US EPA

1772275 

Journal Article 

Monitoring of fatigue crack growth using guided ultrasonic waves 

Masserey, B; Kostson, E; Fromme, P 

2010 

Unk 

Proceedings of SPIE
ISSN: 0277-786X
EISSN: 1996-756X 

Proceedings of SPIE-The International Society for Optical Engineering 

7647 

10.1117/12.848622 

WOS:000285510800010 

Varying loading conditions of aircraft structures result in
stress concentration at fastener holes, where multi layer components are connected, possibly
leading to the development of fatigue cracks. Guided ultrasonic waves propagating along a
structure allow in principle for the efficient non-destructive testing of large plate-like
structures, such as aircraft wings. This contribution presents a study of the detection and
monitoring of fatigue crack growth using both low frequency and higher frequency guided
ultrasonic wave modes. Two types of structures were used, single layer aluminum tensile
specimens, and multi layer structures consisting of two adhesively bonded aluminum plate-strips.
Fatigue experiments were carried out and it was shown that fatigue crack detection and growth
monitoring at a fastener hole during cyclic loading using both guided wave types is possible. The
sensitivity and repeatability of the measurements were ascertained, having the potential for
fatigue crack detection at critical and difficult to access fastener locations. Good agreement
was observed between the experimental results and predictions from full three-dimensional
numerical simulations of the scattering of the low frequency guided ultrasonic wave at the
fastener hole and crack. The robustness of the methodology for practical in-situ ultrasonic
monitoring of fatigue crack growth is discussed. 

Guided Ultrasonic Waves; Fatigue Crack Detection; Structural Health Monitoring