Modal Analysis on Macro-strain Measurements from Distributed Long-gage Fiber Optic Sensors

In a recent study by the authors, an advanced structural health monitoring (SHM) strategy based on distributed fiber optic sensing techniques has been proposed to utilize the strain responses throughout the full or some partial areas of structures to detect the arbitrary and unforeseen damages. As one of the essential components, a two-level scheme based on modal parameters from distributed dynamic macro-strain responses has been developed for damage locating and quantifying. This work further investigates the superiority and some concerns of using distributed long-gage fiber optic sensing technique for vibration based SHM through a theoretical modal analysis on the dynamic macro-strain distribution. Modal testing is also carried out to verify the performance of macro-strain frequency response function (FRF) and identify the modal parameters including resonant frequency, damping ratio, and modal macro-strain vector (MMSV). From the SHM point of view, their applications are summarized finally.