• 한국정밀공학회지
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• 제20권6호
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• pp.105-112
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• 2003

This paper presents the numerical design technology of a passive orifice fluid damper system especially for the characteristics between the damper piston velocity and the damping force. Numerical analysis with the visual interfacial modeling technique was applied into the analysis of the damper system's dynamics. A prototype orifice fluid damper was manufactured and experimentally tested to validate the numerical simulation results. The performances of various damper system schemes were investigated based on the verified numerical simulation model of orifice fluid damper.

• 대한기계학회논문집A
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• 제24권3호
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• pp.691-700
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• 2000

This paper presents a novel type of a semiactive damper featuring an electro-rheological(ER) fluid. Unlike conventional cylindrical ER damper, the proposed one has controllable orifices by the intensity of electric fields (We call it orifice type). The dynamic model of the orifice type ER damper is formulated by incorporating field-dependent Bingham properties of an arabic gum-based ER fluid. Design parameters such as electrode gap are subsequently determined on the basis of the dynamic model. After manufacturing the orifice type ER damper, field-dependent damping forces and damping force controllability are empirically evaluated. In the evaluation procedure, conventional cylindrical ER damper is adopted and its performance characteristics are compared with those of the orifice type ER damper. In addition, the proposed one is installed with a full-car model and its vibration control performance associated with a skyhook controller is investigated.

• 한국산학기술학회논문지
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• 제15권3호
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• pp.1305-1310
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• 2014

MR 댐퍼는 자기장의 영향으로 인한 MR 유체의 응집현상으로 자기전단력을 발생한다. MR 유체는 기존유체와 자기입자로 구성되어 있다. 본 연구에서 밀도 1.3, 1.5, $1.7g/cm^3$ 그리고 점도 1,000, 10,000cP를 가지는 MR 유체 6종과 오리피스 형상 6종에 대한 MR 댐퍼의 댐핑력을 조사하였다. MR 유체의 밀도와 점도 변화에 따라서 MR 댐퍼의 댐핑력이 변하였다. 오리피스 형상변화에 대한 댐핑력은 오리피스 갭이 적고 길이가 짧을수록 크게 나타났다. 이들 연구결과로부터 MR 댐퍼의 최적설계를 위해서는 MR 유체의 선정과 오리피스 형상이 중요한 설계변수임을 확인하였다.

• 드라이브 ㆍ 컨트롤
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• 제9권3호
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• pp.23-28
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• 2012

In this study the flow rate-to-pressure difference characteristics of short-tube type damping orifices for an aircraft door damper were investigated by CFD analyses and experiments. As the design parameters of the damping orifice its diameter, inlet and outlet angle, tube length and the viscosity of the working fluid were taken into consideration. The results showed that the discharge coefficient of the orifices are dependant on the inlet and outlet angle and the oil viscosity, while their length plays an little significant role. Although the short-tube type damping orifice was employed to induce a turbulent flow, their discharge coefficient decreases rapidly as the oil viscosity gets higher than 50mm2/s. Therefore, in order to determine the orifice size, satisfying the working temperature range of the door damper, the oil viscosity as well as the friction force on the damper piston should be kept within proper values. For the verification of the CFD analysis results the actual performance of a door damper was measured and compared with them.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.744-749
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• 2011

Silicon oil in viscous fluid damper has a viscoelastic feature that show stiffness besides damping. These properties depend on frequency and are non-linear. A lot of research has been conducted in order to identify viscoelastic damper with mathematical model. Fractional Derivative Maxwell Model has been widely used, but this model did not explain the effect of damper size change on the damper performance. In this paper, the experimental study was conducted to validate damper's dynamic behaviors when total damper's size is changed while maintaining same aspect ratio and orifice size.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.222-227
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• 2002

MR(Magneto-rheological) fluid is smart fluid that can change its characteristics then magnetic fields are applied. Recently, many researches have been performed on this MR fluid for the application in a vareity 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 viscosity with final saturation thereafter. Herschel-Bulkley model is used to simulate the flow characteristics of MR fluid and magnetic analysis is used to identify the magnetic property of the MR fluid in the orifice of the damper. The dynamic characteristics of the damper was predicted and compared with the experimental results for typical sinusoidal excitations.

• 한국생산제조학회지
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• 제9권5호
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• pp.127-134
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• 2000

This paper presents the development of a semi-active seat damper using MR fluids and the performance analysis of seat suspension system with a MR seat damper. An annular orifice type MR seat damper is proposed for a seat suspension of a commercial vehicle. After formulating the governing equation of motion, then an appropriate size of the seat damper is designed and manufactured. Following the evaluation of field-dependant damping force characteristics, the controllability of the damping force is experimentally demonstrated in time domain by adopting PID controller. A semi-active seat suspension with the proposed MR damper is constructed and its dynamic model is established. Subsequently, vibration control capability of the semi-active suspension system is investigated by employing the sky-hook controller.

• 한국소음진동공학회논문집
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• 제14권6호
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• pp.470-477
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• 2004

This study shows the design process of a MR damper for semi-active suspension systems. Damping force characteristics of the designed damper was predicted through the flow analysis and magnetic analysis. The predicted results were compared with the experimental results and the initial design specification was modified according to the results.

• 한국정밀공학회지
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• 제25권3호
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• pp.73-82
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• 2008

Recently MR CDC damper has been applied to semi-active suspension control system gradually. Compared to former hydraulic CDC damper, it has rapid time response performance as well as simple internal structure and wide range of damping force. In order to develop control logic algorithm which enables to take maximum advantage of unique characteristics of MR CDC damper, it is inevitable to perform a thorough investigation into its nonlinear performance. In many previous researches, MR fluid model was either simply assumed as Bingham Plastic, or a phenomenological model based on experiment was established instead to predict damping performance of MR CDC damper. These experimental flow model which is not based on flow analysis but intentionally built to fit damping characteristics, may lead to totally different results in case of different configuration or structure of MR CDC damper. In this study, a generalized flow formula from mathematical flow model of MR fluid for annular orifice is derived to analyze and predict damping characteristics when current is excited at piston valve.

• 한국항공우주학회지
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• 제40권12호
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• pp.1080-1085
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• 2012

본 논문에서는 작동유의 최대 동점성 계수가 400cSt까지 변하는 조건에서 항공기 도어 댐퍼용 칼날형 댐핑 오리피스를 설계하였다. 전산 유동 해석과 실험을 통하여 칼날 오리피스의 유량계수를 분석하였고, 오리피스의 크기와 칼날 각도, 유동방향, 레이놀즈수가 미치는 영향을 고려하였다. 이 결과를 바탕으로 오리피스의 크기에 따라 댐퍼의 성능 기준을 충족시키기 위해 제한해야 하는 댐퍼의 쿨롱 마찰력 범위를 유도하였다.