High frequency guided wave natural focusing pipe inspection with frequency and angle tuning

Li Zhang, Brian J. Gavigan, Joseph Lawrence Rose

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)433-438
Number of pages6
JournalJournal of Pressure Vessel Technology, Transactions of the ASME
Issue number3
StatePublished - Aug 1 2006

All Science Journal Classification (ASJC) codes

  • Safety, Risk, Reliability and Quality
  • Mechanics of Materials
  • Mechanical Engineering


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