Semi-Real Time Classification of Acoustic Emission Signals for Drive System

Coupling Crack Detection


EWGAE 2004, 26th European Conference on AE testing, September 15-17, 2004 Berlin

V. Godinez, F. Shu, R. Finlayson, Physical Acoustics Corp., Lawrenceville, NJ (USA), A. Anastasopoulos, A. Tsimogiannis, Envirocoustics S.A., Athens (Greece), B. O´Donnell, Naval Air Warfare Center, Patuxent River, MD (USA)


Early detection of mechanical failure in helicopter drive train components is a key safety and economical issue with both military and civil sectors of aviation. Of these components, couplings are particularly critical. The objective of this work is to demonstrate the feasibility of designing and developing a reliable, real time monitoring methodology based on Supervised Pattern Recognition (SPR) for early detection of cracks in couplings used in helicopter and engine drive systems. Within this framework, a portable Acoustic Emission (AE) system was used, equipped with a semi-real time SPR software package. Results from AE tests performed in a gearbox-testing bench at different speeds and different torque values are presented. These results indicate that the energy content of different frequency bands in the AE signals power spectra is strongly correlated with the introduction of EDM notches in the main gear. Further tests indicate that a strong shift in the frequency of the AE signals is observed after spalling occurred in the pinion gear. The variation of displacement and velocity between signal classes are discussed as a potential feature in characterizing crack severity. Finally, a scope of the work for optimizing the methodology in detecting and evaluating coupling cracking in real time will be presented.