BINGHAM AND RESPONSE CHARACTERISTICS OF ER FLUIDS IN SHEAR AND FLOW MODES

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1017-1024 ◽  
Author(s):  
H. G. LEE ◽  
S. B. CHOI ◽  
S. S. HAN ◽  
J. H. KIM ◽  
M. S. SUH
Keyword(s):  
Electric Fields ◽  
Flow Mode ◽  
Shear Mode ◽  
Damping Force ◽  
Response Characteristics ◽  
Operating Modes ◽  
Field Dependent ◽  
Different Temperatures ◽  
Er Damper ◽  
Er Fluid

This paper presents field-dependent Bingham and response characteristics of ER fluid under shear and flow modes. Two different types of electroviscometers are designed and manufactured for the shear mode and flow mode, respectively. An ER fluid consisting of soluble chemical starches (particles) and silicon oil is made and its field-dependent yield stress is experimentally distilled at two different temperatures using the electroviscometers. Time responses of the ER fluid to step electric fields are also evaluated under two operating modes. In addition, a cylindrical ER damper, which is operated under the flow mode, is adopted and its measured damping force is compared with predicted one obtained from Bingham model of the shear and flow mode, respectively.

A Preliminary Parametric Study of Electrorheological Dampers

1994 ◽  
Vol 116 (3) ◽  
pp. 570-576 ◽  
Author(s):  
Z. Lou ◽  
R. D. Ervin ◽  
F. E. Filisko
Keyword(s):  
Cross Section ◽  
Mixed Mode ◽  
Flow Mode ◽  
Shear Mode ◽  
Zero Field ◽  
Damping Force ◽  
Bingham Plastic ◽  
Control Effectiveness ◽  
Er Damper ◽  
Er Fluid

In approaching the design of an electrorheology-based, semi-active suspension, the electrorheological component (ER damper) can be built as either a flow-mode, shear-mode, or mixed-mode type of damper. The source of damping force in the flow-mode is exclusively from flow-induced pressure drop across a valve, while that in the shear-mode is purely from the shear stress on a sliding surface. The dynamics of the fluid flow are included in the derivation of the zero-field damping forces. The control effectiveness is found to be strongly related to the dynamic constant (which is proportional to the square root of the vibration frequency) and, for shear-and flow-mode dampers, the ratio of the piston area to the cross-section of the ER control gap. To achieve the same performance, a flow-mode ER damper is not as compact and efficient as a shear-mode ER damper. With the same ER damping force, a mixed-mode damper is more compact than a shear-mode damper. However, the mixed-mode damper does not have as a low zero-field damping force as the shear-mode damper. The analysis is based on the assumption that the ER fluid is Bingham plastic.

scholarly journals Flow Mode Magnetorheological Dampers with an Eccentric Gap

2014 ◽  
Vol 6 ◽  
pp. 931683 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley
Keyword(s):  
Constitutive Model ◽  
Mr Damper ◽  
Flow Mode ◽  
Rectangular Duct ◽  
Damping Force ◽  
Bingham Plastic ◽  
Mr Dampers ◽  
Annular Gap ◽  
Field Dependent ◽  
Viscous Field

This paper analyzes flow mode magnetorheological (MR) dampers with an eccentric annular gap (i.e., a nonuniform annular gap). To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and damping coefficient, which is the ratio of equivalent viscous field-on damping to field-off damping. In addition, damper capabilities of flow mode MR dampers with an eccentric gap were compared to a concentric gap (i.e., uniform annular gap).

Vibration Control of a Flexible Structure Using ER Dampers

1999 ◽  
Vol 121 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Seung-Bok Choi
Keyword(s):  
Control System ◽  
Vibration Control ◽  
Sliding Mode ◽  
Shear Mode ◽  
Flexible Beam ◽  
Short Columns ◽  
Flexible Beam System ◽  
Er Damper ◽  
External Forces ◽  
Er Fluid

This technical brief addresses the vibration control of a flexible beam structure using ER (electro-rheological) dampers. A clamped-clamped flexible beam system supported by two short columns is considered. An ER damper which is operated in shear mode is designed on the basis of Bingham model of the ER fluid, and attached to the flexible beam. After deriving the governing equation of motion and associated boundary conditions, a sliding mode controller is formulated to effectively suppress the vibration of the beam caused by external forces. In the formulation of the controller, parameter variations such as frequency deviation are treated to take into account the robustness of control system. The effectiveness of the proposed control system is confirmed by both simulation and experimental results.

Nondimensional Damping Analysis of Flow-Mode Magnetorheological and Electrorheological Dampers

Aerospace ◽  
2003 ◽  
Author(s):  
Wei Hu ◽  
Norman M. Wereley
Keyword(s):  
Magnetic Circuit ◽  
Design Method ◽  
Damping Coefficient ◽  
Flow Mode ◽  
Shear Mode ◽  
Number Range ◽  
Bingham Plastic ◽  
Bingham Number ◽  
Er Damper ◽  
The Relationship

In an effort to develop a Magnetorheological (MR) and Electrorheological (ER) damper initial design method, a quasi-steady relationship between force and velocity exhibited by a flow-mode MR/ER damper is developed based on a Bingham plastic model and a parallel plate assumption. A nondimensional damping coefficient is described as a nonlinear explicit function of an independent nondimensional Bingham number. Since the nondimensional damping coefficient is not a simple analytical function of the Bingham number, a uniform rational approximation approaches is used to determine the relationship between nondimensional damping coefficient and Bingham number. Approximate linear relationship is obtained in a certain Bingham number range. Thus, the quasi-steady flow mode damping approximately consists of a controllable damping and a linear viscous or post-yield damping, which is similar to the behavior of a shear mode damper. The effect on the nondimensional damping coefficient due to the magnetic circuit is also considered by introducing a ration of the length of active region to the total flow gap length.

Damping force characteristics of electrorheological shock absorbers with different electrode designs

2010 ◽  
Vol 224 (2) ◽  
pp. 293-304 ◽  
Author(s):  
Y-M Han ◽  
M-S Seong ◽  
S-B Choi ◽  
N M Wereley
Keyword(s):  
Shock Absorber ◽  
Equations Of Motion ◽  
Design Parameters ◽  
Damping Force ◽  
Passenger Vehicles ◽  
Shock Absorbers ◽  
Car Suspension ◽  
Field Dependent ◽  
The Time Domain ◽  
Er Fluid

This article presents the effect of electrode design parameters on the damping force of an electrorheological (ER) shock absorber for passenger vehicles. As a first step, an ER fluid is synthesized by dispersing arabic gum particles into non-conducting oil, and its field-dependent Bingham characteristics are experimentally evaluated. The Bingham model of the ER fluid is then formulated and incorporated with the governing equations of motion of the ER shock absorber. Subsequently, several ER shock absorbers are designed and manufactured with various electrode designs, which have three different electrode gaps, lengths, and materials, respectively. The field-dependent damping force of the manufactured shock absorbers is demonstrated in the time domain and compared with simulation results. In addition, the vibration control performance of a quarter-car suspension system is presented and compared with different electrode gaps and lengths.

The Performance Analysis of Electro-Rheological Damper

2011 ◽  
Vol 179-180 ◽  
pp. 443-448 ◽  
Author(s):  
Yong Guang Chen ◽  
Hua Yan
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Vibration Velocity ◽  
Fluid Viscosity ◽  
Damping Force ◽  
Hydraulic Theory ◽  
Set Up ◽  
Er Damper ◽  
Relationship Of ◽  
Er Fluid

Electro-Rheological (ER) fluid is a smart material. It develops a new path for automotive semi-active intelligent suspension system. The damping force of ER damper can be controlled by applied electric field. Applying the theory of rheodynamics and hydraulic theory, a relationship of damping vs. vibration velocity, electric field strength and gas-filled pressure has been set up. There are three sections of damping force, background damping force of a fluid viscosity, electric damping force of applied electric field and pressure of gas. A new gas-filled ER damper is developed. The main structure parameter of influencing ER damper performance are discussed, some design principles of ER damper are given.

scholarly journals High Loaded Mounts for Vibration Control Using Magnetorheological Fluids: Review of Design Configuration

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
Xuan Phu Do ◽  
Seung-Bok Choi
Keyword(s):  
Vibration Control ◽  
Cross Sections ◽  
Operation Mode ◽  
Design Parameters ◽  
Flow Mode ◽  
Shear Mode ◽  
Operational Mode ◽  
Damping Force ◽  
Mr Fluid ◽  
Advantages And Disadvantages

Design configurations of high loaded magnetorheological (MR in short) mounts are reviewed and discussed. The configurations are analyzed on the basis of three operating modes of MR fluid: flow mode, shear mode, and squeeze mode. These modes are significantly important to develop new type of mounts and improve the efficiency of vibration control. In this paper, advantages and disadvantages of each operation mode are analyzed on the basis of ability of designing high loaded mounts. In order for analysis, the field-dependent damping force equations for typical cross sections of mounts are firstly investigated while maintaining original equations of these cross sections. As a subsequent step, simulation tools for the high loaded mounts are investigated and discussed. These tools which are developed from the analyzed method are expressed as functions of various design parameters such as inside pressure, magnetic field, dimension, stiffness, and damping. These tools are essential for accurate design of MR mount and for careful checking of the operation capability before manufacturing the mounts. This paper can provide very useful information and guidelines to determine an appropriate design configuration of high loaded mounts whose vibration control performances depend on the operational mode of MR fluid.

PRACTICE-RELEVANT ASPECTS OF CONSTRUCTING ER FLUID ACTUATORS

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3243-3255 ◽  
Author(s):  
H. Janocha ◽  
B. Rech ◽  
R. Bölter
Keyword(s):  
Electric Fields ◽  
Electrorheological Fluids ◽  
Flow Mode ◽  
Process Automation ◽  
Rotational Viscometer ◽  
Energy Transducer ◽  
The Individual ◽  
Er Fluids ◽  
The University ◽  
Er Fluid

The flow resistance of electrorheological fluids (ER fluids) can be controlled by applying electric fields. Thus, ER fluids are suitable for the application in actuators, using high-voltage sources for the generation of the field. The behaviour of an ER fluid actuator not only depends on the properties of the individual actuator components (ER fluid, energy transducer and energy source) but especially on their combined efforts as a system. Based on a possible scheme for the design of ER fluid actuators, this paper presents important practice-relevant aspects of a systematic actuator construction. Here the behaviour of a commercial ER suspension is examined and compared to a homogeneous ER fluid without yield point using a rotational viscometer and a flow-mode damper realized at the Laboratory of Process Automation (LPA) of the University of Saarland.

Dynamic Fatigue Characteristics of Electrorheological Fluids: Experimental Results

2006 ◽  
Vol 324-325 ◽  
pp. 177-180 ◽  
Author(s):  
Seung Bok Choi ◽  
Kum Gil Sung
Keyword(s):  
Yield Stress ◽  
Electrorheological Fluids ◽  
Flow Mode ◽  
Electric Voltage ◽  
Operating Cycle ◽  
Field Dependent ◽  
Flow Motion ◽  
Fatigue Characteristics ◽  
Er Fluid ◽  
Dynamic Fatigue

In this study, the dynamic fatigue characteristics of chemical starch-based ER fluid are experimentally investigated. A flow mode type apparatus is manufactured to activate the flow motion of the ER fluid. After evaluating the field-dependent Bingham property, three important dynamic fatigue characteristics; yield stress, current density and response time of the ER fluid are investigated as a function of the operating cycle. The dynamic operation for the flow motions is undertaken up to one million cycles and electric voltage is applied to the electrodes. In addition, the change of the particles of the ER fluid is microscopically observed to advocate the variation of the yield stress.

Study on Vibration Attenuation Performance of a New Structural Electrorheological Fluid Damper

2007 ◽  
Author(s):  
Wangzhong Liu ◽  
Zhaobo Chen ◽  
Mingzhang Li ◽  
Yinghou Jiao
Keyword(s):  
Electrorheological Fluid ◽  
Flow Mode ◽  
Damping Force ◽  
Concentric Cylinders ◽  
Negative Electrodes ◽  
Fluid Damper ◽  
Vibration Attenuation ◽  
Vibration Attenuation Performance ◽  
Er Damper ◽  
Two Degree Of Freedom

A new structural ER (electrorheological) damper based on the characteristic of controllable force of electrorheological fluid (ERF) is proposed. The positive and negative electrodes of the damper consisted of series of concentric cylinders generate great damping forces. The damper works in a state of hybrid of shearing and flow mode. The damping force is generated when electric field is applied. The Bingham model are used to describe the ERF in the post-yielding regime, the theoretical expressions of damping force are developed based on numerical analysis of several ER dampers. A simple two degree of freedom vibration system is taken as an example to evaluate the vibration attenuation performance of the damper. The system is excited by sinusoidal force with certain frequency and the ER damper replaced the conventional damper. The simulation results of the response of displacement as well as acceleration are illustrated to show the effectiveness and feasibility of the damper in vibration control.

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