基于光频域反射技术的表面粘贴分布式光纤传感器应变传递特性分析与试验

分布式光纤传感器由多层结构组成,用于测量土木工程构筑物表面变形时,光纤与结构基体间存在一个应变传递过程。为了揭示表面粘贴分布式光纤传感器应变传递特性规律,结合经典的剪滞理论,分析光纤在不同粘贴长度和中间层参数下,低应变传递系数区段的范围与变化。通过室内试验,在PVC管表面紧邻并行粘贴两条光纤,采用基于光频域反射(optical frequency domain reflectometer,OFDR)的分布式光纤感测技术测量光纤在管中部受不同集中荷载下的应变,得到应变传递系数分布及变化。结果表明:在不同荷载下,OFDR实测光纤应变传递系数的分布规律具有一致性,符合理论分析,研究成果对分布式光纤传感器应用于结构表面变形的检测与监测工作具有一定的指导意义。

Optical Frequency Domain Reflectometry Technology Based Theoretical Analysis and Experiment on Strain Transferring of Surface-attached Optical Fiber Sensor

Distributed optical fiber sensors are composed of multilayer structures. There is a strain transfer rate between the deformation of optical fiber and the structural substrate for measuring the surface deformation of civil engineering structures. In order to reveal the distribution of fiber strain transfer coefficient under different length of pasting and intermediate layer parameters,the classical shear lag theory was used to analyze the range and variation of low strain transmission coefficient section. In the experiment, two optical fibers were pasted on the surface of PVC tube in a parallel manner. The optical frequency domain reflectometry technology (OFDR) was used to measure the strain of the optical fiber pasted under different concentrated loads in the central part of the PVC tube. Then, the distribution and change of strain transfer coefficient of optical fiber were obtained. The result shows that the OFDR monitored distribution of optical fiber strain transfer coefficient is almost the same under different loads, that consistent with the result of theoretical analysis. It will offer guidance for the application of distributed optical fiber sensors in detecting and monitoring of structural surface deformation.