Large dynamic range dual FBG accelerometer for low-frequency vibration detection

Monitoring low-frequency and ultra-low-frequency vibration waves has wide-ranging applications in structural health monitoring, seismic engineering, environmental vibration control, mechanical equipment maintenance, and geological disaster monitoring. This study presents a large dynamic dual-FBG(Fiber Bragg Grating) accelerometer designed for detecting vibration waves. Initially, the mechanical properties of the sensor are theoretically derived. Subsequently, simulation software is utilized to analyze its dynamic characteristics, verifying the theoretical derivations and providing simulation data to support physical fabrication and experimental testing. Following this, physical prototypes are constructed, and a testing platform is established to calibrate various performance metrics of the sensor, followed by an analysis of the test data. The findings show that the developed sensor can capture vibration waves between 0.05 and 30 Hz, with detection acceleration as low as 0.0005 g at the 0.05 Hz frequency point and a dynamic range of 77.61 dB. This ability to detect low acceleration in the low-frequency and ultra-low-frequency bands is expected to address the existing gap in low-frequency micro-vibration monitoring using FBG sensors.