Obtaining Reconstruction Spectra of Acoustic Emission Signals Detected by a Fiber Optic Sensor Built into a Plate of a Polymer Composite Material

A method is reported for reconstructing the amplitude–frequency characteristic (AFC) of the distributed fiber optic sensor (FOS) built into a polymer composite material (PCM), which is necessary for reconstructing the true spectrum of acoustic emission (AE) sources. The FOS AFC is obtained by comparing FOS signal spectra with spectra of a calibrated piezoelectric transducer with allowance for the AE wave propagation channel. The reconstructed AFCs for the sensors located at a distance of 0, 125, and 300 mm from the AE source demonstrate a high correlation in the frequency range of up to 50 kHz with a correlation coefficient of 0.86–0.91. The results confirm the possibility of using this FOS for quantitative analysis of acoustic energy of an AE source and determine the effective operating bandwidth for identification of PCM defects.