RELATION OF LAMELLAR STRUCTURE AND SHEAR STRESS OF DYNAMIC PM-ER FLUIDS

2011 ◽  
Author(s):  
D.K. LIU ◽  
C. LI ◽  
J. YAO ◽  
L.W. ZHOU ◽  
J.P. HUANG
Keyword(s):  
Shear Stress ◽  
Lamellar Structure ◽  
Er Fluids

RELATION OF LAMELLAR STRUCTURE AND SHEAR STRESS OF DYNAMIC PM-ER FLUIDS

2011 ◽  
Vol 25 (07) ◽  
pp. 971-977 ◽  
Author(s):  
D. K. LIU ◽  
C. LI ◽  
J. YAO ◽  
L. W. ZHOU ◽  
J. P. HUANG
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Lamellar Structure ◽  
Inverse Correlation ◽  
Dynamics Simulation ◽  
Rheological Characteristics ◽  
Lamellar Structures ◽  
Dynamic Rheological Behavior ◽  
Moving Particle ◽  
Er Fluids

To understand the dynamic rheological behavior of polar molecular electrorheological (PMER) fluids, the shear stress and viscosity of the colloids are compared with the parameters of their lamellar structures which are obtained simultaneously with the rheological characteristics using an electrorheoscope. The results of the experiments and molecular dynamics simulation indicate that the shear stress is mainly contributed by the moving particle rings, and there is an inverse correlation between the width of the moving particle rings and the shear stress.

scholarly journals THE EFFECT OF ELECTRIC FIELD DIRECTION ON THE-SHEAR STRESS OF ER FLUIDS

1996 ◽  
Vol 45 (4) ◽  
pp. 640
Author(s):  
WANG ZUO-WEI ◽  
LIN ZHI-FANG ◽  
TAO RUI-BAO
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Field Direction ◽  
Electric Field Direction ◽  
Er Fluids

THE METHODS FOR MEASURING SHEAR STRESS OF POLAR MOLECULE DOMINATED ER FLUIDS

2007 ◽  
Vol 21 (28n29) ◽  
pp. 4813-4818 ◽  
Author(s):  
RONG SHEN ◽  
XUEZHAO WANG ◽  
YANG LU ◽  
GANG SUN ◽  
WEIJIA WEN ◽  
...  
Keyword(s):  
Shear Stress ◽  
Stress Measurement ◽  
Measurement Process ◽  
Interface Effect ◽  
Polar Molecule ◽  
High Shear ◽  
High Shear Stress ◽  
Er Fluids ◽  
Metallic Electrodes

A series of ER fluids materials with high shear stress have been developed recently, which named as polar molecule dominated electrorheological (PM-ER) fluids. Difficulties have been met in shear stress measurement process due to the slide of PM-ER fluids on the surface of metallic electrodes. In this paper, two shearing configurations have been developed to remove the interface effect. The intrinsic shear stress of ER fluids can be obtained by using the devices.

Computer Simulation of Electrorheological Fluids in the Binary System of Particle Size

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1822-1827
Author(s):  
Yasushige Mori ◽  
Tetsu Tsunamoto ◽  
Hitoshi Nakayama
Keyword(s):  
Computer Simulation ◽  
Particle Size ◽  
Shear Stress ◽  
Fine Particles ◽  
Volume Fraction ◽  
Dielectric Polarization ◽  
Uniform Size ◽  
Polarization Model ◽  
Effect Of Particle Size ◽  
Er Fluids

One of the typical electrorheological (ER) fluids consists of suspension of fine particles in the liquid of low dielectric constant. Particles for ER fluids generally have a size distribution, and some experimental results were reported which showed the effect of particle size on the shear stress of ER fluids. On the other hand, the simulation by dielectric polarization model concluded that the shear stress calculated did not depend on the particle size under the same volume fraction of particles. In order to understand the effect of particle size, the two dimensional computer simulation was carried out for a system containing particles of different size, by using a model similar to that reported by Klingenberg et al. It was found that the shear stress of uniform size system did not depend on the particle size. When small and large particles, with the diameter ratio of 1:2, were mixed in equal numbers of particles, the chain-like clusters consisiting of both sizes of particles were formed. The shear stress and the response time of the binary size system were close to those of uniform size system, if the total volume fraction of particles was kept constant.

WALL SLIP EFFECTS MEASURING THE RHEOLOGICAL BEHAVIOR OF ELECTRORHEOLOGICAL (ER) SUSPENSIONS

2012 ◽  
Vol 26 (01) ◽  
pp. 1250006 ◽  
Author(s):  
STEFFEN SCHNEIDER
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Behavior ◽  
Wall Slip ◽  
Hydraulic Test ◽  
Slip Effects ◽  
Measured Flow ◽  
Wall Shear ◽  
Er Fluids ◽  
Electrorheological Suspensions

In this work, a new method to determine the wall shear stress was developed step by step. To determine the wall shear stress, methods of the suspension rheology are being used for the first time to characterize ER fluids. This work focuses on investigations of the flow behavior of electrorheological suspensions in flow channels with different geometries at different electrical field strengths. Careful interpretation of the results with respect to different gap geometries has shown that the measured flow curves should undergo a combination of corrections. As a result it can be shown that wall slip effects can be measured under application like conditions on a hydraulic test bench.

A COMPARISON OF THE PERFORMANCE OF ER FLUIDS IN SQUEEZE

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3081-3091 ◽  
Author(s):  
J L Sproston ◽  
A K El Wahed ◽  
E W Williams ◽  
R Stanway
Keyword(s):  
Shear Stress ◽  
Theoretical Model ◽  
Applied Field ◽  
Theoretical Study ◽  
Time Dependent ◽  
Squeeze Flow ◽  
Device Performance ◽  
Displacement Control ◽  
Lower Electrode ◽  
Er Fluids

This paper is concerned with an experimental and theoretical study of the characteristics of two ER fluids and their application to vibration control when used in squeeze flow. It is seen that when the fluids are sandwiched between two electrodes, the lower one oscillating and the upper one fixed, displacement control of the lower electrode can be achieved by control of the applied field. Of particular interest is the dependence of the force transmitted across the fluids on oscillation frequency and applied field. A time-dependent theoretical model is seen to satisfactorily predict the device performance when allowance is made for a non-linear dependence of the post-yield shear stress on shear rate.

Simulated Behavior of a System With Base Excitation Using an Electrorheological Fluid Damper

1993 ◽  
Author(s):  
Paul N. Rieder ◽  
John A. Tichy
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Vibration Isolation ◽  
Fluid Model ◽  
Electrorheological Fluid ◽  
Isolation System ◽  
Yield Shear Stress ◽  
Linear Behavior ◽  
Two Parameters ◽  
Er Fluids

Abstract The flow properties of electrorheological (ER) fluids change with the application of an electric field. Presently, these materials are a novelty with few direct applications, but they have drawn considerable interest. Proposed applications include lubricants, dampers, clutches, brakes, etc. Existing ER fluids are best described by the Bingham fluid model. The Bingham material is described by two parameters, a yield shear stress and a viscosity. When the shear stress magnitude exceeds the yield shear stress, quasi-Newtonian flow results; otherwise the material is rigid. For many ER fluids, the yield shear stress is proportional to the square of the applied electric field. In the present study, the Bingham model is applied to a rectangular flow channel. A rigid core forms midway across the film, the core thickness being proportional to the yield shear stress. The damper force is predicted as a function of a dimensionless parameter which depends on the yield shear stress, the flow rate, and channel geometry. Calculations are performed for a simple vibration isolation system. Such a system may represent a smart shock absorber to minimize vibration response to oscillation input from a bumpy road. The ER damper is shown to be effective in isolating vibration within a band of linear behavior.

THE ELECTRORHEOLOGICAL FLUIDS WITH HIGH SHEAR STRESS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1065-1070 ◽  
Author(s):  
KUNQUAN LU ◽  
RONG SHEN ◽  
XUEZHAO WANG ◽  
GANG SUN ◽  
WEIJIA WEN
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Yield Stress ◽  
High Performance ◽  
Electrorheological Fluids ◽  
Stress Effect ◽  
High Shear ◽  
High Shear Stress ◽  
Effective Factors ◽  
Er Fluids

A series of high performance ER fluids newly manufactured in our laboratory are presented. The yield stress of those ER fluids can reach several tens of kPa, 100 kPa and even 200 kPa, respectively. For understanding the high shear stress effect a model is proposed base on the electric field induced molecular bounding effect. The main effective factors in fabricating the high performance ER are discussed.

DESIGN AND DEVELOPMENT OF FLOW BASED ELECTRO-RHEOLOGICAL DEVICES

1992 ◽  
Vol 06 (15n16) ◽  
pp. 2705-2730 ◽  
Author(s):  
D. A. BROOKS
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
Shear Rate ◽  
Basic Flow ◽  
Control Surface ◽  
Flow Data ◽  
Operational Systems ◽  
Flow Apparatus ◽  
Er Fluids ◽  
Excess Shear Stress

The foundations for the design of electro-rheological (ER) actuating devices that use Poiseuille flow are laid. Systems of measurement to assess ER fluids are described including a high pressure flow apparatus. This was used to examine alternative valve geometries and fluids. A method is shown for the reduction of basic flow data to excess shear stress and shear rate. Standard actuator arrangements are reviewed before the design of a flying control surface servomechanism is discussed. The evaluation of this validates the methods and indicates that the forces developed are within striking distance of those required for operational systems.

THE STRENGTH OF ELECTRORHEOLOGICAL (ER) FLUIDS

1992 ◽  
Vol 06 (15n16) ◽  
pp. 2575-2594 ◽  
Author(s):  
H. CONRAD ◽  
Y. CHEN ◽  
A. F. SPRECHER
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Enhancement Factor ◽  
Reasonable Agreement ◽  
Force Enhancement ◽  
Single Row ◽  
Field Temperature ◽  
Definition Of ◽  
Er Fluids ◽  
Er Fluid

The definition of the strength of an ER fluid is discussed. Studies on the electrorheology of ER fluids containing zeolite particles in various oils indicate that the order of magntiude difference between the measured values of the yield stress and those calculated based on the axial force of interaction between particles in a single-row chain can be explained by an enhancement of the force due to the observed clustering of particles into multi-row chains. The force enhancement factor varied with the shear rate and the concentration of particles, but was relatively independent of the electric field, temperature and host fluid. Reasonable agreement existed between the predicted and the measured shear stress-shear strain curves and the concentration dependence of the yield stress when the appropriate force enhancement factor was taken into account. The present theoretical-experimental considerations suggest that ER fluids may attain a yield strength of ~ 50 kPa .

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