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Modeling and characterization of a porous metallic foam inside ducts
Ain Shams University, Egypt.ORCID iD: 0000-0002-6069-4636
2015 (English)In: SAE International Journal of Materials & Manufacturing, ISSN 1946-3979, E-ISSN 1946-3987, Vol. 8, no 3, 937-945 p.Article in journal (Refereed) Published
Abstract [en]

A novel porous metallic foam has been studied in this work. This composite material is a mixture of resin and hollow spheres. It is lightweight, highly resistive to contamination and heat, and is capable of providing similar or better sound absorption compared to the conventional porous absorbers, but with a robust and less degradable properties. Several configurations of the material have been tested inside an expansion chamber with spatially periodic area changes. Bragg scattering was observed in some configurations with certain lattice constants. The acoustic properties of this material have been characterized from the measurement of the two-port matrix across a cylindrical sample. The complex density and speed of sound can be extracted from the transfer matrix using an optimization technique. Several models were developed to validate the effect of this metallic foam using Finite Elements and the Two-port Theory. There was a good agreement between both models and the measurement results.

Place, publisher, year, edition, pages
SAE International , 2015. Vol. 8, no 3, 937-945 p.
Keyword [en]
Acoustic properties, Acoustic wave absorption, Finite element method, Lattice constants, Sound insulating materials, Transfer matrix method, Area-changes, Bragg scattering, Cylindrical samples, Expansion chamber, Hollow sphere, Metallic foam, Optimization techniques, Sound absorption
National Category
Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-192865DOI: 10.4271/2015-01-2203Scopus ID: 2-s2.0-84978872510OAI: oai:DiVA.org:kth-192865DiVA: diva2:972576
Funder
EU, FP7, Seventh Framework Programme, 289352
Note

QC 20160930

Available from: 2016-09-21 Created: 2016-09-21 Last updated: 2017-11-21Bibliographically approved
In thesis
1. Innovative noise control in ducts
Open this publication in new window or tab >>Innovative noise control in ducts
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of this doctoral thesis is to study three different innovative noise control techniques in ducts namely: acoustic metamaterials, porous absorbers and microperforates. There has been a lot of research done on all these three topics in the context of duct acoustics. This research will assess the potential of the acoustic metamaterial technique and compare to the use of conventional methods using microperforated plates and/or porous materials. 

The objective of the metamaterials part is to develop a physical approach to model and synthesize bulk moduli and densities to feasibly control the wave propagation pattern, creating quiet zones in the targeted fluid domain. This is achieved using an array of locally resonant metallic patches. In addition to this, a novel thin slow sound material is also proposed in the acoustic metamaterial part of this thesis. This slow sound material is a quasi-labyrinthine structure flush mounted to a duct, comprising of coplanar quarter wavelength resonators that aims to slow the speed of sound at selective resonance frequencies. A good agreement between theoretical analysis and experimental measurements is demonstrated.

The second technique is based on acoustic porous foam and it is about modeling and characterization of a novel porous metallic foam absorber inside ducts. This material proved to be a similar or better sound absorber compared to the conventional porous absorbers, but with robust and less degradable properties. Material characterization of this porous absorber from a simple transfer matrix measurement is proposed.The last part of this research is focused on impedance of perforates with grazing flow on both sides. Modeling of the double sided grazing flow impedance is done using a modified version of an inverse semi-analytical technique. A minimization scheme is used to find the liner impedance value in the complex plane to match the calculated sound field to the measured one at the microphone positions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 69 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 58
Keyword
Locally resonant materials, slow sound, acoustic impedance, metallic foam, low frequency noise, mufflers, lined ducts, grazing flow, flow duct, impedance eduction.
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-192927 (URN)978-91-7729-119-0 (ISBN)
Public defence
2016-10-21, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
EU, FP7, Seventh Framework Programme, 289352
Note

QC 20160923

Available from: 2016-09-23 Created: 2016-09-23 Last updated: 2016-09-23Bibliographically approved

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Farooqui, Maaz

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