Research On The Health Monitoring Of Smart Material Structure Using Fiber Bragg Grating

According to its lots of advantages, Fiber Bragg Grating (FBG) has possesed great application prospects in health monitoring of smart material structure. The paper studied the application of FBG sensors in smart structure health monitoring. By researching the sampling method of dynamic structure signal, feature extraction, impact location and energy grade classification, an optic fiber smart structure system with function of impact localization and energy grade determination was constructed. On this base, a preliminary study on dynamic signal health monitoring system of composite material airfoil fuel tank with variable cross section.The main research contents are described as follows:(1) The strain and temperature sensing model of FBG was studied, and a linear relationship between center wavelength offsets and strain values was obtained. The basic foundation of grating length selection was given by spectrum simulation. For improving the reflection index peak of FBG, the depth of refraction index modulation or the grating length can be increased. However, the actual designing must consider multi-parameters comprehensively.(2) A feature extraction method based on empirical mode decomposition and autoregressive model was analyzed, and the dynamic signals of different impact locations and energy grades were obtained. By using the feature parameters as samples, an autoregressive sample model was constructed, the impact localization and energy determination algorithm of composite material was proposed. The feasibility of this new method was verified both theoretically and practically.(3) By using the strain sensing characteristic of FBG, the monitoring of vibration and impact signals on composite material was conducted, and an impact localization and energy determination monitoring system based on FBG sensor network was constructed. By using FBG sensor distribution network for monitoring the flexible strain fields of composite material structure, a further analysis on damage of high velocity impacts was conducted with damage criterion. The proposed energy grades determination method was proved to be accurate.(4) By using finite element analysis of airfoil fuel tank, a FBG vibration\impact monitoring system was constructed. The distribution FBG sensor network was applied on monitoring the flexible strain fields of composite material tank with variable cross section. The offsets of FBG center wavelength were corresponding to the changes of outer and inner parameters, and the dynamic monitoring of whole structure was realized. The impact localization and energy determination of composite material airfoil fuel tank with variable cross section was conducted by using the proposed algorithm.For Fiber Bragg Grating's advantages, Fiber Bragg Grating are Suitable for manufacturing network of structural health monitoring, have extensive potential applications in smart structure and materials health monitoring field. Fiber Bragg Grating sensors are applied for the dynamic signal monitoring of smart structure in the paper. In order to build an impact loading self-diagnosing system, acquisition methods of dynamic signal, feature extraction, loading location and energy algorithm are researched. Meanwhile, a preliminary study of airfoil fuel tank health monitoring based on Fiber Bragg grating sensors is proposed in the paper.