Out-of-plane compressive mechanical properties of square-twist origami folded-stable state

Origami structures are widely favored by engineering applications due to their reconfigurable characteristics and controllable mechanical properties. The square-twist (S-T) origami, featured with typical folded stability, has a broad application prospect. However, researchers usually focus on how the S-T folded-stable configuration is formed and affected by critical designing factors, lacking attention to its out-of-plane mechanical properties. Here, the mechanical properties of out-of-plane compression for the S-T origami in folded-stable state with zero neutral angle are revealed. A finite element compression model of the prestressed S-T origami folded-stable state is established and verified by compression experiments on the typical S-T origami. With the finite element model, the three-stage out-of-plane compressive mechanical behavior of typical S-T origami folded-stable state caused by facet contact and facet-substrate contact is discovered. By investigating the effects of different geometric and material parameters on the out-of-plane compressive mechanical properties for S-T origami folded-stable state, it is found that the self-contact situation of the S-T origami folded state significantly affects its out-of-plane compressive mechanical behavior. The influence of various filling materials in the S-T origami folded-stable state on its out-of-plane compressive mechanical behavior is discussed, highlighting the feasibility of our design in the flexible protection and related applications.