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Surface acoustic admittance and absorption of highly porous, layered, fibrous materialsSome acoustic properties of Kevlar-29 - a fine fibered, layered material is investigated. Kevlar is characterized by very high strength, uniform filaments arranged in a parallel batt where most filaments are random in the x-y plane but ordered as planes in the z direction. For experimental purposes, volume porosity, static flow resistance and mean filament diameter are used to identify the material. To determine the acoustic surface admittance of Kevlar, batts of the material are cut into small pads and placed into a standing wave tube terminated by a rigid brass plug. The attenuation and relative phase shift are recorded at each frequency in the range of 50 to 6000 Hz. Normalized conductance and susceptance are combined to form the acoustic absorption coefficient. The data are compared with theory by plotting the normalized admittance and normal incident absorption coefficient versus cyclic frequency.
Document ID
19840019477
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Tesar, J. S.
(Minnesota Univ. Minneapolis, MN, United States)
Lambert, R. F.
(Minnesota Univ. Minneapolis, MN, United States)
Date Acquired
August 12, 2013
Publication Date
June 30, 1984
Publication Information
Publication: Studies of Acoustical Properties of Bulk Porous Flexible Mater.
Subject Category
Acoustics
Accession Number
84N27545
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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