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.

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.

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.

THE FREQUENCY DEPENDENCE AND NON-LINEAR DIELECTRIC PROPERTY OF ER FLUID

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3073-3080 ◽  
Author(s):  
KUNQUAN LU ◽  
WEIJIA WEN ◽  
CHENXI LI
Keyword(s):  
Dielectric Property ◽  
Field Strength ◽  
Electric Field ◽  
Frequency Dependence ◽  
Threshold Value ◽  
Shear Stresses ◽  
Linear Behavior ◽  
Non Linear ◽  
Er Fluids ◽  
Er Fluid

The frequency dependence of the shear stress in ac field and the non-linear dielectric property of ER fluid have been studied. We find that the shear stresses of some water-free ER fluids increase monotonously with the frequency and tend to reach saturated values at high frequency. The measurements on KNbO 3/silicone ER fluid show that the shear stresses under 103 Hz frequency a.c. field are several times or even an order larger than that under d.c. field for the same field strength. The studies of non-linear dielectric properties of ER fluids show that the permittivity of ER fluid increases linearly with increasing field strength when the electric field exceeds a threshold value E 1 and tends to a saturated constant beyond a high field strength E 2. Correspondingly the current density follows linear behavior no longer in the region between E 1 and E 2. A model based on the rearrangement of the particles under the electric field. which causes the variation of the dielectric property of the ER fluid, is proposed and the analysis is consistent with the measured results.

Rheology of Fluoride Gels

1976 ◽  
Vol 55 (3) ◽  
pp. 353-356 ◽  
Author(s):  
M. Braden ◽  
Ratna Perera
Keyword(s):  
Infrared Spectroscopy ◽  
Shear Rate ◽  
Elastic Behavior ◽  
Shear Stresses ◽  
High Shear ◽  
Shear Rates ◽  
Extreme Stress ◽  
Thickening Agents ◽  
Shear Rate Dependence ◽  
Low Shear

Six commercial fluoride gels have been studied, using a cone and plate viscometer. Also, the thickening agents have been analyzed using infrared spectroscopy. All gels showed stress thinning, which is the decrease of viscosity with shear rate. Such shear rate dependence is clinically convenient in that the gel will flow readily at the high shear stresses present when the gel is applied but will not flow readily under its own weight when on the tooth. Five materials containing hydroxyalkyl celluloses showed similar degrees of shear thinning. One material with a non-cellulosic thickener showed much more extreme stress thinning together with elastic behavior at low shear rates; such behavior may be clinically advantageous. All of the gels showed only slight temperature dependence of rheological properties.

LANTHANUM TITANATE NANOPARTICLES ER FLUIDS WITH HIGH PERFORMANCE

2012 ◽  
Vol 26 (13) ◽  
pp. 1250079 ◽  
Author(s):  
DE WANG ◽  
RONG SHEN ◽  
SHIQIANG WEI ◽  
KUNQUAN LU
Keyword(s):  
Yield Stress ◽  
Silicone Oil ◽  
Heating Temperature ◽  
Hydroxyl Group ◽  
Lanthanum Titanate ◽  
Different Temperatures ◽  
Static Yield ◽  
Er Fluids ◽  
Er Fluid ◽  
Static Yield Stress

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 μA/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

HIGH PERFORMANCE CALCIUM TITANATE NANOPARTICLE ER FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1110-1113 ◽  
Author(s):  
XUEZHAO WANG ◽  
RONG SHEN ◽  
WEIJIA WEN ◽  
KUNQUAN LU
Keyword(s):  
High Performance ◽  
Silicone Oil ◽  
Calcium Titanate ◽  
Hydroxyl Group ◽  
Long Term Stability ◽  
Dc Electric Field ◽  
Wet Chemical ◽  
Er Fluids ◽  
Er Fluid

A type of calcium titanate (CTO) nanoparticles was synthesized by means of wet chemical method [1] without coating on the particles. The CTO/silicone oil ER fluid exhibits excellent electrorheological properties: high shear stress (~50-100 kPa ) under dc electric field, a low current density (less than 2μA/cm2 at 5kV/mm), and long term stability against sedimentation. Although there are not special additives in the ER fluids, it is found from the chemical analysis that a trace of alkyl group, hydroxyl group, carbonyl group and some ions is remained in the particles which may dominate the ER response.

Rheological Properties of an Electrorheological Fluid in Original Transition Zone

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1893-1900
Author(s):  
Fan Zhikang ◽  
Liang Shuhua ◽  
Xue Xu ◽  
Wang Gang
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Transition Zone ◽  
Electrorheological Fluid ◽  
Concentric Cylinder ◽  
Pseudoplastic Fluid ◽  
Applied Fields ◽  
Er Fluid ◽  
Regressive Analysis ◽  
Cylinder Viscometer

The rheological properties of an electrorheological(ER) fluid have been studied in a modified concentric cylinder viscometer. The results show that the relation of shear rate and shear stress is non-linear at certain shear rate defined as an original transition zone. Regressive analysis reveals that the ER fluid is of yield-pseudoplastic fluid in the transition zone. With increase in applied fields, the rheological properties of the ER fluid deviates from Newtonian fluid and the length of the transition zone becomes longer.

Experimental Research on the Heat Transfer Characteristics of Electrorheological Fluid Shock Absorber

2012 ◽  
Vol 594-597 ◽  
pp. 2836-2839
Author(s):  
Rui Wang ◽  
Yi Chun Wang ◽  
Chao Qing Feng ◽  
Fei Zhou
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Research ◽  
Ultrafine Particles ◽  
Shock Absorber ◽  
Silicone Oil ◽  
Electrorheological Fluid ◽  
Heat Transfer Characteristics ◽  
Electric Voltage ◽  
Er Fluids

Abstract：In order to study the thermal conductivity of ER in shock absorber, the AL2O3 and TiO2 ultrafine particles silicone oil ER are prepared to the different weights and been researched by experiment. Experiment result indicated: in the 5 mm scope of the electrode plank, the voltage from zero to three thousand, the thermal conductivity of ER fluids go up linear with the voltage growing, but the range is smaller; from three thousand to four thousand and five hundred voltage, the thermal conductivity of ER fluids go up with the voltage quickly. Under the high electric voltage, the ultrafine particles are polarized, the plus and minus particles are drawn each other, the particles are put in order and increasing the thermal conductivity.

Effect of Particle Size and Distribution on the Viscosity of a Model Electrorheological (ER) Fluid

1999 ◽  
Author(s):  
Ying Chen ◽  
Hans Conrad
Keyword(s):  
Particle Size ◽  
Reasonable Agreement ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Zero Field ◽  
Effect Of Particle Size ◽  
Er Fluids ◽  
Er Fluid ◽  
Modified Equation ◽  
Single Size

Abstract The zero-field viscosity of model ER fluids consisting of glass beads in silicone oil was determined as a function of average particles size (D¯ = 3–75 μm), volume fraction (ϕ = 0.1–0.3) and bimodal mixtures of two sizes. The viscosity increased with ϕ and decreased with D¯. The viscosity of the suspensions ηs in all cases was described reasonably well by the following relation:ηs=ηs,o(ϕ)+b(ϕ)D¯2/D¯3 where ηs,o(ϕ) and b(ϕ) are constants which increase with ϕ. Reasonable agreement with the Mooney crowding equation occurred for the single size particles, giving for the crowding factor k = 1.3 + 1.5/D¯. For ϕ < 0.2 the viscosity of the bimodal mixtures could be described by a modification of the Mooney equationηsηo=exp(2.76ϕ11-k1ϕ1)exp(2.76ϕ21-k2ϕ2) where ηo is the viscosity of the silicone oil, ϕi the volume fraction of each particle size Di and ki the normal crowding factor for that size. At ϕ = 0.3 the measured values of ηs for the bimodal mixtures became appreciably larger than those calculated from the modified equation. The decrease in particle size leads to both an increase in surface area of the particles per unit volume of the suspension and to a decrease in spacing (crowding); both factors probably contributed to the increase in ηs.

ELECTRORHEOLOGY OF DISPERSIONS OF BaxSr(1-x)TiO3 IN SILICONE OIL UNDER AC OR DC ELECTRIC FIELD

2012 ◽  
Vol 26 (14) ◽  
pp. 1250081 ◽  
Author(s):  
GLAUBER M. S. LUZ ◽  
ANTONIO J. F. BOMBARD ◽  
SILVIO L. M. BRITO ◽  
DOUGLAS GOUVÊA ◽  
SHEILA L. VIEIRA
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Electric Field ◽  
Silicone Oil ◽  
Ferroelectric Materials ◽  
Dc Electric Field ◽  
Ac Fields ◽  
Er Fluid ◽  
Constant Shear Rate

Electrorheology (ER) of ferroelectric materials such as nanometric BaTiO 3 is still not fully understood. In this paper, nanoparticles of Ba x Sr (1-x) TiO 3 (where x = 0.8, 0.9 or 1.0) were synthesized using the method of Pechini, calcinated at 950°C, and after, lixiviated under pH 1 or pH 5. A controlled stress rheometer (MCR-301) was used to make the ER characterization of dispersions made of Ba x Ti 1-x O 3 in silicone oil (30% w/w), where (a) shear stress as a function of DC electric field (under constant shear rate) or (b) shear stress as a function of shear rate (under constant AC or DC electric field) were measured. We observed that electrophoresis occurred under electric field DC, creating a concentration gradient which induced phase separation in ER fluid. On the other hand, under AC fields above 1 kV/mm, the ER effect is stronger than for DC field, and almost without electrophoresis. Furthermore, there is an AC frequency, dependent on the disperse phase, where the ER effect has a maximum.

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