Application Of FBG In Structure Health Monitoring

As one of the most developed passive fiber devices, Fiber Bragg Gratings (FBG) have function of reflection or transmission to very wavelength. The primary properties that change the innate optical characteristics of a fiber grating (peak value) are temperature and strain, and transforming the non-optical physics quantity by means of sensitive structure. With many merits that traditional sensors haven't, FBG sensors have broad application development.Encircled the study of FBG sensor system, the main contents of the thesis arelisted as follows:THEORY ANALYSEAnalyse the fundamental theory of FBG.. Enduced the FBG formula by coupling theory and boundary qualification, and have the characters of reflection spectrum.Analyse the sensor theory of FBG. Analyse the temperature and strain effect on reflection spectrum of FBG, and get the principle of FBG in sensor area.The signal demodulation is the key point of the whole system, it directly effect the measurement range, precision and repetition. We discuss a series of demodulation means such as filtering, intervening and analysing in time field, then choose the proper means.EXPERIMENTIn experiment we choose the means of marching FBG filtering to demodulate the signal. We design the cantilever girder to simulate the tuning of the strain and displacement, tuning range 400. Measure the signals after demodulation by means of OSA and OPM. The cure drawed by experiment datas fits the theory. Linearity degree=0.9989, system sensitivity .SYSTEM R&DBBS and OPM design.Marching FBG filtering demodulation, 9 channel detect, 8 for strain and 1 for BBS.System are used on rubber dam model and steel structure bridge. The output signals responding the strain nicely match the results in lab.IMPROVEMENTAccording to the problems during the course of experiment and application, propose some kinds of development, lay the foundation for the future work.