ACOUSTIC
EMISSION & NDT SCIENTIFIC PUBLICATIONS
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.
