Reshapable groovy sheets

Most mechanical metamaterials are designed for a single function. But multifunctional metamaterials need to respond distinctly to different kinds of mechanical input. We show that groovy sheets---thin sheets with parallel corrugations---form patterns of snap-through defects and shift into different shapes, depending on how they are actuated. We show that geometric nonlinearities and frustration lie at the heart of the reversible yet multistable behaviour of groovy sheets.