Study On High Sensitivity Fiber Bragg Grating Strain Sensor

Optical fiber sensing is one of the multidisciplinary high technology whichemerges in recent years. Structural health monitoring based on sensing is becoming animportant direction of structural engineering disciplines. Among a variety of fiber opticsensors, fiber Bragg grating sensors which are suitable for long-term monitoring inharsh environments are the most promising candidate to replace electronic sensors in thenear future.Based on the necessity for structural health monitoring in large project as well asthe oversea and domestic research status of fiber optic sensor, this thesis analyzed ahighly sensitive fiber Bragg grating strain sensor for structural health monitoring,proposed a novel methodology which is applicable to different engineering, andanalyzed the characteristics of ocean applicable nonmetallic corrosion-resistantmaterials, in the FBG packaging process, providing a reference for subsequentresearchers in this field. The main content of this thesis includes:1. A highly sensitive FBG strain sensor structure was proposed. Using the finiteelement analysis software ANSYS to simulate the traditional I-shaped structure and themodified one, their strain distribution contours of entire and the grating region weregiven. The outcomes showed if the overall width and thickness remained unchanged,the sensitivity of the modified structure is about600times higher than the I-shaped one.2. The influence of the6key structure parameters on strain sensitivity andmeasurement range was analyzed in detail. These results provided a basis for structuraloptimum design of fiber Bragg grating strain sensors in different application fields3. Fabricated two metal carriers with different sizes and adopted differentpackaging process for the FBG and tested its sensitivity. The reasons leading to theerror were discussed. The results verified the reliability and accuracy of the simulation.The engineering application situation was also introduced.4. On the basis of high sensitivity structures, studied the properties of thecorrosion-resistant nonmetallic materials which were applicable to the marineenvironment. 5. Three different nonmetallic materials of good corrosion resistance were chosenas the research objects and applied to the highly sensitive structure of fiber Bragggrating strain sensor. The simulation and experiment results revealed that their strainsensitivities are:3.76pm/με,3.02pm/με and3.03pm/με, respectively. In the end, basedon their unique characteristics, the practicability of these materials in large projects wasinvestigated.