• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.2878-2885
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• 2012

In this study, the training and sporting equipment for leg rehabilitation featuring the MR fluids is proposed. The compact MR fluid brake is designed and manufactured to apply to the rehabilitation training and sporting mechanism. The resistance characteristic of the MR fluid brake is controllable by varying the magnetic field around the fluid. Under consideration of spatial limitation, design parameters which are related with the magnetic strength are determined to maximize to a torque using finite element method. The FE analysis is performed using a commercial code, ANSYS Workbench. The proposed brake device is manufactured, and its field-dependant torque is experimentally evaluated. When the electric current is supplied, the torque of the MR fluid brake is increased and the response is very fast. Depending on the strength of the current supply, torques of the MR fluid brake also increase similar to Bingham property of MR fluid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1305-1310
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• 2014

MR(Magneto-Rheological) damper generates the magnetic shear force due to the cohesiveness of MR fluid influenced by a magnetic field. MR fluid consists of magnetic particles and a base liquid. In the present study, the damping forces of MR damper were investigated for density 1.3, 1.5 and $1.7g/cm^3$, and viscosity 1000 and 10000cp, and for the change of orifice shapes. It was found that the increase in the density and viscosity of MR fluid could change the damping force of MR damper due to the magnetic effects. Also, the damping forces on orifice shapes increased as the orifice gap and length decreased. These results showed that the properties of MR fluid and orifice shapes were important for the optimum design of MR damper.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3611-3616
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• 2013

Physical characteristics of a magneto-rheological(MR) fluid can be influenced by a magnetic field. In the present study, the behaviors of MR fluid are visualized and the shear stresses are measured under the magnetic field for density 1.3, 1.5 and 1.7 $g/cm^3$, and viscosity 100, 1000 and 10000cp. When the magnetic field is applied, particles of MR fluid are arranged along lines of magnetic field. It is observed that the flow pattern of MR fluid under the magnetic field is different from that of MR fluid without the magnetic field. Shear stress of MR fluids under the magnetic field changes significantly. Shear stress by the magnetic field increases the shape of a quadratic equation. When the density changes from $1300kg/m^3$ to $1700kg/m^3$ at 2.0A, the shear stress increases about 33%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4747-4752
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• 2013

Physical characteristics of a magneto-rheological(MR) fluid can be influenced by a magnetic field. MR fluid is a suspension of micrometer-sized magnetic particles in a base liquid such as oil. Therefore, the key issue is dispersion stability because density of micrometer-sized magnetic particles are different from that of oil. In the present study, dispersion stability and physical characteristics along chemical compositions of MR fluid are investigated. 216 kinds of MR fluids are made by using magnetic powder(#2), surfactant(#2), base oil(#2), functional additive(#3), density(#3) and viscosity(#3). From experimental results, SEM photograph, magnetic flux density, supernatant and sediment of 216 kinds of MR fluids are obtained.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.141-148
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• 2002

MR 유체 감쇠기는 구조물의 진동을 감소시키기 위한 가장 유망하고 새로운 제진 (制振) 장치 중 하나이다. 이 장치는 기계적인 단순성, 높은 동적 범위, 적은 전력 요구량, 커다란 감쇠 능력, 강인성 등의 장점을 가지고 있기 때문에, 토목 구조 시스템의 내진(耐震) 및 내풍(耐風) 성능을 향상시키는데 매우 유용하다. 많은 연구자들이 MR 유체 감쇠기의 유사-정적 모델을 연구했지만 그 모델이 감쇠기의 설계를 위해서는 유용하다고 하더라도, 동적 하중에 대한 감쇠기의 거동을 모사하는 데는 충분하지 않다. 논문에서는 대용량 20톤 MR 유체 감쇠기의 동적하중에 대한 응답 해석 결과를 이용하여, Bouc-Wen 모델을 기반으로 하는 새로운 역학적 모델을 제안하였다. 이 모델은 MR 유체의 stiction현상과 관성 및 shear thinning 효과를 잘 묘사한다. 또한, 제안된 MR 유체 감쇠기의 동적 모델이 실험 결과와 매우 잘 일치함을 보였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3567-3573
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• 2009

This research proposed a dashpot type mount design using MR fluids, and investigated experimentally the influence of the design parameters of the dashpot MR fluid mount, which affect the damping forces of the dashpot MR fluid mount. In order to observe the influence, the dashpot MR fluid mount which have the different effective length and the core structure is manufactured. The variations of the resistance forces according to different effective lengths of the magnetic pole of MR fluid mount, along which magnetic field is defined, was investigated. It was founded that the resistance forces from the MR mount decreased with increased input frequencies, while increased with increased applied electric current intensities. Nevertheless, there is no appreciable change in the resistance forces with respect to the effective length variations of the magnetic pole of MR fluid mount.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.185-187
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• 2012

In this paper, the MR fluid damper to the application of the paramagnetic (paramagnetic) particles dispersed in the MR fluid inside the magnet current caused by the MR damper using the principles of the internal fluid delivery yield stress variation is characterized in Silky. In other words, the current strength of the MR fluid damper according to the internal friction coefficient varies phenomenon is to use. The MR fluid damper to control the MCU that you want to use Microchip's dsPIC chips, and current control in order to improve performance by using the PWM and UART communication to an external monitor to monitor the entire system was designed. In this study using MR fluid dampers and dsPIC chip dehydration process happens when a washing machine vibration and noise, vibration and noise reduction sikidorok washing machine protection systems are proposed.