Researchers design three-dimensional Kirigami building blocks to create dynamic metamaterials

A new approach to the production of metamaterials uses kirigami techniques to create three-dimensional, reconfigurable building blocks that can be used to create complex and dynamic structures. Because the design approach is modular, these structures are easy to assemble and disassemble.

“Applying kirigami to three-dimensional materials offers a new level of reconfigurability for these structures,” says Jie Yin, corresponding author of a work article and associate professor of mechanical and aerospace engineering at North Carolina State University.

Researchers are optimistic that these 3D metamaterials could be used in applications such as lightweight construction materials for buildings, components for modular robotics, and waveguiding in acoustic metamaterials.

Kirigami is a variation of origami which consists of cutting paper, in addition to folding it. While kirigami is made using two-dimensional materials, such as paper, Yin and his collaborators applied the principles of kirigami to three-dimensional materials cut into connected cubes.

Specifically, the researchers modeled their new approach using a series of eight cardboard cubes connected and open on two sides. Think of each unit of eight connected cubes as a building block. Depending on how the cubes are connected to each other, these building blocks can be folded into over 300,000 different patterns.

“Think of these kirigami units as versatile building blocks that can be put together to create larger structures with different mechanical properties,” Yin explains. “Additionally, larger structures can also be dismantled, allowing users to reassemble kirigami units into new structures.”

To demonstrate the usefulness of the concept, the researchers created more than a dozen reconfigurable building blocks. Each block consisted of eight connected paper cubes and could be reconfigured into eight different shapes. The video highlights the ways each unit can be reconfigured into different structures, how those structures can be assembled into larger structures, and how large assembled structures can be disassembled into reconfigurable blocks. (The video can be viewed at the top of the page.)

Depending on the orientation of the solid cube walls and open sides in each block, and the placement of each block in the larger structure, the structure will behave differently. This allows users to adjust the mechanical properties of each building block. For example, a single building block could be folded into a structure that can be easily compressed, or folded into a different shape capable of supporting a large load.

“The fact that you can disassemble and reconfigure these 3D metamaterials allows users to modify the mechanical properties of a structure as needed to perform different tasks,” Yin explains. “Bend it one way to make it easy to compress, bend it another way to allow lateral movement, bend it a third way to make it stiff or improve its physical strength – and so on. .

“This work focused on demonstrating the fundamental concept,” Yin explains. “Our next step is to demonstrate the applications of the concept. “

The paper, “Modular programmable metamaterials transformable based on Kirigami 3D, ”Is published in the journal Advanced functional materials. The first author of the article is Yanbin Li, who holds a doctorate. student at NC State. The article was co-authored by Yaoye Hong, a Ph.D. student at NC State; and Qiuting Zhang, postdoctoral researcher at Yale University. The work was carried out with support from the National Science Foundation under grant 2005374.

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Note to editors: The summary of the study follows.

“Modular programmable metamaterials transformable in 3D based on Kirigami”

Authors: Yanbin Li, Yaoye Hong and Jie Yin, North Carolina State University; Qiuting Zhang, Yale University

Posted: July 29 Advanced functional materials

DO I: 10.1002 / adfm.202105641

Abstract: Kirigami, the ancient art of paper cutting, has recently emerged as a new approach to constructing metamaterials with new properties conferred by cuts. However, most studies are limited to thin sheet-based 2D kirigami metamaterials with specific shapes and limited reconfigurability due to planar connection constraints of cut units. Here, we introduce 3D modular kirigami by slicing loose materials into spatially closed-loop-connected cut cubes to build a new class of 3D kirigami metamaterials. The module is transformable with multiple degrees of freedom that could turn into separate and versatile daughter building blocks. Their conformable assembly creates a multitude of reconfigurable and demountable metamaterials with diverse structures and unique properties, including reconfigurable 1D column-type materials, 2D lattice-type metamaterials with chirality phase transition, as well as 3D multilayer metamaterials without frustration with 3D auxetic behaviors and programmable deformation modes. This work greatly expands the design space for kirigami metamaterials from 2D to 3D.