Mathematical Modeling, Analysis, and Design of Magnetorheological (MR) Dampers

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Weng Wai Chooi ◽  
S. Olutunde Oyadiji
Keyword(s):  
Model Simulation ◽  
Fluid Model ◽  
Forced Flow ◽  
Physical Parameters ◽  
Parallel Plates ◽  
Damping Force ◽  
Mr Fluid ◽  
Analysis And Design ◽  
Mr Dampers ◽  
Annular Gap

Most magnetorheological (MR) fluid dampers are designed as fixed-pole valve mode devices, where the MR fluid is forced to flow through a magnetically active annular gap. This forced flow generates the damping force, which can be continuously regulated by controlling the strength of the applied magnetic field. Because the size of the annular gap is usually very small relative to the radii of the annulus, the flow of the MR fluid through this annulus is usually approximated by the flow of fluid through two infinitely wide parallel plates. This approximation, which is widely used in designing and modeling of MR dampers, is satisfactory for many engineering purposes. However, the model does not represent accurately the physical processes and, therefore, expressions that correctly describe the physical behavior are highly desirable. In this paper, a mathematical model based on the flow of MR fluids through an annular gap is developed. Central to the model is the solution for the flow of any fluid model with a yield stress (of which MR fluid is an example) through the annular gap inside the damper. The physical parameters of a MR damper designed and fabricated at the University of Manchester are used to evaluate the performance of the damper and to compare with the corresponding predictions of the parallel plate model. Simulation results incorporating the effects of fluid compressibility are presented, and it is shown that this model can describe the major characteristics of such a device—nonlinear, asymmetric, and hysteretic behaviors—successfully.

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).

Design and Performance Verification of Variable Dampers Using MR Fluid

2003 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Tomoya Sakuma ◽  
Shin Morishita
Keyword(s):  
Dynamic Range ◽  
Mr Damper ◽  
Experimental Result ◽  
Damping Force ◽  
Mr Fluid ◽  
Mr Dampers ◽  
Piston Speed ◽  
Analytical Result ◽  
And Performance ◽  
Good Agreement

Two typical types of MR damper were proposed, where the orifice for MR fluid was designed to place between the piston and the cylinder in one type, and to place on the piston in the other type. In the former design, MR fluid was expected to be subjected to shear flow in the orifice, and subjected to Poiseuille flow in the latter design. The damping force of MR dampers was experimentally measured under various conditions of piston speed, piston amplitude and applied electric current to the magnetic coil. The experimental results showed that the maximum damping force were almost the same in both types of damper under the same conditions, except for case under very little amplitude. It was also shown that typical characteristics of MR damper depended on the clearance of orifice and air volume in MR dampers, and the optimal design for the dynamic range of damping force existed in relation to the clearance of orifice. The experimental result of the damping force of these dampers showed good agreement with the analytical result.

Design and Development of Magneto Rheological Dampers for Bicycle Suspensions

1999 ◽  
Author(s):  
Mehdi Ahmadian
Keyword(s):  
Dynamic Performance ◽  
Mr Damper ◽  
Test Results ◽  
Design And Development ◽  
Damping Force ◽  
Mr Fluid ◽  
Performance Improvements ◽  
Mr Dampers ◽  
Force Velocity ◽  
Magneto Rheological

Abstract The design and fabrication of a magneto rheological (MR) damper for bicycle suspension applications is addressed. Two 1998 Judy® Dampers are retrofitted with MR valves, to achieve the damping force adjustability that the MR fluid offers. One design attempts to use as many of the Judy® Damper components as possible. The second design significantly modifies the Judy® Damper, to better accommodate the MR valve and ease of fabrication and assembly, although fitting into the same envelope as the Judy® damper for a direct retrofit. The two MR dampers are fabricated and assembled for force-velocity characterization testing. The test results show that properly-designed MR dampers can provide significant dynamic performance improvements, as compared to conventional passive bicycle dampers.

Damping Force Analysis of Magnetorheological (MR) Dampers

2012 ◽  
Vol 187 ◽  
pp. 311-314
Author(s):  
Hai Jun Xing
Keyword(s):  
Pressure Gradient ◽  
Fluid Pressure ◽  
Algebraic Expression ◽  
Force Analysis ◽  
Damping Force ◽  
Mr Fluid ◽  
Mr Dampers ◽  
Numerical Result ◽  
Force Velocity

In this paper, utilizing Herschel-Bulkley model, the equation of MR fluid pressure gradient is derived in order to predict MR damper’s force-velocity behavior. The equation, showing as a complicated nonlinear algebraic expression including various parameters, is then simplified to a nondimensional equation. This is followed by the analysis of the root of this nondimensional equation and an approximate root closely corresponding to numerical result is given.

Analysis and Design of Magnetorheological Damper

2010 ◽  
Vol 148-149 ◽  
pp. 882-886 ◽  
Author(s):  
Jin Huang ◽  
Jian Min He ◽  
Guo Ping Lu
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Design Method ◽  
Outer Cylinder ◽  
Magnetorheological Damper ◽  
Effective Length ◽  
Damping Force ◽  
Analysis And Design ◽  
Mr Dampers ◽  
Mr Fluids

Magnetorheological (MR) dampers are the semi-active control devices that use MR fluids to produce controllable dampers. In this paper, the design method of the cylindrical MR damper is established. Bingham model is used to describe the constitutive behavior of MR fluids subject to an applied magnetic field. The equation for the damping force is derived to provide the theoretical foundation for the design of the damper. Based on this equation the engineering expressions for the gap and effective length of the annular MR fluid between the piston and the outer cylinder are derived. The result shows that with the increase of the applied magnetic field strength, the damping force is increased. The dimensions of the gap and length can be calculated when the required damping force, the velocity of the piston, and the desired control damping force ratio are specified.

Investigation of Annular Gap Size for Optimizing the Dynamic Range of MR Damper Using Comsol Multiphysics Software

2014 ◽  
Vol 606 ◽  
pp. 187-192 ◽  
Author(s):  
Sharmila Fathima ◽  
Asan Gani Abdul Muthalif ◽  
Md. Raisuddin Khan
Keyword(s):  
Vibration Control ◽  
Dynamic Range ◽  
Active Vibration Control ◽  
Comsol Multiphysics ◽  
Gap Size ◽  
Viscous Stress ◽  
Mr Fluid ◽  
Mr Dampers ◽  
Annular Gap ◽  
Magneto Rheological

Magneto-rheological (MR) fluid technology has made it possible to develop reliable, revolutionary vibration control systems for a variety of commercial, medical and military applications. MR fluid shock absorber systems are enabled by remarkably versatile MR fluid technology, which allows the system to respond instantly and controllably to varying levels of vibration or shock with simple, robust designs. This paper presents a parametric study of the MR dampers for semi-active vibration control. The influence of gap size of the damper on the viscous stress of the MR fluid is examined. It is inferred from the study that the viscous stress of the MR fluid for different parameters such as gap size influences the dynamic range of MR fluid dampers.The simulated results depict a maximum viscous stress of 1765.441 N/m2for a gap size of 1.85 mm. The developed dynamic range would allow for smaller size of the device, higher dynamic yield stress and low power consumption. The simulated results using COMSOL multiphysics for the verification of the parametric strategy have been presented. Results of this study shall enhance the design of MR dampers for different control applications.

Mathematical Modelling and Design and of MR Dampers

Volume 2 ◽  
2004 ◽  
Author(s):  
Weng W. Chooi ◽  
S. Olutunde Oyadiji
Keyword(s):  
Magnetic Field ◽  
Yield Stress ◽  
Active Vibration Control ◽  
Mr Fluid ◽  
Bingham Plastic ◽  
Mr Dampers ◽  
Mr Fluids ◽  
Annular Gap ◽  
Active Valve ◽  
Active Vibration

Most magnetorheological (MR) fluid devices are fixed-pole valve mode devices where the fluid flows through a magnetically active valve. Controlling the strength of the magnetic field inside the valve allows the rheological properties of the MR fluid to be varied. Upon the application of a magnetic field, MR fluids develop a yield stress, which must be overcome before any flow is possible. This behavior can be represented mathematically by models of fluid with a yield stress like the Bingham plastic model. MR dampers have utilized this property of the MR fluids to provide controllable, semi-active vibration control. The most effective and widely used configuration of MR dampers incorporates an annular gap through which the MR fluid is force to flow. This paper presents a solution for annulus flows, derived from fundamental equations of fluid mechanics, of any general model of fluid with a yield stress. An example of the application of the general analytical expressions using the Herschel-Buckley model is given, and the limitations of the parallel plate approximation is illustrated for configurations whereby the size of the annular gap relative to the mean radius is large. Finally, the flow solution is incorporated into the mathematical model of an MR damper designed at the University of Manchester, and simulation results incorporating the effects of compressibility in the modeling procedure are presented. It was shown that this model can describe the major characteristics of such a device — nonlinear, asymmetric and hysteretic behaviors — successfully.

scholarly journals Dynamic Model of MR Dampers Based on a Hysteretic Magnetic Circuit

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Pengfei Guo ◽  
Jing Xie ◽  
Xinchun Guan
Keyword(s):  
High Frequency ◽  
Eddy Currents ◽  
Magnetic Circuit ◽  
Fluid Model ◽  
Magnetic Hysteresis ◽  
Low Frequency ◽  
Circuit Model ◽  
Magnetic Saturation ◽  
Damping Force ◽  
Mr Dampers

As a key to understand dynamic performances of MR dampers, a comprehensive dynamic magnetic circuit model is proposed in this work on the basis of Ampere’s and Gauss’s laws. It takes into account not only the magnetic saturation, which many existing studies have focused on, but also the magnetic hysteresis and eddy currents in a MR damper. The hysteresis of steel parts of MR dampers is described by Jiles-Atherton (J-A) models, and the eddy current is included based on the field separation. Compared with the FEM results, the proposed model is validated in low- and high-frequency studies for the predictions of the magnetic saturation, the hysteresis, and the effect of eddy currents. A simple multiphysics model is developed to demonstrate how to combine the proposed magnetic circuit model with the commonly used Bingham fluid model. The damping force in the high-frequency case obviously lags behind the coil current, which exhibits a hysteresis loop in the current-force plane. The lag of damping force even exists in a low-frequency varying magnetic field and becomes more severe in the presence of eddy currents.

Experimental Evaluation of the Response Time of Magnetorheological Dampers Subjected to Impact Loading

2012 ◽  
Vol 246-247 ◽  
pp. 1007-1011 ◽  
Author(s):  
Li Jie Zhang ◽  
Jia Dong Chang ◽  
Jiong Wang
Keyword(s):  
Response Time ◽  
Impact Loading ◽  
Experimental Testing ◽  
Good Control ◽  
Current Response ◽  
Fast Method ◽  
Damping Force ◽  
Recoil Velocity ◽  
Mr Fluid ◽  
Mr Dampers

In recoil mechanisms applications the response time is an important characteristic for Magnetorheological (MR) fluid dampers, since the recoil cycle is very fast. Method for experimental testing the response time of MR dampers subjected to impact loading was promoted and impact tests were done. Since the viscose damping force of MR dampers is only related to the recoil velocity, which can not be controlled by the operating current, only the controllable damping force response to the input voltage was evaluated, and the viscose damping force were removed by the MR damper’s model. Two factors that may have effect on the response of MR dampers were considered the response of the electromagnetic circuit current of MR damper coils, and the response characteristic of MR fluid material. PI control algorithm was used to shorten the circuit current response. The results indicated that, compared with the much shorter delay of MR fluid, the driving circuit response has more significant effect on the MR dampers’ response time. What’s more, it was also verified that, it is feasible to improve the MR dampers’ response time subjected to impact loading by modifying the electromagnetic circuit through good control algorithms.

Simulation of a Magnetorheological Damper With a Combination of a Commercial CFD and FEA Code

2004 ◽  
Author(s):  
F. Zschunke ◽  
P. O. Brunn ◽  
M. Steven
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Flow Resistance ◽  
Fluid Model ◽  
Deep Understanding ◽  
Magnetorheological Damper ◽  
Damping Force ◽  
Mr Dampers ◽  
Combined Simulation ◽  
The Magnetic Field

Magnetorheological fluids (MRFs) show a high but reversible rise of viscosity upon application of an external magnetic field. This effect can be utilized in controllable dampers, when a deep understanding of the mechanisms for this behavior is available. Today the design of dampers is still quite empiric so it is favorable to be able to simulate the damper geometries first. Measurements on MR dampers are shown and compared with the results of a combined simulation of the problem with a CFD code for the flow and a FEA code for the magnetic field distribution in the damper geometry. It is shown that the flow resistance of the orifices that corresponds to the damping force of the damper can be predicted with this simulation using a simple fluid model.

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