ANALYTICAL MODELLING OF EDDY CURRENTS INDUCED BY A TIME‐VARYING MAGNETIC FIELD IN A CONDUCTIVE PLATE

1994 ◽  
Vol 13 (3) ◽  
pp. 497-508 ◽  
Author(s):  
N.J. SIAKAVELLAS
Keyword(s):  
Magnetic Field ◽  
Eddy Currents ◽  
Analytical Modelling ◽  
Time Varying ◽  
Conductive Plate

3D Analytical model of drag and lift force for a conductive plate moving above a Halbach magnet array

2017 ◽  
Vol 40 (12) ◽  
pp. 3515-3524 ◽  
Author(s):  
Shi Tongyu ◽  
Wang Dazhi
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
Eddy Current ◽  
Eddy Currents ◽  
Magnetic Levitation ◽  
Scalar Potential ◽  
Air Gap ◽  
Steady State Condition ◽  
Conductive Plate ◽  
Drag And Lift

When a conductive plate moves above a Halbach magnetic source, a magnetic field will be created in the air gap. This field induces eddy currents in the plate and creates drag and lift forces simultaneously. This phenomenon may be applied into eddy current brakes, couplings or magnetic levitation systems. In this paper, by utilizing the derived analytical field solutions of the Maxwell equations with magnetic scalar potential and magnetic field strength, the 3D lift and drag forces, and the flux density distribution in the air gap are predicted and analysed in the steady-state condition. Calculation results produced by analytical model are compared with those from the 3D finite element method. A prototype of the disk-type permanent magnetic eddy-current coupling has been manufactured to validate the accuracy of the 3D analytical model. The results confirm that, compared with 2D analytical model from the papers that had already published, the results calculated by the 3D analytical model have a higher accuracy in performance analysis. Finally, the characteristics of different kinds of magnet arrays are compared based on the proposed model, and several main problems are analysed and discussed.

Improved Concept and Model of Eddy Current Damper

2005 ◽  
Vol 128 (3) ◽  
pp. 294-302 ◽  
Author(s):  
Henry A. Sodano ◽  
Jae-Sung Bae ◽  
Daniel J. Inman ◽  
W. Keith Belvin
Keyword(s):  
Magnetic Field ◽  
Theoretical Model ◽  
Eddy Current ◽  
Eddy Currents ◽  
Opposite Polarity ◽  
Image Method ◽  
Time Varying ◽  
Transverse Beam ◽  
Eddy Current Damper ◽  
Improved Model

When a conductive material experiences a time-varying magnetic field, eddy currents are generated in the conductor. These eddy currents circulate such that they generate a magnetic field of their own, however the field generated is of opposite polarity, causing a repulsive force. The time-varying magnetic field needed to produce such currents can be induced either by movement of the conductor in the field or by changing the strength or position of the source of the magnetic field. In the case of a dynamic system the conductor is moving relative to the magnetic source, thus generating eddy currents that will dissipate into heat due to the resistivity of the conductor. This process of the generation and dissipation of eddy current causes the system to function as a viscous damper. In a previous study, the concept and theoretical model was developed for one eddy current damping system that was shown to be effective in the suppression of transverse beam vibrations. The mathematical model developed to predict the amount of damping induced on the structure was shown to be accurate when the magnet was far from the beam but was less accurate for the case that the gap between the magnet and beam was small. In the present study, an improved theoretical model of the previously developed system will be formulated using the image method, thus allowing the eddy current density to be more accurately computed. In addition to the development of an improved model, an improved concept of the eddy current damper configuration is developed, modeled, and tested. The new damper configuration adds significantly more damping to the structure than the previously implemented design and has the capability to critically damp the beam’s first bending mode. The eddy current damper is a noncontacting system, thus allowing it to be easily applied and able to add significant damping to the structure without changing dynamic response. Furthermore, the previous model and the improved model will be applied to the new damper design and the enhanced accuracy of this new theoretical model will be proven.

A CONDUCTING SPHERE IN A TIME VARYING MAGNETIC FIELD

Geophysics ◽  
1951 ◽  
Vol 16 (4) ◽  
pp. 666-672 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Eddy Currents ◽  
Transient Behavior ◽  
Step Function ◽  
Conducting Medium ◽  
Time Varying ◽  
Geophysical Prospecting ◽  
Conducting Sphere

The secondary magnetic fields are evaluated for the case of a conducting sphere in a relatively poorly conducting medium under the influence of a time varying magnetic field. The sinusoidal and step function responses are both considered. The responses so calculated are thought to be useful in a geophysical prospecting method which utilizes the transient behavior of induced eddy currents in a highly conducting ore zone.

Internal Organizational Measurement for Control of Magnetorheological Fluid Properties

2006 ◽  
Vol 129 (4) ◽  
pp. 423-428 ◽  
Author(s):  
John R. Lloyd ◽  
Miquel O. Hayesmichel ◽  
Clark J. Radcliffe
Keyword(s):  
Magnetic Field ◽  
Physical Properties ◽  
High Sensitivity ◽  
Time Varying ◽  
Measurable Effect ◽  
Mr Fluid ◽  
Fluid State ◽  
Mr Fluids ◽  
Fluid Properties ◽  
Field Excitation

Magnetorheological (MR) fluids change their physical properties when subjected to a magnetic field. As this change occurs, the specific values of the physical properties are a function of the fluid’s time-varying organization state. This results in a nonlinear, hysteretic, time-varying fluid property response to direct magnetic field excitation. Permeability, resistivity and permittivity changes of MR fluid were investigated and their suitability to indicate the organizational state of the fluid, and thus other transport properties, was determined. High sensitivity of permittivity and resistivity to particle organization and applied field was studied experimentally. The measurable effect of these material properties can be used to implement an MR fluid state sensor.

A Novel Approach to Accumulate Superparamagnetic Particles in Aqueous Environment Using Time-Varying Magnetic Field

2020 ◽  
Vol 67 (6) ◽  
pp. 1558-1564 ◽  
Author(s):  
Ya-Li Liu ◽  
Jing-Jie Chen ◽  
Fiaz Ahmad ◽  
Tuo-Di Zhang ◽  
Wei-Hong Guo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Aqueous Environment ◽  
Time Varying ◽  
Superparamagnetic Particles ◽  
Novel Approach
Sign in / Sign up

Export Citation Format

Share Document