Realisation of a locally resonant metamaterial on the automobile panel structure to reduce noise radiation

This study aims to demonstrate the reduction in noise and vibration of an automobile dash panel structure by applying a locally resonant metamaterial (LRM). LRMs are implemented by adding a subwavelength array of local resonators to a host structure. Here, the minimum repeated structure is called a unit cell. Owing to dynamic absorption in a unit cell, LRM has a stop band (or also called a band gap), which is a frequency band in which waves cannot propagate. Taking advantage of the stop band, various studies have been conducted on mechanical noise and vibration problems. However, no case has yet been published regarding the application of LRMs to industrial structures such as automobile dash panels because of their complex shape. To overcome the difficulties of LRM realisation in dash panels, an attachable local resonator (ALR) is proposed in this study. The proposed ALR consists of a local resonator and a permanent magnet to be attached on the dash panel surface. To predict the stop band formation, a finite element-based unit cell analysis method is developed, and several ALRs are designed based on the stop band. The designed ALRs are applied to an actual automobile dash panel structure and the acoustic and vibration responses are measured. The measurement results demonstrate that the vibration and noise radiation from the dash panel structure are greatly reduced in the designed stop bands. (C) 2018 Published by Elsevier Ltd.