Abstract
A chirped fibre Bragg grating (CFBG) optical sensor has been used to detect delamination growth in an ENF specimen. CFBG sensors, with a sensor length of 60 mm, have been embedded within ENF specimens fabricated from out-of-autoclave CFRP. Delaminations have been propagated within the specimen from an insert embedded at the specimen midplane during manufacture. The sensor has been interrogated with the specimen subjected to four-point loading, and the perturbations detected within the reflected spectra of the sensor are in reasonable agreement with the physical position of the delaminations measured at the coupon edges. The prediction of the reflected spectrum for one delamination length, using a combination of 3-D finite-element analysis and commercial software for predicting FBG spectra, is in qualitative agreement with the experimental results. Better quantitative agreement is expected to require a more refined finite-element model of the ENF specimen.