Author: ["Johannes T. B. Overvelde","James C. Weaver","Chuck Hoberman","Katia Bertoldi"]
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Abstract
Advances in fabrication technologies are enabling the production of architected materials with unprecedented properties. Most such materials are characterized by a fixed geometry, but in the design of some materials it is possible to incorporate internal mechanisms capable of reconfiguring their spatial architecture, and in this way to enable tunable functionality. Inspired by the structural diversity and foldability of the prismatic geometries that can be constructed using the snapology origami technique, here we introduce a robust design strategy based on space-filling tessellations of polyhedra to create three-dimensional reconfigurable materials comprising a periodic assembly of rigid plates and elastic hinges. Guided by numerical analysis and physical prototypes, we systematically explore the mobility of the designed structures and identify a wide range of qualitatively different deformations and internal rearrangements. Given that the underlying principles are scale-independent, our strategy can be applied to the design of the next generation of reconfigurable structures and materials, ranging from metre-scale transformable architectures to nanometre-scale tunable photonic systems. A robust and scale-independent strategy for the design of reconfigurable architected materials (in which properties are adjusted by altering structure rather than composition) is described, based on space-filling assemblies of polyhedra. Architected materials (metamaterials) achieve new properties from the way their structures are engineered, rather than their composition. They usually have only one fixed geometry, although a recent paper from Katia Bertoldi and colleagues describes a reconfigurable three-dimensional (3D) metamaterial. In the present paper, the same group reports a general design strategy that leads to an entire class of reconfigurable metamaterials. The authors begin with space-filling polyhedra, which they separate and generate connecting faces from the edges of one polyhedron to others in the direction normal to the surfaces (these are said to be prismatic). The researchers then create these structures and identify those that are reconfigurable. They develop a numerical algorithm to identify the parameters that allow the structures to be reconfigurable, and use it to predict mobility and deformation modes in all 28 polyhedral tilings of 3D space. The original unit cells of all 13 reconfigurable architectures contain prisms. The authors further increase the number of reconfigurable architectures by reducing the number of extrusions from the polyhedral surfaces, and find that 10% of the structures they studied could be made reconfigurable. Finally, they identify qualitatively different reconfigurations, including shear and uniform expansion, along one or two principal directions, and internal reconfigurations that do not alter the external shape.Cite this article
Overvelde, J., Weaver, J., Hoberman, C. et al. Rational design of reconfigurable prismatic architected materials. Nature 541, 347–352 (2017). https://doi.org/10.1038/nature20824 