Fiber Bragg Grating-Based Fabry-Perot Interferometer Sensor for Damage Detection on Thin Aluminum Plate

Structural Health Monitoring of engineering structures has become an essential measure for the prevention of catastrophic failures. This study presented a feasibility study of Fiber Bragg Grating-based Fabry-Perot interferometer (FBG-FPI) sensor for damage detection on an aluminum plate, by acoustic Lamb wave technique. In the investigation, a rectangular damage slot was introduced to the plate, at 15 cm from the actuator. Two FBG-FPI sensors were surface-mounted on the aluminum plate for the detection. In the analysis, we observed an additional wave packet with attenuated amplitude and time delay in the time-domain signal for the defect plate. Similar features are observed in the time frequency spectrograms and they are important signatures that can be used for detecting the defect. The findings show the applicability of FBG-FPI sensor for damage detection on a thin-walled metallic structure.