Accession Number:

ADA220762

Title:

Development of a Structurally Rigid, Acoustically Transparent Plastic

Descriptive Note:

Corporate Author:

NAVAL RESEARCH LAB ORLANDO FL UNDERWATER SOUND REFERENCE DETACHMENT

Personal Author(s):

Report Date:

1990-03-01

Pagination or Media Count:

8.0

Abstract:

Some underwater acoustical applications require a window that is both acoustically transparent and structurally rigid. No previous material possesses those properties, the closest being Poly4-methyl-pentene PMP plastic, whose specific acoustic impedance is 17 higher than seawater. A series of partially fluorinated epoxies is described that have sound speeds near water, but densities that are more than 50 higher than water. When these fluoro-epoxies are compounded with glass microspheres to lower their densities, their sound speeds increase too much to permit a match to water. When they are compounded with a mixture of glass microspheres and phenolic plastic microspheres, they achieve both a sound speed and a density match to a water medium. A panel of such a composite had an insertion loss of less than 1 dB from 10 to 100 kHz at normal incidence. The composites have attractive engineering properties. The components are commercially available. Keywords Acoustical windows Piezoelectric materials Reprints.

Subject Categories:

  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE