Accession Number : ADA320488

Title :   Phenomenon of Leaky Free Waves in the Modal Response of a Uniform Cylinder.

Descriptive Note : Research rept. 1 Jan-31 Oct 96,

Corporate Author : NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD

Personal Author(s) : Maidanik, G. ; Becker, K. J.

PDF Url : ADA320488

Report Date : 31 OCT 1996

Pagination or Media Count : 30

Abstract : The phenomenon of leaky free waves in the modal response of a uniform shell is manifest if (1) in the absence of fluid loading the locus of the free waves as a function of frequency crosses from the subsonic region to the supersonic region across the sonic locus and (2) in the presence of fluid loading the fluid surface impedance at and in the vicinity of the sonic locus is high and the introduction of this fluid loading does not prevent the free waves of concern from reaching the sonic locus. The phenomenon of leaky free waves in the modal response of a uniform cylinder is investigated. It is found that two distinct examples of leaky free waves are manifested. The first is associated with the flexural free waves that reside in a frequency range that lies above the critical frequency with respect to the speed of sound in the fluid and the second is associated with the curvature free waves that reside in a frequency range that lies below the ring frequency. The phenomenon of leaky free waves in these two examples is computed, displayed and discussed.

Descriptors :   *ACOUSTIC EMISSIONS, *RADIATION PATTERNS, SHELLS(STRUCTURAL FORMS), CYLINDRICAL BODIES, DYNAMIC LOADS, ACOUSTIC VELOCITY, FLEXURAL PROPERTIES, ACOUSTIC IMPEDANCE, TRANSONIC CHARACTERISTICS.

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE