基于FBG的钻孔应变传感器研制

Development of borehole strainmeter based on FBG

为了监测地壳内部的微应力应变,设计了一种基于光纤布拉格光栅(FBG)的钻孔应变传感器。结合FBG的传感原理,通过有限元分析,构建出曲边三角形的传感应变结构,并根据其传感特点进行相应的封装。使用参考光栅法,在应变片上粘贴两支FBG,在一支FBG测量应变的同时另一支FBG对其进行温度补偿,解决了FBG对温度和应变同时敏感的问题。为了模拟传感器在钻孔中的环境,建立了微应变测试平台。实验结果表明,研制的钻孔应变传感器的灵敏度为0.092 3pm/με,且具有较大的增敏空间。

For now,the strainrneters used are equipped with electrical sensors which are susceptible to electromagnetic interference, difficult to remove the zero drift and inaccurate caused by annual drift, so we develop a borehole strainmeter based on fiber Bragg grating （FBG）. A curve-side-triangle structure used as the strain gauge is designed by finite element analysis software. The gauge is encapsulated by a stainless steel cylinder. The problem of cross-sensitivity of FBG sensor is resolved though the method of reference grating. Two gratings are fixed on the gauge. One is used for temperature compensation, while the other measures the strain. In order to simulate the environment in the borehole, a rnicrostrain platform is established,where the borehole strainmeter＇s feasibility is tested. Experimental results show that the strain sensitivity is 0.092 3ρm/με and can be improved greatly.