Viscoelastic damping layer deformation

The Free Viscoelastic Layer. As we see in Figure 3, the free viscoelastic layer is bonded to the plate to be damped. As the plate vibrates in bending, the viscoelastic layer is deformed principally in extension and compression in planes parallel to the plate surface. Such damping layers have long been known, and at first were applied more-or-less empirically. In the early 1950s Oberst 3.,D and Lienard (, ) published analyses describing quantitative analytical models of free layer behavior. 

Two widely applied damping configurations that use viscoelastic materials are the free viscoelastic layer and the constrained viscoelastic layer, as shown in Fig.9a and 9b. The deformation of the viscoelastic layer is extensional in the first case and shear in the second case. Both these deformations are highly damped by intrinsic absorption in the viscoelastic polymer. In the case of the free viscoelastic layer (Fig.9a) it flexes with the plate participating in the bending stiffness as part of a two-layer beam. The viscoelastic layer must be tightly bonded to the plate and must be continuous over a... 

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