Adv. Mater. http://doi.org/f3f5tx (2015)

Credit: WILEY

Mechanical metamaterials are well known to be capable of nonlinear stress–strain behaviour, associated with their unique architecture rather than their chemical make-up. Now, Ahmad Rafsanjani et al. report a design that permits a series of large serrations — or load drops — during tensile loading, caused by snapping beam buckling. Their design relies on an architecture consisting of two features, bearing and snapping segments, with the snapping segments periodically attached to the bearing segments. During tensile straining of the rubber-like material, the snapping segments behave like clamped beams, reaching a critical strain at which they snap from one configuration to the next. The snapping segments in the multilayered structure are activated at different strains, permitting substantial periodic load-drops in the system's mechanical response. Up to 150% strain is demonstrated for a fully elongated structure and finite element simulations and modelling point towards how mechanical characteristics can be controlled. The authors suggest that such an architecture might be useful in deployable structures, and for vibration isolation and damping.