High-sensitivity dual-FBG acceleration sensor for low frequency vibration measurement

The measurement of low frequency vibration signals is of great significance in seismic monitoring, health monitoring of large and medium-sized engineering structures, resource exploration, etc. A cross spring leaf-based novel FBG accelerometer was designed against the problem that it's hard for FBG acceleration sensors to effectively pick up low frequency vibration signals. Firstly, the vibration model of acceleration sensor was built and its operating principle was analyzed; secondly, the effect of structural parameters of sensor on their sensitivity and natural frequency was analyzed, and the sensor was subjected to static stress analysis and dynamic characteristics analysis through the ANSYS simulation software; finally, the sensors were subjected to performance tests with a low frequency vibration test system. Experimental results suggested that the natural frequency of FBG acceleration sensor was 63.65 Hz, it gives a flat sensitivity response in the low frequency band of 0.1-40 Hz; its sensitivity was not lower than 2000 pm/g, and the transverse interference was not higher than 1.99%; moreover, it offered favorable self-temperature compensation. Such FBG acceleration sensors with high sensitivity response at low frequencies provide important reference for the design of like sensors.