Peaks Over Threshold–based detector design for structural health monitoring: Application to aerospace structures
Résumé
Structural health monitoring offers new approaches to interrogate the integrity of complex structures. The structural
health monitoring process classically relies on four sequential steps: damage detection, localization, classification, and
quantification. The most critical step of such process is the damage detection step since it is the first one and because
performances of the following steps depend on it. A common method to design such a detector consists of relying on a
statistical characterization of the damage indexes available in the healthy behavior of the structure. On the basis of this
information, a decision threshold can then be computed in order to achieve a desired probability of false alarm. To determine
the decision threshold corresponding to such desired probability of false alarm, the approach considered here is
based on a model of the tail of the damage indexes distribution built using the Peaks Over Threshold method extracted
from the extreme value theory. This approach of tail distribution estimation is interesting since it is not necessary to
know the whole distribution of the damage indexes to develop a detector, but only its tail. This methodology is applied
here in the context of a composite aircraft nacelle (where desired probability of false alarm is typically between 1024
and 1029) for different configurations of learning sample size and probability of false alarm and is compared to a more
classical one which consists of modeling the entire damage indexes distribution by means of Parzen windows. Results
show that given a set of data in the healthy state, the effective probability of false alarm obtained using the Peaks Over
Threshold method is closer to the desired probability of false alarm than the one obtained using the Parzen-window
method, which appears to be more conservative.
Origine : Fichiers produits par l'(les) auteur(s)