  A phenomenological method is developed to consider elastic guided wave
propagation in complex curved waveguides. The theory on guided wave propagation
in hollow circular cylinders is used in order to verify the method. The results
are compared with solutions obtained by the Helmholtz decomposition method. The
method given here is used to derive new analytical relations for torsional and
longitudinal phase velocity dispersion curves. In addition, a new excitation
method is proposed and examined for flexural modes. Some conceptual results and
applications of the method are discussed.
