• 한국산학기술학회논문지
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• 제1권2호
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• pp.15-20
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• 2000

본 논문에서는 교량 밑 건축구조물, 각종 기계부품의 진동문제를 보완하기 위한 방법으로서 MR유체를 이용한 댐퍼를 연구하였다. MR 유체의 특성을 이용한 댐퍼를 모델링하여, 설계도면을 기초로 MR 댐퍼를 제작하였다. 만능재료 시험기를 이용하여 주파수와 전류 및 변위를 단계적으로 변화시켜가며 성능실험을 반복적으로 수행하였다. 실험을 통하여 주파수, 전류 및 변위에 따라 댐핑 효과가 다르게 나타남을 확인할 수 있었다.

• 항공우주시스템공학회지
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• 제4권4호
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• pp.44-48
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• 2010

This paper is used the commercial magneto-rheological(MR) damper for landing gear. The damping characteristics of Commercial MR damper by changing the intensity of the magnetic field are investigated and the dynamic responses of the landing gear. it is set up tset equipment, the landing gear drop test system. The landing gear involved drop testing the gear. The landing gear is tested by implementing sky-hook control algorithm and its performance is evaluated comparing to the result.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.626-631
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• 2007

MR(Magneto-rheological) fluid is smart material that can be changed viscosity by controlling the magnetic field. MR damper with MR fluid can control damping force. It can be used extensively many engineering structures for reducing the effect of dynamic external disturbances. There are three kinds of MR dampers, such as valve mode, direct-shear mode and squeeze mode. In this study, design process of direct-shear mode MR damper with the MR fluid gap was developed. The parameters that used in the direct-shear mode MR damper Informed from the experiment of valve mode MR damper of Lord company. Magnetic analysis with finite element method was performed to find the optimal annular gap.

• Ocean Systems Engineering
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• 제8권2호
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• pp.201-221
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• 2018

In this paper a comprehensive study for the structural control of Jacket platform with Magneto-Rheological (MR) damper is presented. The control is implemented as a closed loop feedback of the applied voltage in the MR Damper using fuzzy logic. Nine cases of combinations with MR damper are presented to complete the work. The selection of the MR damper (RD 1005-3) is based on the operating parameters (i.e., the range of frequency and displacement). Bingham model is used to obtain the control forces. The damping co-efficient of the model is obtained using empirical relationship between the voltage in the MR damper and input velocity from the structural members. The force acting on the structure is obtained from Morison equation using P-M spectrum. The results show that the reliable control was obtained when there was a continuous connection of multiple MR dampers with the lower levels of the structure. Independent MR dampers at different levels provided control within a range, while the MR dampers placed at alternate positions gave very high control.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1048-1053
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• 2003

This paper proposed a MR(Magneto-rheological) seat damper for a commercial vehicle. After formulating the governing equation of motion, an appropriate size of damper is designed and manufactured. Following the equation of fie d-dependent damping force characteristics, a semi-active seat suspension installed with the proposed MR-damper is constructed and its dynamic model id established, Subsequently, vibration isolation performance of the semi-active suspension system is demonstrated by incorporating with a MRAC(Model referenced adaptive control) fer the MR Seat Damper

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.739-744
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• 2001

In order to investigate the stability of magneto-rheological fluid based squeeze film damper (MR-SFD), its negative stiffness effect, which arises from magnetization of MR-SFD, is identified theoretically and experimentally. The analytical model of MR-SFD includes the magnetic circuit as well as the displacement stiffness associated with the squeeze mode of MRF. Extensive experiments are carried out to measure the magnetic attraction forces generated in the MR-SFD, with the excitation frequency and the eccentricity of the journal varied, which are controlled by an active magnetic bearing. The simulation and experimental results are found to be in good agreement. It is concluded that the negative stiffness effect dominates only in the low frequency region because its effect diminishes in the high frequency region due to the eddy-current loss.

• Earthquakes and Structures
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• 제11권6호
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• pp.1001-1025
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• 2016

Building structures generally have inherent low damping capability and hence are vulnerable to seismic excitations. Control devices therefore play a useful role in providing safety to building structures subject to seismic events. In recent years semi-active dampers have gained considerable attention as structural control devices in the building construction industry. Magneto-rheological (MR) damper, a type of semi-active damper has proven to be effective in seismic mitigation of building structures. MR dampers contain a controllable MR fluid whose rheological properties vary rapidly with the applied magnetic field. Although some research has been carried out on the use of MR dampers in building structures, optimal design of MR damper and combined use of MR and passive dampers for real scale buildings has hardly been investigated. This paper investigates the use of MR dampers and incorporating MR-passive damper combinations in building structures in order to achieve acceptable levels of seismic performance. In order to do so, it first develops the MR damper model by integrating control algorithms commonly used in MR damper modelling. The developed MR damper is then integrated in to the seismically excited structure as a time domain function. Linear and nonlinear structure models are evaluated in real time scenarios. Analyses are conducted to investigate the influence of location and number of devices on the seismic performance of the building structure. The findings of this paper provide information towards the design and construction of earthquake safe buildings with optimally employed MR dampers and MR-passive damper combinations.

• Structural Engineering and Mechanics
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• 제30권6호
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• pp.679-698
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• 2008

On marine vessels, delicate instruments such as navigation radars are normally mounted on ship masts. However the vibrations at the top of mast where the radar is mounted often cause serious deterioration in radar-tracking resolution. The most serious problem is caused by the rotational vibrations at the top of mast that may be due to wind loading, inertial loading from ship rolling and base excitations induced by the running propeller. This paper presents a method of semi-active vibration control using magneto-rheological (MR) dampers to reduce the rotational vibration of the mast. In the study, the classical optimal control algorithm, the independent modal space control algorithm and the double input - single output fuzzy control algorithm are employed for the vibration control. As the phenomenological model of an MR damper is highly nonlinear, which is difficult to analyse, a back- propagation neural network is trained to emulate the inverse dynamic characteristics of the MR damper in the analysis. The trained neural network gives the required voltage for each MR damper based on the displacement, velocity and control force of the MR damper quickly. Numerical simulations show that the proposed control methods can effectively suppress the rotational vibrations at the top of mast.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.328.1-328
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• 2002

MR(Magneto-rheological) fluid is smart fluid that can change its characteristics when magnetic fields are applied. Recently, many researches are going on this MR fluid for the application in a variety of areas including automobile shock absorbers. This paper describes the design procedure of a MR damper and the analysis results of its dynamic characteristics. MR fluid in the magnetic field shows initial yield shear stress and increasing resistive viscousity with final saturation thereafter. (omitted)

• 동력기계공학회지
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• 제17권2호
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• pp.63-69
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• 2013

Most washing machines are now produced as a drum-type, where a washing drum mounted on a suspension system with springs and dampers, to minimize the transmittance of the vibration from the drum to the frame. A low-cost MR damper, using magneto-rheological fluids, can produce variable damping forces by changing the current values in the magnetic coil. Experimental results show the comparison of the vibration attenuation performances between two different dampers. One test set-up uses a passive damper and another one uses a MR fluid damper. The test results showed that the vibration amplitude of the washing machine with the MR damper is much smaller than the case with the passive damper.