• Title/Summary/Keyword: Electrorheological (ER) fluids

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A Study on Bingham Characteristics of Particle Dispersive Electro-Rheological Fluid (입자분산계 ER유체의 빙햄특성 고찰)

  • 장성철;이선의;김태형;박종근;염만오
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.178-183
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    • 2000
  • Electrorheological(ER) effect on the dispersive system of polarizable fine powder/dielectric oil has been investigated. The electrical and rheological properties of zeolite and starch based ER fluid were reported. The ER fluids were constructed by mixing zeolite and starch power with two different dielectric oils. Yield stress of the fluids were measured on the couette cell type rheometer as a function of electric fields, particle concetrations, and temperatures. The electric field is applied by high voltage DC power supply. The outer cup is connected to positive electrode(+) and the bob becomes ground(-). And the temperatures the viscosity(or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to $200s^{-1}$ in 2 minutes.

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The Effect of phosphoric Ester of Cellulose on the Electrorheological Properties of Anhydrous ER Fluids (셀룰로오스의 인산 에스테르 반응이 비수계 ER 유체의 전기유변학적 특성에 미치는 영향)

  • 최웅수
    • The Korean Journal of Rheology
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    • v.10 no.3
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    • pp.143-151
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    • 1998
  • 실리콘 오일에 인산처리 셀룰로오스 분말을 분산시킨 비수계 전기유변성(ER) 유체 의 전기유변 거동을 상온에서 최대 2.5KV/mm의 전기장하에서 실험하였다. 넓은 온도 영역 에서 사용이 가증한 비수계 ER 유체를 개발하기 위해 셀룰로오스의 인산 에스테르 반응이 ER 유체의 전기유변효과에 미치는 영향을 조사하였다. 먼저 여러 가지의 인산처리 농도로 처리된 인산처리 셀룰로오스 미립자를 분산시킨 ER 유체를 제조한 후 ER 유체의 유전상수, 전류밀도 및 전기전도도 등과 같은 전기적 특성을 측정하였으며 ER 유체의 전기유변 특성 또한 측정하였다. 인산처리 셀룰로오스가 분산된 비수계 ER 유체의 전류밀도는 셀룰로오스 의 인산 에스테르 반응에서의 인산처리 농도에 의해 조절할수 있음을 알수있었으며 셀룰로 오스의 인산처리 농도가 2.5 M과 3.0 M 사이일 때 인산처리 셀룰로오스가 첨가된 비수계 ER 유체의 전기유변효과 ($\tau$/$\tau$0)가 가장 높게 측정되었다.

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Inorganic Materials Based Electrorheological Fluids (무기물 재료를 이용한 전기유변유체)

  • Cho, Min Seong;Sung, Jun Hee;Choi, Hyoung Jin
    • Applied Chemistry for Engineering
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    • v.16 no.1
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    • pp.1-8
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    • 2005
  • Electrorheological (ER) fluids, typically composed of particles having higher dielectric constant or electric conductivity than that of suspending fluids with a low viscosity, undergo dramatic, reversible changes when exposed to an external electric field. Among various electroactive materials, we put our efforts on inorganic materials including zeolite, MCM-41, MCM-41/polyaniline composite and SBA-15/polyaniline composites. Their preparation and ER characteristics are introduced.

The Flow Visualization of ER Fluid Between Two Parallel-Plate Electrodes Separated by Small Distance (좁은 평행평판전극 사이의 ER유체 유동의 가시화)

  • Park, Myeong-Kwan;Rhee, Eun-Jun;Oshima, Shuzo;Yamane, Ryuichiro
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.7
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    • pp.801-810
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    • 1999
  • The purpose of present research was to get characteristics and basic knowledges of electrorheological(ER) suspension. To observe behaviors of the ER suspensions. transparent conductive plates were used to visualize the flow of ER suspensions between two parallel plate electrodes. The influence of flowing speed and intensity of electric field on the ER fluid were examined in circle-shaped electric field, and it takes several hundred milliseconds that suspensions in flow cluster. The present study also conducts a numerical analysis adopting the Bingham model. It is found that simple Bingham model can not property describe the flow behavior in the parallel plates.

Shear stress analysis of phosphorylated potato starch based electrorheological fluid

  • Hong, Cheng-Hai;Choi, Hyoung-Jin
    • Korea-Australia Rheology Journal
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    • v.19 no.4
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    • pp.221-225
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    • 2007
  • Electrorheological characteristics of a dispersed system of phosphorylated potato starch particles in silicone oil investigated via a rotational rheometer equipped with a high voltage generator is being reanalysized. Flow curves of these ER fluids both under several applied electric field strengths and with different degrees of phosphate substitution were mainly examined via three different rheological constitutive equations of Bingham model, De Kee-Turcotte model and our previously proposed CCJ model. Among these, the CCJ equation was found to fit the data of phosphorylated potato starch well.

Damping Performance Analysis of Electro-Rheological Squeeze Film Damper Sealed with Slotted Rings (슬롯 링을 장착한 전기유변 스퀴즈 필름 댐퍼의 감쇠성능 해석)

  • 정시영;김창호;이용복
    • Tribology and Lubricants
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    • v.16 no.2
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    • pp.75-83
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    • 2000
  • The present paper proposes a new type of an electro-rheological squeeze film damper (ER SFD) of which the damping capacity can be controlled by the application of electric field. The new ER .SFD- is sealed with slotted rings having electrodes at the inside of the constant gap. The ER SFD can provent the problem of electric short which might be occurred in a previous ER SFD. Reynolds lubrication equation for a Newtonian fluid and the end leakage equation for ER fluids are numerically solved to get the pressure distributions and the damping coefficients of the ER SFD. The results show that the damping coefficients greatly increase with increasing the yield shear stress of ER fluid. In addition, the unbalance response analysis of a flexible rotor supported on the new ER SFD implies that the rotor system can be operated with the minimum of rotor amplitude and force transmissibility by controlling the yield shear stress of ER fluids properly.

Development of High Voltage Power Supply for Semi-Active Suspension System Using ER Fluids (ER 유체를 이용한 반능동 현가장치용 고전압 전원장치의 개발)

  • 정세교;신휘범
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.5
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    • pp.453-464
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    • 2002
  • The electrorheological(ER) fluid is a new material and is used for the mechanical motion devices such as semi-active suspensions, high speed clutches, and vibration isolators. The ER fluid applications need high voltage power supplies having special requirements to control the viscosity of the ER fluid. This paper deals with the development of the high voltage power supply for the semi-active suspension system using the ER fluid. The characteristics of the ER fluid are analyzed, and the design and implementation of the high voltage power supply are presented. It is well demonstrated through the experiment that the developed high voltage power supply shows a good performance suitable for the ER fluid application.

Vibration Control of Beam Containing ER Fluid Using PPF Control Scheme (PPF 제어기법을 적용한 전기점성유체가 함유된 보의 진동제어)

  • Yun Shin-Il;Chin Do-Hun;Yoon Moon-Chul
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.3
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    • pp.32-37
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    • 2005
  • Several types of smart materials and control scheme are available to adjust the structure actively in various external disturbances. A control scheme was introduced for a specific material. But the effectiveness of the control scheme has some limitation according to the choice of the smart materials and the response of the structure. The ER(Electrorheological) fluid is adequate for a large control force, and the PZT(lead zirconate titanate) patches are suitable for small but arbitrary control force at any point of the structure. It can be used for active control of structure by changing the dynamic characteristics of the structure. But it has some difficulty in suppressing the excited vibration in broad band. To compensate this resonance of the controlled structure, a hybrid controller was constructed using PPF(Positive position feedback) control with PZT and ER fluid control.

A Study on the Damping Characteristics of a Hybrid Smart Structure Using Electrorheological Fluids and PZT (전기유동유체와 압전세라믹을 이용한 복합지능구조물의 감쇠특성 연구)

  • 윤신일;박근효;한상보;최윤대
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.04a
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    • pp.382-387
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    • 2003
  • Many type of smart materials and control laws are available to actively adjust the structure from various external disturbances. Usually, a certain type of control law to activate a specific smart material is tell established, but the effectiveness of the control scheme is limited by the choice of the smart materials and the responses of the structure. ER fluid is adequate to provide small but arbitrary control forces at any point along the structure. It was found that active vibration control of the structure embedded with ER fluids fluidly to suppress the vibration excited with broad band frequency due to the limited change of the structure characteristics. To compensate this limited effect of the control scheme with ER fluid alone, PPF control using PZT as an actuator is added to construct a hybrid controller.

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Performance Analysis of Smart Impact Damper (지능형 완충기의 특성 해석)

  • ;;Y.T. Choi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.323-327
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    • 2001
  • Electrorheological(ER) and magnetorheological(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. Controllable fluids such as ER and MR fluids have received considerable attention as several components of engineering devices. One of them is a smart impact damper using ER/MR fluids. Impact damper system can be used in the joint mechanism of railroad vehicle, protection equipment of elevator's drop, and launch equipment of aircraft. This paper presents the results of an analytical study of the performance of a smart impact damper to suppress vibration during impact excitation. The damping capabilities of MR impact damper for variable applied current are analyzed using Bingham model under sudden impact load.

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