Fluid‐loaded constrained‐layer analysis by exact elasticity theory

Abstract

The constrained‐layer damping technique is based on the attachment of an absorbing viscoelastic layer and a stiff constraining layer to the surface of a metal structure to be damped. Starting from the model by F. M. Kerwin [J. Acoust. Soc. Am. 31, 952–962 (1959)], based on thinplate theory for the base plate, a hybrid model of a fluid‐loaded plate was developed whereby only the base plate is described by exact elasticity theory [P.S. Dubbelday, J. Acoust. Soc. Am. Suppl. 1 80, S121 (1986)]. A description based on exact elasticity theory for all three layers, without fluid loading, was also formulated [D. W. Fausett, L. V. Fausett, and P.S. Dubbelday, J. Acoust. Soc. Am. Suppl. 1 80, S121 (1986)]. The present study further explores the interaction of viscoelastic damping and fluid loading by a description according to exact elasticity theory of all three layers, combined with fluid loading. For flexural waves, the model shows reasonable agreement with the earlier hybrid model at intermediate frequencies, but discrepancies occur at lower and higher frequencies. These are discussed, and possible mechanisms for the behavior are brought forward. [Work supported by ONR.]