• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문초록집
• /
• pp.325.1-325
• /
• 2002

This paper presents property of the squeeze mode type mount using Magneto-Rheological fluid (MR fluid). The mount can isolate multi-directional vibrations, and also effectively reduce the vibrations in a wide range of disturbance frequency by controling the applied magnetic field. The shape of the mount is the same that of squeeze film damper. In the present work, the performance of this mount was experimentally investigated according to changing the magnetic field strength. (omitted)

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 1998년도 강연회 및 연구개발 발표회 논문집
• /
• pp.220-227
• /
• 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.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.374-378
• /
• 2003

This paper presents investigation of damping characteristics of squeeze mode type MR (Magneto-Rheological) mount experimentally. Since damping property of the MR fluid is changed by variation of the applied magnetic field strength, squeeze mode type MR mount proposed in the study has variable damping characteristics according to the applied magnetic field s strength. In the present work, the performance of the mount was experimentally investigated according to the magnetic field strength and exciting frequencies. The experimental results present that the MR mount can effectively reduce the vibration in a wide range of frequency by controlling the applied electromagnetic filed strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents in this study and MR effect is reduced by increasing exciting frequency.

• 한국소음진동공학회논문집
• /
• 제13권6호
• /
• pp.490-495
• /
• 2003

This paper presents investigation of damping characteristics of squeeze mode type MR (magneto-rheological) mount experimentally. Since damping property of the MR fluid is changed by variation of the applied magnetic field strength, squeeze mode type MR mount proposed in the study has variable damping characteristics according to the applied magnetic field strength. In the present work, the performance of the mount was experimentally Investigated according to the magnetic field strength and exciting frequencies. The experimental results present that the MR mount can effectively reduce the vibration in a wide range of frequency by controlling the applied electromagnetic field strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents in this study and MR effect is reduced by increasing exciting frequency.

• Computational Structural Engineering : An International Journal
• /
• 제3권1호
• /
• pp.61-68
• /
• 2003

A recently developed semi-active control system employing magneto-rheological (MR) fluid dampers is applied to vibration control of a wind excited tall building. The semi-active control system with MR fluid dampers appears to have the reliability of passive control devices and the adaptability of fully active control systems. The system requires only small power source, which is critical during severe events, when the main power source may fail. Numerical simulation studies are performed to demonstrate the efficiency of the MR dampers on the third ASCE benchmark problem. Multiple MR dampers are assumed to be installed in the 76-story building. Genetic algorithm is applied to determine the optimal locations and capacities of the MR dampers. Clipped optimal controller is designed to control the MR dampers based on the acceleration feedback. To verify the robustness with respect to the variation of the external wind force, several cases with different wind forces are considered in the numerical simulation. Simulation results show that the semi-actively controlled MR dampers can effectively reduce both the peak and RMS responses the tall building under various wind force conditions. The control performance of the MR dampers for wind is found to be fairly similar to the performance of an active tuned mass damper.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.111-112
• /
• 2006

A new MR cylinder with built-in valves using Magneto - Rheological fluid (MR valve) is proposed for fluid power control systems. The MR fluid is a newly developed functional fluid whose obvious viscosity is controlled by the applied magnetic field intensity. This MR cylinder, which is composed of cylinder with small clearance and piston with electromagnet, has the characteristics of simple, compact and reliable structure. This paper presents a method to control the pressure of MR cylinder by using Generalized Predictive Control (GPC) algorithm. The differential pressure is controlled by applying magnetic field intensity to MR fluid. The use of GPC controller is to generate a control sequence by minimizing a cost function in such a way that the future system output is driven close to reference over finite prediction horizons. Experimental results from real time control using GPC method compared with conventional PID control method are also shown in this paper.

• 유변학
• /
• 제11권2호
• /
• pp.105-111
• /
• 1999

감쇠기는 기계 시스템에서 에너지를 소모하는데 사용되는 요소이다. 이러한 감쇠기에는 수동 감쇠기, 능동 감쇠기, 반능동 감쇠기 등의 종류가 있다. 반능동 감쇠기는 수동 감쇠기에 비해서 더 좋은 성능을 내면서 능동 감쇠기보다는 더 작은 동력원을 필요로 하는 장치로 상황에 따라서 그 감쇠력 특성을 변화 시킬 수 있다. 본 논문은, 자기 유변 유체를 이용한 반능동 감쇠기의 개발에 관한 것이다. 자기 유변 유체는 가제어성 유체의 일종으로 인가 자기장에 대해서 그 유동학적 성질이 변하며 높은 항복응력, 낮은 점성계수, 불순물에 대한 안정성과 넓은 사용 온도 범위 등의 장점을 가진 재료이다. 이를 이용할 경우 간단한 구조로 반능동 감쇠기를 설계할 수 있을 뿐만 아니라 빠른 응답성 등의 효과도 기대할 수 있다. 본 연구에서는 자기 유변 유체를 이용하여 설계·제작된 몇 가지 종류의 감쇠기들을 통하여 그 응용 방법과 범위 그리고 응용 시 수반되는 문제점 등을 제시하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.464-467
• /
• 2002

This paper presents investigation of damping characteristics of squeeze mode type MR (magneto-Rheological) mount experimentally. Since damping property of the MR fluid is changed by variation of the applied magnetic field strength, squeeze mode type MR mount proposed in the study has variable damping characteristics according to the applied magnetic field strength. Impact and excitation tests were performed to investigate the dynamic properties of squeeze mode type MR mount. Responses of the mount were compared in proportion to the applied magnetic field strength. The experimental results show that the mount can effectively reduce vibration amplitude in a wide frequency range by changing the applied magnetic field strength.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.313-317
• /
• 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.

• 한국소음진동공학회논문집
• /
• 제27권2호
• /
• pp.182-188
• /
• 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.