Ultrasonic Guided Wave Scattering Matrices and Tomography Using Sparse Arrays for Defect Characterization

Ultrasonic sparse array can increase the resolution by enlarging the aperture without adding system complexity, and it has characteristics of large scanning range and high detection accuracy, which is one of the most promising applications of ultrasonic nondestructive testing technology. The application of reciprocity theory to scattering of guided waves by flaws was studied. A finite element model of sparse array ultrasonic testing was established, to investigate the scattering field distribution characteristics and the interaction of different typical defects, using the finite element model, analyzes the influence of scattering characteristics of defects for sparse array ultrasonic imaging detection. Based on tomography imaging, proposed a defect recognition method based on the sparse scattering information extracted from defect scattering coefficient matrix, and analyzed the relation between sparse scatting coefficient matrix and full scattering coefficient matrix. Based on the principle of ultrasonic guided wave tomography, a sparse array ultrasonic guided wave imaging technique has been realized. The results show that the method successfully detects and displays defects correctly. Ultrasonic guided wave imaging techniques can potentially be useful in detecting defects in plate-like structures.