LAUSR

Abstract This letter explores the mechanical behavior of the origami hyperbolic paraboloid or hypar which is a bistable thin sheet structure with symmetric stable states. We use experiments to evaluate the global and local behaviors of the structure, which are unique from other bistable origami systems. In theory, for the hypar to reconfigure between the stable states, the thin sheet which is initially patterned with acute and reflex folds needs to fully flatten. However, we find that axial stretching as well as two distinctly different buckling patterns in the origami can allow for portions of the sheet to remain folded during the reconfiguration. The spacing of folds in the hypar, the resulting buckling characteristics, the stretching of the sheet, and the local material nonlinearity at the fold lines all have significant effects on the force–displacement response of the system. The work gives insight to these phenomena which are often omitted in the testing and modeling of more conventional origami-inspired systems. We reinforce our understanding of the hypar behavior by establishing an analytical model that can simulate the kinematics, the buckling, and the force–displacement behavior of the structure. The letter also discusses topics for future extension and introduces hypar chains where multiple hypars are connected in series to achieve multistability.