Propagation behavior of ultrasonic Love waves in functionally graded piezoelectric-piezomagnetic materials with exponential variation

Abstract

The current research is devoted to studying the propagation behavior of Love waves in a functionally graded piezoelectric film perfectly bound to a homogeneous piezomagnetic substrate named FGPPM. All the material properties are supposed to be exponential through the piezoelectric film. Using the stiffness matrix method (SMM), the phase and group velocities are numerically calculated for magneto-electrically open and shorted cases. A detailed investigation of the gradient coefficient effect on the dispersion curve, the magneto-electromechanical coupling factor, the cutoff wave-number, and the modal shape is undertaken. It is found that quite a high magneto-electromechanical coupling factor for the structure at some appropriate wave number can be achieved by a simple adjustment of the gradient coefficient. As the variation of magneto-electromechanical properties of the film changes gradually with depth, and since the initial stress is supposed negligible during the manufacturing process, this calculation model could serve as a perfect match for the laminated piezoelectric-piezomagnetic structures used as surface acoustic wave devices (SAW). Thus, it can provide a theoretical basis for the design of the SAW devices with high performance.