"This thesis proposes the use of a W-band wideband differential probe for crack detection on riveted structures, such as aircraft fuselage lap joints. Detection of crack at its early stage (surface-breaking) is particularly important to prevent the development of a fatigue crack. This probe utilizing millimeter-wave frequencies serves as a viable candidate on detecting surface-breaking cracks, as it can be employed in measurements in a non-contact fashion, while allowing for high spatial-resolution images and the abilities to penetrate through dielectric materials (paint), making it attractive for detecting small cracks. In previous works, a V-band differential probe has shown promise for detecting surface breaking crack near a fastener head. This work is extended in this thesis by investigating the surface crack detection capability of the W-band differential probe. The W-band probe is tested with various intentional misalignments of the probe, as well as a paint layer covering the crack, the variations in its crack detection capability are then observed. The measurement results indicate that this fabricated probe is capable of detecting a surface crack at a length of 1.27 mm (adjacent to a fastener head), and the detection is not significantly affected by a slight misalignment, although consequently some undesired signals may also be registered. In addition, a layer of thick paint over crack introduces uncertainties to the detection signals and complicates the evaluations. To reduce the significance of these undesired signals, SAR filter is applied to the results. The outcome demonstrates an enhanced crack detection and weakened undesired signals, but the influence of a thick paint layer cannot be completely removed. A more in-depth analysis regarding the influence of paint on crack detection may be desired to fully understand the crack detection capabilities of the W-band differential probe"--Abstract, page iii.
Ghasr, Mohammad Tayeb Ahmad, 1980-
Newkirk, Joseph William
Electrical and Computer Engineering
M.S. in Electrical Engineering
Missouri University of Science and Technology
xxiv, 383 pages
© 2017 Kuang Ping Ying , All rights reserved.
Thesis - Open Access
Electronic OCLC #
Ying, Kuang Ping, "Application of millimeter-wave differential probe for crack detection on riveted structures" (2017). Masters Theses. 7682.