Investigation and identification of damage mechanisms of unidirectional carbon/flax hybrid composites using acoustic emission
Résumé
The objective of the present experimental work is to determine the damage mechanisms appearing in unidirectional carbon/flax hybrid composites during tensile tests. The specimens tested consist of unidirectional carbon and flax fiber plies with different stacking sequences. Laminated composites were manufactured using a manual lay-up process. The specimens were tested under uniaxial tensile loading in static and cyclic fatigue tests. The tests carried out were monitored by the acoustic emission (AE) technique in order to identify the damage mechanisms evolutions. This identification was made with an unsupervised clustering technique. The recorded events were classified with the k-means algorithm based on temporal classification parameters. For each kind of specimen, four classes of AE events were obtained. Then, the contribution of each damage mechanism to overall failure was evaluated by the amplitude range, the cumulative number of hits and the acoustic energy activity. The AE classes obtained were correlated with scanning electron microscopy (SEM) observations in order to identify the damage mechanisms observed.
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