Damage detection in structures using SH waves sensed with FBG sensors

To perform active Structural Health Monitoring (SHM) Guided Waves (GW) have received great interest as they can inspect large areas with a few sensors and are sensitive to barely visible structural damages. Fiber Bragg Grating (FBG) sensors offer several advantages, but their use has been limited for the GW sensing due to its limited sensitivity. FBG sensors in the edge-filtering configuration have overcome this issue with sensitivity and there is a renewed interest in their use. In addition, the FBG sensors have been shown to be capable of sensing the Shear Horizontal (SH wave) when deployed in perpendicular configuration to the propagating wave. The SH₀ wave is non-dispersive and hence simplifies the signal processing. As a result the SH₀ wave may improve the quality of damage detection and localization. Thus, in this paper the use of SH₀ waves sensed using FBG sensors in edge-filtering configuration has been investigated. The SH wave is generated using d36 based piezo actuators and sensed using FBG sensors. The method is developed for a simple aluminum plate with simulated damage scenarios. The method shows promising results and has potential to be used for reference-free damage detection.