Thermal tuning of negative effective mass density in a two-dimensional acoustic metamaterial with hexagonal lattice

The unique characteristics like periodic and locally resonant behaviors of acoustic metamaterials result in an anomalous response to the wave propagation and exhibit complete elastic wave bandgaps. However, these unusual properties arise from the geometry of the artificially designed metastructure and can be significantly affected under the exposure of the thermal environment. In this paper, we present a thermally tunable two-dimensional acoustic metamaterial with a hexagonal lattice. The numerical results demonstrated that by adjusting the externally applied temperature to the structure and imposing several different load conditions like thermal deformation and thermal stress, a tunable effective mass density of the metamaterial could be obtained. The proposed concept further extends the ongoing research in the field of tunable acoustic metamaterials.