Damage mechanisms identification of polymer based composite materials: time-frequency investigation of acoustic emission data based on Hilbert-Huang transform
Résumé
Presented in this paper, a time-frequency damage characterization procedure in Glass Fiber Reinforced Polymer (GFRP) composite materials based on the analysis of the acoustic emission (AE)signals by the Hilbert-Huang transform (HHT). It is to be noted that the study of damage by means of AE in polymer composites prompted the possibility of correlating a specific damage mechanism with its acoustic signature. Several studies highlighted the relevance of frequency spectral analysis in order to reconstruct the whole damage process. Thus, the assessment of the time-varying dominant frequencies present in a typical AE signal acquisition, can make easier the assessment of its structural damage potential. The main difficulty in defining a relationship between a specific damage mode and its acoustic signature is that the AE signals in GFRP materials are usually non- stationary and comprise overlapping transients. Signals of this kind require, first of all, a joint time-frequency analysis. In this context, the newly developed HHT is exclusively used in the present work for AE signals waveform analysis to describe the damage behavior as a first step for in situ detection of structural damages in polymer based composite materials.
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