Distributed photoacoustic ultrasound damage imaging based on self-construction dictionary matching pursuit

The distributed photoacoustic ultrasonic nondestructive testing system demonstrated effective functionality in challenging environments, including those with electromagnetic interference. The scope of damage imaging on metal plates is significantly enhanced by the simultaneous excitation of multiple sources. However, the ultrasonic Lamb wave signals generated by these multiple excitation sources are susceptible to crosstalk, which can negatively impact the accuracy of damage imaging. To mitigate signal aliasing, a matching pursuit algorithm based on a self-construction dictionary was employed. This study introduces a damage imaging method utilizing a distributed ultrasonic nondestructive testing system based on the initial excitation signals that differ among excitation sources. Experimental validation indicates that this method can effectively represent sparsely and accurately reconstruct the damage signal, thereby enabling the precise localization of three simultaneous damages on an aluminum alloy 6061 plate with dimensions of 1500×1500×1 mm³.