A Model for Multiview Ultrasonic Array Inspection of Small Two-Dimensional Defects

The multiview total focusing method (TFM) is an imaging algorithm for ultrasonic full matrix array data that exploits internal reflections and mode conversions in the inspected object to create multiple images, the views. Modeling the defect response in multiview TFM is an essential first step in developing new detection and characterization methods that exploit the information present in these views. This paper describes a ray-based forward model for small 2-D defects and compares its results against finite-element simulations and experimental data for the inspection of a side-drilled hole, a notch, and a crack. A simpler version of this model, based on a single-frequency approximation, is derived and compared. A good agreement with the multifrequency model and a speedup of several orders of magnitude are achieved.