Study On Thin Plate Deformation Monitoring Method And System Based On FBG Distribution Sensor

With the rapid development of aerospace industry,the performance requirements of spacecraft are more and more high.The high performance spacecraft can not be separated from the high reliability wind tunnel equipment and high quality flow field.As the key structure of wind tunnel equipment to control the flow field accurately,monitoring the deformation of flexible plate is the key technology of wind tunnel structure health monitoring and fault diagnosis.At present,strain detection and deformation reconstruction of thin plate structure based on FBG sensing technology is one of the important research directions in this field.According to the requirements of deformation detection and real-time visual reconstruction of thin plate structure,firstly,the sensing characteristics of fiber Bragg grating are studied and applied to the strain detection of thin plate deformation;secondly,based on the distributed strain information of thin plate,a reconstruction algorithm of thin plate deformation with error compensation is proposed;secondly,the on-line monitoring system of thin plate deformation is developed to visualize the thin plate Finally,on the basis of deformation monitoring system,the experiment system of sheet metal deformation reconstruction based on strain deformation is built.The main work and research results of this paper are as follows:(1)Based on the study of the sensing characteristics of fiber Bragg grating(FBG),a packaging technology of full coverage FBG strain sensor is proposed,which can not only effectively protect the FBG,but also improve the consistency of the sensor after packaging.Finally,the sensing characteristics of the encapsulated sensor are studied.The results show that the sensitivity of the encapsulated sensor is consistent.The strain sensitivity of FBG is 1.1967 pm/μ ε,the temperature sensitivity is 39.455 pm /℃.(2)According to the characteristics of thin plate structure and deformation,combined with the elastic mechanics and finite element analysis method,the corresponding relationship between the strain and deformation of thin plate structure is established,and the transformation between the distributed strain information and the curvature information of thin plate is realized.Based on the analysis of the accumulated error characteristics of the traditional recurrence calculation method of tangent angle,a curvature integral algorithm with error compensation is derived,using the recurrence algorithm of tangent angle and the Curvature integral algorithm is used to reconstruct the deformation of thin plate.The simulation results show that the error compensation factor can improve the reconstruction accuracy of the algorithm.(3)Combined with FBG sensor network and curvature integral algorithm,a set of on-line monitoring system for sheet metal deformation is developed.The system can process the strain and temperature detection results of sheet metal in real time,and display the calculated deformation,strain and temperature data in real time.Finally,based on the on-line monitoring system of sheet metal deformation,the static test and dynamic test of sheet metal deformation are carried out.The deformation monitoring system of thin plate calculates the deformation of thin plate under different loading modes in real time.At the same time,the laser displacement sensor is used to measure the deformation of thin plate synchronously and take it as the standard value to draw the static reconstruction results and dynamic reconstruction results of thin plate under different loading modes.The results show that the relative error of static deformation reconstruction is about 8%,and the real-time performance of dynamic deformation display is about 0.2 seconds.