An origami sonic barrier composed of cylindrical inclusions attached onto an origami sheet is proposed. The idea allows for tunable sound blocking properties for application in attenuating complex traffic noise spectra. Folding of the underlying origami sheet transforms the periodicity of the inclusions between different Bravais lattices, viz. between a square and a hexagonal lattice, and such significant lattice re-configuration leads to drastic tuning of dispersion characteristics. The wave tuning capabilities are corroborated via performing theoretical and numerical investigations using a plane wave expansion method and an acoustic simulation package of COMSOL, while experiments are performed on a one-seventh scaled-down model of origami sonic barrier to demonstrate the lattice re-configuration between different Bravais lattices and the associated bandgap adaptability. Good sound blocking performance in the frequency range of traffic noise spectra combined with less efforts, required for actuating one-degree of freedom folding mechanism, makes the origami sonic barrier a potential candidate for mitigating complex traffic noise.

We introduce a framework of utilizing origami folding to redistribute the inclusions of a phononic structure to achieve significant phononic bandgap adaptation. Cylindrical inclusions are attached to the vertices of Miura-Ori sheet, whose one degree-of-freedom rigid-folding can enable fundamental reconfigurations in the underlying periodic architecture via switching between different Bravais lattice-types. Such reconfiguration can drastically change the wave propagation behavior in terms of bandgap and provide a scalable and practical means for broadband wave tailoring.

Lattices and their underlying symmetries play a central role in determining the physical properties and applications of many natural and engineered materials. By bridging the lattice geometry and rigid-folding kinematics, this study elucidates that origami offers a comprehensive solution to a long-standing challenge regarding the lattice-based materials: how to systematically construct a lattice and transform it among different symmetric configurations in a predictable, scalable, and reversible way? Based on a group of origamis consisting of generic degree-4 vertices, we successfully construct all types of 2D and 3D Bravais lattices, and demonstrate that they can undergo all diffusionless phase transformations via rigid-folding (i.e., dilation, extension, contraction, shear, and shuffle). Such folding-induced lattice transformations can trigger fundamental lattice-symmetry switches, which can either maintain or reconstruct the nearest neighborhood relationships according to a continuous symmetry measure. This study can foster the next generation of transformable lattice structures and materials with on-demand property tuning capabilities. Lattices and their underlying symmetries play a central role in determining physicalpropertiessuch as band structure, compressibility, and elastic modulusof many natural (1, 2) and engineered materials (3, 4). Such lattice-property relationship is particularly evident in the metamaterials (5-7). Therefore, purposefully designing and adjusting lattice topology can significantly expand the achievable material property range (8-10). However, constructing lattice structures from the ground-up is quite challenging, and once the material is synthesized, its constituent lattice typically cannot be modified. There is a lack of an integrated and scalable approach for constructing and reconfiguring lattice structures on-demand, let alone transforming their symmetry properties. Here we demonstrate that origami folding offers a solution to fill this gap.Origami has become a popular subject among mathematicians, educators, physicists, and engineers owning to the seemingly infinite possibilities of transforming two-dimensional (2D) sheets into three-dimensional (3D) shapes via folding (11)(12)(13)(14)(15). Historically, such folding-induced shape transformations have been examined based on the spatial positions and orientations of its facet surfaces and crease lines (16,17). For example, many origami-based mechanical metamaterials are analyzed by considering the folding as coordinated facet rotations with respect to the hinge-like creasesessentially a linkage mechanism (18,19). Here, we examine the origami folding through a different lens by asking: How folding can spatially arrange and re-arrange the characteristic entities in the origami? These characteristic entities can be the vertices where crease lines intersect, or the center points of crease lines and facets. By treating these entities as the elements of a lattice (aka. lattice points), we uncover that origami offers a remarkably c...

The ability to create directional sound beams is fundamental to acoustic sensing. Traditionally, acoustic beams are most commonly produced by phased arrays, which increase the cost and complexity of the systems in which they are implemented. Phononic structures have theoretically been shown to possess Dirac cones that can be manipulated to produce angular collimated beams. Dirac cones are usually encountered in phononic crystals with inclusions significantly more compressible than the surrounding media, e.g., rubber inclusions in a water medium, a characteristic not easily realized in air. In addition, there are no effective and practical means to tune phononic structures that can achieve a broad range of Dirac point manipulation, which is essential to changing the direction and focus of acoustic beams. To advance the state of the art, this research proposes a novel approach to produce steerable collimated beams in air by harnessing reconfigurable origami phononic structures with adjustable metamaterial inclusions. The proposed structure is shown to produce dramatic lattice reconfiguration and control of Dirac points in a broad range, and thus achieve collimated beams with on-demand tunable frequency and angle. These advancements provide a simple, cost-effective alternative to acoustic phased arrays, greatly expanding the potential of acoustic sensing.