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A study of tailoring acoustic porous material properties when designing lightweight multilayered vehicle panels
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present work explores the possibilities of adapting poro-elastic lightweight acoustic materials to specific applications. More explicitly, a design approach is presented where finite element based numerical simulations are combined with optimization techniques to improve the dynamic and acoustic properties of lightweight multilayered panels containing poro-elastic acoustic materials.

The numerical models are based on Biot theory which uses equivalent fluid/solid models with macroscopic space averaged material properties to describe the physical behaviour of poro-elastic materials. To systematically identify and compare specific beneficial or unfavourable material properties, the numerical model is connected to a gradient based optimizer. As the macroscopic material parameters used in Biot theory are interrelated, they are not suitable to be used as independent design variables. Instead scaling laws are applied to connect macroscopic material properties to the underlying microscopic geometrical properties that may be altered independently.

The design approach is also combined with a structural sandwich panel mass optimization, to examine possible ways to handle the, sometimes contradicting, structural and acoustic demands. By carefully balancing structural and acoustic components, synergetic rather than contradictive effects could be achieved, resulting in multifunctional panels; hopefully making additional acoustic treatment, which may otherwise undo major parts of the weight reduction, redundant.

The results indicate a significant potential to improve the dynamic and acoustic properties of multilayered panels with a minimum of added weight and volume. The developed modelling techniques could also be implemented in future computer based design tools for lightweight vehicle panels. This would possibly enable efficient mass reduction while limiting or, perhaps, totally avoiding the negative impact on sound and vibration properties that is, otherwise, a common side effect of reducing weight, thus helping to achieve lighter and more energy efficient vehicles in the future.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xi, 43 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2012:52
Keyword [en]
porous material, optimization, Biot theory, acoustic wave propagation
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-100701ISBN: 978-91-7501-448-7 (print)OAI: oai:DiVA.org:kth-100701DiVA: diva2:544480
Public defence
2012-09-07, F3, Lindstedsvägen 26, KTH, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20120815

Available from: 2012-08-15 Created: 2012-08-14 Last updated: 2013-04-11Bibliographically 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. Material Property Steered Structural and Acoustic Optimization of a Multifunctional Vehcile Body Panel
Open this publication in new window or tab >>Material Property Steered Structural and Acoustic Optimization of a Multifunctional Vehcile Body Panel
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Conventional vehicle passenger compartments often achieve functional requirements using a complex assembly of components. As each component is optimized for a single task, the assembly as a whole is often suboptimal in achieving the system performance requirements. In this paper, a novel iterative design approach based on using a multi-layered load bearing sandwich panel with integrated acoustic capabilitiesis developed focusing on material properties and their effecton the systems behavior. The proposed panel is meant to fulfilmultiple system functionalities simultaneously, thus simplifying the assembly and reducing mass. Open cell acoustic foams are used to achieve acoustic performance, and the effect of altering the stacking sequence as well as introducing an air gap within the acoustic treatment is studied in detail to determine effects on the acoustic and structural performance of the panel as a whole.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-31110 (URN)
Note
QC 20110311Available from: 2011-03-09 Created: 2011-03-09 Last updated: 2012-08-15Bibliographically approved
3. A Design Method using Toplogy, Property, and Size Optimization to Balance Structural and Acoustic Performance of Sandwich Panels for Vehicle Applications
Open this publication in new window or tab >>A Design Method using Toplogy, Property, and Size Optimization to Balance Structural and Acoustic Performance of Sandwich Panels for Vehicle Applications
(English)Manuscript (preprint) (Other academic)
Keyword
Vehicle Design, Topology Optimization, NVH, FEM, Sandwich Structures, Acoustic Optimizatio, Porous Foam
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-31111 (URN)
Note
QS 2012Available from: 2011-03-09 Created: 2011-03-09 Last updated: 2012-08-16Bibliographically approved
4. Alignment of anisotropic poro-elasticlayers: Sensitivity in vibroacoustic response due to angular orientation of anisotropicelastic and acoustic properties
Open this publication in new window or tab >>Alignment of anisotropic poro-elasticlayers: Sensitivity in vibroacoustic response due to angular orientation of anisotropicelastic and acoustic properties
(English)Manuscript (preprint) (Other academic)
Identifiers
urn:nbn:se:kth:diva-100704 (URN)
Note

QS 2012

Available from: 2012-08-15 Created: 2012-08-15 Last updated: 2016-11-11Bibliographically approved

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