Fiber Bragg Grating low-frequency accelerometer based on spring structure

Abstract

To meet the needs of accelerometers for seismic wave monitoring in the field of low-frequency oil exploration, a Fiber Bragg Grating (FBG) low-frequency accelerometer based on spring structure is proposed. The accelerometer consists of two FBGs, two semi-profile metal capillaries, a spring, and a mass block. In addition, the accelerometer is encapsulated in a cylindrical housing to enhance its stability. Firstly, the working principle of the accelerometer is introduced in detail and the theoretical model of the accelerometer is established, then the accelerometer is simulated by finite element analysis software and the dimensional parameters of the accelerometer are optimized by numerical analysis software. Finally, the experimental study of the accelerometer is carried out to test the shock response, amplitude-frequency response, and sensitivity response of the accelerometer. The experimental results show that the proposed new accelerometer has a resonant frequency of 115 Hz, dynamic resolution up to 0.123 mg/Hz in the operating range 0.5–60 Hz, the sensitivity is 932.25 pm/g, the linearity is up to 99.9 %, the higher sensitivity, and sufficient operating range, so that the accelerometer is expected to be used in the field of low-frequency oil exploration.