Gradation and porosity's effect on Love waves in a composite structure of piezoelectric layers and functionally graded porous piezoelectric material

Love waves propagation in a composite structure lying over an elastic half-space are studied. The composite structure contains n piezoelectric layers and a functionally graded porous piezoelectric material(FGPPM) layer. The linear and exponential gradation of mechanical and electrical properties of the FGPPM layer are considered. The WKB technique is applied for obtaining the solution of the equations in the FGPPM layer. The transfer matrix is obtained for multilayers of piezoelectric materials. The frequency equations for both electrically open and short boundaries have been obtained. Numerical computations have been done to solve the frequency equations and to obtain electromechanical coupling, stress and displacements. The effect of porosity, wavenumber and gradation on the phase velocity and group velocity of Love waves have been studied and observed that group velocity is more affected by porosity than the phase velocity. Better resolution without compromising the magnitude of surface wave velocity seems to be achievable for piezoceramic having 20% to 30% porosity. Apart from these, the variations of attenuation and electromechanical coupling factor with grading parameters and porosity have also been examined and noticed that the grading type has a considerable effect on the coupling factor and attenuation quality factor. A relative study is conducted to demonstrate the impact of the number of piezoelectric layers above the FGPPM layer on dispersion curves and it is found that more energy is trapped with layering in a stack and an initial increase in the number of layers in the stack of composites is more effective. The effects of porosity and wavenumber on mechanical displacement, electrical displacement and stress have been studied numerically. Also, lateral and vertical variations of the mechanical displacement, electrical displacement and stress have been studied. The findings of the study are expected of use in improving the efficiency of SAW devices.

Automated summary

This study focuses on the propagation of Love waves in a composite structure consisting of piezoelectric layers and a functionally graded porous piezoelectric material (FGPPM) layer. The effects of porosity, wavenumber, and gradation on the phase velocity and group velocity of Love waves are investigated. The study also examines the variations of attenuation and electromechanical coupling factor with grading parameters and porosity. Numerical computations are conducted to analyze the mechanical and electrical displacement, stress, and attenuation. The findings provide valuable insights for improving the efficiency of surface acoustic wave (SAW) devices.