Acoustic Wave in Piezoelectric Coupled Plates with Open Circuit

An accurate modeling of the piezoelectric effect of coupled structures is essential to application of piezoelectric materials as sensors and actuators in engineering structures, such as Micro-Electro-Mechanical Systems and Interdigital Transducer for health monitoring of structures. This paper presents a simulation for the shear horizontal wave propagation in an infinite metal plate surface bonded by a piezoelectric layer with open electrical circuit, with focus on the dispersion characteristics of a metal core bonded by a layer of piezoelectric material to be used in health monitoring of structures. The dispersive characteristics and mode shapes of the deflection, electric potential, and electric displacement of the piezoelectric layer are theoretically derived. The results from numerical simulations show that the phase velocity of the piezoelectric coupled plate approaches the bulk-shear wave velocity of the substrate at high wavenumbers. The mode shapes of electric potential and deflection of the piezoelectric layer with steel substrates change from a shape with few zero nodes to one with more zero nodes at higher wavenumbers and with thicker piezoelectric layer. For the coupled plate with gold substrates at higher wavenumbers, the electric potential is found to jump from null at the interface of the piezoelectric layer and the substrate to a constant at the surface of the piezoelectric layer along the thickness direction. These findings are useful to the design of sensors using the piezoelectric coupled structures.