Focusing guided waves using surface bonded elastic metamaterials

Bonding a two-dimensional planar array of small lead discs on an aluminum plate with silicone rubber is shown numerically to focus low-frequency flexural guided waves. The effective mass density profile of this type of elastic metamaterials (EMMs), perpendicular to wave propagation direction, is carefully tailored and designed, which allows rays of flexural A(0) mode Lamb waves to bend in succession and then focus through a 7 x 9 planar array. Numerical simulations show that Lamb waves can be focused beyond EMMs region with amplified displacement and yet largely retained narrow banded waveform, which may have potential application in structural health monitoring. (C) 2013 AIP Publishing LLC.