Vibration analysis of beams with multiple constrained layer damping patches

A new analytical, energy based approach is described that predicts the harmonic vibration response of a damped beam with multiple viscoelastic patches. Each damping patch consists of a metallic constraining layer and an adhesive viscoelastic layer with spectrally-varying material properties. Since this approach relates all deformation variables in various layers, only flexural shape functions need to be incorporated in the complex eigenvalue problem. Consequently flexural, longitudinal and shear deformation eigenvectors can be calculated. In particular, the shear deformation modes of the viscoelastic core provide useful information regarding the effect of patch damping. The proposed method has been validated by comparing predictions with modal measurements and with those published in the literature. Also, an estimation technique is developed that determines the shear modulus and loss factor properties of two different viscoelastic materials used in experimental studies. An uncertainty study is also performed to establish the error bounds of the estimated material loss factors. Effects of patch boundary conditions, patch cutouts and locations, and mismatched patch combinations are analytically and experimentally examined. (C) 1998 Academic Press Limited.