Wave focusing in pipe-like structures via gradient-index metamaterial lens toward damage detection and localization

In this paper, we explore a metamaterial lens layer integrated within the pipe design to amplify the signal energy at the positions of the receiving sensors and damage initiation position enabling the transmission of damage information long distances. The gradient-index metamaterial layer is composed of unit cells with a hyperbolic secant profile distribution of refractive index to focus the wave energy transmitted by ultrasonic wave used in guided wave. The proposed methodology is implemented on a steel pipe typically used in the distribution networks utilized in cities and wave focusing performance is verified through numerical models.