AsianScientist (Apr. 7, 2017) – To bring metamaterials out of the lab and into the market, researchers have adopted a modular approach which could make metamaterials easier to use. Their findings have been published in the Proceedings of the National Academy of Sciences.
Metamaterials go beyond what’s found in nature by assembling simple elements into repeating patterns. At large scales, these smaller components influence the larger construction in unusual ways.
“The variety of applications is growing. Today we see mechanical metamaterials used to shape the flow of vibrational waves like earthquakes to protect buildings. Tomorrow, who knows what will be next,” said study co-author Dr. Yang Nan from Tianjin University of Technology.
The researchers, however, were concerned that these discoveries haven’t been moving from the lab to the market fast enough. A challenge they noted was the time and difficulty of designing for real-world applications.
“Metamaterials are driving a revolution in material science. The current approach of building every-day stuff turns out to be limited because the materials we work with have a relatively narrow range of properties and capabilities,” said Dr. Jesse Silverberg from the Wyss Institute for Biologically Inspired Engineering at Harvard University, the other author of the paper.
A few years ago, origami—the art of paper-folding—was recognized for its ability to rapidly convert flat sheets into 3D patterns with unusual metamaterial properties.
“While easy to fold, the time required to find good designs for practical problems is often too costly,” said Silverberg. “Suppose you wanted a mechanical metamaterial to absorb impact during a car crash. What’s the best design for that? And even if you find a good folding pattern, does it even fit with the car’s chassis?”
Both Yang and Silverberg have young children, and they turned out to be an important part of the discovery.
“We were working late one night over Skype and we realized the solution was literally on the floor in front of us. What if we could build metamaterials like our kids build with Legos?” Yang said.
This ‘ah-ha’ moment led them to design basic units that had different mechanical properties, much like how Lego blocks come in different colors. Once designed, the team was able to create larger and more elaborate structures the same way their children were creating multi-colored ships and robots.
As examples, the researchers showed how to assemble two different types of mechanical ‘cloaking materials.’ They also gave examples of how a pre-determined set of properties can be engineered into arbitrary 3D structures, a highly elusive challenge since the beginning of metamaterial research.
“Now that have a basic strategy, we’re working out the design for even more ‘bricks’ and methods to rapidly assemble them,” Yang said. “Looking ahead, we foresee tools that allow anyone with a computer to easily design complex metamaterials.”
The article can be found at: Yang & Silverberg (2017) Decoupling Local Mechanics from Large-scale Structure in Modular Metamaterials.
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Source: Tianjin University of Technology; Photo: Pixabay.
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