Acoustic Properties Of Reticulated Plastic Foams

✍ Scribed by A. Cummings; S.P. Beadle

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 840 KB
• Volume: 175
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1994.1315

✦ Synopsis

Some general aspects of sound propagation in rigid porous media are discussed, particularly with reference to the use of a single-dimensionless-frequency parameter and the role of this, in the light of the possibility of varying gas properties, is examined. Steady flow resistance coefficients of porous media are also considered, and simple scaling relationships between these coefficients and "system parameters" are derived. The results of a series of measurements of the bulk acoustic properties of 12 geometrically similar, fully reticulated, polyurethane foams are presented, and empirical curve-fitting coefficients are found; the curve-fitting formulae are valid within the experimental range of values of the frequency parameter. Comparison is made between the measured data and an alternative, fairly recently published, semi-empirical set of formulae. Measurements of the steady flow-resistive coefficients are also given and both the acoustical and flow-resistive data are shown to be consistent with theoretical ideas. The acoustical and flow-resistive data should be of use in predicting the acoustic bulk properties of open-celled foams of types similar to those used in the experimental tests.