Composite Loss Factors of Selected Laminated Beams

Abstract

The composite loss factors for beams having alternate laminae of elastic and viscoelastic materials have been computed for variations of frequency for 3- and 5-layer beams using the results obtained by Kerwin [E. M. Kerwin, D. Ross, and E. E. Ungar, “Damping of Plates in Flexural Vibrations by Means of Viscoelastic Laminae,” in Structural Damping (Am. Soc. Mech. Eng., New York, 1959)]. To properly design structures with laminated materials, in order to withstand and attenuate vibratory energy, it is desired to know the composite loss factor of the beam for different cross sections and materials. The results of this investigation obtained through the use of high-speed computers as a series of curves displaying the variations of composite loss factors as a function of frequency for different cross sections and materials. The cross-sectional configurations and materials were selected so that trends in composite loss factor could be obtained for such considerations as changes in thickness and/or physical properties of the elastic and/or viscoelastic material. These results may serve as a guide to the proper vibratory design of laminated materials.

Vibration Analysis of Cylindrical Sandwich Aluminum Shell with Viscoelastic Damping Treatment

“…Mead and Markus developed sixth-order equations of motion for the transverse displacement of the damped sandwich beams with arbitrary boundary conditions [7]. Blasingame and DiTaranto added the extensional stiffness of the dissipative core layer to Kerwin's formulation of the laminated sandwich plate [8]. Siu and Bert investigated the material damping of laminated anisotropic rectangular plates, considering the thickness-shear flexibility and rotary and coupling inertia [9].…”