A multi-wave elastic metamaterial based on degenerate local resonances

In this letter, an experimental and numerical study of the influence of symmetric resonators on Lamb waves that propagate in a thin metallic plate is reported. The resonators consist of a set of small, closely packed rods that pass through the plate from side to side to create a locally resonant metamaterial. Adjusting the symmetry of these rods creates degenerate flexural resonances that can be tuned to couple only with a given Lamb mode that is either symmetric (S0) or anti-symmetric (A0). This approach offers promising perspectives in the development of metamaterials for elastic waves that involve non-scalar interactions.