Morphing origami takes a new shape, expanding the possibilities of use

Origami-based structures have been used to create space-deployable solar panels, adaptable acoustic systems for symphony halls, and even collision avoidance systems for drones in flight.

Now, researchers at the Georgia Institute of Technology have created a new type of origami, able to switch from one pattern to another, or even a hybrid of two patterns, instantly changing many of its structural features.

The research, funded by the National Science Foundation, is to be published April 19 in the journal Letters of physical examination, could open new types of origami-based structures or metamaterials that take advantage of the characteristics of two types of origami.

"This hybrid origami allows reprogrammable mechanical properties and the ability to modify these properties as long as the material is in use," said Glaucio Paulino, a professor at the Georgia Tech School of Civil and Environmental Engineering.

The researchers started with two types of origami motifs: the Miura-ori and the egg box, both of which can be formed into repeating patterned leaves. The Miura-ori looks like a row of folded zigzags, while the pattern of the egg box looks like a mountain range with peaks and valleys that are repeated.

Both are able to be compressed in a very small space, but when they are developed, they behave differently with respect to how they respond to bending. The pattern of the egg box looks like a dome when it is folded and the Miura-ori takes the shape of a saddle.

"Traditionally, if you have an egg box pattern, you are locked into the characteristics of that particular pattern," said Paulino, who is also the Raymond Allen Jones Chair in Engineering School of the United States. civil and environmental engineering. "With this new pattern, which we call morph, this is no longer the case."

The new origami pattern reaches its transformability by redesigning the geometry of two of the four planes that make up a section of origami. By narrowing these two planes on one side, this allows their folds to pass from a mountain to a valley or, in other words, to bend in the opposite direction.

And most importantly, the transition from peak to valley may occur as 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 able to expand and contract to increase or decrease the volume of the acoustic response – could go even further. , by modifying their behavior in view of a greater range of resonant responses. In the example of the drone collision protection system, the new origami model could potentially offer other customization options or alter certain aspects of its impact resistance, Paulino said.

"NSF's investments in fundamental research on architectural materials have pushed boundaries and created" shape-change "structures for applications in space exploration, robotics and medicine," Robert B. said. Stone, Director of NSF's Civil, Mechanical and Manufacturing Innovation Division.

The new origami pattern is also able to take a hybrid structure, where some lines are folded in one configuration and others folded in the other. In such a configuration, the structure would have characteristics of both types.

"There are a lot of combinations in terms of configuration, which offers many opportunities for customization for morphing-based structures," said Ke Liu, a former Georgia Tech graduate student and now a postdoctoral fellow at the University of New York. 39, California Institute of Technology.

Another unique feature of the morphing pattern is what happens when a row of Miura-ori is located between two rows of egg cartons. Generally, when the tension is applied to separate one of the patterns, these respond by yielding and flattening their shape. However, in this new case, the Miura-ori pattern is locked.

"The lock is very strong and there is no other way to break this barrier than to demolish the entire structure," said Phanisri Pratapa, a former Georgia Tech postdoctoral fellow and today assistant professor in civil engineering at the Indian Institute of Technology Madras.

The lock could allow structures to limit the amount of expansion possible and change that limit on the fly, Pratapa said.