An origami metamaterial with distinct mechanical properties in three orthotropic directions

Origami-inspired mechanical metamaterials have recently gained increasing attention in various engineering fields due to their unique properties determined by the microstructure geometry. Most origami metamaterials are designed and optimized to achieve specific targets, such as smooth force response or high energy absorption, while it is difficult for a single origami structure to bear distinct mechanical behaviors in different directions simultaneously. In this paper, we present a novel origami metamaterial which demonstrates remarkably programmable anisotropic mechanical properties in three orthotropic directions under quasi-static compression. Through a combination of theoretical analysis, experiments and numerical simulations, this newly designed metamaterial is proved to exhibit a rigid origami folding mode when loaded in the x-direction, resulting in low specific energy absorption (SEA) and compressive stiffness. Conversely, when loaded in the y-direction, the metamaterial achieves high SEA and stiffness due to buckling deformation, which is three times larger than the corresponding data in the x-direction. Furthermore, in the z-direction, the metamaterial initially undergoes a rigid origami folding mode followed by panel buckling, resulting in a graded response with intermediate SEA and stiffness. The proposed metamaterials demonstrate significant potential for applications in versatile scenarios.