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Influence of inhomogeneous damping distribution on sound radiation properties of complex vibration modes in rectangular plates

Unruh, Oliver (2016) Influence of inhomogeneous damping distribution on sound radiation properties of complex vibration modes in rectangular plates. Journal of Sound and Vibration. Elsevier. ISSN 0022-460X (In Press)

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In order to reduce noise emitted by vibrating structures additional damping treatments such as constraint layer damping or embedded elastomer layers can be used. To save weight and cost, the additional damping is often placed at some critical locations of the structure, what leads to spatially inhomogeneous distribution of damping. This inhomogeneous distribution of structural damping leads to an occurrence of complex vibration modes, which are no longer dominated by pure standing waves, but by a superposition of travelling and standing waves. The existence of complex vibration modes raises the question about their influence on sound radiation. Previous studies on the sound radiation of complex modes of rectangular plates reveal, that, depending on the direction of travelling waves, the radiation efficiency of structural modes can slightly decrease or significantly increase. These observations have been made using a rectangular plate with a simple inhomogeneous damping configuration which includes a single plate boundary with a higher structural damping ratio. In order to answer the question about the influence of other possible damping configurations on the sound radiation properties, this paper addresses the self- and mutual-radiation efficiencies of the resulting complex vibration modes. Numerical simulations are used for the calculation of complex structural modes of different inhomogeneous damping configurations with varying geometrical form and symmetry. The evaluation of self- and mutual-radiation efficiencies reveals that primarily the symmetry properties of the inhomogeneous damping distribution affect the sound radiation characteristics. Especially the asymmetric distributions of inhomogeneous damping show a high influence on the investigated acoustic metrics. The presented study also reveals that the acoustic cross-coupling between structural modes, which is described by the mutual-radiation efficiencies, generally increases with the presence of travelling waves.

Item URL in elib:https://elib.dlr.de/104375/
Document Type:Article
Title:Influence of inhomogeneous damping distribution on sound radiation properties of complex vibration modes in rectangular plates
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Unruh, Oliveroliver.unruh (at) dlr.deUNSPECIFIED
Journal or Publication Title:Journal of Sound and Vibration
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Status:In Press
Keywords:Structural acoustics; Complex vibration modes; Sound radiation; Inhomogeneous damping
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Structures and Materials
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems
Deposited By: Unruh, Oliver
Deposited On:30 May 2016 05:57
Last Modified:30 May 2016 05:57

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