Origami-inspired material absorbs force of landing, could help make rockets reusable

Rocket legs made from this material could make odds of their reusability much higher.

Inspired by the paper-folding art of origami, scientists are designing materials that can withstand high impact collisions — an advance that may be used to build reusable spacecraft.

Landing is stressful for reusable rockets because they must handle the force from the impact with the landing pad. One way to combat this is to build legs out of materials that absorb some of the force and soften the blow. Researchers from the University of Washington in the US have developed a novel solution to help reduce impact forces.

Taking inspiration from the Japanese paper-folding art of origami, the team created a paper model of a metamaterial that uses "folding creases" to soften impact forces and instead promote forces that relax stresses in the chain.

"If you were wearing a football helmet made of this material and something hit the helmet, you'd never feel that hit on your head. By the time the energy reaches you, it's no longer pushing. It's pulling," said Jinkyu Yang, an associate professor at the University of Washington.

Representational image of origami dragon. Image credit: Pexels

Representational image of origami dragon. Image credit: Pexels

For the research, published in the journal Science Advances, the team designed a metamaterial to have the properties they wanted. "Metamaterials are like Legos. You can make all types of structures by repeating a single type of building block, or unit cell as we call it," said Yang. "Depending on how you design your unit cell, you can create a material with unique mechanical properties that are unprecedented in nature," he said.

The researchers turned to the art of origami to create this particular unit cell. "Origami is great for realising the unit cell. By changing where we introduce creases into flat materials, we can design materials that exhibit different degrees of stiffness when they fold and unfold," said Yasuhiro Miyazawa, a doctoral student at the University of Washington.

"Here we've created a unit cell that softens the force it feels when someone pushes on it, and it accentuates the tension that follows as the cell returns to its normal shape," said Miyazawa.

Just like origami, these unit cell prototypes are made out of paper. The researchers used a laser cutter to cut dotted lines into the paper to designate where to fold.  The team folded the paper along the lines to form a cylindrical structure and then glued acrylic caps on either end to connect the cells into a long chain.

"Impact is a problem we encounter on a daily basis, and our system provides a completely new approach to reducing its effects. For example, we'd like to use it to help both people and cars fare better in car accidents," Yang said.  "Right now it's made out of paper, but we plan to make it out of a composite material. Ideally, we could optimise the material for each specific application," he said.

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