TITLE:
Experimental Study of Acoustic Noise Correlation Technique for Passive Monitoring of Rails
AUTHORS:
Laïd Sadoudi, Emmanuel Moulin, Jamal Assaad, Farouk Benmeddour, Michaël Bocquet, Yassin El Hillali
KEYWORDS:
Acoustic Noise Correlation, Signal Processing, Passive Green’s Function Reconstruction, Non-Destructive Testing (NDT), Structural Health Monitoring (SHM), Rail Monitoring
JOURNAL NAME:
Materials Sciences and Applications,
Vol.7 No.12,
December
13,
2016
ABSTRACT: The work presented in this paper aims at investigating the ability of acoustic noise correlation technique for railway infrastructure health monitoring. The principle of this technique is based on impulse responses reconstruction by correlation of random noise propagated in the medium. Since wheel-rail interaction constitutes a source of such noise, correlation technique could be convenient for detection of rail defects using only passive sensors. Experiments have been carried out on a 2 m-long rail sample. Acoustic noise is generated in the sample at several positions. Direct comparison between an active emission-reception response and the estimated noise correlation function has confirmed the validity of the equivalence relation between them. The quality of the reconstruction is shown to be strongly related to the spatial distribution of the noise sources. High sensitivity of the noise-correlation functions to a local defect on the rail is also demonstrated. However, interpretation of the defect signature is more ambiguous than when using classical active responses. Application of a spatiotemporal Fourier transform on data recorded with variable sensor-defect distances has allowed overcoming this ambiguity.