Mutual Inductance Problem for a System Consisting of a Current Sheet and a Thin Metal Plate
- Author:
- Fulton, J. P.
- Published:
- [1993].
- Physical Description:
- 1 electronic document
- Additional Creators:
- Namkung, M., Nath, S., and Wincheski, B.
Online Version
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- Unclassified, Unlimited, Publicly available.
Free-to-read Unrestricted online access - Summary:
- Rapid inspection of aircraft structures for flaws is of vital importance to the commercial and defense aircraft industry. In particular, inspecting thin aluminum structures for flaws is the focus of a large scale R&D effort in the nondestructive evaluation (NDE) community. Traditional eddy current methods used today are effective, but require long inspection times. New electromagnetic techniques which monitor the normal component of the magnetic field above a sample due to a sheet of current as the excitation, seem to be promising. This paper is an attempt to understand and analyze the magnetic field distribution due to a current sheet above an aluminum test sample. A simple theoretical model, coupled with a two dimensional finite element model (FEM) and experimental data will be presented in the next few sections. A current sheet above a conducting sample generates eddy currents in the material, while a sensor above the current sheet or in between the two plates monitors the normal component of the magnetic field. A rivet or a surface flaw near a rivet in an aircraft aluminum skin will disturb the magnetic field, which is imaged by the sensor. Initial results showed a strong dependence of the flaw induced normal magnetic field strength on the thickness and conductivity of the current-sheet that could not be accounted for by skin depth attenuation alone. It was believed that the eddy current imaging method explained the dependence of the thickness and conductivity of the flaw induced normal magnetic field. Further investigation, suggested the complexity associated with the mutual inductance of the system needed to be studied. The next section gives an analytical model to better understand the phenomenon.
- Other Subject(s):
- Collection:
- NASA Technical Reports Server (NTRS) Collection.
- Note:
- Document ID: 20040129661.
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- Copyright, Distribution as joint owner in the copyright.
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