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Non-axisymmetric guided waves including flexural longitudinal and flexural torsional modes have shown natural focusing characteristics in pipe inspection. A flexural torsional mode theory was developed in this paper based on flexural longitudinal mode theory. Flexural mode experiments were then carried out to show the natural focusing phenomena. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The guided wave field excited in a plate-like structure from any weakly coupled transducer can be calculated from the superposition of the guided wave fields due to a number of suitable point or line excitation sources. In this paper, the fields from various point and line excitation sources are reviewed and relationships between them are demonstrated. The performance of pancake coil EMATs is modeled using the superposition of the fields from point sources and the results compared with experiment. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The sensitivity of a permanently attached guided wave array for the detection of corrosion damage in plates is studied. The thickness reduction due to corrosion is modeled as a circular part-through hole. The scattering and mode conversion of the A0 Lamb wave mode is calculated numerically employing a three-dimensional finite element model and verified in laboratory experiments. Good agreement is found and the sensitivity of the guided wave monitoring of large areas can be predicted. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A hybrid three-dimensional boundary element normal mode expansion technique is developed to study the guided wave scattering from an arbitrary shape defect in a plate. Lamb wave incident into a circular through plate hole were studied as an example. The scattered wave displacement field and each normal mode component are given. Mode conversion from Lamb wave to SH wave and vice versa at the defect boundary were observed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Guided wave calculation using a semi-analytical finite element method is described in this study. Two dimensional discretization modeling and its optimization technique by the use of the symmetry of a pipe are developed for wave propagation in a pipe with a defect. The effect of guided wave focusing, having been developed by Penn State group, is investigated for torsional waves. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Circumferential guided waves are used for the inspection of stress corrosion cracking (SCC). A simplified two dimensional model for crack sizing in pipes is presented. 2-dimensional hybrid boundary element modeling analysis was used to study defect sizing and discrimination in a pipe-like structure. The theoretical results agree with the experiments in utilizing a magnetostrictive sensor (MsS) technology for generating circumferential shear horizontal guided wave in pipe. An approximate 2-dimensional theory based on an axial scan has been developed that improves the defect depth estimate considerably. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]