Curved-crease origami inspires self-locking flat-packed tubular structures

Engineers have designed a tubular structural system that can be packed flat for easier transport and pop up into strong building materials.

A tube in the self-locked position
A tube in the self-locked position - Will Wright, RMIT

This advance from RMIT University in Australia is made possible by a self-locking system inspired by curved-crease origami, a technique that uses curved crease lines in paper folding.

Lead researchers, Dr Jeff (Ting-Uei) Lee and Distinguished Professor Mike (Yi Min) Xie, said bamboo, which has internal structures providing natural reinforcement, inspired the tube design.

“This self-locking system is the result of an intelligent geometric design,” Lee said in a statement. “Our invention is suitable for large-scale use - a panel, weighing just 1.3kg, made from multiple tubes can easily support a 75kg person.”

Flat-pack tubes are used in engineering and scientific applications, such as in biomedical devices, aerospace structures, robotics and civil construction, including pop-up buildings as part of disaster recovery efforts.

The new system is claimed to make these tubes quicker and easier to assemble, with the capability to automatically transform into a strong, self-locked state.

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“Our research not only opens up new possibilities for innovative and multifunctional structural designs, but it can also significantly improve existing deployable systems,” said Xie from RMIT’s School of Engineering.

“When NASA deploys solar arrays, for example, the booms used are tubes that were packed flat before being unfurled in space,” said Lee, who is also affiliated with the School of Engineering. “These tubes are hollow though, so they could potentially deform under certain forces in space. With our new design, these booms could be a stronger structure.”   

Xie said their smart algorithm enabled control over how the structure behaved under forces by changing the tube orientations.

“With our origami-inspired innovation, flat-pack tubes are not only easy to transport, but they also become strong enough to withstand external forces when in use,” said Xie.

“The tube is also self-locking, meaning its strong shape is securely locked in place without the need for extra mechanisms or human intervention.” 

The team will continue to improve the design and explore new possibilities for its development.

“We aim to extend the self-locking feature to different tube shapes and test how the tubes perform under various forces, such as bending and twisting,” said Lee. “We are also exploring new materials and manufacturing methods to create smaller, more precise tubes.”

The research is published in Proceedings of the National Academy of Sciences (PNAS). Other contributors to this work include Drs Hongjia Lu, Jiaming Ma and Ngoc San Ha from RMIT’s School of Engineering and Associate Professor Joseph Gattas from the University of Queensland.