Research On Deformation Measurement And Reconstruction Method For Composite Structures Based On Strains

Modern structures are increasingly becoming larger and more complicated.Structural difficulties are increasing.Many structures in a project are affected by factors such as a complex working environment.Performance is declining and even destroyed,In order to avoid the above-mentioned situations,multi-domain and multi-disciplinary structural health monitoring technologies have emerged as the times require.This paper focuses on the technical measures related to the measurement and reconstruction of structural deformation in structural health monitoring based on strain information.,and the measurement object includes a beam structure,a plate structure,and a plate-beam composite structure.The simulation and experiment verify the reliability of the reconstruction method.The first part of this paper,the least-squares relationship between the actual cross-section strain and the theoretical cross-section strain is deduced,and the relationship between the strain field and the displacement field is established based on the Timoshenko Beam Theory(TBT),The circular cross-section cantilever beam is used as an example.The deformation of the cantilever beam was reconstructed by an inverse finite element method(IFEM),and the effect of the method on the defor mation of the beam structure was verified.Secondly,the least squares relationship between the actual surface strain and the surface strain in the theory is deduced,and the transformation from strain to displacement is established based on the Mindlin-Reissner Plate Theory(MRPT),and taking the deformation of the cantilever plate as an example to verify the effect of this reconstruction method.In the second part of this paper,a deformation measurement method suitable for the plate beam composite structure is proposed based on the inverse finite element method,and sub-surface leg structure of reflector antenna is used as the background.The finite element modeling and simulation of the plate-beam composite structure is carried out.In this process,the problems such as coordinate transformation and matrix assembly are included.Finally,the simulation and experiment of the plate-beam composite structure model are carried out,and the errors are analyzed by combining the simulation and experimental data.The feasibility of the method based on strain reconstruction of plate-beam composite structure deformation is verified.The last part of the thesis,the deformation measurement system demonstration platform is introduced,the necessity of the software platform is analyzed,the necessary basic functional modules in the software are summarized and implemented.The interface construction of the demonstration platform is completed.The method proposed in this paper has the advantages of the inverse finite element method.It can perform deformation reconstruction of the structure under unknown load conditions and does not require structural material properties.Through different topological relations,this method can be applied to the deformation measurement of more complex structures.Experiments show that the measurement method of this paper has better effect of measuring deformation.