Coated and Uncoated Models; What is the Difference? Part 2: Cavity Resonances
Abstract
The rudimentary model of Part I is elaborated by introducing a baffle below the equivalent plate. In the cavity that forms, between the equivalent plate and the baffle, fluid is introduced. The cavity induces resonances and anti-resonances in the response of the equivalent plate. In turn, these resonances and anti-resonances imprint their presence on the regular transfer functions. These imprints are modulated by the resonance between the surface mass impedance of the equivalent plate and the surface stiffness (compliance) impedance of the coating when the coating is present. In the absence of coating, this modulation is also absent, although the imprints of the resonances and anti-resonances in the transfer functions persist. The influence of the coating, on the imprints of the cavity resonances and anti-resonances, is isolated by presenting the ratio of the transfer function in the presence of coating to that in absence of coating. The transfer functions and their ratios are computed as functions of the normalized frequency. Variations on the theme, in which parameters are changed from standard values, are examined and displayed. In particular, the major hump and minor dump emerge in these displays. Since resonances (and anti-resonances) are sensitive to damping, a number of types and degrees of damping are examined and assessed for effectiveness as noise control agents.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2004
- Accession Number
- ADA425384
Entities
People
- Gideon Maidanik
- K. J. Becker
- L. J. Maga
Organizations
- Naval Surface Warfare Center Carderock Division