NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Acoustic behavior of a fibrous bulk materialA semiempirical model is presented describing the acoustic behavior of Kevlar 29, a bulk absorbing material. The model is based on an approximate solution to the one-dimensional equations representing conservation of fluctuating mass, momentum and energy. By treating the material as a momentum sink, theoretical expressions of the material complex propagation constants and characteristic impedance were derived in terms of a single constant. Evaluating the constant at a single frequency for a particular specimen, excellent agreement between prediction and measurement was achieved for a large range of sound frequencies and material porosities and thicknesses. Results show that Kevlar 29 absorbs sound efficiently even at low frequencies. This is explained in terms of a frequency dependent material phase speed.
Document ID
19790042897
Document Type
Conference Paper
Authors
Hersh, A. S. (Hersh Acoustical Engineering, Inc. Chatsworth, CA, United States)
Walker, B. (Hersh Acoustical Engineering Chatsworth, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1979
Subject Category
ACOUSTICS
Report/Patent Number
AIAA PAPER 79-0599
Meeting Information
American Institute of Aeronautics and Astronautics, Aeroacoustics Conference(Seattle, WA)
Funding Number(s)
CONTRACT_GRANT: NAS3-19745
Distribution Limits
Public
Copyright
Other