Free vibration analysis of five-layered composite sandwich plates with two-layered viscoelastic cores

This paper deals with the free vibration analysis of two kinds of five-layered composite sandwich plates with two-layered viscoelastic cores based on the first-order shear deformation theory for the first time. To fulfill this purposes, first, the Hamilton's principle is employed to derive the equations of motion that govern the free vibrations of the sandwich plates, and solved by employing the method of the closed-form Navier method. Then, the present solutions are compared with those available in the previous literature to confirm their validity. Next, the variations of frequency and loss factor with system parameters are evaluated and presented graphically. Owing to considering the effect of rotary inertias and shear deformation, thin-to-moderately thick shells can be analyzed. New results for free vibration analysis of five-layered composite sandwich plates with two-layered viscoelastic cores are also presented for the first time and they may be served as benchmark for researchers in this field.