Flat-deployable programmable morphing metastructures based on origami and symmetrical parallel mechanisms

Shape-morphing capability is critical to enhancing mechanisms or structures’ adaptability in complex environments. However, it is a challenge to design mechanisms that realize 1-to-multi-layer reconfiguration without module separation/recombination. Inspired by origami, this paper proposes a construction method for flat-deployable programmable morphing metastructures based on symmetrical parallel mechanisms with bifurcation motions. First, based on the mobility and singularity analyses of the Pa-linkage, a symmetrical parallel mechanism is constructed. Cellular units with different side numbers are further designed via an origami equivalent method. A novel bifurcation mechanism induced by double Pa-linkages (4R parallelogram mechanisms) is revealed after mobility and singularity analyses of the representative quadrilateral cellular unit. Then, three large-scale networking methods are proposed to network metastructures. Subsequently, key mechanical properties are analyzed, and their mapping curves are established to achieve performance pre-programming. Finally, prototypes of quadrilateral cellular units and four-module metastructure are fabricated to verify the feasibility of the design method. The results show that the metastructure has two bifurcation paths: Path 1 achieves single-DOF synchronous deployment, while Path 2 has 9 DOFs. It enables 1-to-5-layer reconfiguration and has different 2D-to-3D transformation modes.