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Proceedings Paper

Monitoring of hidden fatigue crack growth in multi-layer aircraft structures using high frequency guided waves
Author(s): H. Chan; B. Masserey; P. Fromme
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Paper Abstract

Varying loading conditions of aircraft structures result in stress concentration at fastener holes, where multi-layered components are connected, potentially leading to the development of hidden fatigue cracks in inaccessible layers. High frequency guided waves propagating along the structure allow for the structural health monitoring (SHM) of such components, e.g., aircraft wings. Experimentally the required guided wave modes can be easily excited using standard ultrasonic wedge transducers. However, the sensitivity for the detection of small, potentially hidden, fatigue cracks has to be ascertained. The type of multi-layered model structure investigated consists of two adhesively bonded aluminum plate-strips with a sealant layer. Fatigue experiments were carried out and the growth of fatigue cracks at the fastener hole in one of the metallic layers was monitored optically during cyclic loading. The influence of the fatigue cracks of increasing size on the scattered guided wave field was evaluated. The sensitivity and repeatability of the high frequency guided wave modes to detect and monitor the fatigue crack growth was investigated, using both standard pulse-echo equipment and a laser interferometer. The potential for hidden fatigue crack growth monitoring at critical and difficult to access fastener locations from a stand-off distance was ascertained. The robustness of the methodology for practical in situ ultrasonic monitoring of fatigue crack growth is discussed.

Paper Details

Date Published: 23 March 2015
PDF: 8 pages
Proc. SPIE 9438, Health Monitoring of Structural and Biological Systems 2015, 94381Q (23 March 2015); doi: 10.1117/12.2083840
Show Author Affiliations
H. Chan, Univ. College London (United Kingdom)
B. Masserey, Univ. of Applied Sciences (Switzerland)
P. Fromme, Univ. College London (United Kingdom)

Published in SPIE Proceedings Vol. 9438:
Health Monitoring of Structural and Biological Systems 2015
Tribikram Kundu, Editor(s)

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