Research On Torsion Beam Fiber Grating Acceleration Sensor

With the rapid development of construction engineering,aerospace engineering,power grid engineering,traffic engineering and other engineering fields,it is necessary to carry out health monitoring and fault diagnosis of the project in order to be able to promptly discover hidden problems in the project.FBG accelerometers based on FBG have unique advantages over traditional electromagnetic sensors and other optical sensors and are more suitable for harsher engineering environments.Therefore,it is of great scientific importance to study FBG accelerometers.This paper designs and develops a fiber grating acceleration sensor based on a torsion beam,which combines the torsional strain variable with the acceleration,and detects the magnitude of the acceleration signal by detecting the torsional strain.The sensor can increase the sensitivity of the sensor properly while ensuring a certain natural frequency,which overcomes the contradiction between the natural frequency and the sensitivity of the traditional beam sensor.The main research content of this article is as follows:(1)Design a torsion beam fiber grating acceleration sensor.The fiber grating is attached to the thin piece on the torsion beam with negligible mass.By increasing the radius of the slice,the radius of the fiber grating is increased,which the sensitivity of the fiber grating to the torsional strain of the torsion beam is increased.The sensor avoids the contradiction between the resonant frequency and acceleration sensitivity of the traditional beam fiber grating acceleration sensor.That is,when the resonant frequency of the traditional beam fiber grating acceleration sensor is high,the acceleration sensitivity is low;when the acceleration sensitivity is high,the resonant frequency is low.(2)Based on the structure of the fiber grating acceleration sensor and the sensing principle of the fiber grating,analyzed the model of the torsion beam fiber grating acceleration sensor,and calculated the mathematical model of the sensing principle of the torsion beam fiber grating acceleration sensor which using the knowledge of mechanics.(3)Finite element analysis and optimization of the structure of the torsion beam fiber grating accelerometer.The three optimal structures of the sensor are simulated by changing the dimensions of the sensor structure,and according to the simulation results,the sensitivity and resonant frequency parameters of the sensor are calculated.The resonant frequency of sensor A was 1032.2 Hz and the acceleration sensitivity was 5.882 pm/g.The resonant frequency of sensor B was 689.7Hz and the acceleration sensitivity was 13.362pm/g.The resonant frequency of sensor C was 1022.7Hz and the acceleration sensitivity was 6.715pm/g.(4)According to the optimization results,the sensor is processed and manufactured,and an acceleration sensor test system is built to test the sensor.Through analyzing and calculating the test results,the performance parameters of the real sensor are obtained.The resonant frequency of sensor A was 1180 Hz and the acceleration sensitivity was 5.115 pm/g.The resonant frequency of sensor B was 460 Hz and the acceleration sensitivity was 18.283 pm/g.The resonant frequency of sensor C was 1120 Hz and the acceleration sensitivity was 6.290 pm/g.