Accession Number : ADD017713

Title :   Anechoic and Decoupling Coating.

Descriptive Note : Patent, Filed 30 Apr 79, patented 22 Aug 95,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Sevik, Maurice M

Report Date : 22 Aug 1995

Pagination or Media Count : 7

Abstract : An anechoic and decoupling coating for use on the surface of an underwater structure for decoupling struc- tural vibrations from the water and for absorbing water- borne acoustic waves directed toward the structure from an external source such as a sonar. The coating is an elastomeric matrix containing sealed air-filled cavi- ties as well as random labyrinths of small water-filled passages running throughout and in open communica- tion with a surface facing the water. Acoustic waves incident upon the water-facing surface cause time vary- ing shear and bulk deformations within the matrix. As a result of these deformations, acoustic energy is dissi- pated by hysteretic damping of the elastomeric matrix as well as by viscosity due to water movement to and fro within the passages and into and out of the matrix. (MM) (SEE FIRST PAGE FOR ABSTRACT. PLEASE DELETE THIS NOTE.)

Descriptors :   *ABSORBERS(MATERIALS), *ANECHOIC CHAMBERS, *PATENTS, *ACOUSTIC COUNTERMEASURES, *ACOUSTIC COATINGS, VIBRATION, ACOUSTIC WAVES, DEFORMATION, DAMPING, ELASTOMERS, MATRIX MATERIALS, DECOUPLING, VISCOSITY, UNDERWATER ACOUSTICS, SONAR, HYSTERESIS

Subject Categories : Coatings, Colorants and Finishes
      Acoustic Countermeasures

Distribution Statement : APPROVED FOR PUBLIC RELEASE