Japanese Journal of Applied Physics · 2013 · 47 citations · 29 references
Natural SciencesMechanical EngineeringPhysicsAcousticsMaterials CharacterizationUltrasoundAcoustic MeasurementAcoustic Wave PropagationMode ShapesPhysical AcousticsTransducer TechnologyUltrasonicsMode ConversionMode Conversion AnalysisMode PropagationMode TheoryTorsional WavesWall Thickness VariationWave Mode ConversionWave Propagation In Pipes
The group velocity of each higher torsional mode in a pipe depends on the wall thickness and it will convert to a lower mode when the thickness is smaller than a critical value, the so-called cut-off thickness. The fundamental torsional mode, T(0,1), and the first higher mode, T(0,2), are generated in pipes by an electromagnetic acoustic transducer (EMAT) and their mode conversion behaviors are investigated by changing the shape of a defect on the pipe. It is confirmed that the conversion behavior is sensitive to the shape of thickness transition and the total reflection of the T(0,2) mode occurs in a pipe with a tapered defect. On the basis of the mode conversion, defects with a cross-sectional loss larger than 35% are detectable.
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Defect detection in pipes using guided waves
M. J. S. Lowe, David Alleyne, P. Cawley · Ultrasonics · 1998 · 589 citations