Utilization of embedded optical fibre sensors for delamination characterization in composite laminates using a static strain method

Embedded fibre Bragg grating (FBG) sensors are utilized to characterize a delamination in glass fibre-reinforced epoxy (GF/EP) composite laminates using a static strain method. Composite beams with different edge delaminations in the thickness-wise direction are monitored by the FBG sensors, whose centres are located at delamination tips of the beams, under a three-point bending test. A surface bonded strain gauge is employed to calibrate the FBG sensor using the bending test. Moreover, strain distribution within the sensing region of the delaminated composite beams is numerically calculated by the finite element method (FEM). FEM results establish the relationship between the strain distribution of the beams and the shape of reflection spectra from the FBG sensors. A correlation between delamination location in the thickness-wise direction of the beams and the shape of the reflection spectra is then highlighted.