Research On Structure Joint Invalidation Monitoring And Pattern Recognition

The joint of aviation aerospace structure is where the bolt joint invalidation easy happens, to prevent from disasters and losses incurred by structural damage, 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.On the background of Aeronautics and Astronautics structural health monitoring requirement, on a stiffened plate, aimed at the safety matter of structure joint invalidation, build a health monitoring system based on fiber Bragg grating sensor's strain monitoring. In the thesis the discussion as following:The research background of this topic is introduced 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, working principle of fiber optic Bragg sensor is introduced. on the basis of the principle, the paper probed the technical points in the sensing applications of optic Bragg sensor. Thirdly, the joint invalidation monitoring system aimed on stiffened plate and the definition of joint invalidation modes are introduced, its main content consists of the finite element analysis about strain field on the plate and the monitoring system design. Fourthly, the pattern recognition algorithms in this system are discussed, positions and degrees of screwed off bolt are recognized. The research emphasis aimed to the feature of aviation aerospace structure is recognition algorithm's generalization ability.