The characteristics of a time variant magnetic field near a defect in a metal due to induced pulsed eddy currents Dissertation abstracts international, vol. 47, no. 8, p. 3463 (Feb. 1987)

1989 ◽  
Vol 22 (3) ◽  
pp. 184
Author(s):  
K Cavcey
Keyword(s):  
Magnetic Field ◽  
Eddy Currents ◽  
Pulsed Eddy Currents

DIFFUSION OF PULSED EDDY CURRENTS IN THIN CONDUCTING PLATES

2008 ◽  
Author(s):  
T. W. Krause ◽  
C. Mandache ◽  
J. H. V. Lefebvre ◽  
Donald O. Thompson ◽  
Dale E. Chimenti
Keyword(s):  
Eddy Currents ◽  
Thin Conducting ◽  
Pulsed Eddy Currents

Electromagnetic Effect of Eddy Currents in Composites with Conductive Components: Magnetic Field Strengthening and its Simple Analytical Estimation

2018 ◽  
Vol 284 ◽  
pp. 37-42 ◽  
Author(s):  
R.R. Sattarov ◽  
T.A. Volkova ◽  
I.Z. Gubaydullin
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Compatibility ◽  
Eddy Currents ◽  
Electromagnetic Effect ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Compatibility Analysis ◽  
Dynamic Materials ◽  
Analytical Estimation ◽  
Non Destructive

Composites and dynamic materials that include conductive components are becoming a suitable choice in different applications. The eddy currents are generated when the conductive components are placed in alternating magnetic field. The eddy currents decrease the primary field and this effect has been well studied and it is used for electromagnetic shielding. Besides, the magnetic field increases in small space near edges of the conductive components. While this effect of magnetic field strengthening is known, it is rarely examined. We will introduce a simple model that can be appropriate for the conductive components in form of long thin sheets. We analytically analyze the model and obtain expressions that give upper bounds for increasing of the net magnetic field. The electromagnetic effect of strengthening should be taken into account when considering an application of the composites. The results are useful for electromagnetic compatibility analysis, non-destructive testing and monitoring of composite and dynamic materials with conductive components.

scholarly journals Effective Suppression of Residual Magnetic Interference in a Conductive Shielded Room for Ultra-Low Field Nuclear Magnetic Resonance

2020 ◽  
Vol 10 (11) ◽  
pp. 3745
Author(s):  
Yiqiu Tan ◽  
Danfeng Zhou ◽  
Mengxiao Song ◽  
Jie Li
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Eddy Currents ◽  
Small Scale ◽  
Signal Loss ◽  
Low Field ◽  
Residual Magnetic Field ◽  
Control Electronics ◽  
Nuclear Magnetic

Residual magnetic interference induced by applied magnetic field pulses inside a conductive shielded room (SR) has been a common issue in ultra-low-field (ULF) nuclear magnetic resonance (NMR). The rapid cutoff of the applied pre-polarizing field (Bp) induces eddy currents in the walls of the SR, which produces a decaying residual magnetic interference that may cause severe image distortions and signal loss. In this study, a pair of cancellation coils (CC) and control electronics were designed for the suppression of the residual magnetic interference in a SR. Simulations show that this method was effective in suppressing the residual magnetic field (Br) after removal of the pre-polarizing magnetic field. Then, a small-scale SR was designed and the effectiveness of this cancellation scheme was experimentally verified. The test results showed a good agreement with the simulation, which indicated that the cancellation scheme was capable of reducing Br field to a much lower level. The scheme proposed in this study provides a solution for suppressing the residual magnetic field in the ULF NMR system. After decoupling the eddy–current field, the effect of the suppression may be further improved by optimization of the cancellation coil in further work.

scholarly journals RANCANG BANGUN EXTERNAL ELECTROMAGNETIC RETARDERS SYSTEM PADA MOTOR 1 PHASA

2016 ◽  
Vol 18 (4) ◽  
pp. 1
Author(s):  
Bima Dicky Anugrah Dewantara ◽  
Saiful Manan
Keyword(s):  
Magnetic Field ◽  
New York ◽  
Eddy Currents ◽  
Focal Point ◽  
Metal Plate ◽  
Rotating Shaft ◽  
Braking System ◽  
Motor Current ◽  
Safety Systems ◽  
The Relationship

Bima Dicky Anugrah Dewantara, Saiful Manan, in this paper explain that Electromagnetic retarders are generally known as electromagnetic inhibitors or brakes, the braking system eliminates most braking mechanics, thereby reducing conventional braking systems. Safety requirements and safety systems are developed and become a focal point of an equipment. Electromagnetic brakes are a safety component with a control system that is easy to control. With this electromagnetic brake, it will reduce maintenance costs, because it only requires a factor of electricity to be able to move it. The braking system uses electromagnetic forces to slow down a movement, which is generally a shaft motion. A dish with non-ferromagnetic metal material is attached to a rotating shaft. The disk is flanked by the side of the stator in the form of an electromagnetic coil system that can generate a magnetic field from electricity. Electric current generates a magnetic field in the coil. And the metal plate that cuts the magnetic field will cause eddy currents on the disk itself. This eddy current will generate a magnetic field whose direction is opposite to the previous magnetic field, thus inhibiting the rotary motion of the shaft. In designing, experimenting and making an External Electromagnetic Retarders System Design on 1 Phase Motor, use the NE 555 IC as the control duty cycle. So that the relationship between braking current and braking time is inversely proportional if the higher the current, the shorter the time it takes for the rotor to stop. And the relationship between braking current and motor current is directly proportional, by increasing the braking current will increase the load on the motor causing the motor current to increase. Keywords: Electromagnetic Retarders, Electromagnetic Brakes, Eddy Flow EffectReferencesTipler, P. 2008. Physics for Scientist volume 2. New York : WH Freeman and Company..Ishaq, M. 2007. Fisika Dasar Elektisitas dan Magnetisme. Yogyakarta: Graha Ilmu.Millman, Halkias, M.Barmawi, dan M.O.Tjia. 1971. Integrated Electronics:Analog and Digital Circuits and Systems. Jakarta : Erlangga.Ramdhani, Mohamad. 2008. Rangkaian Listrik. Jakarta : Erlangga.Bishop, Owen. 2004. Dasar-Dasar Elektronika. Jakarta : Erlangga.Halliday, David. Robert Resnick. 1978. Fisika Jilid II Edisi Ketiga. Jakarta : Erlangga

Electromagnetic damping of elastic waves: Experimental results

1968 ◽  
Vol 5 (4) ◽  
pp. 825-829 ◽  
Author(s):  
F. E. M. Lilley ◽  
C. M. Carmichael
Keyword(s):  
Magnetic Field ◽  
Elastic Wave ◽  
Applied Magnetic Field ◽  
Elastic Waves ◽  
Applied Field ◽  
Eddy Currents ◽  
Electrical Conductor ◽  
Electromagnetic Damping ◽  
The Waves ◽  
The Magnetic Field

The passage of an elastic wave causes straining and translation in the transmitting material. If a magnetic field is applied, and the medium is an electrical conductor, some of the energy of the wave is dissipated by the flow of electrical eddy currents. Usually the amount of energy lost is very small, but it may be greatly increased if the applied field is strongly non-uniform.Laboratory experiments are described which demonstrate this effect for standing elastic waves in a metal bar. The applied magnetic field changes from almost zero to its full strength over a distance which is short compared to the length of the standing wave. The result of this strong non-uniformity is that the energy lost due to the translation of the bar in the field greatly exceeds the energy lost due to the straining of the bar in the field.The dependence of the attenuation of the waves by the magnetic field is investigated for variation in frequency of vibration, bar thickness, and field gradient.

Fraction Solid Measurements on Solidifying Melt

2004 ◽  
Vol 126 (2) ◽  
pp. 193-197 ◽  
Author(s):  
Sayavur I. Bakhtiyarov ◽  
Ruel A. Overfelt ◽  
Sorin G. Teodorescu
Keyword(s):  
Magnetic Field ◽  
Aluminum Alloy ◽  
Indirect Method ◽  
Eddy Currents ◽  
Solid Phase ◽  
Molten Metals ◽  
Metal Sample ◽  
Fraction Solid ◽  
The Magnetic Field ◽  
Good Agreement

A new indirect method to measure fraction solid in molten metals is presented. The method is based on the phenomena that when a metal sample (solid or liquid) rotates in a magnetic field (or the magnetic field rotates around a stationary sample), circulating eddy currents are induced in the sample, which generate an opposing torque related to amount of solid phase in a solidifying melt between the liquidus and solidus temperatures. This new technique is applied for measuring fraction solid on commercial A319 aluminum alloy. The solidification curves obtained by the proposed method at different cooling rates are in good agreement with predictions made by the Scheil model.

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