Visualization Study on the Mechanism of Clusters Formation of ER Fluid in a Cylindrical ER Clutch

2003 ◽  
Author(s):  
Dae-Young Kim ◽  
Myeong-Kwan Park ◽  
Ryuichiro Yamane ◽  
Shuzo Oshima
Keyword(s):  
Shear Rate ◽  
Response Times ◽  
Nonlinear Behavior ◽  
Video Camera ◽  
Shear Mode ◽  
Application Fields ◽  
Almost All ◽  
Er Fluids ◽  
Er Fluid ◽  
Low Shear

Since interest in ER fluids has increased, recently numerous and quite diverse application fields has been proposed. In the studies concerning devices using ER fluids, the behavior of the fluids has been assumed to be almost that of bingham plastics. Also, many differences have been observed between experimental and theoretical result of application devices. But the behavior of ER fluid differs from bingham plastics in the region of low shear rate. Almost all the research concerning application devices using ER fluids is based on the assumption similarity with bingham plastics. And studies have not been performed in this area because of the nonlinear behavior in the region of low shear rates. In spite of the use of improved control methods, research concerning the application of devices using ER fluids has encountered many problems due to modeling error of the basic governing equations. In this study, the motion of particles of an ER fluid in a cylindrical ER clutch is visualized by video camera in order to examine the mechanism of ER effects under the shear mode. The particle type ER fluid is used in this study. The particle size of ER fluids used in the devices is very small, and the response times are in the range of milliseconds. Hence, ER fluids that have a slow response time, fluids with extremely large particles and low concentration were selected. A cylindrical ER clutch is consists of input and output rotational cylinders and ER fluid between them. The cylinders also serve as electrodes. The torque of a cylindrical ER Clutch/Break is measured by torque meter. And then discuss the behavior of cylindrical ER clutch/Break influenced of the nonlinear behavior of ER fluid through results of visualization. As result, the shear stress of a cylindrical ER Clutch/Break is nonlinear at low shear rate because ER fluid in a cylindrical ER clutch is different to form the cluster according to the strength of electric field.

Hysteresis Behaviors of Poly (Naphthalene Quinone) Radical Electrorheological Fluid

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1901-1907 ◽  
Author(s):  
Hyoung J. Choi ◽  
Min S. Cho ◽  
Myung S. Jhon
Keyword(s):  
Shear Rate ◽  
Silicone Oil ◽  
Electrorheological Fluid ◽  
Shear Stresses ◽  
Hysteresis Phenomenon ◽  
Rate Region ◽  
Er Fluids ◽  
High Voltage Generator ◽  
Er Fluid ◽  
Low Shear

As a potential electrorheological(ER) material, poly(naphthalene quinone) radical (PNQR) ER fluid was prepared, and its rheological behavior and hysteresis phenomenon were investigated. PNQR was synthesized by Friedel-Crafts acylation between naphthalene and phthalic anhydride, using zinc chloride as a catalyst at 256°C. A Physica rheometer equipped with a high voltage generator was used to measure the rheological properties of the ER fluids, which were prepared by dispersing PNQR in silicone oil at several particle concentrations. Shear stresses were observed to decrease as shear rate increased in the region of slow deformation rate. It was further found that ER fluid showed different hysteresis behaviors according to the shear rate ranges; thixotropy was observed in the low shear rate region (0.007-0.51/s) and anti-thixotropy in the high shear rate region (0.5-10001/s). Controlled shear stress mode was also applied to observe similar behaviors.

ELECTRIC-FIELD-INDUCED PHASE SEPARATION IN ELECTRORHEOLOGICAL FLUIDS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2811-2822 ◽  
Author(s):  
XIN-LU TANG ◽  
KE-QIN ZHU ◽  
E. GUAN ◽  
XIAO-PING WU
Keyword(s):  
Phase Separation ◽  
Electric Field ◽  
Strong Electric Field ◽  
Processing System ◽  
Video Camera ◽  
Two Dimensional ◽  
Critical Fields ◽  
Computer Image Processing ◽  
Er Fluids ◽  
Er Fluid

The phase separation into a high-density and a low-density phase, which occurs after a strong electric field is applied to an ER fluids, is demonstrated in terms of the Coulomb interaction energy of the system. The phase separation is manifested by two-dimensional pattern observed in the field direction by means of a pair of transparent glass (TG) electrodes. The development of phase separation with an increasing field is recorded by a computer image processing system consisting of a CCD video camera. The patterns are irregular and their characteristic sizes are determined by two-dimensional auto-correlation approach. The dependency of those patterns on external electric field is analyzed based on statistical methods. Two critical fields are presented to characterize the electric-field-induced phase separation process in the ER fluid.

scholarly journals CHARACTERIZATION OF ELECTRO-RHEOLOGCIAL FLUIDS UNDER HIGH SHEAR RATE IN PARALLEL DUCTS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 6029-6036 ◽  
Author(s):  
X. W. ZHANG ◽  
C. B. ZHANG ◽  
T. X. YU ◽  
W. J. WEN
Keyword(s):  
Shear Rate ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
High Shear Rate ◽  
Shear Stresses ◽  
High Shear ◽  
Er Fluids ◽  
The Impact ◽  
Er Fluid

Electro-rheological (ER) fluid is a smart suspension which can be changed promptly from Newtonian to Bingham plastic material when subjected to a high-intensity electric field. This property of ER fluid makes it possible to be applied in adaptive energy absorbers. As the impact velocity encountered in applications could be very large, it is necessary to characterize the ERF under high shear rate. In this study, a capillary rheo-meter with parallel duct was designed and manufactured which is capable of producing a shear rate as high as 5000(1/s). Two giant ER fluids with mass concentration C = 51% and 44.5% and a commercial density-matched ER fluid with C = 37.5% were characterized. The experimental results show that when the ER fluids are free of electric field (E = 0 kV / mm ), they are Newtonian. However, for the former two ER fluids, the deposition effect is very remarkable and stirring has to be made continuously to keep the suspension stable. With the increase of the electric field intensity, the yield shear stresses of ER fluids increase exponentially but their viscosities do not change much. It is also found that within the parallel duct, the flow of ER fluids exhibits notable fluctuations, whose period increases with the increase of electric field intensity and is independent of the shear rate.

POLAR-MOLECULE-DOMINATED ELECTRORHEOLOGICAL (PM-ER) FLUIDS: THE PROPERTIES AND EVALUATIONS

2011 ◽  
Vol 25 (07) ◽  
pp. 957-962 ◽  
Author(s):  
KUNQUAN LU ◽  
RONG SHEN ◽  
XUEZHAO WANG ◽  
DE WANG ◽  
GANG SUN
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Linear Dependence ◽  
Polar Molecule ◽  
High Yield ◽  
Electric Response ◽  
New Type ◽  
Er Fluids ◽  
Er Fluid

In recent years, a new type ER fluids named as polar-molecule-dominated electrorheological (PM-ER) fluids have been developed, of which the yield stress can reach more than 100 kPa and behaves a linear dependence on the electric field. A brief description on the composition and synthesizing method for the materials is given. The main merits of PM-ER fluid are as follows: high yield stress, the shear stress increasing with shear rate up to more than 103 s -1, low current density, rapid electric response and anti-sedimentation. Some perspectives on PM-ER fluid and its applications are presented.

scholarly journals Epitaxial Crystallization of Poly(ε-caprolactone) on Reduced Graphene Oxide at a Low Shear Rate by In Situ SAXS/WAXD Methods

ACS Omega ◽  
2020 ◽  
Vol 5 (49) ◽  
pp. 31535-31542
Author(s):  
Weijun Miao ◽  
Feng Wu ◽  
Shiman Zhou ◽  
Guibin Yao ◽  
Yiguo Li ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Shear Rate ◽  
Reduced Graphene Oxide ◽  
Epitaxial Crystallization ◽  
Reduced Graphene ◽  
Low Shear

Coating of Polyaniline with an Insulating Polymer to Improve the Power Efficiency of Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1931-1939 ◽  
Author(s):  
J. Akhavan ◽  
K. Slack ◽  
V. Wise ◽  
H. Block
Keyword(s):  
Power Efficiency ◽  
Electrorheological Fluids ◽  
Emeraldine Base ◽  
Heavy Duty ◽  
Base Form ◽  
Static Yield ◽  
High Fields ◽  
Er Fluids ◽  
Er Fluid ◽  
A Current

Currents drawn under high fields often present practical limitations to electrorheological (ER) fluids usefulness. For heavy-duty applications where large torques have to be transmitted, the power consumption of a ER fluid can be considerable, and for such uses a current density of ~100μ A cm -2 is often taken as a practical upper limit. This investigation was conducted into designing a fluid which has little extraneous conductance and therefore would demand less current. Selected semi-conducting polymers provide effective substrates for ER fluids. Such polymers are soft insoluble powdery materials with densities similar to dispersing agents used in ER formulations. Polyaniline is a semi-conducting polymer and can be used as an effective ER substrate in its emeraldine base form. In order to provide an effective ER fluid which requires less current polyaniline was coated with an insulating polymer. The conditions for coating was established for lauryl and methyl methacrylate. Results from static yield measurements indicate that ER fluids containing coated polyaniline required less current than uncoated polyaniline i.e. 0.5μ A cm -2. The generic type of coating was also found to be important.

Formation of cylindrite structures in shear-induced crystallization of isotactic polypropylene at low shear rate

Polymer ◽  
2007 ◽  
Vol 48 (4) ◽  
pp. 1105-1115 ◽  
Author(s):  
Chenggui Zhang ◽  
Haiqing Hu ◽  
Xiaohong Wang ◽  
Yonghua Yao ◽  
Xia Dong ◽  
...  
Keyword(s):  
Shear Rate ◽  
Isotactic Polypropylene ◽  
Induced Crystallization ◽  
Low Shear

The Place of Dielectric Spectroscopy in Probing Electrorheology

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1829-1836 ◽  
Author(s):  
S. Kyvelidis ◽  
G. M. Maistros ◽  
P. Rattray ◽  
H. Block ◽  
J. Akhavan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Working Conditions ◽  
High Shear ◽  
Empirical Correlations ◽  
Electrical Parameters ◽  
Shear Rates ◽  
Uniform Shear ◽  
High Shear Rates ◽  
Er Fluids ◽  
Er Fluid

The measurement of the dielectric spectra of PAnQR based ER fluids under shear and electric fields is discussed and results presented. Data in which either but not both shear or electric fields are present are submitted to analysis in terms of known theories. For flow alone, that analysis provides information on the attenuation of polarization by the uniform shear fields whilst the polarization of quiescent fluids by electric fields may lead to estimates of particles packing within the columns. Permittivity data when both fields are acting is presented, but in the absence of suitable theory, not modelled quantitatively. Empirical correlations are discussed and the conclusion drawn that fibrillation is readily suppressed by even moderate shear rates, although long range dipolar forces still persist to high shear rates. The dc conductance of these fluids have also been measured. This together with permittivity data under ER fluid working conditions has importance in establishing the electrical parameters for any ER fluid.

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