Method for constructing electromagnetic ultrasonic guided wave tomography signals based on A-NA

Abstract A method for extracting electromagnetic ultrasonic guided wave tomography signals using Absolute-Normalized Amplitude (A-NA) is proposed. This approach aims to mitigate the degradation of structural damage tomography quality resulting from pseudo-modal phenomena in electromagnetic ultrasound. By leveraging the normalization and suppression function of the absolute echo amplitude, the elements of the measurement vector matrix are defined to reduce the influence of pseudo-modal signals on imaging results, thereby enhancing the quality of electromagnetic ultrasonic guided wave tomography reconstruction. Experimental results, evaluated through structural similarity analysis, show that the proposed method improves imaging quality by 2.2% for square defect structures and 0.46% for circular defect structures in the processed results. Additionally, the similarity of crack defect structures achieved through A-NA imaging can be improved by up to 5.05% compared to traditional methods. This signal construction method significantly mitigates the influence of pseudo-modes on the quality of tomographic imaging.