A new approach to interfacial material effects on plane wave reflection–transmission in PZT-5A–epoxy composite structure

This study introduces a new method on the reflection–transmission of obliquely incident quasi-Primary (qP) waves at an interface among two semi-infinite piezoelectric media, namely, a piezoelectric fiber-reinforced composite (PFRC) occupying the lower half-space and a homogeneous piezoelectric medium in the upper half-space. The two media are mechanically and electrically coupled through a common piezoelectric thin plate at the interface, modeled using the extended Gurtin–Murdoch surface elasticity framework. The angular dependence of all the reflected and transmitted waves follows a generalized Snell’s law, and energy flux analysis has confirmed near-conservation of total energy at the interface. Numerical computations demonstrate that interfacial stiffness, piezoelectric coupling, and PFRC volume fraction significantly influence wave reflection, transmission, and mode conversion. The results are relevant to the design and optimization of piezoelectric sensors, actuators, and energy harvesting devices in smart composite structures and acoustic waveguides.