A Comparison of Optical Sensing Systems with Piezo-Electric Sensors for Impact Identification of Composite Plates

This paper proposes using Fibre Bragg Grating (FBG) and piezoelectric (PZT) sensors for impact identification. The main objective is to evaluate the ability of the state-of-the-art sensors to estimate the impact energy, using the results of the PZTs as a reference. This approach allows a fair comparison and overcomes the inherent variability of different test runs of the same measurement. The comparison of sensor technologies consists of evaluating sensitivity to features for impact energy estimation, signal strength, repeatability, directivity, and signal correlation. Small-mass impacts were applied to a square composite plate at different locations and energies. The energy was kept low enough to avoid damaging the panel. The PZT and FGB sensors were placed at the same
locations but on either side of the panel to compare signals evenly. The results showed that the energy from the measured response reflects the impact energy level. Moreover, FBGs and PZTs had comparable responses and an apparent similarity in time response, besides consistency in the frequency domain. The higher sampling rate for the PZTs allows for the analysis of higher frequency bands, compared to FBGs, showing relevant amplitudes above 10kHz. Future work will focus on developing and validating a force reconstruction algorithm and defining the optimal sensor configuration.