Mechanical responce of Kirigami sheet materials

Kirigami is a technique for cutting of a sheet to realize some complex deformation of sheet materials. With a large number of slits, sheet materials can be stretched far beyond the original failure strain. It means that we can make a hard sheet flexible with simple “Kirigami” processing.
In this study, we perform experiments to elucidate the mechanical response of Kirigami structure from a fundamental point of view. We created a sample with one column of the kirigami structure and apply a tensile force. The overall relation between elongation and force which we measured is similar to the one typically observed in plastic materials. This behavior is divided into three regimes: (1) an initial linear elastic region, (2) a plateau region, and (3) a hardening region just before breakage. From this mechanical response, we see that high extensibility, which is a feature of Kirigami structure, emerges as a result of out-of-plane (three-dimensional) deformation that follows
in-plane (two-dimensional) deformation. This change in the mode of deformation defines the transition point. In this presentation, we focus on the initial region and discuss scaling laws demonstrating a good agreement between theory and experiment. [Ref. Isobe and Okumura, Sci. Rep. 6, 24758 (2016).]