Measuring Modal Parameter Variation on Composite Structures by Fiber Bragg Grating Sensors

A criticaI issue in practical structural health monitoring is related to damage detection and identification. To this aim, many techniques have been proposed invoIving dynamic measurements such as modal analysis (low frequencies), acoustic emission (medium frequencies) and ultrasonics (high frequencies). This paper relies on the use of embedded Fiber Bragg Grating Sensors for performing an experimental modaI analysis on awing of an aircraft model. Time domain response of the fiber optic sensors induced by impact hammer are acquired and transformed into the frequency domain. Using classical technique based on Frequency TransferFunction the first displacement and strain mode shapes of the wing have been retrieved in terms of natural frequencies and amplitudes.