Improved mirror-assisted multi-view digital image correlation for accuracy-enhanced dual-surface profile and deformation measurement

Abstract

Accurate measurement of dual-surface kinematic fields is essential for characterizing the mechanical behavior and anisotropic parameters of sheet specimens. To this end, a cost-efficient and simple-to-implement mirror-assisted multi-view digital image correlation (MV-DIC) was recently proposed and has been proven to be effective. Nevertheless, this method conventionally relies on reflection transformation calibration to map the measured virtual surfaces to their actual positions. The positional transformation for each surface is mutually independent and lacks constraint relationships. This work proposes an improved mirror-assisted MV-DIC method for accuracy-enhanced dual-surface deformation measurement by utilizing the overlapped region of the virtual surfaces instead of reflection transformation calibration. Through preliminary feature matching and precise matching of subsets for corresponding points in the overlapped regions, the relative positional transformations between the measured surfaces of the specimen can be accurately determined. As the accuracy of positional transformations primarily depends on the matching accuracy of corresponding points rather than the accuracy of multiple plane fitting, this method provides better relative positional relationships between the two surfaces compared to conventional methods. The results of several real experiments well validated the practicality and accuracy of the proposed method.