Research On Temperature Compensation Of Surface-mounted Fiber Bragg Grating Sensor

In the health monitoring of bridge structures,sensors,as information collection tools,are located at the forefront of the monitoring system.The stability and reliability of their output signals are crucial to the entire monitoring system.Fiber Bragg Grating(FBG)sensors have been widely used in structural health monitoring due to their advantages of small size,high durability,low loss,good electrical insulation,anti-electromagnetic interference,sensitivity,and high measurement accuracy.This thesis proposes a method of using surface-bonded FBG sensors for monitoring bridge cables,which reflects changes in cable tension through the wavelength change of the FBG sensor after temperature compensation.This method provides a solid foundation for the application of surface-bonded FBG sensors in actual engineering.This thesis takes the surface paste type FBG sensor as the research object,adopts a combination of theoretical derivation,finite element simulation and experimental method to study the temperature response and temperature compensation of the surface paste type FBG sensor for the problem of temperature and strain cross-sensitivity in the measurement process of FBG sensor,and applies to engineering practice,the main research contents and results are as follows:(1)On the basis of the strain transfer efficiency and minimum paste length of the surface paste FBG sensor,the temperature response model of the surface paste FBG sensor was established,the temperature response formula of the FBG sensor was derived,the correctness of the formula for calculating the temperature sensitivity coefficient was verified through finite element simulation and temperature response experiments,and the order of influence of the parameters of the surface paste FBG sensor on the temperature sensitivity coefficient was determined through orthogonal experiments.(2)Based on the actual temperature response of the surface-adhesive FBG sensor,a theoretical formula for temperature compensation of the surface-adhesive FBGsensor was derived.The capillary encapsulated FBG temperature sensor was designed and fabricated,and the temperature sensitivity coefficient of the sensor was calibrated by a water bath test,and the validity of the theoretical equation for temperature compensation of the surface-pasted FBG sensor was verified.(3)The surface paste type FBG sensor is applied to the actual project,after the correction of capillary tube encapsulated FBG temperature sensor,the test results can reflect the actual state of the inclined cable,and achieved a better monitoring effect.