Liste des publications

Nombre total de résultats : 552
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Acoustic emission signal denoising to improve damage analysis in glass fibre reinforced composites

Abida Satour, Silvio Montrésor, Mourad Bentahar, Rachid Elguerjouma and Fouad Boubenider  (2014)

In this contribution, continuous wavelet denoising technique is developed to enhancethe signal to noise ratio of acoustic emission (AE) signals. The time– frequency characteristics of the recorded noise are first determined by calculating the noisewavelet coefficients. Then, an algorithm able to proceed denoising by extracting noise features from those corresponding to AE signals is developed. The denoising procedure is applied to get meaningful signals when the detection threshold is decreased from 30 dB to 25 dB. Furthermore, the spectral flatness measure was applied to eliminate signals originating from noise. Experiments were conducted on cross-ply composite specimens [±45°]6S to examine the efficacy of the proposed technique. The denoised signals were analysed using the continuous wavelet transform and were also analysed in terms of the dominant frequency band which was processed by a fast Fouriertransform. Results show that denoised low-amplitude AE hits are well correlated withhigh-amplitude AE hits (A≥30 dB) in terms of damage characterisation. Voir les détails

Mots clés : acoustic emission, polymer-based composite, Denoising, Signal processing, damage characterisation

Use of Guided Waves for Inspection of Composite Skin-Honeycomb Core

A. Satour, F. Boubenider, A. Badidibouda, R.Halimi  (2010)

Sandwich plates, made of two aluminum layers and a metal honey comb core are used inthe aircraft industry. The purpose of this study is to show the ultrasonic guided waves sensibility to discover delamination in skin-honeycomb sandwich structures used in aeronautics. Separation between the skin and the core can appear during the manufacture or after use. In this work, Lamb's waves are used to control this kind of plane structure. Indeed, these waves have the advantage to putin vibration the totality of the plate that we want to control and they propagate on long distances without too much attenuation. The revealing, by the guided waves, of the unsticking which canmeet on such sandwiches, between the plate and the honeycomb core is studied and commented. Voir les détails

Mots clés : Lamb waves, Sandwich structure, Dispersion curves, Displacements.