Multilevel structural defects-induced elastic wave tunability and localization of a tensegrity metamaterial

Defects are generally inevitable when fabricating the constituent structures of tensegrity metamaterials. How structural defects affect the mechanical properties of such metamaterials is an interesting and vital issue, which may provide a new approach for their elastic wave control. We here construct a metamaterial chain composed of two types of prismatic tensegrities, and investigate its bandgap characteristics with considering multilevel structural defects, namely, unit defect and cell defect. Both the Bloch theorem-based derivations and frequency–response simulations show that the chain can exhibit multi defect states, that is, several flat bands within the bandgap, which depend on the form and degree of the structural defects. Furthermore, we performed sweep frequency experiments to verify the existence of defect state induced by unit defect. Moreover, when force excitation is applied at the frequency of defect state, the excited elastic wave in the chain can be sensitively localized around the defect position. This work deepens the understanding of the defect mechanisms of tensegrity metamaterials and helps to design novel filters, flaw detectors, and energy harvesters.