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Tuning sound transmission loss for multi-layer panels with anisotropic foams
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. Volvo Construction Equipment.ORCID iD: 0000-0001-9948-249X
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.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), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. Le Mans Université, CNRS, LAUM, UMR 6613, IA-GS.ORCID iD: 0000-0001-9071-6325
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0002-6555-531X
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2022 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Multilayer panels consisting of a load carrying structure, a porous material for thermal and acoustic insulation and an interior trim panel is a very common type of design for vehicles. Weight as well as total build height are usually limiting constraints on the design. The idea of using an anisotropic porous material instead of an isotropic one to improve the sound transmission loss without adding a lot of weight or thickness is explored in the paper. By using a state space formulation of the transfer matrix method transmission loss it is possible to include anisotropic material properties in the calculation. The anisotropic material is modelled by a combination of a simplified analytical model for the acoustic losses and inverse estimation of the 21 independent elastic constants of the Hooke’s tensor. The porous material, which has typical dimensions possible to 3D print, is based on a Kelvin cell micro model that has a controlled degree of anisotropy. 

Place, publisher, year, edition, pages
2022. article id ID399
Keywords [en]
Transmission loss, anisotropic, foam, micro-structure, analytical, open-cell
National Category
Fluid Mechanics and Acoustics Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-317065OAI: oai:DiVA.org:kth-317065DiVA, id: diva2:1693054
Conference
ISMA 2022, International Conference on Noise and Vibration Engineering, Leuven, Belgium
Funder
Vinnova, 2016-05195
Note

Proceedings will be published after the conference taking part 12th-14th September 2022. The conference paper has been submitted.

QC 20220909

Available from: 2022-09-05 Created: 2022-09-05 Last updated: 2022-10-12Bibliographically approved
In thesis
1. Micro-structural based acoustic modelling of anisotropic open cell materials
Open this publication in new window or tab >>Micro-structural based acoustic modelling of anisotropic open cell materials
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2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A method for the calculation of the acoustic performance of open-cell foammaterials is discussed. From a known micro-structural geometry and theconstituent material, the relevant acoustic properties are computed using apreviously published analytical method for the calculation of the dynamicdrag impedance and a previously published method for the calculation of theelastic moduli. These have been combined and are here used to generate thenecessary inputs to a fully anisotropic state space formulation of a TransferMatrix Method (TMM) based solution where only geometry and materialproperties need to be known. From the TMM solution, the sound absorptionand sound transmission loss of multilayer panels including anisotropic opencell materials is estimated. It is shown that the proposed method may beused in an optimization of sound absorption in multi-layer porous materials, where the different layers can have different degrees of anisotropy in theiracoustic and elastic properties. In the current work, the micro-geometry is based on the Kelvin cellwhich then is modified to achieve a controlled degree of anisotropy. The method has been validated by comparing the absorption and sound transmission loss for isotropic porous materials have been compared to equivalent structures computed with a commercial TMM mode, including a porous material which has been fully characterized with regard to previously published Johnson-Champoux-Allard parameters. In addition the calculated dynamic drag impedance has been compared to measurements conductedon a series of small samples with a defined 3D printed micro geometry forwhich the static flow resistivity has been measured. The method in general underestimates the dynamic drag impedance compared to the static flowresistivity due to not including the contributions to the losses from the constrictions between the struts close to the cell vertices. All verification showa good degree of agreement, confirming that for open-cell porous materials with reasonably high porosity the method may be used for design of novel acoustic treatments.

Abstract [sv]

En metod för beräkning av de akustiska egenskaperna hos skummaterialmed öppna celler diskuteras. Baserat på en känd mikrogeometri and de ingående materialen kan de relevanta akustiska egenskaperna beräknas. Metoden bygger på arbeten för dynamiskt flödesmotstånd och beräkning avelastiska egenskaper som publicerats tidigare. De egenskaperna ¨ar inkluderade i en fullt anisotrop formulering för lösning av en state space TransferMatrix Method (TMM) beräkning, där endast geometri och material krävs som indata. Från TMM-beräkningen kan ljudabsorption och ljudtransmission i konstruktioner med flera skikt uppskattas. Möjligheten att göra optimering av ljudabsorption av flera kombinerade skikt med olika grader avanisotropi i beräknade akustiska och styvhetsegenskaper har visats. I detta arbete baseras mikrogeometrin på en Kelvincell-geometri, som modifierats för att uppnå en definerad grad av anisotropi. Metoden har validerats genom att jämföra absorption och ljudtransmission av ekvivalenta strukturer beräknade med ett kommersiellt TMM-program på ett skum-material som karaktäriserats med avseende på publicerade Johnson-Champoux-Allard parametrar. Dessutom har de beräknade dynamiska flödesmotstånden jämförts medmätningar av statiskt flödesmotstånd på små prov tillverkade med 3D-printer. Metoden underskattar generellt flödesmotståndet jämfört med det uppmätta statiska flödesmotståndet eftersom inverkan av trånga sektioner mellan mikro-strävorna negligeras. All verifiering visar en god nivå av överensstämmelse och bekräftar att metoden skulle kunna användas för att göra nya typer av akustiska konstruktioner i flera lager med porösa material med öppna celler och relativt hög porositet .

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH Royal Institute of Technology, 2022. p. 43
Series
TRITA-SCI-FOU ; 2022:40
Keywords
sound absorption, vehicle, anisotropic, foam, micro-structure, resource efficient, transfer matrix method, ljudabsorption, anisotrop, skum, mikrostruktur, TMM, fordon, resurseffektiv
National Category
Vehicle Engineering Fluid Mechanics and Acoustics
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-317221 (URN)978-91-8040-328-3 (ISBN)
Public defence
2022-09-30, Kollegiesalen, Brinellvägen 8, KTH Campus, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
VinnExcellence Center for ECO2 Vehicle design, VinnExcellence Center for ECO2 Vehicle design
Funder
Vinnova, 2016-05195
Note

QC 220905

Available from: 2022-09-08 Created: 2022-09-07 Last updated: 2022-09-08Bibliographically approved

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Lundberg, EvaMao, HuinaGaborit, MathieuRumpler, RomainSemeniuk, BradleyGöransson, Peter

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Lundberg, EvaMao, HuinaGaborit, MathieuRumpler, RomainSemeniuk, BradleyGöransson, Peter
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VinnExcellence Center for ECO2 Vehicle designMarcus Wallenberg Laboratory MWL
Fluid Mechanics and AcousticsVehicle Engineering

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