Spectral super-elements for wave propagation in structures with local non-uniformities

The spectral element method for the analysis of wave propagation in structures is extended by the introduction of a super-element concept to handle local regions of non-uniformity. The region of interest is meshed with conventional finite elements and its stiffness and mass matrices dynamically condensed leaving only the connection degrees of freedom. These are further condensed to just waveguide connectivities thus making the element suitable for assembly with other spectral elements. The formulation is verified by comparison with 2-D finite element solutions. Examples of its use in waveguides with cracks, holes and extended joints are demonstrated