Exploitation of Acoustic Noise Correlation for Structural Health Monitoring Applications

ABSTRACT

Many recent studies in different domains exploited the ambient noise correlation to retrieve the Green's function between two points. This technique allows a passive characterization of a given medium in the presence of a perfect diffuse field. The aim of this paper is to apply this principle in an aeronautic context. Thus we are looking to exploit the mechanical vibrations in a plane during the flight, to realize a passive structural health monitoring. Indeed, a natural acoustic noise field is produced by engines and aero acoustic effects. That being said, such a field is not spatially and temporally perfectly diffused, which yields to imperfect conditions where convergence towards the Green's function is not ensured. Despite that, in this paper we show that since the obtained information is sensible to the medium state, it is still exploitable for damage detection. In fact, experimental studies presented in this paper allow verifying two necessary conditions to the applicability of this technique: the reproducibility of the cross-correlation function, and its potential to detect a defect in the medium. Finally, the influence of the source position on the cross-correlation function is shown.

Keywords: