Effects of the self distortions of embedded FBG sensors on spectral response due to torsional and combined loads

Abstract

The response spectra of FBG sensors embedded in a cylindrical hollow composite beam, under torsion and combined torsion - bending loading, were obtained. It has been seen that the spectrum of FBG has been chirped due to torsional loading. Further, the spectra of the embedded FBGs located at the vicinity of a point of damage inside the tube under torsional and combined loading conditions were also obtained, and found that the spectrum has been chirped. These observations have suggested that the spectral distortion of an embedded FBG is not only due to damage but also the loading type. Additionally embedded FBG sensors in flat composite plates were subjected to lateral pressure and torsional loads independently in order to investigate further this behaviour. In all cases similar chirp was observed when torsional and combined loads are applied.