Mode II fracture behaviour monitoring for composite laminates using embedded fibre Bragg grating sensors

This paper presents the utility of embedded fibre Bragg grating (FBG) sensors for monitoring mode II fracture behaviour of glass fibre-reinforced epoxy (GF/EP) composite beams bearing a mid-plane delamination. Stress concentration at the delamination tip of the beam, induced during an end notched flexure (ENF) test, was monitored by means of the reflection spectrum obtained from the FBG sensor whose centre was located at the tip of delamination. The Bragg wavelength shift, bandwidth and intensity in such a reflection spectrum associated with a load–displacement graph were then used to characterize the fracture behaviour of the delaminated beam.