Free vibration analysis of a sandwich nano-plate including FG core and piezoelectric face-sheets by considering neutral surface

In this article, two-variable sinusoidal shear deformation theory, nonlocal piezoelasticity relations incorporating with concept of neutral surface are employed for free vibration analysis of a sandwich nano-plate. Due to using the functionally graded materials, the concept of neutral surface must be employed through formulation of the problem. A parametric study is performed to show how natural frequencies of sandwich nano-plate are changed in terms of nonlocal parameter, non-dimensional geometric parameters and in-homogeneous index. Before presentation of full numerical results, a comparison with a valid reference is performed to confirm our formulations and corresponding numerical results.