Deformation and strain measurement on origami structures with depth-guided strain analysis method

Origami structures and origami metamaterials have rapidly emerged as research frontiers and hotspots in fields such as materials science, smart structures, and robotics in recent years. Accurate measurement of the mechanical properties of origami structures is essential for their analysis, design, and application. Digital image correlation (DIC) technology is a non-contact optical measurement method that can be used for three-dimensional (3D) shape, deformation reconstruction and strain analysis. However, the depth discontinuities in origami structures cause discrepancies between two-dimensional (2D) image mapping and true 3D deformation, leading to accuracy decrement of image-based DIC for strain analysis on 3D geometric surfaces. This paper proposes a depth-guided strain analysis method to accurately achieve deformation and strain measurement on origami structures. By selecting the data points from a continuous and smooth subset under the guidance of depth map, the method can accurately compute strain distribution on 3D surfaces with complex geometric structures. Experiments on a Miura-ori structure validate the proposed method's capability for accurate deformation and strain measurement on complex structures, providing a feasible experimental approach for analysis of 3D structural behavior of origami structures.