Vibration analysis of functionally graded material sandwich structures with passive damping

In this work a finite element model is developed for vibration analysis of pure functionally graded material (FGM) structures, and for passive damped sandwich structures, with a soft viscoelastic core between the FGM layers. The FGM layers are modeled using the classical plate theory and the core is modeled using Reddy's third-order shear deformation theory. The finite element is obtained by using specific assumptions on the displacement continuity at the interfaces between layers. The dynamic analysis of these types of structures is conducted in the frequency domain to obtain the natural frequencies and, for the case of a viscoelastic core, the respective modal loss factors. It is also conducted in the time domain for steady state harmonic motion. For both analyses, the finite element code is implemented. The model is applied in the solution of some illustrative examples and the results are presented and discussed.