Digital image correlation method based on quasi-conformal mapping for large deformation measurement

Digital image correlation (DIC) has the advantages of non-contact full-field measurement and high measurement accuracy in optical mechanics, but still faces challenges in large deformation measurement. This work developed an initial estimation algorithm, using geometric distortion as an indicator. And the more accurate deformation is adjusted by the modified inverse compositional Gauss-Newton (IC-GN) algorithm that introduces the inverse mapping of the initial estimation. The simulation experiment proves that the proposed method has good measurement ability for large deformation, and the accuracy is about 0.02 pixels. The uniaxial tensile test of vulcanized rubber and the three-point bending test of the polycarbonate sheet are used to verify the effectiveness of the method in this paper.