A novel multiplexed fiber Bragg grating sensor with application in structural health monitoring

The use of fiber Bragg gratings (FBGs) on a single fiber for analyzing the strain in two dimensions is presented. The effects of the simultaneous transversal and longitudinal force on an FBG sensor is analyzed and its perturbed reflected spectrum is modeled by introducing the change of the refractive indecies and grating period along the fiber to the transfer matrix formulation method ('measured' spectrum). Furthermore, the use of genetic algorithm for reconstruction of nonuniform applied transverse forces from the 'measured' spectrum is presented. The genetic algorithm requires only the measured spectra information and the refractive index distribution is encoded along the Bragg grating into the genes. The presented method is verified through the numerical examples and the results show that our methodology can effectively represent and model the applied transverse force profile. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim