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Analytical method for predicting micro-geometry based flow resistivity in anisotropic foams to improve sound absorption of vehicle panels
KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.ORCID iD: 0000-0001-9948-249X
KTH, School of Engineering Sciences (SCI).
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. 1.ORCID iD: 0000-0001-9980-0144
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.ORCID iD: 0000-0002-6555-531X
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2021 (English)In: Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021) / [ed] O'Reilly, Ciarán J. et al., Stockholm, Sweden, 2021Conference paper, Published paper (Other academic)
Abstract [en]

Vehicle structures such as train floors or car roofs are usually built as multi-layer panels, where a foam is placed between a load-carrying structure and an interior panel. The foam adds acoustical and thermal performance, but very little weight. In most contributions introducing foams for acoustic treatment, these have been considered isotropic, with acoustic losses mainly dependingon properties in the thickness direction. Another mechanism investigated here is the possibilityfor the acoustic flow in the foam to change from acting only in the thickness direction but rather to be re-directed to also travel in-plane, where dimensions are substantially larger than in the thickness direction, permitting more losses as the wave travels through the material. That kind of effect would result in higher acoustic losses without increasing the thickness of the vehicle panel and better use of the allowable space to achieve acoustic and functional requirements, i.e. a better functional density. A first step is to investigate how the absorption properties of an anisotropic foam differs from an isotropic foam. The chosen approach is to use an analytical micro-modelto calculate the dynamic drag impedance (flow resistivity on micro-scale) for an anisotropic opencell foam material. Based on a simple micro-scale geometry of Kelvin cells, it has been shown that  simple cell alterations to the micro-geometry, such as stretching, twisting and tilting results in an anisotropic foam structure. The anisotropic flow resistivity tensor is not diagonal and uniform, but different directions can have different magnitudes and it can display off-diagonal coupling terms. The influence of such micro-scale distortions on the flow resistivity, and on the resulting sound absorption is investigated with the purpose of improving the acoustic performance without adding volume. Future steps include to modify the functional density and tailor the sound transmission loss to a specific application.

Place, publisher, year, edition, pages
Stockholm, Sweden, 2021.
Keywords [en]
sound absorption, Vehicle, anisotropic, foam, micro-geometry, resource efficient
National Category
Mechanical Engineering Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
URN: urn:nbn:se:kth:diva-309380OAI: oai:DiVA.org:kth-309380DiVA, id: diva2:1641385
Conference
Resource Efficient Vehicles Conference, 14-16 June 2021
Funder
Vinnova, 2016-05195
Note

QC 20220315

Available from: 2022-03-01 Created: 2022-03-01 Last updated: 2022-06-25Bibliographically approved

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Lundberg, EvaSemeniuk, BradleyMao, HuinaRumpler, RomainGöransson, Peter

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Engineering MechanicsVinnExcellence Center for ECO2 Vehicle designSchool of Engineering Sciences (SCI)Aeronautical and Vehicle Engineering
Mechanical EngineeringVehicle Engineering

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CiteExportLink to record
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