Identification of fiber breakage in fiber reinforced plastic by low-amplitude filtering of acoustic emission data

A new low-amplitude filtering technique has been developed for the identification of fiber breakage in fiber reinforced plastics from acoustic emission data. In this approach, the acoustic emission hits associated with fiber breakage are separated from the hits associated with other failure mechanisms by filtering out the low amplitude hits from the measured data. The lowest remaining amplitude upon the cumulative plot of the remaining hits vs. load coinciding with the cumulative signal strength vs. load plot is taken as the borderline between fiber breakage hits and non-fiber breakage hits. Experiments were conducted on unidirectional-fiber specimens and complex-fiber specimens to examine the efficacy of the proposed technique. Evaluation of the experimental results by visual inspection and extensive scanning electron microscope studies verifies the low-amplitude filtering technique as a reliable tool for identifying fiber breakage in fiber reinforced plastics.