Surface shear interface waves in a prestressed piezoelectric layered structure

To automatically actualize ultrasonic nondestructive testing applications for structures with subsurface damage, we investigate horizontal shear interface waves in a prestressed piezoelectric layered structure. The elastic material with subsurface gradient damage can be considered as a structure in an elastic half-space covered by a gradient layer, and the upper covered piezoelectric layer can be considered as a piezoelectric half-space. We derive the field control equations with respect to the displacement function and the electrical potential function, and we solve the equations by the power series method. The results show that horizontal shear interface waves can propagate in this structure. The relation between wave number and wave velocity and the distribution of displacement amplitude, potential amplitude, and stress amplitude are illustrated. Numerical examples reveal the horizontal shear interface wave to have a normal dispersion. The more serious the subsurface damage is, the lower the phase velocity is. The method presented and the conclusions herein can provide a theoretical basis for ultrasonic nondestructive testing.