Accession Number : AD0808575

Title :   UNDERWATER SOUND RADIATION FROM A FINITE CYLINDER. PART II: STATISTICAL ANALYSIS,

Corporate Author : BOLT BERANEK AND NEWMAN INC CAMBRIDGE MA

Personal Author(s) : Smith, P. W., Jr

Report Date : 30 JAN 1967

Pagination or Media Count : 60

Abstract : Sound radiation underwater from a homogeneous, finite, airfilled cylindrical shell, forced at a point, is investigated analytically for a 6:1 range of frequencies centered near the shell's 'ring resonance' frequency. The analysis is based on a multi-modal description of the vibration and takes advantage of the simplicity resulting from statistical averaging (1) with respect to driving point location; (2) with respect to frequency within narrow bands, and (3) with respect to modal characteristics of resonance and coupling to the fluid, within classes of similar modes. Sound radiation is found to be dominated by contributions of resonant, moderately well-coupled ('edge') modes. Structural damping does not significantly affect these modes unless it is artificially enhanced. Shell velocity and near-field sound pressure are dominated by contributions of resonant, poorly-coupled modes, whose response is controlled by inherent structural damping. Closed-form analytic predictions based on simplified approximations yield fair estimates of radiated power at frequencies greater than half the ring resonance frequency. (Author)

Descriptors :   (*UNDERWATER SOUND, SOUND TRANSMISSION), RESONANCE, RESONANT FREQUENCY, SHELLS(STRUCTURAL FORMS), CYLINDRICAL BODIES, STATISTICAL ANALYSIS, MATHEMATICAL PREDICTION, VIBRATION, NOISE, NARROWBAND, APPROXIMATION(MATHEMATICS), DAMPING, PRESSURE.

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE