Stability analysis of axially loaded sandwich beams with a five-layered composite core made of viscoelastic and functionally graded material layers

Abstract

In this paper, a five-layered viscoelastic composite laminate is proposed for the constrained layer damping (CLD) treatment of axially loaded beam structures. The CLD arrangement is taken in the conventional form of a sandwich beams. But, the main focus is to investigate the change in the static and dynamic stability characteristics of the axially loaded sandwich beam while the conventional pure viscoelastic core layer is replaced by the present five-layered composite laminate. First, the design of the five-layered composite laminate using three viscoelastic and two meatal-ceramic functionally graded (FG) material layers is presented. Next, an incremental nonlinear finite element model of the axially loaded sandwich beam is formulated based on the fractional Zener constitutive relation and harmonic balance method (HBM). The HBM is implemented with an arbitrary number of harmonic terms. The corresponding complexity in the formulation of the nonlinear system matrices/vectors is handled using a special factorization of the nonlinear strain–displacement matrix and an analytical time-integration strategy. The numerical results mainly illustrate the influence of the geometrical and graded material properties of the FG layers on the critical buckling load and damping in the axially loaded sandwich beam. These results reveal that the five-layered composite core provides not only an augmented damping for attenuation of vibration through the parametric resonance but also a significantly improved static stability of the axially loaded sandwich beam in comparison to the conventional pure viscoelastic core. Therefore, the present five-layer composite laminate may be a potential material for an improved CLD treatment of axially loaded beam structures.