Shape-switching Undulating Sheets

We present thin, undulating sheets that switch rapidly and reversibly between many distinct shapes. Local, hysteretic snap-through events underlie this shape-switching behaviour. Snapped-through 'defects' deform the sheet; their interactions, which we predict using a simple numerical model, govern the material's overall shape. We identify external forcing conditions that lead to the organized assembly of local defects, resulting in controllable shape-switching.