Research On Damage Identification Of Plate Structure Attachment Quality Based On Displacement Modal Correlation Coefficient

As one of the classic structural shapes,thin-walled plate and shell structures are widely used in facilities and structures in use in various fields.Composite materials are used in high-tech fields such as high-speed trains,military industry,energy,aerospace and electronics due to their excellent quality.However,due to the different types of damages formed in composite materials during processing or actual use,the existence of these damages will inevitably affect various performance indicators of the material,which may cause serious safety accidents and economic losses.Therefore,there is an urgent need for research on damage identification of composite structures.This paper takes the health monitoring of plate structures in service as the engineering background,uses the attachment quality to simulate the damage on the structure,and proposes a damage identification index based on vibration mechanics.The research method combining finite element numerical simulation and experimental analysis is used to verify the proposed identification index.The main research contents are as follows:First,the development and application of composite panels are introduced,the current damage identification indicators based on dynamic response are briefly introduced,and the advantages and disadvantages of various methods are discussed.Then,the finite element software Abaqus is used to establish the plate structure model under different damage conditions,and the modal analysis of the plate structure model established under the center fixed and cantilever boundary conditions is carried out,and the displacement mode is deduced based on the basic principle of Gaussian curvature.The differential Gaussian curvature identification index is used to identify the damage of the plate structure based on the damage identification index.The results show that the proposed identification index overcomes the shortcomings of the existing Gaussian curvature difference identification index in the identification of attachment quality under two boundary conditions,and can identify the damage location,size and quantity.Secondly,based on the deficiencies of the existing identification indicators for the identification of the damage to the attachment quality of composite panels,the weighted displacement modal Gaussian curvature identification index A and the weighted displacement modal difference Gaussian curvature identification index B are proposed.Taking composite cantilever slabs with different damage conditions as an example,the slab model is analyzed by finite element and experimental modal.Based on the first three vibration modes,four identification indicators are used to identify and analyze the damage of composite slabs.The results show that the identification index suitable for the plate structure is not suitable for the composite material plate,and the simulation and experimental results based on the proposed identification index A and B are in good agreement,indicating that the proposed identification index can effectively identify the composite material.The damage number and location of the cantilever plate are verified,and the validity of the finite element analysis model is verified.Finally,the vibration equation of the composite plate is established through the laminated plate theory,and the Galerkin method is used to solve the discrete solution,and the inherent characteristics of the analytical solution and the simulation analysis are compared.Then,under complex boundary conditions,the modal analysis of the composite plate under different working conditions is carried out.Based on different identification indicators,the damage identification of plates with different spring positions,damage positions,damage sizes and multiple damages is carried out.The results show that the proposed identification indicators A and B can detect the existence of plate damage under the constraint of any spring position,and whether it is a single plate Whether there is a single injury or multiple injuries,both can detect the location and area of the injury,and distinguish the size of the injury through different identification index values.