Colombi et al., JASAEL (2014)

This article presents the results of a numerical analysis of a system composed of a thin metallic plate coupled with a ensemble of metallic rods of length L (see Fig.1). When a transverse force is impulsed to the plate, zero-order Lamb waves are generated. From the plate point of view, the ensemble of rods (pact on a sub-wavelength scale) forms a locally resonant metamaterial generating, for example, bandgaps in the plate (see spectrum of Fig.1). The present study concentrates on the propagative band (see the dark grey region of the spectrum in Fig.1).

When reducing the length of one rod situated in the middle of the metamaterial, and looking at the total energy trapped in it compared to the one trapped in the others, we observe an energy boost of about 2 whatever the length Ld of the defect (see Fig.1(a): Ld=L/2;Fig.1(b): Ld=L/4; Fig.1(c) same as (b) but with some randomness in the arrangement).