Wave Modelling Techniques for Medium and High Frequency Vibroacoustic Analysis Including Porous Materials
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Numerical methods based on wave modelling are explored for the vibroacoustic analysis of wave propagation, sound transmission and interior noise in vehicles and buildings at medium and high frequencies. The presence of sound absorbing porous materials in practical engineering structures is also considered. The wave modelling techniques provide computational efficiency and physical insight, and two such methods having these advantages are developed in this thesis namely: the semi-analytical finite element method and the wave expansion method.
The semi-analytical finite element method is applicable to structures which have constant properties in one direction, and it uses a finite element discretization of the cross-section and analytical functions in the third direction. Equations of motion are derived from this method to study wave propagation characteristics, which help understand the vibroacoustic behavior of structures. These characteristics may also be used by high frequency techniques, such as statistical energy analysis. The wave propagation in sandwich panels with a poroelastic core, which is modeled with Biot's theory, is investigated thoroughly.
The semi-analytical finite element method retains the flexibility of the finite element method on geometry and also dramatically increases the computational speed thanks to the orthogonality of the analytical functions when used to calculate forced response. The calculated response of partitions is integrated into diffuse field sound transmission loss calculations of, for example, built-up train floor partitions and multilayer panels lined with porous materials. The calculations are computationally efficient and show good agreement with measurements, thus it is interesting for industrial optimizations.
The wave expansion method uses a priori defined plane wave solutions to the Helmholtz equation for approximation of the sound field in geometrically complex enclosures. It reduces the requirements regarding the number of degrees of freedom compared to the finite element method, which, furthermore, is polluted by dispersion errors. Therefore, the wave expansion method is particularly appealing for high frequency (or large wavenumber) calculations. Its application in interior sound field predictions is assessed within the automobile context.
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , xvi, 46 p.
TRITA-AVE, ISSN 1651-7660 ; 2014:51
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-151271ISBN: 978-91-7595-269-7OAI: oai:DiVA.org:kth-151271DiVA: diva2:747405
2014-10-01, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (English)
Ichchou, Mohamed, Professor
Finnveden, Svante, Associate ProfessorLopez Arteaga, Ines, Professor
FunderEU, FP7, Seventh Framework Programme, 214909
QC 201409162014-09-172014-09-162014-09-17Bibliographically approved
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