Abstract
When FBG sensors are applied to detection of transverse cracks in CFRP laminates, there is the possibility that the resin coating of the optical fibers will deteriorate the sensitivity of the sensors. Hence, in this study, the strain transfer from the 0° ply to the core of the optical fiber was calculated by a theory developed from the shear-lag model. As a result, it was found that the variation of axial strain in the core of a polyimide-coated FBG sensor was smaller than that of an uncoated FBG sensor. Nevertheless, the reflection spectra of the coated and uncoated FBG sensors calculated from the strain distributions were almost the same. This result shows that the coating of the optical fiber does not deteriorate the sensitivity of the FBG sensor for the detection of transverse cracks.
