Buckle in
Motivated by the desire to determine the simplest 3-D structure that could take advantage of mechanical instability to collapse reversibly, a group of engineers at MIT and Harvard University were stymied — until one of them happened across a collapsible, spherical toy that resembled the structures they’d been exploring, but with a complex layout of 26 solid moving elements and 48 rotating hinges.The toy inspired the engineers to create the “buckliball,” a hollow, spherical object made of soft rubber containing no moving parts, but fashioned with 24 carefully spaced dimples. When the air is sucked out of a buckliball with a syringe, the thin ligaments forming columns between lateral dimples collapse. 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.When the buckliball’s thin ligaments buckle, the thicker ligaments forming rows...