Modeling Defects in Ultrasonic Nondestructive Testing: State-of-the-Art and Prospects

In the introduction to the article we mention four factors that are most important for ensuring the accuracy of characterizing defects during ultrasonic inspection, viz., parameters of artificial reflectors in samples, compliance of the acoustic properties of the material of tuning samples and tested products, transient characteristics of electroacoustic paths, and methodological features of measurements. The present article is devoted to the analysis of the first and partly fourth of listed factors. The review of reflectors, the use of which is regulated in various standards, is carried out. Advantages and disadvantages of flat-bottomed holes, segmental and corner reflectors (“notches”), lateral (SDH) and vertical cylindrical holes, and grooves are noted. Taking into account the specific features of ultrasonic wave scattering, it is noted that artificial “reflectors” such as “grooves” and SDHs are used to adjust the parameters of modern diffraction testing methods. It is recommended to expand the use of grooves, SDHs, and vertical drilling when revising the standards governing the use of conventional echo methods. The estimation of accuracy of measurement of defects parameters, first of all, the crack tip coordinates, with application of modern digital methods of information processing during ultrasonic testing is given. It is indicated that to increase the measurement accuracy and to determine the position and orientation of cracks in welds, it is necessary to create a database of digital twins of samples with artificial reflectors and products with real defects. A general scheme of executing the quality control is given that takes into account the use of standards (measures), digital models of artificial reflectors, and digital twins of the testing process to ensure the necessary detectability of defects and reliability of manual, automated, and, potentially, automatic testing.