• Title/Summary/Keyword: electrorheological

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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.

Electrorheological Properties of Chitin and Chitosan Suspensions

  • Choi, Ung-Su
    • KSTLE International Journal
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    • v.6 no.1
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    • pp.8-12
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    • 2005
  • The electrorheological properties pertaining to the electrorheological (ER) bebaviour of chitin and chitosan suspensions in silicone oil were investigated. Chitosan suspension showed a typical ER response (Bingham flow behavior) upon application of an electric field, while chitin suspension acted as a Newtonian fluid. The difference in behaior results from the difference in the conductivity of the chitin and chitosan particles, even though they have a similar chemical structure. The shear stress for the chitosan suspension exhibited a linear dependence on the volume fraction of particles and a 1.18 power of the electric field. The experimental results for the chitosan suspension correlated with the conduction model for ER response.

Transient Response of an Electrorheological Fluid in Shear Flow (전단 유동 하에서 전기유변유체의 과도응답 특성)

  • Choi, Byung-Ha;Nam, Yun-Joo;Park, Myeong-Kwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.6
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    • pp.411-417
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    • 2009
  • The transient shear stress response of an electrorheological fluid is investigated experimentally. The characteristic time constants of an electrorheological fluid sheared between two concentric cylinders were obtained under various electric field strengths and shear rates. Also, two experimental modes are adopted to investigate the effect of the shear flow on the dynamic behavior of the fluid; one is that the electric field is induced before shearing, and the other is the electric field is induced after shearing. From the difference in the response time between two modes, the cluster formation time were obtained. The response times were decreased with the increase of the shear rate, irrelatively of the electric field strength. The cluster formation time were monotonically increased with increase of shear rate, and thereafter, were converged with a certain value.

Advances in modelling the mechanisms and rheology of electrorheological fluids

  • See, Howard
    • Korea-Australia Rheology Journal
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    • v.11 no.3
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    • pp.169-195
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    • 1999
  • An electrorheological fluid (ERF) is typically a suspension of semi-conducting solid particles dispersed in an insulating carrier fluid, and shows a dramatic change in rheological properties when an external electric field is applied. This rapid and reversible change in flow properties has potential application in many electronically controlled mechanical devices, but the development of efficient devices and optimal materials for ERF is still hindered by incomplete understanding of the fundamental physical mechanisms involved. In recent years there have been considerable advances In relating microstructural models to the rheological behaviour, and these will form the basis of this review. Results of the theoretical calculations and simulations will be compared to the key experimental evidence available. An overview of the fundamental physical concepts behind electrorheological fluid behaviour will also be presented.

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Maneuver Analysis of Full-Vehicle Featuring Electrorheological Suspension and Electrorheological Brake (ER 현가장치 및 ER 브레이크를 적용한 전체차량의 거동분석)

  • Sung, Kum-Gil;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.1125-1130
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    • 2007
  • This paper presents a maneuver analysis of a full-vehicle featuring electrorheological (ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

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Study on Electrorheological Properties of the Synthesized Chitosan Derivatives (키토산 유도체의 합성과 이의 전기유변학적 특성에 관한 연구)

  • 고영건;임세환;손태일;최웅수
    • Tribology and Lubricants
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    • v.19 no.2
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    • pp.72-77
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    • 2003
  • Chitosan derivatives, Fluorinated chitosan, and N,N,N-Trimethyl chitosan iodide were synthesized as the disperse phases for the electrorheological fluid. The synthesis of these materials were confirmed by Fourier transform infrared spectroscopy (FT-lR). Chitosan derivative suspensions showed ER effect under the electric field. Especially, N,N,N-Trimethyl chitosan iodide suspension showed better electrorheological and electric properties than Fluorinated chitosan. It is due to difference in electron strength of polar groups composed derivatives. N,N,N-Trimethyl chitosan iodide suspension exhibited a linear dependence on an electric field power of 2.07.

Parametric resonance of axisymmetric sandwich annular plate with ER core layer and constraining layer

  • Yeh, Jia-Yi
    • Smart Structures and Systems
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    • v.8 no.5
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    • pp.487-499
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    • 2011
  • The parametric resonance problems of axisymmetric sandwich annular plate with an electrorheological (ER) fluid core and constraining layer are investigated. The annular plate is covered an electrorheological fluid core layer and a constraining layer to improve the stability of the system. The discrete layer annular finite element and the harmonic balance method are adopted to calculate the boundary of instability regions for the sandwich annular plate system. Besides, the rheological property of an electrorheological material, such as viscosity, plasticity, and elasticity can be changed when applying an electric field. When the electric field is applied on the sandwich structure, the damping of the sandwich system is more effective. Thus, variations of the instability regions for the sandwich annular plate with different applying electric fields, thickness of ER layer, and some designed parameters are presented and discussed in this study. The ER fluid core is found to have a significant effect on the location of the boundaries of the instability regions.

The Effect of Surfactant on the Electrorheological Properties of Phosphoric Ester Cellulose ER Fluids (인산 에스테르 셀룰로오스 ER 유체의 전기유변학적 특성에 대한 계면활성제의 영향)

  • 안병길;최웅수;권오관
    • Tribology and Lubricants
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    • v.15 no.3
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    • pp.240-247
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    • 1999
  • The electrorheological (ER) behavior of suspensions in silicone oil of phosphoric ester cellulose particles (average particle size : 18$\pm$1${\mu}{\textrm}{m}$) coated with octadecylamine ( $C_{18}$ $H_{37}$ N $H_2$) as surfactant was investigated at room temperature. For development of anhydrous ER suspension using at real application, it should be researched how can reduce deposition of ER particles in ER suspension. Anhydrous ER suspensions mixing with phosphoric ester cellulose particles coated with octadecylamine were measured. As increasing the coating concentration of octadecylamine, not only analysis of electrical properties such as dielectric constant, current density and electrical conductivity but also rheological properties of ER suspensions were studied. From the experimental results, coating concentration of surfactant had large influence to ER properties of anhydrous ER suspension. Current density, conductivity and electrorheological effect ($\tau$/$\tau$$_{0}$) of ER suspension were linearly reduced with increasing the coating concentration of octadecylamine. But ER suspensions dispersed the phosphoric ester cellulose particles coated with octadecylamine showed reducing deposition of ER particles and could be redispersed easily.

Maneuver Analysis of Full-vehicle Featuring Electrorheological Suspension and Electrorheological Brake (ER 현가장치 및 ER 브레이크를 적용한 전체차량의 거동분석)

  • Sung, Kum-Gil;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.5 s.122
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    • pp.464-471
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    • 2007
  • This paper presents a maneuver analysis of a full-vehicle featuring electrorheological(ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

Electrorheological Properties of Water Activated Silica Gel Suspensions (수분 활성 실리카 겔 분산계의 전기유변학적 특성)

  • 안병길;최웅수;권오관;문탁진
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.115-123
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    • 1997
  • The electrorheological (ER) behavior of suspensions in silicone oil of silica gel powder (average particle size 49 $\mu$m) absorbed water was investigated at room temperature with electric fields up to 2.4 KV/mm. In this paper, for development of succcessful ER fluids used for wide temperature range later, we would like to know a fundamental understanding of water on ER effect. As a first step, the ER fluids involving water activated silica gel were measured not only the electrical characteristics such as dielectric constant, current density and electrical conductivity but also the rheological properties on the strength of electric field, the quantity of dispersed phase and absorbed water. From the experimental results that water absorbed to the particles directly affects to the surface charge density of electric double layer model proposed by Schwarz and makes dielectric constant and current density of ER fluids increase. The current density and dynamic yield stress $($\tau$_y)$ of water activated silica gel suspensions was in exponential proportion to the strength of electric field, the quantity of dispersed phase and absorbed water. And the optimum water quantity and weight concentration of silica gel for electrorheological effect were 4-5 wt% and 15 wt%, respectively.