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Proceedings Paper

Evaluation of the performance of an electromagnetic SHM system for composite, comparison between numerical simulation, experimental data, and ultrasonic investigation
Author(s): Michel B. Lemistre; Dominique Placko
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Paper Abstract

Recently, a new SHM system has been developed at ONERA. This system based on the interaction between an electromagnetic field and a composite structure, allows detecting all types of damages having an influence on the electrical characteristics of the structure such as carbon fiber breaking, organic matrix pyrolysis, liquid ingress... The basic principle of this SHM system, called HELP-Layer (Hybrid ELectromagnetic Performing Layer), consists to induce eddy currents inside the structure and to perform a local measurement of the resulting electric field. All damages inducing a significant variation of the two main electrical parameters (i.e. electrical conductivity and dielectric permittivity), induce a significant variation of the resulting electric field. The sensitivity of this technique depends of the type of damage; as regard to “mechanical” damages (e.g. delaminations, fiber breaking, crack), the sensitivity is comparable to techniques using ultrasonic methods, as regard to other kind of damages (e.g. matrix pyrolysis, liquid ingress...) the electromagnetic method is more sensitive than ultrasonic methods. The analysis of the two resulting components of electric field (i.e. Ex and Ey, the conductivity direction being y) allows to determine the kind of damage (mechanical or other), by resolution of a part of the inverse problem, the direct problem being solved by the DPSM (Distributed Point Source Method) concept.

Paper Details

Date Published: 21 July 2004
PDF: 9 pages
Proc. SPIE 5394, Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems III, (21 July 2004); doi: 10.1117/12.539524
Show Author Affiliations
Michel B. Lemistre, ONERA (France)
Dominique Placko, Ecole Normale Superieure de Cachan (France)

Published in SPIE Proceedings Vol. 5394:
Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems III
Tribikram Kundu, Editor(s)

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