Transformable Surface Mechanisms Based on Bending-active Scissors Structures

Deployable structures made of elastic materials connected by rotational pivots that transform from a flat state to a curved surface have advantages such as being lightweight and construction efficiency. In particular, the geodesic grid shell, in which flat members follow the geodesics of the surface, has one degree of freedom for in-plane deformation, which makes its deployment easy to control. In this study, we propose a design method for deployable surface mechanisms based on a combination of bending-active scissors structures. The mechanism transforms into a 3D curved surface due to the incompatibility of the in-plane shear deformation of the scissors' units. In this paper, we geometrically show that if two states of the same combination of unis exist, they can smoothly transition between them. Using this feature, we propose a design method for a mechanism that can deploy to a target surface by creating two states of equal length. We also present design examples and physical prototypes. Our structure can be efficiently fabricated by the assembly of short, straight members in the 2D state. We believe this method can be applied to deployable structures such as temporary shelters and flexible partitions.