Ultrasonic guided wave focusing beyond welds in a pipeline

Li Zhang, Wei Luo, Joseph L. Rose

Research output: Chapter in Book/Report/Conference proceedingConference contribution

18 Scopus citations


Ultrasonic guided wave inspection techniques are well-known for the inability to scan a long range axial distance of a pipe from a single transducer position. A phased array focusing technique was developed to improve the ultrasonic guided wave inspection results by concentrating the energy onto a defect. Focusing can increase the energy impinging onto the defects, reduce false alarm ratio, locate the defects, and enhance the propagation distance of the guided waves. An ultrasonic system with n (n>1) individual excitation channels is required to achieve phased array focusing. When phased array focusing was carried out, time delays and amplitude factors were applied to control the input signals for each excitation channel. Different from the time delays for bulk wave linear array focusing, the time delays and amplitude factors for guided wave array focusing are non-linear functions of the focal distance, the pipe size, excitation conditions, and the active frequency. A challenge of this technique is to focus beyond welds, defects, or other obstructions. The influence of axisymmetric welds is investigated with 3D FEM simulations and an experimental example. The theoretical analysis and experiments shows that although welds usually decrease the penetration energy, a limited number of welds rarely affects the phased array focal location.

Original languageEnglish (US)
Title of host publicationReview of Progress in Quantitative Nondestructive Evaluation
Subtitle of host publicationVolume 25A
Number of pages8
StatePublished - Mar 6 2006
EventReview of Progress in Quantitative Nondestructive - Brunswick, ME, United States
Duration: Jul 31 2005Aug 5 2005

Publication series

NameAIP Conference Proceedings
Volume820 I
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherReview of Progress in Quantitative Nondestructive
Country/TerritoryUnited States
CityBrunswick, ME

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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