Broadband quasi perfect absorption using chirped multi-layer porous materials

TL;DR

This paper presents a theoretical study of a chirped multi-layer porous material that achieves broadband unidirectional sound absorption by optimizing impedance matching and loss balance, demonstrated through transfer matrix formalism and finite element simulations.

Contribution

It introduces a novel design for broadband unidirectional sound absorption using chirped multi-layer porous materials, combining impedance matching with loss management for improved low-frequency absorption.

Findings

Achieves broadband unidirectional absorption

Demonstrates excellent agreement between theory and simulation

Uses less material for effective low-frequency absorption

Abstract

This work theoretically analyzes the sound absorption properties of a chirped multi-layer porous material including transmission, in particular showing the broadband unidirectional absorption properties of the system. Using the combination of the impedance matching condition and the balance between the leakage and the intrinsic losses, the system is designed to have broadband unidirectional and quasi perfect absorption. The transfer and scattering matrix formalism, together with numerical simulations based on the finite element method are used to demonstrate the results showing excellent agreement between them. The proposed system allows to construct broadband sound absorbers with improved absorption in the low frequency regime using less amount of material than the complete bulk porous layer.