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Reduction of Low-Frequency Sound Transmission Using an Array of 3D-Printed Resonant Structures

Algermissen, Stephan and Monner, Hans Peter (2018) Reduction of Low-Frequency Sound Transmission Using an Array of 3D-Printed Resonant Structures. ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS), 10.-12. Sept. 2018, San Antonio, TX, USA.

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Abstract

The reduction of low-frequency noise transmission through thin-walled structures is a topic of research for many years now. Due to large wavelengths and the mass law, passive solutions usually gain low performance in the frequency range below 500 Hz. Active systems promised to fill the gap and to achieve significant reductions of transmitted sound. Nevertheless, experiments showed the outstanding performance of such specialized systems, but also demonstrated the computational and hardware effort of such solutions. The upcoming additive manufacturing technology enabled new multi-material designs of complex structures. Based on this technology, acoustic metamaterials emerged in the laboratories and in literature. Arrays of miniaturized locally resonant structures are able to change the noise transmission of thin walled structures beyond the limits of the given mass law in certain frequency bands. For future aircraft contra-rotating open rotor (CROR) engines are a promising technology to reduce their CO2 footprint. Since the contribution of CROR engines to the cabin noise is higher than for jet engines, new strategies for the reduction of noise transmissions for frequency bands below 200 Hz are necessary. For the tonal noise of the CROR engines, acoustic metamaterials seem to be an appropriate solution. In this paper a 110x110x1 mm^3 thin-walled sample plate is presented. It is covered with a 5x5 array of multi-material resonant structures, which are printed as mass on a beam. The rubber-like beam material combines a low Young's modulus with a high material damping, leading to a low eigenfrequency of the resonators. The design of the resonators using simulations and experimental data is shown. To explore the potential of the design, an acoustic test box is manufactured. Starting with all resonators unblocked the emitted sound intensity of the plate is measured. Sequential blocking of selected resonators proves the concept. Additional laser scanning vibrometer measurements give insights into the vibration behavior of single resonators.

Item URL in elib:https://elib.dlr.de/121713/
Document Type:Conference or Workshop Item (Speech)
Title:Reduction of Low-Frequency Sound Transmission Using an Array of 3D-Printed Resonant Structures
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Algermissen, StephanStephan.Algermissen (at) dlr.dehttps://orcid.org/0000-0002-0507-8195
Monner, Hans PeterHans.Monner (at) dlr.dehttps://orcid.org/0000-0002-5897-2422
Date:12 September 2018
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:smart structures, acoustic metamaterial, 3d printing
Event Title:ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS)
Event Location:San Antonio, TX, USA
Event Type:international Conference
Event Dates:10.-12. Sept. 2018
Organizer:ASME
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L - no assignment
DLR - Research theme (Project):L - no assignment
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Adaptronics
Deposited By: Algermissen, Dr.-Ing. Stephan
Deposited On:24 Sep 2018 07:53
Last Modified:24 Sep 2018 07:53

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