• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 추계학술대회논문집
• /
• pp.460-465
• /
• 2008

This paper proposes a new type of MR (magentorheological) fluid based suspension system and applies it to military vehicle for vibration control. The suspension system consists of gas spring and MR damper. The nonlinear behavior of spring characteristics is evaluated with respect to the wheel travel and damping force model due to viscosity and yield stress of MR fluid is derived. Subsequently, a military vehicle of 6WD is adopted for the integration of the MR suspension system and its nonlinear dynamic model is establishes by considering vertical, pitch and roll motion. Then, a sky-hook controller associated with semi-active actuating condition is designed to reduce the vibration. In order to demonstrate the effectiveness of the proposed MR suspension system, computer simulation is undertaken showing vibration control performance such as roll angle and pitch angle evaluated under bump and random road profiles.

• 한국소음진동공학회논문집
• /
• 제19권1호
• /
• pp.17-23
• /
• 2009

This paper proposes a new type of MR(magnetorheological) fluid based suspension system and applies it to military vehicle for vibration control. The suspension system consists of gas spring and MR damper. The nonlinear behavior of spring characteristics is evaluated with respect to the wheel travel and damping force model due to viscosity and yield stress of MR fluid is derived. Subsequently, a military vehicle of 6WD is adopted for the integration of the MR suspension system and its nonlinear dynamic model is established by considering vertical, pitch and roll motion. Then, a sky-hook controller associated with semi-active actuating condition is designed to reduce the imposed vibration. In order to demonstrate the effectiveness of the proposed MR suspension system, computer simulation is undertaken showing vibration control performance such as roll angle and pitch angle evaluated under bump and random road profiles.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2007년도 추계학술대회 논문집
• /
• pp.21-22
• /
• 2007

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 춘계학술대회 논문집
• /
• pp.21-22
• /
• 2010

• 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.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.1298-1302
• /
• 2000

Electrorheological(HER) and magnetorheologica(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. ER and MR fluid-based dampers are typically analyzed using Bingham-plastic shear flow analysis under Quasi-steady fully developed flow conditions. An alternative perspective, supported by measurements reported in the literature, is to allow for post-yield shear thinning and shear thickening. To model these, the constant post-yield plastic viscosity in Bingham model can be replaced with a power-law model dependent on shear strain rate that is known as the Herschel-Bulkley fluid model. The objective of this paper is to predict the damping forces analytically in a typical ER bypass damper for variable electric field, or yield stress using Herschel-Bulkley analysis.

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

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.496-500
• /
• 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
• /
• 제24권8호
• /
• pp.2143-2150
• /
• 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.

• 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.