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Proceedings Paper

Frequency-mode selection for ultrasonic detection and characterization of circumferential cracks in pipelines
Author(s): Yichi Lu
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Paper Abstract

Ultrasonic propagation in hollow cylinders is dispersive; velocities, displacements, stresses, and, more importantly, the average power flow are all functions of frequency. The average power flow of a wave mode is directly related to its transmissibility, and the displacement/stress distribution of a wave mode is related to its capability of defect detection and characterization. Mode selection and frequency selection, therefore, are both important issues for long-range ultrasonic pipeline inspection. Circumferential crack detection and characterization capabilities of the lowest and the second lowest longitudinal modes [L(0,1) and L(0,2)] and the lowest flexural mode [F(1,1)] are investigated analytically based on average power flow and axial displacement/stress distributions. It is found that the L(0,1) mode has strong power flow only in the low kHz region, and the L(0,2) in the lower-middle kHz region. The F(1,1) mode, however, is found to have strong power flow in a broad frequency range, starting from the low kHz region, and is therefore a preferred wave mode for long-range ultrasonic pipeline inspection.

Paper Details

Date Published: 15 March 1998
PDF: 10 pages
Proc. SPIE 3398, Nondestructive Evaluation of Utilities and Pipelines II, (15 March 1998); doi: 10.1117/12.302529
Show Author Affiliations
Yichi Lu, Southwest Research Institute (United States)


Published in SPIE Proceedings Vol. 3398:
Nondestructive Evaluation of Utilities and Pipelines II
Walter G. Reuter, Editor(s)

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