Damping Characteristics of Flexural Vibration for Partially Covered Beams with Constrained Viscoelastic layers

Abstract

A beam partially covered with a constrained viscoelastic layer shows superior damping capacity to that of a fully covered beam, depending on the beam geometry and the properties of the viscoelastic layer. This damping effect, the so-called partial cover effect, however, had not been examined in detail until now. In this paper, the strain energy analjsis of the three types of partially covered five-layered beam is carried out in order to explain the damping mechanism. The results of analysis for the center-covered beam and the end-constrained beam indicate that the partial cover effect is caused by the shear strain energy dissipation at the outer edges of the viscoelastic layer, and also, such energy dissipation depends on the tensile stiffness of the constraining layer. The separately covered beam has a superior damping capacity to that of the center-covered beam with the same cover ratio, due to the energy dissipation of the inner edges of the viscoelastic layers. These damping characteristics of the three types of beam presented are confirmed by experimental results.