Acoustic Emission Monitoring of CFRP Laminated Composites ...

In order to analyse the data new approaches for processing and presenting
the data were developed and new AE signal features were introduced.
The principal contribution of this thesis is a methodology for processing,
presenting, and quantifying AE data so that it can be used for identifying
multiple AE sources and for tracking their locations relative to the phase
of a reference signal. The results show that the tracking of AE sources
can be used to facilitate early damage diagnosis and failure prognosis. The
methodology is neither limited to AE signals nor to periodic reference signals.
It can be used to study changes, or artifacts, in other signals using
either periodic or aperiodic reference signals. Another corollary of the
work presented here is an algorithm to detect and determine AE hits in
signals which include large number of overlapping transients with variable
strengths. Other contributions include new AE features, an AE-based failure
criterion, and a probability-based approach for providing early warning
of imminent failure. These last two are based on a 10% displacement failure
criterion which was used for determining the failure of prosthetic feet.