NEW APPROACHES TO ULTRASONIC EQUIVALENT SIZING FOR SMALL FLAWS

Ultrasonic equivalent flaw sizing methods size defects in a material by obtaining a best-lit simple defect shape (such as an ellipsoid or ellipse) from relatively small amounts of ultrasonic data. In these equivalent flaw sizing methods, it is essential that the origin of time be determined precisely with respect lo a fixed spatial location. Current methods for this determination are not entirely adequate, leading to an important “ zero-of-lime” problem In this work, two new approaches to equivalent flaw sizing for relatively small flaws are developed: (1) an amplitude-based equivalent (ABE) sizing method for obtaining best-lit equivalent flaws by the use of amplitude ratios measured at different transducer orientations, and (2) a first moment (FM) method for estimating the equivalent radius from a first moment calculation of the lime domain flaw response. We show how these approaches can address the zero-of-lime problem and demonstrate the performance of these methods with experiments