Flexoelectric Effect on SH-Wave Propagation in Functionally Graded Fractured Porous Sedimentary Rocks with Interfacial Irregularity

Abstract

Purpose: The present paper focuses on the propagation behaviour of Shear Horizontal (SH) waves in a fluid-saturated functionally graded fractured porous material layer consisting of sedimentary rocks perfectly bonded to an irregular piezoelectric semi-infinite substrate with flexoelectric effect. Two distinct cases corresponding to two differently shaped irregularities, viz. rectangular and parabolic, are considered at the layer-substrate interface. Methods: With the help of Fourier transform, inverse Fourier transform, and perturbation technique, complex frequency relation has been derived for each type of irregular interface. Two different flexoelectric materials, viz. Lithium niobate (Formula presented.) and Barium titanate (Formula presented.), are taken into account for performing comparative graphical analysis. Results: Obtained frequency relations are dissociated into real and imaginary components representing the dispersion and damping of SH-wave propagation. Dispersion and attenuation characteristics of SH-waves are executed graphically on the basis of several key parameters, such as irregularity, functional gradient, flexoelectric coefficient, volume fraction of matrix and fracture pores, piezoelectric, and dielectric constants. Conclusions: On applying the referred conditions, the dispersion equations for both type of irregularities fairly match with the Classical Love wave equation. This fact validates the consideration of the layered composite structures. The noteworthy effects of the key parameters on the dispersion and damping of SH-waves are revealed graphically. Moreover, the phase and damped velocities of SH-waves are observed to be significantly greater for LiNbO (Formula presented.) than for BaTiO (Formula presented.) in each irregular case.