The purpose of the paper is to present an innovative application within the Non Destructive Testing (NDT) field based upon vibration measurements developed by the authors, and already tested for analysing damage of many structural elements. After having tested this application on different test articles in laboratory condition, experimental tests have been executed, in collaboration with the ATR company, on a turboprop ATR-72 aircraft, in order to validate the technique on a real aeronautical structure. The monitoring system have operated an off-line check on the structure, during the aircraft ground operations, as if it were a normal maintenance procedure. The results are reported in the paper. This proposed new method is based upon the acquisition and comparison of the Frequency Response Functions (FRFs) of the monitored structure before and after damage occurs. Structural damage modify the dynamic behaviour of a structure affecting its mass, stiffness and damping, and consequently the FRFs of a damaged structure, when compared with the FRFs of its sound configuration, making the identification, localization and quantification of damage possible. The activities presented in the paper focus mainly on a new FRFs processing technique based upon the determination of a representative 'Damage Index' for identifying and analysing damage. Furthermore, a dedicated neural network algorithm has been elaborated aimed at obtaining a 'recognition-based learning' method which permits to train the neural network in order to enable it to recognise only 'positive' examples, discarding 'negative' ones. Within the structural NDT a 'positive' example means a 'healthy' state of the analysed structure, while a 'negative' example means a 'damaged' or perturbed state. From an architectural standpoint, piezoceramic patches have been used as both actuators and sensors. These results promise to bring a step forward in the implementation of an automatic 'health monitoring' system which will be able to identify structural damage in real time thereby improving safety and reducing maintenance costs.
Implementation of an experimental system for structural health monitoring in a turboprop commercial aircraft
Implementierung eines experimentellen Systems für die Funktionssicherheitsüberwachung von Bauteilen in einem Turboprop-Verkehrsflugzeug
2006
8 Seiten, 9 Bilder, 4 Quellen
Conference paper
English