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Predicting and optimising acoustical and vibrational performance of open porous foams
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis concerns the modelling of acoustical and vibrational properties of open cell porous foams in multi-layered structures, especially multi-layered panels. The object is to enable optimisation of the microscopic geometry of the foam with respect to macroscopic quantities such as sound pressure level, surface velocity, total mass or cost. The developed method is based on numerical solutions to Biot's equations were scaling laws has been used to connect the microscopic geometry of the foam to macroscopic properties such as density, flow resistivity and characteristic length. Efforts have also been made to establish a scaling law for tortuosity that allows for adaptation to different strut shapes.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 16 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2008:37
Keyword [en]
porous material, foam, Biot, optimisation, tortuosity, permeability
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-4820ISBN: 978-91-7415-013-1 (print)OAI: oai:DiVA.org:kth-4820DiVA: diva2:14135
Presentation
2008-06-12, Sal D3, KTH, Lindstedtsvägen 5, Stockholm, 14:00
Opponent
Supervisors
Note
QC 20101117Available from: 2008-06-11 Created: 2008-06-11 Last updated: 2010-11-17Bibliographically approved
List of papers
1. Optimising open porous foam for acoustical and vibrational performance
Open this publication in new window or tab >>Optimising open porous foam for acoustical and vibrational performance
2010 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 329, no 7, 753-767 p.Article in journal (Refereed) Published
Abstract [en]

A computational method for designing optimal arrangements of multilayer noise and vibration treatments in general and porous open cell foam in particular is discussed. The method uses finite element solutions to Biot's equations for poroelastic materials and provides data to evaluate cost functions and gradients. The porous material is parameterised using scaling laws linking the microscopic properties to the classical parameters, i.e. averaged elasticity, flow resistivity and characteristic viscous and thermal lengths. The cost function is either in terms of weight or in terms of the pressure response in a finite cavity, complemented with constraints on the other. However, care must be taken when choosing the cost function, as this will greatly affect the outcome of the optimisation. Observations made during the optimisation process indicate a limited number of minima within the parameter range of interest as well as beneficial continuity around these minima, thus enabling a meaningful optimisation. The results suggest that if alterations of the microscopic properties of the foam are made, the foam may be adapted to specific environmental conditions and thereby achieve improved acoustic behaviour as well as reduced weight.

Keyword
optimization, media, propagation, equations, panels
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-19139 (URN)10.1016/j.jsv.2009.10.009 (DOI)000273913900001 ()2-s2.0-71049195295 (Scopus ID)
Note
QC 20100525 Uppdaterad från submitted till published (20101117). Tidigare titel: "Optimising open porous foams for acoustical and vibrational performance"Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
2. Evaluation of tortuosity models for open porous foams
Open this publication in new window or tab >>Evaluation of tortuosity models for open porous foams
2008 (English)Article in journal (Other academic) Submitted
Keyword
open porous foam, tortuosity, strut shape, permeability
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-8733 (URN)
Note
QS 20120314Available from: 2008-06-11 Created: 2008-06-11 Last updated: 2012-03-14Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
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More styles
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  • Other locale
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Output format
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