Damping properties of two-layered cylindrically curved plates with an unconstrained viscoelastic layer (the case of curved plates with simply supported straight edges)

A theoretical study is presented for the damping of cylindrically curved plates with an unconstrained viscoelastic layer. Natural frequencies and loss factors of flexural vibration are calculated, using the equations of motion on the basis of the Flugge's shell theory. Boundary conditions considered in this paper are as follows: straight edges are simply supported, and curved edges are simply supported, clamped, or free. It is found that the damping properties of a curved plate depend on the existence of extensional deformation in the datum surface of displacements. In the case of the inextensional deformation, the damping properties are similar to those of a flat plate. On the other hand, if the deformation is extensional, loss factor of a curve plate is smaller than that of a flat plate, and the decrease of the loss factor with bending depends on the aspect ratio, the ratio of thickness to length, mode of vibration and boundary condition.