The work summarized here specifcally addresses the steady-state time-harmonic propagation of circumferential shear horizontal (SH) guided waves in a multi-layered hollow cylinder. The development of the dispersion equation for the single-layer case is discussed and then extended to the multi-layer case using the global matrix method. Phase and group velocity dispersion curves are presented for the case of a 20 inch diameter pipe with a protective coating layer with properties similar to that of a hot-applied coal-tar wrap. Several features pertinent to the detection of disbonded coating are identified. Theoretical results are experimentally validated using SH wave electromagnetic acoustic transducers (EMATs) and a 20 inch diameter pipe with a hot-applied coal-tar coating.

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