Date of Award
Doctor of Philosophy
Lester W. Schmerr
Flaw classification (determination of the flaw type) and flaw sizing (prediction of the flaw shape, orientation and sizing parameters) are very important issues in ultrasonic nondestructive evaluation of materials. In this work, new techniques for both classification and sizing are described;In the area of flaw classification, a methodology is developed which can solve classification problems in weldments using probabilistic neural networks. In the area of flaw sizing, four new approaches are presented including (1) the determination of distance-gain-size (DGS) curves and frequency response curves for flat-bottom holes based on a theoretical ultrasonic scattering model, (2) a time-of-flight equivalent (TOFE) sizing method for relatively large (>1 mm) flaws in materials, (3) an amplitude-based equivalent (ABE) sizing method and (4) a first moment (FM) sizing method. Both the third and fourth methods are shown to be new viable techniques for sizing relatively small (<1 mm) flaws in materials.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Song, Sung-Jin, "Ultrasonic flaw classification and sizing " (1991). Retrospective Theses and Dissertations. 9776.