Three point bending test of glass/epoxy composite health monitoring by acoustic emission

As glass epoxy composites have special properties, they are used in different structures. Health monitoring of this kind of composite is very important due to its use in many industries. Acoustic emission technique is one of the best methods for health monitoring. Since flexural loading is widespread in utilization of this type of composite, in this research acoustic emission method was used to monitor and check the different failure mechanisms of glass epoxy composite flexural loading. In order to determine different failure mechanisms, the wavelet transform and Choi-Williams transform analysis was used to process acoustic signals. Three types of dominant failure mechanisms (matrix fracture, debonding and fiber breakage) in this composite were identified and the frequency ranges corresponding to these failure mechanisms were determined. Wavelet transform results showed that, this three type of dominant failure mechanisms (matrix fracture, debonding and fiber breakage) in flexural loading have frequency range of 62.5–125 kHz, 125–187.5 kHz and 187.5–250 kHz respectively. Also energy distribution of each frequency ranges obtained and fitted with fracture mechanisms. Finally the observations of scanning electron microscope from fracture surface of specimen validated the obtained results. This research showed the possibility of acoustic emission technique as a monitoring tool of glass/epoxy composite in flexural failure. Keywords: Failure mechanisms, Wavelet, Energy range, Flexural failure, Structural health monitoring