Sound trapping and waveguiding in locally resonant viscoelastic phononic crystals

Abstract

We describe the trapping and absorption of audible sound in centimeter-scale claddings of two-dimensional, locally resonant phononic crystals. In a square lattice of local resonators consisting of steel cores and cellulose shells, embedded in a viscous foam, dual acoustic-range band gaps extending from about 200 to $$2850 \text { Hz}$$ 2850 Hz are achieved. The spectral range consists of a low-frequency, local resonance gap, separated from a higher frequency Bragg resonance gap, by narrow bands of slow-sound modes. We demonstrate that thin claddings of such phononic crystal, of only three unit cells in thickness, can effectively prevent sound transmission, by a combination of reflection and absorption, over much of the audible spectrum. Moreover, frequency-selective sound transmission can be enabled by engineering waveguide channels that transmit sound through the local resonance gap, the Bragg gap, or both. This offers a path to sound-sculpting claddings that can surround a noise-generating source. The viscoelastic foam in our cladding is treated using a fractional Voigt model, capable of describing experimentally observed responses.

Molecular dynamics simulation and experimental verification of the effects of vinyl silicone oil viscosity on the mechanical properties of silicone rubber foam

“…Currently, the regulation of cellular structure, rheology, viscoelasticity, and aging of the SRF have been studied. 15–19 Few researchers have conducted in-depth the impact of vinyl silicone oil viscosity on the performance of the SRF via all-atom molecular dynamic simulation. 20,21 This article has investigated in detail the molecular motion trajectories, molecular interactions, and the crosslinking process of the SRF prepared from vinyl silicone oil with different viscosities through MD simulation.…”