Large Structural Safety Monitoring Applications Research Based On Fiber Bragg Grating

In recent years, economy of China has developed rapidly. With a large number oflarge power stations, high-speed railway, subway, bridges, tunnels, oil and gasexploitation and other infrastructure’s construction, engineering accidents happenfrequently, and huge property losses and casualties are caused. Therefore, it is veryimportant to monitor the safety of these large-scale structures, and sensor and sensingtechnology is in great demands. For example, Fiber Bragg Grating (FBG) sensors,have already been widely used in applications of large civil structures, aerospaces,communication and electric power setups, petro-and chemical-related fields, healthstructure monitoring and so on. FBG sensors can be made to measure differentphysical quantities such as strain, pressure, displacement, temperature, settlement,which have advantages of high-precision, low-cost, good stability, andanti-electromagnetic interference wavelength coding, and etc. Therefore, they havebroad application prospects in the field of large-scale structure’s safety monitoring.In this paper, a demodulation scheme of low-cost and high-precision has beendeveloped. Practical applications in three different cases for large structures safetymonitoring are also explored. The contents are as follows:1) It is analyzed the research and application status of large-scale structure’ssafety monitoring based on FBG, and it is also summarized the advantages ofFBG sensors in these applications.2) It is analyzed the FBG’s sensing principle, and summarized the multiplexingand demodulation techniques.3) Based on the low-cost I-MON80D module with lower sampling rate, it isdesigned a FBG demodulator and the demodulating software is also developedwith VC++, in which Gaussian fitting algorithm is used for getting betterspectral signals. And finally we got a low-cost FBG wavelength demodulatorwith high-precision.4) For the first application, FBG strain sensors are installed on ZJ70DBderrick model, and the safety alarm software is developed. Loading and unloading tests are carried to verify the sensor performance and the softwarequality. Besides, the designed FBG temperature sensing systems are applied inthe outlet cover monitoring of the nuclear power generators in DongfangElectrical Machinery Factory. No-loads and short-circuits are both tested inthe field experiments.