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Identification of the full anisotropic flow resistivity tensor for multiple glass wool and melamine foam samples
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics. (The Marcus Wallenberg Laboratory of Sound and Vibration Research)
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Numerical acoustics.ORCID iD: 0000-0003-1855-5437
2013 (English)In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 134, no 6, 4659-4669 p.Article in journal (Refereed) Published
Abstract [en]

The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of porous materials used in acoustic treatments. Due to the manufacturing processes involved, these porous materials are most often geometrically anisotropic on a microscopic scale, and for demanding applications, there is a need for improved characterization methods. This paper discusses recent refinements of a method for the identification of the anisotropic flow resistivity tensor. The inverse estimation is verified for three fictitious materials with different degrees of anisotropy. Measurements are performed on nine glass wool samples and seven melamine foam samples, and the anisotropic flow resistivity tensors obtained are validated by comparison to measurements performed on uni-directional cylindrical samples, extracted from the same, previously measured cubic samples. The variability of flow resistivity in the batch of material from which the glass wool is extracted is discussed. The results for the melamine foam suggest that there is a relation between the direction of highest flow resistivity, and the rise direction of the material.

Place, publisher, year, edition, pages
2013. Vol. 134, no 6, 4659-4669 p.
Keyword [en]
Inverse Estimation, Fibrous Materials, Absorption, Frame
National Category
Aerospace Engineering Applied Mechanics Vehicle Engineering Fluid Mechanics and Acoustics
URN: urn:nbn:se:kth:diva-133593DOI: 10.1121/1.4824841ISI: 000328654900009ScopusID: 2-s2.0-84890155492OAI: diva2:662345
EU, European Research Council, MRTN-CT-2006-35559

QC 20140121

Available from: 2013-11-06 Created: 2013-11-06 Last updated: 2014-01-21Bibliographically approved
In thesis
1. Vibro-acoustic modelling of anisotropic poroelastic materials: characterisation of the anisotropic properties
Open this publication in new window or tab >>Vibro-acoustic modelling of anisotropic poroelastic materials: characterisation of the anisotropic properties
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present-day challenges in the transport industry, steered by the increasing environmental awareness, necessitate manufacturers to take measures to reduce emissions related to the movements of goods and humans. In particular, the measures aiming at a reduced mass or higher load capacity to increase fuel efficiency,  generally deteriorate the noise and vibration insulation properties of their products. In order to comply with the regulations and customer demands, modern vehicles increasingly move towards a multifunctional integrated design approach, if possible for all subcomponents involved. Such a multifunctional design approach is an iterative process, evaluating the proposed solutions in every stage, and is therefore best performed in a virtual testing environment. \\Poroelastic materials are interesting to include in a multifunctional design, offering reasonably good vibro-acoustic insulation properties at a low weight penalty. These materials can also be combined in multilayer arrangements to further enhance the overall performance. \\In order to achieve an accurate modelling of the vibro-acoustic behaviour of poroelastic materials, the input data describing the material properties should be of a high quality. Two characteristics inherent to these materials encumber a precise characterisation with traditional techniques. Poro-elastic aggregates are anelastic due to the constituent material used, and anisotropic as a consequence of the production process. Characterisation techniques allowing for an accurate determination of the material properties need to take these intrinsic characteristics into account.\\The objective in this thesis is to enable the characterisation of a constitutive material model for poroelastic materials which is as general as possible, and includes the inherent material anelasticity and anisotropy. For this purpose, a set of advanced characterisation techniques has been developed to characterise the anisotropic flow resistivity tensor and the anisotropic dynamic Hooke's tensor. \\These advanced characterisation techniques are based on an inverse estimation procedure, used consistently throughout the work, and includes both experiments and numerical predictions. The property to characterise is isolated in a specially designed set-up such that it can be modelled by physics solely involving this property. The obtained experimental and numerical data then serve as the input to an optimisation, which returns the material properties for which the difference between both is as small as possible. These methods have been successfully applied to melamine foam, which is found to be both anisotropic and anelastic, confirming the need for such advanced characterisation techniques.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xiv, 58 p.
Trita-AVE, ISSN 1651-7660 ; 2013:67
National Category
Fluid Mechanics and Acoustics Textile, Rubber and Polymeric Materials
urn:nbn:se:kth:diva-137809 (URN)978-91-7501-983-3 (ISBN)
Public defence
2014-01-20, sal F3, KTH, Lindstedtsvägen 26, Stockholm, 13:15 (English)
EU, European Research Council, MRTN-CT-2006-035559

QC 20131219

Available from: 2013-12-19 Created: 2013-12-16 Last updated: 2013-12-19Bibliographically approved

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Van der Kelen, ChristopheGöransson, Peter
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