Programming shape morphing in metamaterials

The internal structuring of materials on a mesoscale, e.g., μm-cm enables to design almost arbitrary effective physical properties into so called metamaterials. Moreover, programmable materials can be useful in application where conflicting conditions to the shape of the material exist (e.g., wings, personalized tools). They use a stimuli-excited change in the meso-structure to manipulate macroscopic properties in a controlled manner. The mesostructure is no longer static, but responsive to stimuli. The property changes can be either continuous, as a designed non-linear elastic behavior (processing a function), or abrupt (if-then-else condition). Such a logical behavior is implemented into unit cells to control the local Poisson’s Ratio as well as the stiffness. These properties are related to geometrical parameters (angles, beam thicknesses) of unit cells that can be varied over a material’s volume. The combination of the local unit cell logic and the global parameter distribution leads to a specific shape morphing behavior. Multiscale models and mathematical optimization methods enable us to compute optimal unit cell parameters for large cell arrays. Several unit cells created by different manufacturing methods (3D-printing, foil stacking) will be shown. The designed shape morphing behavior will be presented based on simulations as well as with physical demonstrators.