Shape and vibration mode sensing using a fiber optic Bragg grating array

Abstract

This paper discusses the use of wavelength division multiplexed fibre Bragg gratings for structural shape sensing and vibrational mode analysis. The gratings are surface attached to a cantilever beam and demodulated by a scanning fibre Fabry - Pérot filter to obtain strain information at different locations along the structure. Two demodulation schemes are used, namely a single-sensor locked mode interrogation technique which permits vibrational analysis and a scanning multi-sensor approach for beam shape determination. Static beam deformation prediction is performed using a Rayleigh - Ritz type analysis with three optimized trial functions and the strain information obtained from the fibre Bragg grating sensors. The strain information is read into a PC which performs the shape modelling of the beam.