scholarly journals Strong Electrorheological Performance of Smart Fluids Based on TiO2 Particles at Relatively Low Electric Field

2021 ◽  
Vol 8 ◽  
Author(s):  
Yuchuan Cheng ◽  
Zihui Zhao ◽  
Hui Wang ◽  
Letian Hua ◽  
Aihua Sun ◽  
...  
Keyword(s):  
Electric Field ◽  
Yield Stress ◽  
Sol Gel ◽  
Interfacial Polarization ◽  
High Yield ◽  
Characteristic Structure ◽  
High Yield Stress ◽  
Large Yield ◽  
Er Fluids ◽  
Er Fluid

Electrorheological (ER) fluids are a type of smart material with adjustable rheological properties. Generally, the high yield stress (>100 kPa) requires high electric field strength (>4 kV/mm). Herein, the TiO2 nanoparticles were synthesized via the sol–gel method. Interestingly, the ER fluid-based TiO2 nanoparticles give superior high yield stress of 144.0 kPa at only 2.5 kV/mm. By exploring the characteristic structure and dielectric property of TiO2 nanoparticles and ER fluid, the surface polar molecules on samples were assumed to play a crucial role for their giant electrorheological effect, while interfacial polarization was assumed to be dominated and induces large yield stress at the low electric field, which gives the advantage in low power consumption, sufficient shear stress, low leaking current, and security.

TIO2 BASED ELECTRORHEOLOGICAL FLUID WITH HIGH YIELD STRESS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1104-1109 ◽  
Author(s):  
RONG SHEN ◽  
XUEZHAO WANG ◽  
WEIJIA WEN ◽  
KUNQUAN LU
Keyword(s):  
Yield Stress ◽  
Chemical Method ◽  
Electrorheological Fluid ◽  
High Yield ◽  
Oxide Nanoparticles ◽  
Wet Chemical Method ◽  
Titanium Oxide Nanoparticles ◽  
High Yield Stress ◽  
Wet Chemical ◽  
Er Fluids

We have fabricated several TiO 2 based ER fluids with doping and without designed doping, which exhibit the high yield stress up to more than 100kPa. The titanium oxide nanoparticles were synthesized by using wet chemical method. The ER effect of those materials is dominated by the special additives, such as amide or its ramification, as well as the remained molecules or ions in the sample preparation. It is found that the yield stress is also strongly dependent on the viscosity of the oil. The prepared ER fluids possess other attractive characters, for instance the current density is low and against sedimentation.

Polar-molecules-driven enhanced colloidal electrostatic interactions and their applications in achieving high active electrorheological materials

2008 ◽  
Vol 23 (2) ◽  
pp. 409-417 ◽  
Author(s):  
L. Xu ◽  
W.J. Tian ◽  
X.F. Wu ◽  
J.G. Cao ◽  
L.W. Zhou ◽  
...  
Keyword(s):  
Yield Stress ◽  
Electrostatic Interactions ◽  
Colloidal Particles ◽  
Sol Gel ◽  
Polar Molecules ◽  
Highly Active ◽  
Static Yield ◽  
Er Fluids ◽  
Er Fluid ◽  
Static Yield Stress

We have fabricated a class of colloidal electrorheological (ER) fluids, in which suspended TiO2 particles were synthesized by a sol-gel method and modified by 1,4-butyrolactone molecules with a permanent molecular dipole moment of 4.524 D. Compared with pure TiO2 ER fluids, the quasi-static yield stress of the polar- molecules-modified ER fluid is enhanced as high as 48.1 kPa when subjected to an external electric field of 5 kV/mm. Also, it possesses other attractive characters such as low current density (<14 μA/cm2) and low sedimentation. Based on a Green’s function method, we present a first-principles approach to investigate colloidal electrostatic interactions. Excellent agreement between experiment and theory has been shown for the enhancement ratio of quasi-static yield stress, which quantitatively reveals that enough polar molecules oriented within the field-directed gap between the colloidal particles can unexpectedly enhance the interactions, thus yielding the unusual enhancement. This shows a promising and flexible direction for achieving more highly active ER materials.

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.

Dielectric and Rheological Behaviors of Semiconductive Polymer Suspension as an Electrorheological Fluid

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1852-1859 ◽  
Author(s):  
B. D. Chin ◽  
O. O. Park ◽  
Y. S. Lee
Keyword(s):  
Yield Stress ◽  
Interfacial Polarization ◽  
Electrorheological Fluid ◽  
Model Studies ◽  
Wide Range ◽  
Potential Applicability ◽  
Stress Behaviors ◽  
Er Fluids ◽  
Er Fluid ◽  
Particle Medium

We have studied the dielectric and rheological characteristics of semiconductive polymer based ER fluids. Under static electric field, yield stress of suspension was found to be closely related to the dielectric properties that is in accord with the Maxwell–Wagner interfacial polarization. The dielectric constant showed maximum then decreased with increasing bulk conductivity of particle as the yield stress behaviors did. Particle-medium interaction on ER response was also examined by utilizing appropriate surfactant. These experimental results were consistent with the prediction based on the recent model studies. Over wide range of temperature, our ER fluid maintains its activity so that it can broaden the potential applicability as a smart material.

Electrorheological fluid with an extraordinarily high yield stress

2002 ◽  
Vol 80 (5) ◽  
pp. 888-890 ◽  
Author(s):  
Yuling Zhang ◽  
Kunquan Lu ◽  
Guanghui Rao ◽  
Yu Tian ◽  
Shaohua Zhang ◽  
...  
Keyword(s):  
Yield Stress ◽  
Electrorheological Fluid ◽  
High Yield ◽  
High Yield Stress

MOLECULAR ORIENTATION AND ELECTROHYDRODYNAMIC FLOW IN HOMOGENEOUS ER FLUIDS

2001 ◽  
Vol 15 (06n07) ◽  
pp. 973-979 ◽  
Author(s):  
HIROKI IWATSUKI ◽  
NAOTO GOHKO ◽  
HIROSHI KIMURA ◽  
YUICHI MASUBUCHI ◽  
JUN-ICHI TAKIMOTO ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Electric Field ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Polypropylene Glycol ◽  
Homogeneous Fluid ◽  
Immiscible Liquids ◽  
Electrohydrodynamic Flow ◽  
Er Fluids ◽  
Er Fluid

Homogeneous ER fluid is an ER fluid which consists of a homogeneous fluid only; it is neither a suspension nor a blend of immiscible liquids. Various liquid crystals are typical examples of homogeneous ER fluids. Recently, we have found that urethane-modified polypropylene glycol (UPPG) is one of the very few examples of homogeneous ER fluids which show no liquid crystalline order. In order to clarify the mechanism of the ER effect in this fluid, we have studied, in this paper, electrohydrodynamic flow under shear and electric field.

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.

scholarly journals Internal Damper Characteristics of Rotor System with Submerged ER Fluid Journal Bearing

1997 ◽  
Vol 3 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Siyoul Jang ◽  
John A. Tichy
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Shear Strain ◽  
Yield Stress ◽  
Electric Fields ◽  
Journal Bearing ◽  
Shear Strain Rate ◽  
Newtonian Flow ◽  
Damping Coefficients ◽  
Er Fluid

Electro-Rheological (ER) fluid behavior is similar to Bingham fluid’ s. Only when the shear stress magnitude of ER fluid exceeds the yield stress, Newtonian flow results. Continuous shear strain rate equation about shear stress which simulates Bingham-like fluid shows viscosity variations. Shear yield stress is controlled by electric fields. Electric fields in circumferential direction around the journal are also changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds' equation for submerged journal bearing. Fluid film pressure and perturbation pressures are solved using switch function of Elord's algorithm for cavitation boundary condition. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor-bearing system is computed. It is found that there are no big differences in load capacities with the selected electric field parameters at low eccentric region and higher electric field can support more load with stability at low eccentric region.

Extensive application of TMCP steel plates to ship hulls: 40 kgf/mm2 class high yield stress steel

1988 ◽  
Vol 1 (3) ◽  
pp. 219-243 ◽  
Author(s):  
Susumu Machida ◽  
Hiroshige Kitada ◽  
Hiroshi Yajima ◽  
Akinobu Kawamura
Keyword(s):  
Yield Stress ◽  
Steel Plates ◽  
High Yield ◽  
Ship Hulls ◽  
High Yield Stress
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