signal. Though many MRCs have been developed for years, there has not been an research on the method to predict the performance of MRC except the simplified mathematical models. But the simplified mathematical models do not fit well since their performance has close relations with shapes of clutches and viscosity distribution throughout the fluids caused by applied magnetic fields. in this study, the CFD and FEM analyses were applied to various shape of MRC and the methods were examined in experiments.

The Comparison of Properties of ER and MR Fluids Using a Rotational Viscometer (회전식 점도측정기를 이용한 ER 및 MR유체의 특성 비교)

  • 이영록;전도영
    • The Korean Journal of Rheology
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    • v.11 no.2
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    • pp.73-81
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    • 1999
  • The intention of this research is to give criteria of designing devices using ER fluids and MR fluids. The Properties of commercial ER fluids and MR fluids are compared using a rotational viscometer. The yield strength is compared upon changes of shear rate, temperature and applied fields. MR fluids seem less sensitive to temperature change than ER fluids. In cases of MR and ER fluid dampers, the time delay and damping force are measured in tension and compression mode when the applied field changes.

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A Study on the Effect of the Material and Applied Magnetic Field Strength on the Friction Characteristics of Magnetorheological Fluids (재질과 자기장 세기가 자기유변유체의 마찰 특성에 미치는 영향)

  • Zhang, Peng;Lee, Kwang-Hee;Lee, Chul-Hee
    • Tribology and Lubricants
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    • v.29 no.1
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    • pp.39-45
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    • 2013
  • Magnetorheological (MR) fluid belongs to the group of smart materials. In MR fluid, iron particles in base oil form chains in the direction of the applied magnetic field, thus resulting in a variation in the stiffness and damping characteristics of the fluid. Research is being carried out on controlling the stiffness and damping characteristics as well as the tribological characteristics of the MR fluid. In this study, the friction characteristics of MR fluid have been evaluated using three types of materials and magnetic fields of different strengths. The coefficients of friction of the three types of MR fluid are measured, and the relationship between the coefficient of friction and the strength of the applied magnetic field is obtained.

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.