• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.439-440
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.237-238
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• 2010

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.390-391
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• 2014

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.241-242
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• 2009

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.475-476
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.191-192
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• 2011

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.496-500
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• 2004

A new, commercially available polishing process called magnetorheological finishing is used to polish and figure precision optics. To understand and model this process correctly it is important to determine the mechanical properties of the fluid under the influence of the magnetic field. Magnetorheological (MR) fluids are commonly modeled as Bingham fluids, so one of the essential properties to measure is the yield stress. Since MR fluids are inherently anisotropic, the yield stress will depend on the mutual orientation of the magnetic field and the direction of deformation. The relative orientation of the field and deformation in polishing does not coincide with common rheological setups, so a new rheometer has been designed and tested. This new magnetorheometer design has been shown to give correct stresses during calibration experiments using Newtonian fluids with a known viscosity. The measured stress has also been shown to have a magnitude consistent with published finite element approximations for magnetic fluids. The design of the instrument was complicated because of the requirements imposed upon the magnetic field, and the difficulty in satisfying the no slip boundary condition. Our results show the importance of having a homogeneous field in the test region during measurements. The solutions to these problems and discussion of the measurements on nonmagnetic and magnetic fluids are given.

• 대한기계학회논문집A
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• 제41권9호
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• pp.861-868
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• 2017

본 연구는 자기유변 겔의 강성 및 댐핑 제어에 필수적으로 요구되는 자기장 제어를 위한 자기장 발생기의 설계를 제안한다. 자기유변 물질은 자기장의 세기에 따라서 동적 점 탄성 특성이 바뀌는 스마트 물질로 진동 흡수기, 자동차의 서스펜션과 같은 분야에 사용되기 위해 여러 방면으로 연구되고 있다. 자기유변 물질의 어플리케이션 적용을 위해 현재 사용되고 있는 자기장 발생기의 종류로는 전자석과 영구자석이 있으며, 대부분의 실제 산업에서는 주로 전자석을 이용하여 자기장을 발생 및 제어한다. 하지만 전자석은 발열문제 등 여러 단점으로 인해 장시간 사용에 적합하지 않으며, 영구자석의 경우 자기장 세기의 변화에 필요한 자기유변 물질과 영구자석 간의 거리 조절을 위해 여분의 공간이 요구되어 시스템 부피가 커지는 단점이 있다. 따라서 본 연구에서는 자기 차폐 원리를 기반으로 한 자기장 발생기를 제안하여 기존의 전자석과 영구자석이 가지는 단점을 해결하고 장시간 사용 및 실제 산업에서 적용이 가능하도록 하고자 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.350-355
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• 2005

This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR Product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant Properties; the minor loop property and the wiping-out property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.369-374
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• 2007

This paper presents yaw vibration control performances of railway vehicle featuring controllable magnetorheological damper. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid resistance and MR effect. Design parameters are determined to achieve desired damping force level. The MR damper model is then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. Subsequently, computer simulation of vibration control via proportional-integral-derivative (PID) controller is performed using Matlab. Various control performances are demonstrated under external excitation by creep force between wheel and rail.