Constrained-layer model investigation based on exact elasticity theory

Abstract

The model for constrained-layer damping proposed by Kerwin [J. Acoust. Soc. Am. 31, 952–962 (1959)] provides a direct insight into the effect of the various physical and geometric parameters on the attenuation. It does not account for extensional-wave damping and is limited to lower frequencies since the analysis is based on thin-plate theory. Kerwin’s model is extended to improve upon these points. To check the extended model, a new hybrid model is developed that uses exact elasticity theory to describe the base plate, while the damping and constraining layers are treated analogous to Kerwin’s analysis. It is shown that for flexural waves the extended Kerwin model gives a good approximation to the hybrid constrained-layer model when the phase speed is computed according to either exact elasticity or thick-plate theory.