Bistable reconfigurable origami metamaterials with high load-bearing and low state-switching forces

Bistable shape-reconfigurable metamaterials can achieve large morphological changes under a relatively low state-switching force and can maintain the configuration autonomously after removing the force. However, the state-switching force and the load-bearing forces are usually coupled in the same direction, resulting in low loadability at the deployed state. Here we separate the load-bearing direction and the state-switching direction of bistable unit, and combine the directional folding feature of origami to design a shape-reconfigurable metamaterial with high bearing force and low switching force, named mechanical relay metamaterial. The feasibility of the design concept is first validated experimentally. The bearing force of the mechanical relay metamaterial is at least 4 times the switching force and 100 times the gravity of self-weight. Then the geometric design domain of the unit is derived by spherical trigonometry. Finally, the effect of geometric parameters on the load carrying capacity of the unit is investigated by finite element simulations, and the optimal geometric parameters are determined. This work provides an effective solution for bistable shape-reconfigurable metamaterials with high bearing force and low switching force.