Shape morphing from instability and frustration

In most studies, the occurrence of shape morphing requires either symmetry breaking or defects in undeformed structures. Furthermore shape morphing needs to be actuated by an input control, such as pneumatic networks or external magnetic fields. Here we present a new type of shape morphing method that can be achieved by the use of periodic structures. Due to the instability, the periodic structure automatically generates a frustration under a homogeneous compression. The frustration breaks the symmetry of the deformation and therefore generates a global bending deformation. Although the direction of the bending seems random, it can be manipulated by programming  the geometric parameters of the structure. The presented structure has the potential to be used as a robotic arm and achieves programmable responses by simple input control.