High Precision Structural Stability Monitoring Technology Based On DSPI And DIC

It is of great significance to carry out thermal deformation monitoring of key structures in aerospace and other manufacturing and assembly sites to obtain the threedimensional deformation distribution of structures under different temperature environments,so as to provide guidance for structural design and assembly processing.Aiming at the problems of low measurement efficiency and secondary deformation caused by traditional contact 3D deformation measurement methods,a new method based on Digital speckle pattern interferometry(DSPI)and Digital image correlation(DIC)is proposed to realize non-contact three-dimensional deformation measurement.The overall design and calibration method of the measurement system are analyzed,and the index and performance of the measurement system are verified through experiments.The main research work of this paper is as follows:(1)This paper introduces the principle of DSPI out of plane deformation measurement,and studies the matching method of DIC.Several sub-pixel search methods are compared in DIC,and the selection of matching window size and other parameters is simulated.(2)This paper analyzes the phase extraction method of DSPI,and proposes a phase image filtering method combining sine cosine transform and BM3D(Block-matching and 3D filtering).The simulation and experimental results show that the denoising effect of this method on DSPI phase image is better than several traditional filtering methods,which proves that this method is helpful to demodulate the out of plane deformation information accurately.(3)A method of 3D deformation measurement based on DSPI and DIC is studied.The two-color light source is used for illumination,and the speckle image is collected by two cameras with narrow band filter.The out of plane deformation and in-plane deformation are calculated respectively.The synchronous dynamic measurement of 3D deformation is realized through the calibration of two cameras.The software and hardware design of the system is completed.(4)Laser interferometer and laser autocollimator are introduced to verify the out of plane and in-plane resolution of the measuring instrument.Then the 3D deformation measurement system is used to measure the local thermal deformation of the metal plate for simulating spacecraft structure,and the results are compared with the simulation results.The results show that the method proposed in this paper is feasible and can meet the accuracy requirements of the existing workplace.