Active control of wave propagation direction of elastic metamaterial

This paper proposes a novel active control strategy for manipulating wave propagation directions in elastic metamaterials using magnetorheological elastomers (MREs) without structural modifications. A broadband elastic metamaterial with quasi-lattice structure was developed, consisting of metallic mass blocks and MRE components. The dynamic equations for both one- and two-dimensional metamaterials were established, yielding the dispersion relations. The reliability of analytical method was verified through comprehensive comparisons among theoretical solutions, finite element simulations, and experimental results. The results demonstrate that the bandgap of metamaterial can be effectively tuned by applying different magnetic flux densities. For directional wave control, a modified two-dimensional metamaterial model was designed by strategically redistributing MRE components. Through selective application of magnetic fields, independent switching of elastic wave propagation in two orthogonal directions was achieved. Furthermore, a hexagonal metamaterial structure was proposed to enable more precise wave steering in three principal directions. The proposed control strategy and structural design can be extended to develop elastic metamaterials with multi-directional wave manipulation capabilities.