Damping Properties of Two-Layered Curved Beams with an Unconstrained Viscoelastic Layer

Abstract

A theoretical and experimental study is presented for the damping of curved beams with an unconstrained viscoelastic layer. Natural frequencies and loss factors of flexural vibration are calculated for various boundary conditions, when a beam of the constant finite length is bent cylindrically. Boundary conditions considered in this paper are simple support-simple support, free-free, clamped-clamped, hinged-hinged and clamped-free. It is found that the loss factor of a curved beam changes complicatedly as the subtended angle increases. This behaviour may be divided into two groups according to the type of the boundary conditions and the modes of vibration; as the subtended angle increases, the loss factor for symmetric modes of clamped-clamped and hinged-hinged beams changes remarkably and behaves complicatedly, while that for all modes of free-free, simply supported-simply supported and clamped-free beams and antisymmetric modes of clamped-clamped and hinged-hinged beams changes slightly. This difference could be verified experimentally for curved beams with clamped-clamped and clamped-free ends.