A High-Sensitivity Strain Sensor With Femtosecond Fiber Bragg Grating for Pipeline Deformation Monitoring
Yongjian Gong, Yongxing Guo, Li Xiong, Chang Liu, Wanhuan Zhou, Zhongchun Hu, Xiudong Li, Yu Zhang
Abstract
Structural health monitoring (SHM) of hydraulic pipelines plays a crucial role in preventing catastrophic failures, particularly when measuring large strains with high sensitivity. This study presents a novel high-sensitivity strain sensor utilizing femtosecond fiber Bragg grating (FS-FBG) technology to overcome the limitations of conventional monitoring techniques in extreme conditions. The sensor incorporates two key components: sensing and measuring members, featuring an innovative skeletonized sensitized shaft design. A pre-stressed FS-FBG is suspended axially within the structure. The relationship between fiber Bragg grating (FBG) wavelength displacement and pipe surface strain was validated using Bernoulli-Euler beam theory and finite element analysis. In order to accurately calibrate the performance of the sensor, a precision pipe deformation device was designed. Experimental results demonstrate that the sensor achieves a sensitivity of 4.19 pm/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula>, which is 3.4 times higher than that of the FBG sensor, in the range of 0–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1650~\mu \varepsilon $ </tex-math></inline-formula> of the pipe surface microstrain, and at the same time, it has excellent linearity, creep-resistant performance, and temperature compensation effect. The results provide a reliable solution for large strain monitoring of hydraulic pipelines under severe conditions.