Multifunctional and customizable lattice structures for simultaneous sound insulation and structural applications

With noises being omnipresent in the modern society, sound-insulating materials are implemented in almost all walks of life. For implementations in practical applications, those that are air-ventilating and mechanically robust are highly sought-after. Herein, we present a novel concept of using lattice structures as potential ventilated sound-insulating structural materials. Focusing on a superimposed tubular and plate morphology, using a defined geometrical factor, a wide range of elastic properties can be achieved. For the isotropic lattice consisting of three layers at a cell size of 20 mm, experimentally measured, a maximum sound attenuation occurs at 1810 Hz with a high intensity of 32 dB. Past 5000 Hz, another strong attenuation band appears. Being porous, the lattice is highly ventilating with 35% of the airflow retainable. Through numerical simulations, the attenuation mechanisms are found to attribute to local Helmholtz resonance and Bragg scattering, successively. Discretizing the lattice microstructure, we propose a microstructure-based analytical model that can be used to predict and design the transmission properties of lattices. Through these, we thus come up with an overall sound transmissibility and mechanical property map based on geometrical factors. Overall, we show the potential of lattice structures as multifunctional sound-insulating materials.