Free vibration and parametric instability of viscoelastic sandwich plates with functionally graded material constraining layer

Free vibration and parametric instability analyses of a three-layered sandwich plate with viscoelastic constrained layer and functionally graded material constraining layer are carried out in this work. A finite element model is developed for the vibration and parametric instability analyses of the sandwich plate. The lateral and transverse displacements of the viscoelastic core layer are considered as linear functions of top and bottom layer displacements. The first-order shear deformation theory is used to incorporate the effect of transverse sheer of the face layers, and in addition to the effect of shear deformation of the core, the effects of transverse and longitudinal deformations are also considered in this analysis. So that the present finite element model can be applied to the sandwich plates with thin as well as thick layers of core. The variations of fundamental frequency, mode loss factors and instability regions with different aspect ratios, thickness ratios, and boundary conditions are examined.