Effect of End Constraints on the Damping of Laminated Beams

Abstract

The use of laminated elastic-viscoelastic beams as a means for obtaining vibration damping, together with reasonable structural stiffness, has been the object of extensive theoretical and experimental investigations. The particular theoretical and experimental work considered herein is the effect of end constraints on the composite loss factor of vibrating laminated beams. According to theoretical findings, the damping of laminated beams is independent of boundary conditions and depends solely on the geometry of the beam's cross section and properties of the damping material [R. A. DiTaranto, “Theory of Vibratory Bending of Laminated Beams,” (to be published)]. To check the theory, 3- and 5-layer laminated beams were investigated for ends constrained in several different manners: namely, free-free with and without bolted ends, and both ends clamped. For both the 3- and 5-layer beams, satisfactory agreement was obtained with theory, indicating the variation of composite loss factor with frequency of vibration to be independent of end conditions.