Structural health monitoring of aircraft structures: development of a phased array system.




Rocha, Bruno Filipe Ferreira Graca

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This work consisted in the research and development of a phased array embedded system for Structural Health Monitoring (SHM) of aircraft structures. This system is based on piezoelectric (PZT) transducers to excite fast propagating first symmetric Lamb wave mode (S0) wavefronts. The intent of this research is to contribute for an increasing safety and efficient operation of aircraft. Currently applied ultrasound inspections to aircraft structures in operation, as a conventional Non Destructive Tests and Evaluations (NDT&E) technique, were reviewed. Such and the previous development of a Lamb wave based SHM system using PZT transducers in a network configuration served as the basis and for comparison to the phased array SHM system developed. Lamb waves’ propagation behaviour was carefully analyzed and a linear PZT phased array SHM system was developed and experimentally tested. The PZT phased array was applied to representative aircraft structural aluminum panels, considering also the existence of structural reinforcements and joints. New techniques, hardware and software, leading to automated damage detection and location, were researched, developed and implemented. Tests for damage detection and location were performed, with the introduction of damages into the specimens being simulated by surface and through the thickness holes and cuts. Damages with a maximum dimension of 1mm applied cumulatively to the specimens subject to different boundary conditions were successfully detected and located.



airframes, aircraft structures