Multi-field coupling and free vibration of a sandwiched functionally-graded piezoelectric semiconductor plate

Sandwiched functionally-graded piezoelectric semiconductor (FGPS) plates possess high strength and excellent piezoelectric and semiconductor properties, and have significant potential applications in micro-electro-mechanical systems. The multi-field coupling and free vibration of a sandwiched FGPS plate are studied, and the governing equation and natural frequency are derived with the consideration of electron movement. The material properties in the functionally-graded layers are assumed to vary smoothly, and the first-order shear deformation theory is introduced to derive the multi-field coupling in the plate. The total strain energy of the plate is obtained, and the governing equations are presented by using Hamilton's principle. By introducing the boundary conditions, the coupling physical fields are solved. In numerical examples, the natural frequencies of sandwiched FGPS plates under different geometrical and physical parameters are discussed. It is found that the initial electron density can be used to modulate the natural frequencies and vibrational displacement of sandwiched FGPS plates in the case of nano-size. The effects of the material properties of FGPS layers on the natural frequencies are also examined in detail.