NDTnet 1998 Aug, Vol.3 No.8

Abstract

Introduction
During the control by Eddy Current, we exploit the information provided from a distance by the impedance variation of a solenoid in the vicinity of a conductive material. It is the indication of an energy transfer from a distance between the solenoid and the conductive material. The cause of the variation of the observed impedance is the modification of the magnetic flow through the solenoid. The flow varies in amplitude and in phase.

The Physical Model
We propose a physical model, based on the variation of the magnetic flow, allowing the determination of defects characteristics. Whatever the material and whatever the geometry of the product, the presence of a defect allocates the flow in the straight section of the solenoid.
The theoretical model we propose allows to find defects characteristics from the analysis of the impedance variation.The results of this study can be exploited in the industrial control of long products in conductive materials.
The measure of the inductance variation observed during the movement of the product in the solenoid generator allows to calculate directly the surface of the straight section of the defect of greater length that the solenoid. In addition, the variation of the resistance allows to determine the height of the defect.

Conclusion
It would be, thus, easy to obtain in real time, on computer, the image of a long switchboard defect that is to even to produce the impedance variation observed. It would be thus possible to realize the control by absolute measures and to avoid the recourse to switchboard defects.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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