Investigation On Profiled Thin-walled Beam Structural Complex Deformation Reconstruction Method

Domestic and foreign scholars highly value distributed optical fiber sensors because of their full-scale continuity,network intelligence,long distance,large capacity,and low cost,etc.Distributed optical fibers based on back-scattering Rayleigh scattering have been widely used in structural health online monitoring and structural state assessment because of their sub-millimeter spatial resolution and extremely high measurement accuracy.During the master's degree,a deformation reconstruction method for profiled thin-walled beam structures based on distributed optical fiber strain measurement information was proposed.The method can accurately identify the deformation of the beam structure under the action of tension/compression,bi-bending and constrained torsion coupling.By designing and arranging the axial strain measurement path on the beam surface,the complex deformation of the profiled thin-walled beam can be effectively decoupled,and the structural displacement distribution under each load type can be calculated by the reconstruction algorithm.The final displacement distribution of the structure is obtained by linear superposition of the displacements under each load type,and then the full field stress and strain of the structure can be derived based on the full field displacement.In the theoretical derivation process,reconstructing the beam structure displacement under the constraint torsional load was taken as the principal research object;the torsion angle and warping displacement distribution of each section of the beam structure were accurately reconstructed according to axial strain.The effectiveness and accuracy of the proposed method were verified by the finite element simulation method;the complex deformation of the hat-section thin-walled cantilever beam under the constraint torsion and uniaxial bending was reconstructed.In the experimental verification stage,identifying the complex deformation of the aluminum hat-section thin-wall cantilever beam;the axial strain distribution of the beam surface was measured by using the distributed optical fiber sensors.During the experiment,the reconstructed displacement was compared with the structural deformation obtained by the non-contact digital image correlation measurement system(DIC).The comparison results show that the proposed method has ideal deformation reconstruction accuracy.