MIT and Harvard Engineers Create Collapsible Buckliball

Posted on March 26, 2012


A group of engineers at MIT and Harvard University were inspired by a collapsible, spherical toy (the Hoberman Sphere) to create the buckliball, a hollow, spherical object made of soft rubber containing no moving parts, designed with 24 carefully spaced dimples. When the air is sucked out of the buckliball with a syringe it morphs into a rhombicuboctahedron about half the size of the original sphere.

Collapsed Buckliball

When the air is sucked out the thin ligaments forming columns between lateral dimples in the buckliball collapse. The researchers say this is the engineering equivalent of applying equal load on all beams in a structure simultaneously to induce buckling, a phenomenon first studied by mathematician Leonhard Euler in 1757. The researchers also say the buckliball is the first morphable structure to incorporate buckling as a desirable engineering design element. Take a look:

The researchers say in a release that morphable structures like the buckliball concept have the potential for widespread applications, from the micro- to macroscale. These include large buildings with collapsible roofs or walls, tiny drug-delivery capsules, soft movable joints requiring no mechanical pieces and cool new toys.

Pedro Reis, Assistant Professor of Civil and Environmental Engineering and Mechanical Engineering at MIT, says, "In civil engineering, buckling is commonly associated with failure that must be avoided. For example, one typically wants to calculate the buckling criterion for columns and apply an additional safety factor, to ensure that a building stands. We are trying to change this paradigm by turning failure into functionality in soft mechanical structures. For us, the buckliball is the first such object, but there will be many others."

The research paper on the buckliball was published here in PNAS.

Photos: Jongmin Shim, Katia Bertoldi and Pedro Reis