Deep subwavelength acoustic metamaterial for low-frequency sound absorption

¹ MOE Key Laboratory for Multifunctional Materials and Structures Xi'an Jiaotong University - Xi'an 710049, PRC
² State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University Xi'an 710049, PRC
³ Department of Mechanical Engineering, The University of Hong Kong - Pokfulam Road, Hong Kong

^(a) fengxian.xin@gmail.com
^(b) tjlu@mail.xjtu.edu.cn

Received: 22 April 2017
Accepted: 5 July 2017

Abstract

A novel class of low-frequency sound absorbers based on a honeycomb sandwich panel is theoretically designed and numerically demonstrated. The absorber with a remarkably small thickness (e.g., 1/131 of wavelength) is comprised of a perforated facesheet, a perforated honeycomb core and a non-perforated back panel. Built upon the classical microperforated panel absorber (MPPA), the idea of introducing a perforated honeycomb core which creates a double-layer perforated absorber (DLPA) without adding to the total thickness greatly enhances the low-frequency absorption performance. Theoretical predictions of the sound absorption coefficient are obtained and compared with numerical simulations obtained using the finite element method (FEM). A good agreement is achieved. The proposed sound absorber is promising for low-frequency noise absorption especially when limited space and high mechanical stiffness/strength are simultaneously demanded.