Effect of interfacial defect on Love waves in composite structures with piezoelectric thin film

Based on the shear spring model,the dispersion equation was established for Love waves propagating in a composite structure with interfacial defect.The composite structure consists of an elastic substrate covered by a piezoelectric thin film.The effect of the interfacial defect on the propagation properties of Love waves was investigated.The dispersion curves were presented for Love waves propagating in an aluminum substrate covered by a PZT4 piezoelectric thin film.Numerical results show that:(1) For different interfacial defects,the phase velocities of Love waves of the first mode at long wavelength region approach to the velocities of shear waves in elastic substrate,while those at short wavelength region approach to the velocities of Bleustein-Gulyaev(B-G) waves in piezoelectric thin film;(2) The existence of the interfacial defect always decreases the phase velocities of Love waves.At some special frequency ranges,the phase velocities of Love waves are more sensitive to the interfacial defect;(3) The interfacial defect has significant effect on the mode shapes of the mechanical displacement and the electric potential in the piezoelectric thin film,and the most susceptive region appears near the interface.