Holey Sheet! A Programmable Mechanical Metamaterial

We probe the mechanics of BiHolar metamaterials, 2D elastic media with a square lattice of circular holes of two different sizes. Biaxial loading of these BiHolar structures leads to a wealth of mechanical responses, including mechanically switchable hysteresis and memory effects. We show that we can program the mechanical response with the loading force and the hole size ratios.\footnote{Bastiaan Florijn, Corentin Coulais, and Martin van Hecke, Phy. Rev. Lett. \textbf{113}, 175503 (2014)}