Research On Spatial Structure Deformation Monitoring Method Based On 3D-DIC And Finite Element Model Updating

With the continuous improvement of satellite observation accuracy,the deformation of several microns at key structures such as the satellite load installation plane may directly affect the pointing accuracy and working state of the payload,and even directly affect the overall working life of the satellite.Therefore,effective measurement method for measuring the deformation of the key structure of the satellite must be studied.Visual measurement methods such as 3D digital image correlation have the advantages of non-contact and full-field measurement,which are widely used in the field of deformation measurement.Restricted by the measurement environment,the deformation measurement in extreme space environment cannot be completed.The finite element model method can obtain the full-field continuous deformation of the structure through theoretical calculation.The method has high analysis efficiency and is not limited by actual environmental conditions.However,it is difficult to accurately measure the influence of factors such as material properties and boundary conditions.There is often a deviation between the calculated value and the true value.The main research direction is to carry out detailed tests in the ground simulation environment,use the measured results to correct the finite element model,and then grasp the highprecision deformation of the key structural positions of the satellite in the space environment.In view of the high-precision deformation measurement requirements in the space environment,this paper studies the deformation monitoring method of spatial structures based on 3D-DIC and finite element model correction.The main work of this paper is as follows:1.The principle of binocular vision and 3D-DIC measurement method is introduced,the accuracy and efficiency of different matching algorithms are analyzed,a 3D-DIC measurement unit according to the measurement accuracy requirements is designed,the displacement measurement accuracy is verified,the design and implementation of the measurement unit are completed.2.A multi-view global deformation measurement method based on 3D-DIC is proposed,a global control point is established to perform external calibration of multiple measurement units,and the global deformation field is obtained by splicing local deformation fields.The error model of the proposed method is analyzed,the overall measurement accuracy is verified,and the design and accuracy verification of the full-field high-precision deformation measurement method for key satellite structures in the ground simulation environment is completed.3.The finite element model correction and measurement method based on BP neural network is proposed,the finite element model correction method considering boundary conditions is analyzed,the optimal model is constructed,and the BP neural network algorithm is introduced to complete the nonlinear mapping between model parameters and outputs,the training samples and structure of the neural network are designed according to the finite element model correction process.4.The deformation of the typical honeycomb panel structure under thermal load is taken as the research object,and the accuracy of the updated model and the prediction accuracy of the model of the structural deformation in the simulated space environment are analyzed,and the reliability of the method in the paper is verified.