Optimizing focal resolution imaging in Lamb wave time-reversal through periodic plate-column structures: Simulation and experimental study

Ultrasonic guided wave non-destructive testing technology, as one of the most widely used techniques in non-destructive testing, has encountered challenges in breaking the diffraction limit to achieve finer super-resolution imaging during its development. As a type of wave accompanying ultrasonic guided wave damage detection, the transient wave has had the potential to achieve super-resolution imaging in recent years due to its high wave number and sub-wavelength characteristics. In order to overcome its spatial attenuation characteristics, this study constructs a periodic plate-column structure metamaterial. By utilizing its resonance with sub-wavelength Bloch modes at specific frequencies and the interaction with transient waves carrying sub-wavelength information, the wave carrying sub-wavelength signals is amplified, transformed, and transmitted to the far field, thereby achieving super-resolution imaging. The dispersion characteristics of the periodic plate-column structure were simulated and experimentally investigated. The super-resolution imaging effect of the periodic plate-column structure metamaterial was simulated using the time-reversal imaging method and experimentally validated, providing a basis for achieving damage super-resolution imaging with periodic plate-column structures.