ACOUSTIC
EMISSION & NDT SCIENTIFIC PUBLICATIONS
Unsupervised Classification of Acoustic Emission Sources from
Aerial Man Lift Devices
Proceedings of 15th World Conference on NDT,
Rome, Italy, 15-21 October, 2000
A.
Anastasopoulos,
D.
Kouroussis, A. Tsimogiannis
Where complicated
Acoustic Emission (AE) signatures are present, (e.g. in cases where
high background noise exists, or in composite structures where
several failure mechanisms have to be discriminated), conventional
graphical and statistical analysis may not provide the necessary
resources for source discrimination. In such cases, Unsupervised
Pattern Recognition (UPR) techniques extend the AE user’s
capabilities in identifying the hidden structure and correlation of
data categories in a multidimensional space. In this work,
Unsupervised Pattern Recognition techniques are applied for the
analysis and evaluation of AE data recorded during testing of five
Insulated Aerial Man Lift devices.
Various types of AE sources are expected during testing of Aerial
Man Lift Devises, arising from the fibreglass components, the metal
parts of the arm, the high strength pins, the welds, as well as the
hydraulic systems and the lift mechanisms. The use of pattern
recognition analysis, as applied in the present work, aims to
identify noise sources from the mechanisms used to manipulate the
arm movements and to discriminate signals from various failure
mechanisms arising from the different materials.
Results from different unsupervised classification schemes, applied
either on the AE feature set, or to its principal component
projection are presented. Discussion is focused on the validity of
the resulting partitions by using numerical optimisation criteria
and common
Acoustic Emission practices such as cumulative plots and emissions
during load hold.
The
proposed methodology proved efficient for the discrimination of AE
sources recorded during proof testing of Aerial Man Lift Devices and
can be used as a basis for automating the evaluation of Acoustic
Emission data from future tests of similar devices.