Development of a Fiber Bragg Grating Accelerometer Based on a Tandem Single-notched Hinge Structure

A Fiber Bragg Grating low-frequency accelerometer with a single-notched hinge in series is proposed to improve the hinge structure's sensitivity and the cross-sensitivity of the accelerometer of low-frequency seismic waves. The sensitivity and the cross-sensitivity of the accelerometer are improved by connecting the single-notched hinge structure in series and experimentally verified. Based on the theoretical analysis, the resonance frequency and sensitivity formula of the accelerometer are derived. At the same time, the accelerometer is simulated by finite element analysis software to simulate and analyze the characteristics of the accelerometer in terms of resonance frequency, strain distribution, and amplitude-frequency response. The structural parameters of the accelerometer are optimized by numerical analysis software, and the effects of the structural parameters on the sensitivity and resonance frequency of the accelerometer are analyzed. The experimental results show that the resonance frequency of the accelerometer is 110 Hz, the flat region is 0.6-50 Hz, the linearity is as high as 98.9%, the sensitivity is 1040.41 pm/g, and the cross-sensitivity of the accelerometer in the flat interval is 4.94%. This indicates that the accelerometer shows good linearity and cross-sensitivity in the flat interval, which well meets the needs of seismic wave signal monitoring in low-frequency oil and gas exploration.