Tracking of cracks in airplane components using nonlinear surface wave propagation techniques
Faculty of Applied Engineering Sciences
Engineering sciences. Technology
KEY ENGINEERING MATERIALS
6th International Conference on Damage Assessment of Structures (DAMAS, 2005), July 04-06, 2005, Gdansk, Poland
, p. 549-556
Ultrasonic surface waves provide a sensitive means to detect cracks in airplane structures. Until now several obstacles remained to use ultrasonic surface waves for on-line damage detection (i.e. in-flight). In this article a method will be proposed to detect a growing fatigue crack while the aircraft is operating. In contrast to classical ultrasonic measurement methods, that use a high voltage pulse, we applied an optimized multi-sine excitation signal with an amplitude of a few volts only (this agrees better with the applicable safety regulations for aircraft). Furthermore, an indicator quantifying the nonlinearity of the ultrasonic surface wave propagation is used. By using a nonlinearity index the influence of changing operation conditions that can be observed with most linear methods is eliminated. The proposed method is validated on a steel beam that is fatigue loaded with a force signal obtained from in-flight data.