Wave Propagation Analysis of Functionally Graded Graphene-Reinforced Piezoelectric Sandwich Nanoplates via Nonlocal Strain Gradient Theory

This article elaborates on the dispersion of waves in piezoelectric sandwich nanoplates resting on a viscoelastic foundation. The nanoplate comprises a functionally graded (FG) graphene-reinforced composite core layer with two piezoelectric surface layers. By combining the Halpin–Tsai model and related mixture rules, the properties of the composite material have been obtained. The Euler–Lagrange equation is obtained using the third-order shear deformation theory (TSDT) and Hamilton’s principle. Subsequently, based on the nonlocal strain gradient theory (NSGT), the equation of motion is presented. Finally, the effects of scale parameters, hygrothermal conditions, graphene distribution, and viscoelastic foundation on the propagation characteristics are numerically studied. The results reveal that the scale effect is more evident when the wave number is larger. Furthermore, critical damping increases with a rise in the wavenumber and Winkler modulus.