• KSTLE International Journal
• /
• 제10권1_2호
• /
• pp.13-16
• /
• 2009

The electrorheological(ER) behavior of hollow polyaniline(PANI) sebacate suspension in silicone oil was investigated by varying the electric fields and shear rates, respectively. The hollow PANI sebacate susepnsion acted as a typical Bingham fluid caused by the polarizability of an amide polar group and showed shear yield stress due to the formation of chains upon application of an electric field. The shear stress for the hollow PANI sebacate suspension exhibited an electric field power of 1.24. On the basis of the experimental results, the newly synthesized hollow PANI sebacate suspension was found to be an anhydrous ER fluid.

• 한국지반공학회지:지반
• /
• 제13권5호
• /
• pp.125-132
• /
• 1997

토석류는 다양한 크기의 흙 입자와 물이 고루 섞여 점성을 가진 유체처럼 하방향으로 이동한다는 사실이 관찰되었다. 이 관찰로부터 토석류를 비선행적인 점도를 가진 비뉴톤 유체처럼 거동하는 것으로 간주할 수 있다. 이 논문에서는 토석류의 레올로지적 특성을 규명하기 위해 산사태 현장에서 채취한 시료를 가지고 점도계를 사용하여 일련의 점도시험을 수행하였다. 그 결과, 토석류는 비뉴톤 유체 중 빙함 소성 모델로 거동한다는 사실이 밝혀졌다. 이 모델을 이용하면 토 석류의 이동을 예측할 수 있다.

• Tribology and Lubricants
• /
• 제25권3호
• /
• pp.176-181
• /
• 2009

Aminated polyacrylonitrile as the new organic disperse phases of the anhydrous ER fluid has been synthesized and ER effect of the suspension composed of aminated polyacrylonitrile in silicone oil investigated. The suspension showed a typical ER response (Bingham flow behavior) upon application of an electric field. The shear stress for the suspension exhibited the dependence with a factor equals to 1.6 power on theelectric field. The current density and the conductivity of the of aminated polyacrylonitrile suspension increase with the electric field intensity and moreover the conductivity of the suspension is about 8 order of magnitude higher than that of the silicone oil. On the basis of the the results, aminated polyacrylonitrile suspension showed the ER flow behavior upon application of the electric field due to the polarizability of the branched amine polar group of the aminated polyacrylonitrile particles.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 추계학술대회 논문집
• /
• pp.1044-1047
• /
• 1996

This paper presents durability characteristics of electrorheological(ER) fluids which undergo a reversible phase change depending upon the imposition of electric fields. The field-dependent Bingham properties are subjected to be altered from long time use of the ER fluid. The level of the changed properties depends upon employed device and test conditions. A piston-rod system which has same mechanism as ER dampers is adopted in this study and tested by increasing operation cycle up to 1 million. Bingham properties of initial and us ER fluids are tested and compared. In addition, these ER fluids are applied to ER damper in order to evaluate damping force performance.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.784-787
• /
• 2003

Electrorheological(ER) and magnetorheological(MR) fluid-based dampers are typically analyzed using Bingham-plastic shear model under quasi-steady fully developed flow conditions. A Herschel-Bulkley constitutive shear flow relationship is that the linear shear stress vs. strain rate behavior of Bingham model is replaced by a shear stress that is assumed to be proportional to a power law of shear rate. This power is called the flow behavior index. Depending on the value of the flow behavior index number, varying degrees of post-yield shear thickening or thinning behavior can be analyzed. But it is not practical to analyze the damping force in a flow mode damper using Herschel-Bulkley model because it is needed to solve a polynomial equation. A useful guide is suggested to analyze the damping force in a damper using the Herschel-Bulkley model.

• 한국자동차공학회논문집
• /
• 제3권6호
• /
• pp.69-77
• /
• 1995

This paper presents performance investigation of a continuously variable ER(Electro-Rheological) damper for passenger vehicles. A dynamic model of the damper is formulated by incorporating electric field-dependent Bingham properties of the ER fluid. The Bingham properties are experimentally obtained through Couette type electroviscous measurement with respect to two different particle concentrations. The governing equation of the hydraulic model treating three components of fluid resistances;electrode duct flow, check valve flow and piston gap flow, is achieved via the bond graph method. A prototype ER damper is then designed and manufactured on the basis of parameter analysis. The damping forces of the system are experimentally evaluated by changing the intensity of the electric field, the particle concentration and the electrode gap.

• Smart Structures and Systems
• /
• 제2권1호
• /
• pp.61-80
• /
• 2006

The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.

• 유변학
• /
• 제10권1호
• /
• pp.31-37
• /
• 1998

전기장이 인가되고 있는 유로를 유동하는 전기유변유체의 기본성질을 파악하기 위 한 실험 및 해석적 연구를 수행하여 빙햄유체로서의 유효성에 대해 알아보고 전기장과 유로 면 형상 및 진동유동으로 인한 영향에 대해 조사함으로써 ER밸브 및 ER대퍼로의 응용과 관련한 감쇄력 제어에 대해 검토하였다. 첫 번째 실험은 ER밸브의 높이가 2mm인 적극면이 평탄한것과 요철로 된 것을 사용하여 압력손실을 압력변환기로 측정함으로써 전기장 및 유 로형상에 대한 영향을 알아보았다. 압력손실 및 전단응력이 전기자세기와 함수관계를 가짐 을 알수 있었고 전기장세기와 유속의 변화시 손실계수에 의한 ER효과의 상이함이 확인되었 으며 레이놀즈수가 커지면 항복전단응력의 영향은 나타나지 않았다. 두 번째 실험은 실린더 를 정현파로 진동시켜 ER밸브에서 감쇠력제어가 가능한가를 알아보고 빙햄유체모델로 설계 된 ER댐퍼의 모델과 비교하였다. ER배르와 ER댐퍼의 수학적 모델을 시뮬레이션한 결과는 약간 벗어남이 보이기는 하나 실험결과와 일치하요 있다. 이것은 ER유체를 단순히 빙행유 체로 취급할수없으나 거시적으로는 빙햄유체로 취급할수 있음을 시사한다.

• Tribology and Lubricants
• /
• 제16권5호
• /
• pp.341-350
• /
• 2000

The study reported in this paper deals with the development for parametric investigation of the influence of the rheological properties of the lubricant in the thermohydrodynamic (THD) film conditions which occur in slider and journal bearings. A parametric investigation based on a Bingham model with a shear yield stress which best fit the experimental pressure is performed for predicting the thickness of the shear Bone in lubricating films with fixed geometry between the stationary and moving surfaces. The results suggest that the shear yield stress for the lubricating film is proportional to the pressure developed in the film within the range of the investigated cases and the shear zone thickness which is of the same order of magnitude as that obtained by the empirical formula is significantly smaller than the fluid film thickness in the lubrication zone.

• Tribology and Lubricants
• /
• 제13권2호
• /
• pp.27-38
• /
• 1997

ER clutch is a device using ER fluid, so called "intelligent material" and is a power transmission system controlled with electric field strength. This device responses very rapidly when controlled by rapid and continuous electrical signal and can form a servosystem. Wear, noise and vibration during operation is very low level. This study was undertaken to investigate substitutive possibilities of this ER clutch for existing power transmission mechanism. An analytic relationships using rheological model (so called, 'Bingham plastic model') of ER fluid were developed, and operation constraints and optimum design concepts were constructed. With this relationships, typical responses of ER clutch and effects of changing geometric, kinetic parameters of ER clutch and ER fluid properties were described. In conclusion, compared with existing mechanisms, an excellent performance of ER clutch was confirmed.confirmed.