Origami-based structures were used to create implantable solar arrays for space, adaptive acoustic systems for symphony rooms, and even collision protection systems for flying drones.
Now researchers at the Georgia Institute of Technology have created a new type of origami that can change from one pattern to another, or even a hybrid of two patterns, instantly altering many of its structural features.
The research, which was supported by the National Science Foundation and will be published on April 19 in the journal Physical Review Letters, could unlock new types of structures or metamaterials based on origami that take advantage of the characteristics of two types of origami.
"This hybrid origami allows reprogrammable mechanical properties and the ability to change these properties while the material is in service," said Glaucio Paulino, a professor at Georgia Tech's School of Civil and Environmental Engineering.
Researchers began with two types of origami patterns: the Miura-ori and the egg carton, which can be formed into sheets of repetitive patterns. The Miura-ori looks like rows of folded zigzags, while the pattern of the egg carton resembles a mountain range with repeated peaks and valleys.
Both are capable of being compacted in a very small space, but when expanded, they behave differently from each other in how they respond to flexion. The pattern of the egg carton resembles a dome when bent, and the Miura-ori takes the form of a saddle.
"Traditionally, if you have an egg carton pattern, you're stuck with the characteristics of that particular pattern," said Paulino, who is also the director of Engineering Raymond Allen Jones at the School of Civil and Environmental Engineering. "With this new standard, which we are calling morph, this is no longer the case."
The new origami pattern reaches its transformational capacity by redesigning the geometry of two of the four planes that make up a section of origami. By shrinking these two planes on one side, it allows your creases to move from a mountain to a valley, or, in other words, to bend in the opposite direction.
And, more importantly, the transition from peak to trough can occur if origami is formed from a flexible material such as paper or a rigid material such as metal.
This means, for example, that the origami-based structures used for acoustic systems – which are already capable of expanding and contracting to increase or decrease the volume of the sound response – could go one step further, changing the way of offering greater range of resonant responses. In the example of the crash drop protection system, the new origami pattern could offer other customization options or change aspects of its impact strength, Paulino said.
"NSF's investments in fundamental research into architected materials have crossed borders and created 'shape-shifting' structures for applications in space exploration, robotics, and medicine," said Robert B. Stone, director of the Innovation Division Civil, Mechanical and Manufacturing Engineering of the NSF.
The new origami pattern is also capable of assuming a hybrid structure where certain lines are folded in one configuration and others are folded in the other. In such a configuration, the structure would exhibit characteristics of both types.
"There are a lot of combinations in terms of how they can be configured, which offers many possibilities for customizing structures based on the metamorphosis pattern," said Ke Liu, a Georgia Tech graduate student and currently researcher at post doctoral. California Institute of Technology.
Another unique feature of the metamorphosis pattern is what happens when a Miura-ori line is situated between two lines of egg boxes. Normally, when the tension is applied to separate any of the patterns, they respond by yielding and flattening their shape. However, in this new example, the Miura-ori pattern fits.
"The blockade is very strong, and there is no way to break that control beyond destroying the entire structure," said Phanisri Pratapa, a former postdoctoral fellow at Georgia Tech and now assistant professor of civil engineering at the Indian Institute of Technology. Madras Technology.
The blockade could allow the structures to limit the amount of possible expansion and change that limit on time, Pratapa said.
This research was supported by the National Science Foundation (NSF) under the grant CMMI-1538830 and the chair Raymond Allen Jones at the Georgia Institute of Technology. Content is the sole responsibility of the authors and does not necessarily represent the official views of these organizations.
Citation: Phanisri P. Pratapa, Ke Liu, Glaucio H. Paulino, "Geometric mechanics of origami patterns exhibiting the Poisson ratio by changing the Mountain / Valley attribution" (Physical Review Letters, April 2019).
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