When ultrasonic guided wave nondestructive evaluation is used to inspect pipelines, partial loading of transducers around the circumference leads to a non-axisymmetric energy distribution. At particular axial distances and frequencies, the ultrasonic energy is naturally focused at some spots via constructive wave interference. This so-called “natural focusing” phenomenon can be used to improve guided wave sensitivity for a defect by impinging more energy onto it. However, defects located in other places can be missed, unless we can move the natural focusing points throughout the pipe. We have done this by frequency and circumferential angle tuning for specific circumferential loading lengths. In order to utilize the natural focusing phenomenon to enhance detection sensitivity, a frequency and angle tuning (FAT) technique is employed to extend the area that can be scanned by focal energy. It is observed that the natural focal points at a fixed axial distance move with frequency variation and circumferential excitation length change. In this paper, the natural focusing phenomenon with FAT is theoretically calculated and experimentally investigated. The results show that the natural focusing inspection technique can sufficiently inspect an entire pipe with FAT.
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August 2006
Research Papers
High Frequency Guided Wave Natural Focusing Pipe Inspection With Frequency and Angle Tuning
Li Zhang,
Li Zhang
Department of Engineering Science & Mechanics,
The Pennsylvania State University
, University Park, PA 16802
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Brian J. Gavigan,
Brian J. Gavigan
Department of Engineering Science & Mechanics,
The Pennsylvania State University
, University Park, PA 16802
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Joseph L. Rose
Joseph L. Rose
Department of Engineering Science & Mechanics,
The Pennsylvania State University
, University Park, PA 16802
Search for other works by this author on:
Li Zhang
Department of Engineering Science & Mechanics,
The Pennsylvania State University
, University Park, PA 16802
Brian J. Gavigan
Department of Engineering Science & Mechanics,
The Pennsylvania State University
, University Park, PA 16802
Joseph L. Rose
Department of Engineering Science & Mechanics,
The Pennsylvania State University
, University Park, PA 16802J. Pressure Vessel Technol. Aug 2006, 128(3): 433-438 (6 pages)
Published Online: April 20, 2005
Article history
Received:
January 21, 2005
Revised:
April 20, 2005
Citation
Zhang, L., Gavigan, B. J., and Rose, J. L. (April 20, 2005). "High Frequency Guided Wave Natural Focusing Pipe Inspection With Frequency and Angle Tuning." ASME. J. Pressure Vessel Technol. August 2006; 128(3): 433–438. https://doi.org/10.1115/1.2218348
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