Application Of Digital Image Correlation For Deformation Measurement Of Aerostat Skin

When the traditional contact measurement method applied to the skin deformation measurement,there will be contact impact,low accuracy and other issues,Therefore,an important non-contact measuring method in digital mechanics--the digital image correlation method is introduced and studied systematically.Based on the flexible large strain characteristic of the skin,the key problems of the initial value estimation algorithm and sub-pixel search algorithm are optimized.Finally,based on the digital image correlation theory proposed in this paper,a skin deformation measurement system is set up.The contents of this paper are as follows:1 A method of initial value estimation based on SURF feature point matching is proposed.In this method,the SURF feature point matching is introduced,and the feature points and the subarea association are solved,which can not only effectively avoid the effect of surface rotation and large deformation,improve the matching accuracy,but also avoid the unstable factors introduced by human-computer interaction,Improve the automation of the system.The experimental results show that the experimental results are very stable and accurate.2 A sub-pixel displacement search algorithm based on hybrid genetic algorithm is proposed.In this paper,a conjugate gradient algorithm with good search ability but low precision is proposed.Based on the conjugate gradient operator and genetic algorithm,three hybrid genetic algorithms are proposed,which are hybrid genetic algorithm The algorithm of pixel displacement search: CG hybrid genetic algorithm,CG hybrid genetic algorithm and parallel CG hybrid genetic algorithm,and the principle analysis and algorithm implementation of these three algorithms.Experimental results show that the latter two algorithms have higher accuracy and better stability.3 Based on the correlative theory of digital image correlation method,the airborne skin measurement system is built and the tensile test of the skin specimen is carried out.Experimental results show that the method proposed in this paper can effectively measure the deformation of the skin.