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On multilayered system dynamics and waves in anisotropic poroelastic media
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0003-2140-0479
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The mechanical and acoustic anisotropy of media is a governing factor in the behaviour of multilayered systems including such media. The understanding of the mechanisms conditioning the dynamic behaviour of multilayered systems is of paramount importance. In particular, the intrinsic anisotropy of poroelastic media presents a potential for the optimal design of systems for multifunctional performances. Indeed, these multilayered systems are bound by stiffness, thermal and acoustic performance constraints in simultaneously. A plane wave method is presented to study the influence of material orientation in the dynamic behaviour of multilayered systems composed of anisotropic poroelastic media. The method is applied to a system composed of an anisotropic open-celled melamine foam core in between two metal sheets. This particular multilayered configuration allows to shed light on phenomena intrinsic to layers composed of anisotropic poroelastic materials, such as the frequency shift of the fundamental resonance of the panel, or the compression-shear coupling effects taking place in the poroelastic core layers. The latter phenomena is of particular importance, as it is evidenced on the unconventional polarisation of waves in anisotropic poroelastic media. Finally, the method is adapted to the optimisation of multilayered systems for acoustic performance. the design variables are consequently the core material orientations with respect to the global coordinate system. The solutions to the optimisation problem are analysed in terms of dynamic behaviour, thus allowing to correlate acoustic performance of the overall structure, and the response of each individual layer.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , 57 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2016:77
Keyword [en]
poroelastic media, anisotropy, plane waves, multilayered systems, dynamics, acoustics, optimisation
Keyword [fr]
matériaux poro-visco-élastique, anisotropie, ondes planes, panneaux multicouches, dynamique, acoustique, optimisation
Keyword [sv]
Poroelastiska material, anisotropi, planvågor, flerskiktssystem, dynamik, akustik, optimering
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
URN: urn:nbn:se:kth:diva-195801ISBN: 978-91-7729-172-5OAI: oai:DiVA.org:kth-195801DiVA: diva2:1045470
Public defence
2016-12-06, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20161110

Available from: 2016-11-10 Created: 2016-11-09 Last updated: 2016-11-10Bibliographically approved
List of papers
1. Acoustic analysis of anisotropic poroelastic multilayered systems
Open this publication in new window or tab >>Acoustic analysis of anisotropic poroelastic multilayered systems
2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, ISSN 1089-7550, Vol. 119, no 8, 084907- p.Article in journal (Refereed) Published
Abstract [en]

The proposed method allows for an extended analysis of the wave analysis, internal powers, and acoustic performance of anisotropic poroelastic media within semi-infinite multilayered systems under arbitrary excitation. Based on a plane wave expansion, the solution is derived from a first order partial derivative as proposed by Stroh. This allows for an in-depth analysis of the mechanisms controlling the acoustic behaviour in terms of internal powers and wave properties in the media. In particular, the proposed approach is used to highlight the influence of the phenomena intrinsic to anisotropic poroelastic media, such as compression-shear coupling related to the material alignment, the frequency shift of the fundamental resonance, or the appearance of particular geometrical coincidences in multilayered systems with such materials.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
Keyword
Anisotropy, poroelastic materials, acoustic, mechanical waves, porous materials, acoustic waves
National Category
Vehicle Engineering Applied Mechanics Materials Engineering
Research subject
Materials Science and Engineering; Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-183351 (URN)10.1063/1.4942443 (DOI)000371601800038 ()2-s2.0-84959549758 (ScopusID)
Note

QC 20160310

Available from: 2016-03-07 Created: 2016-03-07 Last updated: 2016-11-09Bibliographically approved
2. Derivation of the state matrix for dynamic analysis of linear homogeneous media
Open this publication in new window or tab >>Derivation of the state matrix for dynamic analysis of linear homogeneous media
2016 (English)In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 140, no 2, EL218-EL220 p.Article in journal (Refereed) Published
Abstract [en]

A method to obtain the state matrix of an arbitrary linear homogeneous medium excited by a plane wave is proposed. The approach is based on projections on the eigenspace of the governing equations matrix. It is an alternative to manually obtaining a linearly independent set of equations by combining the governing equations. The resulting matrix has been validated against previously published derivations for an anisotropic poroelastic medium.

Place, publisher, year, edition, pages
Acoustical Society of America (ASA), 2016
Keyword
Anisotropic media, Excited states, A-plane, Eigenspaces, Governing equations, Homogeneous media, Homogeneous medium, Linearly independents, Poroelastic medium, State matrices
National Category
Other Mechanical Engineering
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-190728 (URN)10.1121/1.4960624 (DOI)000383916100012 ()2-s2.0-84983405426 (ScopusID)
Note

QC 20161014

Available from: 2016-08-12 Created: 2016-08-12 Last updated: 2016-11-09Bibliographically approved
3. Wave analysis of intrinsic phenomena related to anisotropic poroelastic materials in multilayered systems
Open this publication in new window or tab >>Wave analysis of intrinsic phenomena related to anisotropic poroelastic materials in multilayered systems
Show others...
2016 (English)Conference paper (Refereed)
Abstract [en]

An analysis of intrinsic dynamic phenomena in anisotropic poroelastic media is presented, based on a plane wave formulation. The latter is derived from the Stroh formalism on the state variables governing the beha- viour of such media. A particular interest is given to the compression-shear coupling related to the material alignment of the anisotropic poroelastic core. This coupling motion can be directly correlated to the ma- terial mechanical parameters and affects the response of the overall structure in specific frequency ranges. Furthermore, the effect of the anisotropic poroelastic material coordinate orientation on the the acoustic and elastical response of multilayered systems with such material cores is investigated under diffuse field excita- tion conditions (i.e. only a part the mechanics which doesnt include maximum stress at rupture). An insight into other effects of anisotropy is provided, such as the frequency shift of the fundamental resonance related to the core material alignment and the appearance of particular geometrical coincidences in the acoustic behaviour of the system.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-192661 (URN)
Conference
ISMA 2016 International Conference in Noise and Vibration Engineering and USD 2016 International Conference on Uncertainty in Structural Dynamics, Leuven, Belgium
Note

QC 20160923

Available from: 2016-09-19 Created: 2016-09-19 Last updated: 2016-11-09Bibliographically approved
4. Optimal alignment of anisotropic poroelastic cores in multilayered systems for acoustic performance
Open this publication in new window or tab >>Optimal alignment of anisotropic poroelastic cores in multilayered systems for acoustic performance
2016 (English)Article in journal (Other academic) Submitted
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-195800 (URN)
Note

Qc 20161114

Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2016-11-14Bibliographically approved

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