Localization of Lamb wave source with a single transmitter-receiver combination by elastic metamaterials

Many nondestructive testing and structural health monitoring systems utilize Lamb wave transducer arrays for identification and localization of scattering wave sources. A large number of transducers are usually required during array signal processing and source localization, which increases hardware cost and reduces system reliability. To overcome this limitation, a metamaterial structure is designed in this study to realize source localization with a single transmitter-receiver combination. The basic design principle is the utilization of local resonators to customize propagation characteristics of Lamb waves. In particular, amplitude-frequency modulation and velocity dispersion are customized during metamaterial design. Uncorrelated amplitude-frequency modulation is extracted from signal frequency spectrum for orientation identification. Velocity dispersion is extracted from signal time-frequency spectrum for distance evaluation. After orientation identification and distance evaluation, wave source localization is then realized. Finally, the metamaterial structure is 3D printed using PA2200 nylon and bonded to the aluminum specimen to experimentally demonstrate the effectiveness of source localization with a single transmitter-receiver combination.