Location

Brunswick, ME

Start Date

1-1-1992 12:00 AM

Description

In solving ultrasonic flaw characterization problems, flaw type information is often needed in order to pursue succeeding tasks such as flaw sizing. In a typical inspection, the interaction of the incident ultrasonic pulse with the flaw results in a series of signal trains. A variety of signal features are extracted from these flaw signals and then used as the basis for the classification process. This classification process is made difficult by the large number of possible scattered waves. For example, typical ultrasonic signals from a planar crack-like defect consist of reflected responses, surface traveling waves, edge diffracted waves and head wave components. For a volumetric void-like defect, the returned signal pattern similarly contains reflected waves of the same mode as well as mode-converted reflections and “creeping” waves. However, in pulse-echo testing a fundamental difference exists between a crack-like flaw and a volumetric flaw that can be used for classification purposes. This difference is reflected in the fact that a significant mode-converted diffracted wave component can exist for a crack-like defect (Fig. 1(a)) which does not exist in pulse-echo testing for a volumetric defect (Fig.1(b)).

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

11A

Chapter

Chapter 3: Interpretive Signal Processing and Image Reconstruction

Section

Imaging and Inversion Techniques

Pages

843-848

DOI

10.1007/978-1-4615-3344-3_108

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Ultrasonic Flaw Classification Using a Quasi-Pulse-Echo Technique

Brunswick, ME

In solving ultrasonic flaw characterization problems, flaw type information is often needed in order to pursue succeeding tasks such as flaw sizing. In a typical inspection, the interaction of the incident ultrasonic pulse with the flaw results in a series of signal trains. A variety of signal features are extracted from these flaw signals and then used as the basis for the classification process. This classification process is made difficult by the large number of possible scattered waves. For example, typical ultrasonic signals from a planar crack-like defect consist of reflected responses, surface traveling waves, edge diffracted waves and head wave components. For a volumetric void-like defect, the returned signal pattern similarly contains reflected waves of the same mode as well as mode-converted reflections and “creeping” waves. However, in pulse-echo testing a fundamental difference exists between a crack-like flaw and a volumetric flaw that can be used for classification purposes. This difference is reflected in the fact that a significant mode-converted diffracted wave component can exist for a crack-like defect (Fig. 1(a)) which does not exist in pulse-echo testing for a volumetric defect (Fig.1(b)).