Next-generation inflatable buildings maintain their shape without constant pressure

In 2016, an inflatable archway wreaked havoc on the Tour de France bike race, when it deflated and crashed into a cyclist, throwing him off the bike and delaying the race while officials rushed to remove debris from the road. Officials blamed the fall of a passing spectator’s buckle for the collapse of the arch, but the real culprit was physics.

Today’s inflatable structures, used for everything from field hospitals to sports complexes, are monostable, which means that they need a constant supply of pressure to maintain their state of inflation. You lose this pressure and the structure returns to its only stable shape – flat.

What if these structures had more stable states? What if the bow was as stably inflated as it is flat on the ground?

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

The research is published in The nature.

“This research provides a direct pathway for a new generation of robust, large-scale inflatable systems that lock after installation and do not require continuous pressure,” said Katia Bertoldi, William and Ami Kuan Danoff, professor of applied mechanics at SEAS and main author of the paper.

Inspired by origami and guided by geometry, the research team has developed a library of triangular building blocks that can appear or fold flat and can be combined in different configurations to build closed, multistable shapes.

“We rely on the geometry of these building blocks, not the characteristics of the materials, which means we can make these building blocks from almost any material, including cheap recyclable materials,” said Benjamin Gorissen, associate in materials science and mechanical engineering at SEAS. and co-author of the paper.

Taking their real-world design process, the researchers designed and built an 8-foot, 4-foot inflatable shelter made of thick plastic sheets.

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

The shelter can be set up by one or two people, as opposed to a dozen or so, to run 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 number of other structures, including an archway, an extendable arm and a pagoda-style structure. The researchers also designed shapes with more than two stable shapes.

“We’ve unlocked an unprecedented design space for large-scale inflatable structures that can fold flat and stay in shape without the risk of catastrophic rupture,” said Chuck Hoberman, Pierce Anderson’s lecturer in design engineering at the Graduate School of Design and co-author of the paper. “By using inflatable, reversible drive to make hard-walled structural enclosures, we see important applications, not only here on Earth, but potentially as habitats for lunar or Mars exploration.”