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Effects of fiber motion on the acoustic behavior of an anisotropic, flexible fibrous materialThe acoustic behavior of a flexible fibrous material was studied experimentally. The material consisted of cylindrically shaped fibers arranged in a batting with the fibers primarily aligned parallel to the face of the batting. This type of material was considered anisotropic, with the acoustic propagation constant depending on whether the direction of sound propagation was parallel or normal to the fiber arrangement. Normal incidence sound absorption measurements were taken for both fiber orientations over the frequency range 140 to 1500 Hz and with bulk densities ranging from 4.6 to 67 kg/cu m. When the sound propagated in a direction normal to the fiber alignment, the measured sound absorption showed the occurrence of a strong resonance, which increased absorption above that attributed to viscous and thermal effects. When the sound propagated in a direction parallel to the fiber alignment, indications of strong resonances in the data were not present. The resonance in the data for fibers normal to the direction of sound propagation is attributed to fiber motion. An analytical model was developed for the acoustic behavior of the material displaying the same fiber motion characteristics shown in the measurements.
Document ID
19900046258
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Dahl, Milo D.
(NASA Lewis Research Center Cleveland, OH, United States)
Rice, Edward J.
(NASA Lewis Research Center Cleveland, OH, United States)
Groesbeck, Donald E.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Acoustical Society of America, Journal
Volume: 87
ISSN: 0001-4966
Subject Category
Acoustics
Accession Number
90A33313
Distribution Limits
Public
Copyright
Other

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