薄板挠曲型光纤Bragg光栅土压力传感器设计与分析

根据土压力传感器与土介质的匹配原则，设计了一种圆平膜片薄板挠曲型FBG土压力传感器。通过在圆膜片上设计一组对称的光栅固定柱，有效避免了传感器在使用过程中产生谱峰分裂。同时，利用光栅固定柱张角引起的应变效应，大幅度地提高了传感器的压力灵敏度。理论分析了该结构的增敏机理并给出传感器灵敏度公式，计算结果表明，传感器的压力灵敏度可达1 374.3 pm/MPa。使用ANSYS建立薄板挠曲的有限元模型，通过提取固定柱中心点处在光纤方向上的位移，获得了有限元模型的压力灵敏度为1 360.8 pm/MPa。有限元分析和理论设计结果的相对误差为0.98%，具有很高的一致度，验证了理论设计和分析的正确性。

Design and analysis of fiber Bragg grating soil pressure sensor with flexure of sheet structure

Based on the matching principle of soil medium and pressure transducer, a circular flat diaphragm with flexure of sheet structure fiber Bragg grating (FBG) soil pressure sensor was designed. By designing two symmetric fix ends on the diaphragm, we could successfully solve the problem that the reflection spectra of the FBG subject to the transverse force split in two main peaks. As the same time, for the strain effect caused by the fix ends-flare angle, the sensor-s pressure sensitivity was enhanced dramatically. By analyzing the sensor-s enhancement effect theoretically, we got the sensor-s pressure sensitivity formula. Computed result showed the sensor-s pressure sensitivity was 1374.3 pm/MPa. ANSYS was used to establish the finite element model for the flexure of sheet structure. By extracting the displacement of fix ends- coordinate point on the fiber-s direction, we got the finite element model-s pressure sensitivity about 1360.8 pm/MPa. ANSYS analysis result has high entropy with theoretical analyis- conclusion and the relative error is 0.98%, which verifies theory design and analysis.