Bleustein-Gulyaev waves in a functionally graded piezoelectric half-space with exponential variation

The existence and propagation of Bleustein-Gulyaev (B-G) waves in a functionally graded piezoelectric substrate with exponential variation is studied by analytical technique. The dispersion equations for the existence of the B-G waves with respect to phase velocity are obtained for both electrically open and short conditions. A detailed investigation of the effect of the gradient coefficient on dispersion relation, phase velocity, electromechanical coupling factor is carried out. It is found by numerical examples that adjusting gradient coefficient makes the electromechanical coupling factor of the B-G waves achieve quite high values at some appropriate wave number. Because of the negligible initial stress in functionally graded piezoelectric materials, this model could serve as an excellent substitute for the typical layered piezoelectric structures used in surface acoustic wave (SAW) devices, which provides with a theoretical foundation for designing SAW devices with high performance.