Research On Structure Joint Invalidation And Strain Monitoring Based On Fiber Bragg Grating Sensors

With increasing demand for security and reliability of aviation aerospace structure, the online monitoring and diagnosis of structure damage attract more attention of people. The joint of aviation aerospace structure is where the bolt joint invalidation easy happens, so it is necessary to monitor structure effectively. The fiber Bragg grating sensors have lots of advantage, such as small size, light weight, anti-electromagnetism interference, wavelength division multiplexing, wavelength code and so on ,so they have a vast of applied foreground in the field of aviation aerospace structure health monitoring.This paper introduces the research background of this topic first, including summary of structure health monitoring and fiber Bragg grating, and domestic and international condition of structure health monitoring based on fiber Bragg grating. Secondly, the sensing principle of fiber Bragg grating is expatiated. The temperature and strain sensing ability of the grating is optimized through experiments, studying the influence of the gluewater on the sensory performance of the fiber Bragg grating and a practical method of fiber Bragg grating temperature compensation. Then, a health monitoring system aimed at structure joint invalidation of a stiffened aluminum plank structure is studied. The system uses the fiber Bragg grating sensor to monitor strain, and uses the neural network to analyze the data. This experiment confirms that system can monitor the location of structure joint invalidation between stiffener and plank effectively. Finally, the fiber Bragg grating sensors are set in a true plane wing box, which are used to monitor the strain of the box under different loading .The data that grating measured have good consistency with the normal strain gauge, and verifying the applied possibility and the credibility of the fiber Bragg grating in the true structural healthy monitoring.