Next generation inflatable buildings retain their shape without constant pressure input

In 2016, an inflatable bow wreaked havoc at the Tour de France bike race when it blew up on a cyclist and collapsed, tossing him off his bike and slowing the race while officials scrambled to clear the rubble of the road . Officials blamed the stubborn belt muscle of a spectator for the collapse of the arch, but the physical culprit.

The inflatable structures of today, used for everything from field hospitals to sports complexes, are monostable, meaning they need a constant pressure to maintain their inflated condition. Loses the pressure and the structure returns to its only stable shape – flat.

But what if these structures had more than one stable state? What if the arch was inflated just as stably as flat on the ground?

Now researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed bistable inflatable structures inspired by origami.

The research is published in Earth.

“This research provides a direct path to a new generation of robust, large-scale inflatable systems that can lock in place after deployment and do not require continuous pressure,” said Katia Bertoldi, William and Ami Kuan Danoff Professor of Applied Mechanics. SEAS, said. and senior author of the paper.

Inspired by origami and led by geometry, the research team developed a library of triangular building blocks that can pop up or fold flat and be combined into different configurations to build closed, multistable shapes.

“We rely on the geometry of these building blocks, not the material properties, which means we can make these building blocks from almost any material, including inexpensive recyclable materials,” said Benjamin Gorissen, a Materials and Mechanical Engineer at SEAS and co-first author of the paper.

The researchers took their design process to the real world and designed and built an 8-by-4-foot inflatable shelter from thick plastic sheets.

“You can imagine these shelters being deployed as part of the emergency response in a disaster area,” said David Melancon, a Ph.D. student at SEAS and co-first author of the paper. “They can be stacked flat on a truck and you only need one source of pressure to inflate it. Once inflated, you can remove the source of pressure and move to the next tent.”

The shelter could be set up by one or two people, as opposed to the dozen needed to deploy today’s military field hospitals.

The building blocks of these origami structures can be mixed and matched to create a structure of any shape or size. The researchers built a series of other structures, including an arch, an extendable tree and a pagoda structure. The researchers also designed shapes with more than two stable shapes.

“We have unlocked an unprecedented design space of large-scale inflatable structures that can fold flat and maintain their deployed shape without the risk of catastrophic breakage,” said Chuck Hoberman, Pierce Anderson Lecturer in Design Engineering at the Graduate School of Design and co-author of the paper. “By using inflatable, reversible ministries to create hard-walled structural fences, we see important applications, not only here on earth, but also as habitats for exploring the moon or Mars.”