Sensing Application Research Based On FBG

In recent years, fiber Bragg grating has shown great potential in the application ofstructural health monitoring of bridges, dams and tunnels etc. Due to the intrinsiccharacteristics of the fiber Bragg grating, it has already been used to monitor stress andtemperature changes, which are considered as important physical factors in a lot ofengineering projects. In many areas, the fiber Bragg grating is widely used in these areas inorder to ensure the safety of industrial production.In this thesis, we mainly study the application characteristics of fiber grating sensors inthe sensor field. The systematic research of fiber grating sensor technology, the packagingdesign of sensor head and the applications of temperature, strain and pressure measurement isstated in this paper, mainly includes: the research of fiber grating with non-uniform phaseshift; fiber grating for solid-liquid phase transition monitoring and sensing applications ofsolution concentration; experimental study of high temperature, high pressure and strain fibergrating sensor in the steam boiler.Firstly, in this paper we reviewed the development progress of the fiber sensingtechnology in the sensing area and stated the feature and advantage of the fiber gratingsensing technology; simply introduced the coupled-mode theory of the fiber Bragg gratingand the transfer matrix theory; and analyzed the reflection spectrum’s features of non-uniformphase shift grating based on the transfer matrix theory. Then simulate a non-uniform phaseshift fiber bragg grating from the view of experimental point, and its temperature sensingcharacteristics test and theoretical analysis are given.Secondly according to theory of fiber grating sensing, adding to a reasonable packagedesign, this paper proposes a test of liquid phase transition process by using FBG, weobserved the phenomenon of supercooling in this process; then we use this sensing system forthe solution concentration sensing, when temperature dropped from20℃to-20℃in theprocess, the average sensitivity coefficient Kc of concentration sensing is-11.3pm/%, itmeans that when the concentration is increased by1%, the smallest wavelength differencereduces about0.01nm. Finally, according to the high temperature and high pressure environment of the steamboiler, this paper proposes several specific fiber bragg grating packaging design, includingtemperature sensors, strain sensors and pressure sensors, and the sensitivity of each sensor istested.Then we applied them to the practical engineering projects, and analyzed theexperimental results monitored by the sensors in theory, the results we got from the analysisshowed that it has both validity and practicability.