为了适应公路边坡倾斜监测的需要, 提出了一种新型的水银柱活塞差动式光纤布拉格光栅(FBG)倾角传感器。传感器所测对象的倾角发生变化时, 水银柱在金属壳内的有效长度发生改变, 对传压活塞的压力也相应改变。传压活塞通过传力杆将水银的压力传递给等强度悬臂梁自由端, 使得粘贴在等强度悬臂梁左右两侧的FBG中心波长变化。利用有限元方法在不同倾斜角度下运用两点粘贴法分析等强度悬臂梁与FBG的应力特性, 根据仿真参数研制了倾角传感器, 并对该传感器进行了角度标定实验和温度敏感实验。实验结果表明, FBG倾角传感器量程范围为0°~40°, 灵敏度为21.8 pm/(°), 拟合度R2为0.998, 重复性为1.12%。

In order to meet the need of slope monitoring, a new fiber Bragg grating (FBG) differential tilt sensor combining mercury column and piston is proposed. When the tilt angle of measured object changes, the pressure to the piston changes as the effective mercury column length changes in the metal shell. The pressure of the mercury is passed to the free end of the cantilever beam by the piston and leads to the central wavelength change of FBG, which is pasted on the left and right ends of the cantilever beam. By use of the finite element method, the stress characteristics of the cantilever beam and FBG are analyzed with two point bonding method at different tilt angles. According to the simulation parameters, the tilt sensor is developed. Angle calibration test and temperature sensitivity test are carried out on the sensor. Experimental results show that the measuring range of the FBG tilt sensor is 0°-40°; sensitivity is 21.8 pm/(°); the fitting degree R2 is 0.998, and the repeatability is 1.12%.