DIC measurement method for large rotation based on improved grid-based motion statistics

As a noncontact optical measurement method, the digital image correlation (DIC) method can provide full-field displacement and strain measurement during object deformation. In the case of small rotation deformation, the traditional DIC method can obtain accurate deformation measurement results. However, when the object rotates at a large angle, the traditional DIC method cannot obtain the extreme value of the correlation function, resulting in the occurrence of decorrelation. In order to address the issue, a full-field deformation measurement DIC method based on improved grid-based motion statistics is proposed for large rotation angles. First, the speeded up robust features algorithm is applied to extract and match the feature point pairs between the reference image and the deformed image. Furthermore, an improved grid-based motion statistics algorithm is proposed to eliminate the wrong matching point pairs. Then, the deformation parameters of the feature point pairs obtained by the affine transformation are taken as the initial deformation value for DIC calculation. Finally, the intelligent gray-wolf optimization algorithm is used to obtain the accurate displacement field. The effectiveness of the proposed method is proved by simulation and practical experiments, and the comparative experiments show that the proposed method is faster and more robust.(c) 2023 Optica Publishing Group