岩石变形光纤光栅传感检测的应变传递分析

岩石变形过程可以通过光纤光栅的表面粘贴法进行检测。建立了考虑表面凹槽时的应变传递模型,经过力学分析得出了应变传递方程及传递系数的表达式;在MTS伺服机上进行了单轴压缩实验,借助光纤光栅对加载过程进行了测试。结果表明,传递方程与粘贴层厚度均匀分布时的方程形式相同,只是特征值k不同;换算后光栅的轴向应变与MTS位移计吻合很好,相对误差仅为3.2%;环向测试优于MTS的环向应变计,而两种方法都明显地优于应变片。实验验证了所建模型的正确性。经应变传递换算后,通过光纤光栅可以实现岩石变形过程中与MTS精度相当的高精确测试。

Strain Transfer Analysis of Rock Deformation based on FBG Sensing

Rock deformation process can be tested by using the fiber Bragg grating (FBG) surface pasting method. Strain transfer model considering the surface groove was established, and the expression of strain transfer equation and transfer coefficient was obtained by mechanics analysis. Rock uniaxial compression experiment on MTS was conducted, and the loading course was tested by using FBG. Results indicate that the transfer equation is the same as the equation used when the thickness of the adherence layer is uniformely distributed with the only different eigenvalue k. The converted axial strain of FBG accords with MTS displacement gauge with the relative error 3.2%. The effect of ring strain test is better than MTS radial strain gauge, and both methods are all obviously better than electrical strain gauges. This experiment validates above mentioned strain transfer model of surface pasting. After strain transfer conversion, high precision rock deformation test will be achieved by FBG with equivalent accuracy with MTS.