Research On Structural Deformation Monitoring Method Based On Fiber Bragg Grating

Structural deformation monitoring is a significant research area in structural health monitoring(SHM), structural control, and condition assessment of aerospace structures. The thesis researches on a new deformation shape-sensing method based on fiber Bragg grating(FBG) sensing technology and Ko displacement theory, for the purposes of real-time structural deformation monitoring of flexible lightweight aerospace structures. The main contents in this thesis are listed as follows:(1) Starting from the transmission theory of FBG, strain sensing mechanism and the demodulation theory are researched and analyzed. On this basis, the implementation of tunable Fabry-Perot filtering based interrogation system is discussed on light source unit,Bragg wavelength detect unit and central control unit.(2) In this thesis, Ko displacement theory based shape reconstruction algorithm is proposed and different strain-displacement transfer functions for bending load case and torsion load case are developed. Algorithm that has existed is optimized for the uncertainty of aerospace structure’s neutral surface. Experiments are conducted to validate the veracity and feasibility.(3) The proposed deformation shape-sensing method is applied in a complex carbon fiber composite wing structure of Unmanned Aerial Vehicle based on finite element analysis. The reconstructed displacement results demonstrate that FBG sensing technology and Ko displacement theory based deformation reconstruction method can be used for in-flight monitoring of various lightweight structures and flexible wings, as well as various commercial airplanes.