Mechanical properties of novel folded kirigami metamaterials under quasi-static compression

Origami and kirigami are effective approaches to fabricate lightweight cellular metamaterials with extraordinary mechanical properties. However, the novel designs of such metamaterials are still limited. In this paper, a novel metamaterial similar to typical Kelvin foams is proposed and fabricated via origami and kirigami methods, and its mechanical properties are investigated. Quasi-static compression tests are first conducted to analyze the deformation characteristics and stress-strain responses. Numerical simulations are then carried out to simulate the tests. Furthermore, two methods including adjusting the wall thickness and introducing openings are adopted to alter the relative density of the metamaterials, and their influences on the plateau stress and specific energy absorption (SEA) are explored. Finally, analytical studies are conducted to predict the plateau stress, and good agreement between the analytical, numerical, and experimental results are obtained. The results reveal that the kinetic energy is primarily dissipated by unfolding the constitutive elements along the creases, and three typical stages of linear-like elastic, plateau, and densification are generated in the stress-strain curves. Increasing the wall thickness significantly improves the plateau stress and SEA. Introducing smaller openings has minor influences on the plateau stress, while the stress level drops remarkably when the opening size exceeds a critical value. By adopting an appropriate opening size, the increment of the SEA can be up to 29% in comparison with non-opening counterparts. The findings of the present study provide an alternative to fabricating cellular materials with outstanding performance.