Low-frequency vibration measurement technology has significant application value in various engineering fields such as earthquake monitoring, disaster early warning, underground resource exploration, and anti-seismic monitoring of important structures like dams and bridges [[1], [2], [3], [4], [5]]. As a new type of sensing element, FBG accelerometers can effectively measure low-frequency vibration signals. Compared to traditional electromagnetic [6] or piezoelectric sensors [7], fiber optic accelerometers offer a broader measurement range and smaller size, and provide better solutions in distributed monitoring, corrosion resistance, and electromagnetic interference resistance.

In recent years, extensive and in-depth research on FBG accelerometers has been conducted by many scientists. Based on the design structure, these can be broadly classified into core-axis type [8,9], diaphragm type [10,11], hinge type [12,13], and cantilever beam type [14]. The performance of core-axis type FBG accelerometers is greatly influenced by the elasticity of the material, where stiffness and sensitivity are mutually restrictive, necessitating the selection of an appropriate elastic body. Diaphragm-based FBG sensors are mostly suitable for high-frequency seismic exploration environments and not for measuring low-frequency signals. Hinge-type FBG sensors have a wide frequency range and high sensitivity, but their principle structure is complex. Cantilever beam-type FBG vibration sensors, known for their simplicity, high stability, and strong transverse interference resistance, are widely used in vibration signal measurement. Fan W et al. [15] proposed a new fiber Bragg grating accelerometer based on a diaphragm-type cantilever beam, with a working bandwidth of 5–60 Hz and a sensitivity of 485.75 p.m./g, offering strong transverse interference resistance, but performing poorly at low frequencies. Kok-Sing Lim et al. [16] proposed a horizontal cantilever beam FBG accelerometer with a magnetic damper, with a working frequency band of 20–100 Hz and a sensitivity of 7.1 p.m./g. However, this sensor, using a magnet as a mass block and forming a magnetic damper with a U-shaped groove, is large in size and mass, making it unsuitable for use in narrow spaces. Liu Q P et al. [17] developed an FBG accelerometer based on a small strain gradient dual cantilever beam, optimized in size and mass, with a working band of 4–30 Hz. Although it meets the requirements for miniaturization, its sensitivity is only 8.58 p.m./g. Hafizi et al. [18] developed a sensor based on a polyphenyl ether thermoplastic cantilever beam, capable of measuring 2 Hz low-frequency signals at an acceleration of 0.04 g, with a sensitivity of 110 p.m./g and a natural frequency of 9 Hz, but its flat band is narrow, only 0–8 Hz. Gan W B et al. [19] proposed a fiber Bragg grating accelerometer based on an F-type beam, with a natural frequency as low as 168 Hz. After filling the sensor with silicone oil, the sensitivity can reach 133 p.m./g, and the working bandwidth is 1.5–100 Hz. However, the F-type beam structure is complex and does not consider the problem of silicone oil sealing, resulting in a short lifespan. While these research achievements have advanced the development of FBG accelerometers, the existing challenges in effectively measuring low-frequency vibration signals and practical engineering applications still remain.

To address the challenges of FBG accelerometers in measuring low-frequency vibration signals and their application in practical engineering, this paper proposes a dual straight-wing FBG accelerometer for low-frequency vibration measurement. Through theoretical derivation and modeling and simulation analysis using Solidworks and ANSYS, a prototype of the accelerometer is developed and a low-frequency vibration testing system is set up to test and analyze its performance.