Deployable structures harness curved beams

1 min read

Harvard engineers and designers have developed a new technique that uses rotating curved supports to transform flat, 2D objects into 3D structures.

Known as Kiriform, the manufacturing method has so far been used to create an array of prototypes from small medical devices to pieces of furniture. It is created by layering flat sheets of precisely cut elastic material on top of each other, with the different layers interacting to support each other once the 2D object is rotated into its 3D form. Unlike traditional folding furniture, the deployment mechanism for Kiriform is ‘compliant’ rather than ‘rigid’, meaning little effort is required to extend or collapse devices made using this method.

"Most buckling-induced deployable structures, like folding chairs, are activated by compressive forces that are created through the linear displacement of elements," said Saurabh Mhatre, a research associate the Harvard Graduate School of Design (GSD) and first author of the paper, which appears in Advanced Functional Materials.

"Our approach is different in that the compression force is generated through a rotational movement, which in turn induces buckling as the trigger for the 2D-to-3D transformation."

Researchers from the GSD worked with colleagues from Harvard’s John A Paulson School of Engineering and Applied Sciences (SEAS), using experiments and numerical analyses to understand the geometry of curved, slender beams and their performance under rotation and buckling. Kiriform prototypes built by the team include a lampshade that can be rotated to adjust the amount of light in a room and a coffee table that can fold flat and pop up in a single rotational motion.

"This new platform can be extended to realise functional structures and devices from the millimetre to metre scale using a variety of different materials," said senior author Katia Bertoldi, Professor of Applied Mechanics at SEAS.

"These structures could be used as medical devices, optical devices like camera focusing mechanisms, deployable wheels and turbines, furniture, or deployable shelters."