Millimeter Wave Differential Probe System for Surface Crack Detection in Painted Aircraft Fuselage


In this paper, a W-band (75-110 GHz) differential probe system is designed for detecting tight cracks near fasteners and under paint in aircraft fuselage. First, the operation principle of differential probe and the design of the system is introduced, followed by numerical electromagnetic simulations to verify the capability of designed probe. Simulation results show that the designed probe is capable of detecting tight surface crack extending by as much as 1.27 mm beyond a fastener hole, and it is not adversely influenced by the paint coating layer. Finally, the designed probe was mounted on a 3-axis scanner to form an automated scanning crack detection system. The fabricated system was used on many different crack specimens, and the results show that it successfully detected the 2 mm long surface crack (extending beyond a fastener hole) on a lap joint metallic plate with up to 0.1 mm-thick paint. Furthermore, the aperture offset and non-uniform paint clump effects were examined in the simulations, and corroborated in the measurement.

Meeting Name

2019 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2019 (2019: May 20-23, Auckland, New Zealand)


Electrical and Computer Engineering

Keywords and Phrases

Aircraft Fuselage; Differential Probe; Millimeter Wave; Nondestructive Testing; Surface Crack

International Standard Book Number (ISBN)


International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


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© 2019 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 May 2019