A continuum model reproducing the multiple frequency crossovers in acoustic attenuation in glasses

Structured metamaterials are at the core of extensive research, promising for acoustic and thermal engineering. Nevertheless, the computational cost required for correctly simulating large systems imposes to use a continuous model to describe the effective behavior without knowing the atomistic details. Crucially, a correct description needs to describe both the extrinsic interface-induced and the intrinsic atomic scale-originated phonon scattering, especially when the component material is made of glass, a highly dissipative material in which wave attenuation is strongly dependent on frequency as well as on temperature. In amorphous systems, the effective acoustic attenuation triggered by multiple mechanisms is now well characterized and exhibits a nontrivial frequency dependence with a double crossover of power laws. In this work, we propose a continuum viscoelastic model based on the hierarchical strategy multi-scale approach, able to reproduce well the phonon attenuation in a large frequency range, spanning three orders of magnitude from GHz to THz with a omega(2) -omega(4) -omega(2) dependence, including the influence of temperature.

Automated summary

Structured metamaterials hold great promise in acoustic and thermal engineering, but simulating large systems can be computationally expensive. A continuous model is often used to describe the effective behavior, especially for materials like glass that have strong frequency and temperature-dependent wave attenuation. This study proposes a viscoelastic model based on a hierarchical multi-scale approach that accurately reproduces the phonon attenuation over a wide frequency range.