Thesis Abstracts 2005

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Optimization of Flexible Coils for Embedded Detection and Monitoring of Cracks in Aluminum Structures Using Pulsed Eddy Current

By: Lee A. Wendland, Capt. MSc Candidate

Supervisor: Capt. S. Dubois

Abstract

Advancements in sensor networks and technologies, such as micro-mechanical systems – MEMS, nanotechnology, communication networks, and distributed computing, are leading the way to an aerospace maintenance philosophy shift. The introduction of structural health monitoring systems will do away with the requirement for costly in-service periodic inspections while improving safety. The use of integrated nondestructive sensor systems to detect and monitor structural changes will reduce vehicle downtime and increase the probability of damage detection prior to catastrophic failure. This thesis focuses on the application of flexible coil technology using pulsed eddy current techniques for detection, localization, and characterization of cracks radiating from rivet holes. Washer type eddy current probes, consisting of two planar spiral coils arranged in a driver/pick-up configuration with a magnetic material backing, were investigated for use as an embedded sensor. Probe detection and localization capability was quantified against surface breaking and non-surface breaking EDM notches ranging from 1.27 mm (.05”) to 12.7 mm (.5”) in length.