Locally resonant structures for sound shielding applications

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dc.contributor.author Calius, Emilio en
dc.contributor.author Hall, Andrew en
dc.contributor.author Wester, E en
dc.contributor.author Chan, KL en
dc.contributor.author Smith, B en
dc.contributor.author Dodd, George en
dc.coverage.spatial Bejing en
dc.date.accessioned 2018-10-02T22:31:53Z en
dc.date.issued 2011-05-23 en
dc.identifier.uri http://hdl.handle.net/2292/38345 en
dc.description.abstract The intrusion of unwanted sound is a matter of increasing concern worldwide. Growing sound pollution has significant implications for human health, productivity and wellbeing in industrial, educational, and residential settings. Lower frequency noise in particular is subjectively important, as this is the range in which the human ear is most sensitive and irritating acoustic intrusion frequently occurs, yet sound insulation at low frequencies is technically challenging and expensive, specially for lighter construction. Meta-materials theory offers a relatively new approach to achieving high levels of acoustic transmission loss (TL) through the generation of band gaps where wave propagation is forbidden. This theory is being applied to develop panels with internal resonant structures that generate low-frequency acoustic band gaps yet are only a few centimetres thick. These resonant structures may exhibit negative mass behaviour, but it has been found that the key performance indicator is the ratio of the absolute value of the effective mass to the rest mass near resonance. This paper focuses on the behaviour of single and multi-layer systems with a multiplicity of closely spaced resonances, and examines the effect of resonator variability resulting from material and manufacturing imperfections. The acoustic response of these systems can be significantly richer than that of the individual resonant elements. This allows the system to, for example, compensate for dips in TL associated with Mass-Air-Mass resonances in double layer walls. Tailoring the individual resonator properties was shown to enable the maximisation of performance while minimising any detrimental effects. Scalability of the resonant elements was found to be a major issue at lower frequencies due to fundamental characteristics of mechanical oscillators. A combination of analytical and finite element modelling was used to explore the system design space, evaluate and rank the impact of design parameters. The models were verified by dynamic and acoustic measurements of small-scale specimens containing limited numbers of resonant elements. Various resonator elements have shown a peak effective mass up to fifty times greater than their rest mass. When incorporated into multi-layer structures, some of these local resonances have resulted in transmission loss peaks approaching 80dB, tens of decibels higher than that of non-resonant structures of equivalent area density. en
dc.relation.ispartof ISAM2011 en
dc.relation.ispartof International Symposium on Acoustic Metamaterials en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Locally resonant structures for sound shielding applications en
dc.type Presentation en
dc.rights.holder Copyright: The author en
pubs.finish-date 2011-05-25 en
pubs.start-date 2011-05-23 en
dc.rights.accessrights http://purl.org/eprint/accessRights/RestrictedAccess en
pubs.subtype Conference Oral Presentation en
pubs.subtype Invited en
pubs.elements-id 707520 en
pubs.org-id Engineering en
pubs.org-id Mechanical Engineering en
pubs.record-created-at-source-date 2017-11-07 en

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