Fiber Bragg Grating Strain Sensor Technology And Application Study

In recent years, there is wide attention on fiber grating and its application in fiber sensors and fiber communications. As an excellent sensor, Fiber Bragg ggrating (FBG) sensor offer many important advantages, and can measure lots of properties, such as termperature, pressure, strain and so on. It is suitable to form FBG array, by means of writing them into a fiber continuously. With Time Division Multiplexing (TDM) and Wavelength Division Multiplexing (WDM) Technology, the FBG sensor array can build FBG sensor network, which has wide prospect for detecting the properties of the huge buildings and dangerous situations, such as the dam, bridge, mine, oil field etc.As a Ph.D candidate studing in Zhejiang University and GFZ-Pptsdam (GeoForschungsZenturm Potsdam), supported by Germany BMBF (Project No: CHN/167) and GFZ-Potsdam, I had studied in germany for one and half year. In the period, I had taken part in the Europen Union Corinth Rift Laboratory 3F (Faults, Fractures & Fluids) -Corinth Porject and Germany Potsdam Kaiser Bahnhof building strain detecting project.In the dissertation, the FBG sensor is studied, including FBG static strain sensor network, FBG dynamic strain measurement, Compareing between FBG strain sensor and traditional strain sensor, FBG strain sensor character etc. The main contents are taken as follows:The fundamental theory of the fiber grating is introduced. The spectrum of FBG is analyzed by the coupling-mode theory, and FBG sensor theory for strain and temperature is analyzed. The FBG strain senor technology which applied in the dissertation is discussed.A distributed FBG static strain sensor network is designed and established. The system is focus on the solution of FBG sensor field application. With TDM and WDM technology, system can measure a long distance strain in very deeply underground well. The system can drop the wrong signal beside a high resolution. With a backup FBGs, the system can adapt the badly condition, which will damage the FBG. With a center computer communication with all devices, the system became a smart system, which can measure the strain automatically and can be remote controlled.A FBG dynamic strain sensor system based on temperature controlledfilter FBG is designed and established, which sloved the filter FBG and sensor FBG wavelength match problem caused by the temperature variation. The system is totally computer controlled and smart work. The singal noise ratio (S/N) of system reach 15dB, dynamic resolution is 9.745x10-10/(Hz1/2), and the absolute resolution is 160nThe FBG strain sensor applied in cantilever is studied in experiments and theories. The FBG sensor signal is compared with the result of acceleration sensor, modal analysis and finite element analysis.FBG strain sensor character is studied in experiments and theories. The memory effect of FBGand linear relationship between FBG Bragg wavelength and strain are analyzed.