The reflection of guided waves from simple supports in pipes

• Published in: The Journal of the Acoustical Society of America Vol. 129; no. 4; pp. 1869 - 1880
• Main Authors: Galvagni, Andrea, Cawley, Peter
• Format: Journal Article
• Language: English
• Published: Melville, NY Acoustical Society of America 01.04.2011; American Institute of Physics
• Subjects: Acoustical measurements and instrumentation; Acoustics; Chemical Industry; Construction Materials; Cross-disciplinary physics: materials science; rheology; Cut-off; Defects; Exact sciences and technology; Flaw detection; Fundamental areas of phenomenology (including applications); Materials science; Materials testing; Mathematical analysis; Models, Theoretical; Petroleum; Physics; Pipe; Reflection; Reflection coefficient; Ultrasonics - methods; Ultrasonics, quantum acoustics, and physical effects of sound; Wave propagation; Guided wave; Piping; Ultrasonic control; Wave reflection
• ISSN: 0001-4966; 1520-8524; 1520-8524
• DOI: 10.1121/1.3543958

Successful ultrasonic guided wave detection of flaws at support locations relies on the ability to distinguish between the reflection produced by a simple support on an undamaged pipe and the reflection produced by pipe flaws. Consequently, it is essential to know how the reflections produced by simple supports behave; very little work has so far been reported on this subject. Through finite element simulations and experiments, this study develops a systematic understanding of how ultrasonic guided waves propagating along a pipe, in particular the T (0, 1) mode, interact with simple supports. It is shown that, unlike the T (0, 1) mode in a free pipe, the torsional mode in a supported region has a cut-off frequency, below which it will not propagate; below this frequency the T (0, 1) reflection coefficient is large, and it quickly reduces beyond the cut-off.