Guided waves hold great potential for applications in non-destructive testing. An example of research in this field is the development of novel procedures for ultrasonic testing and structural health monitoring of wheelset-axles which can be described as cylindrical structures with varying cross-section. A major drawback of the well established mesh based numerical procedures that are available for the simulation of guided wave propagation through such structures, like for example the finite element method, is that they can be very expensive in terms of computation time in cases where large geometries have to be discretized with a comparatively fine mesh. The use of a multimodal method seems to be a promising alternative approach that can be expected to provide results significantly faster than a mesh based procedure. This method uses the guided wave modes of a corresponding waveguide with a constant cross-section as base in which the local sound field at any given position in a waveguide with varying size of the cross-section can be expressed thus reducing the problem to solving the one dimensional differential equation that governs the evolution of the coefficients in the mode spectrum along the waveguide. Once the sound field along the waveguide has been calculated, a time dependence that also allows the simulation of pulse propagation can easily be included. In this work, the implementation of a multimodal method for simulation of guided waves in plates with varying thickness is adapted to cylindrical structures with varying radius. An overview of the results obtained for simulations of guided waves in cylindrical rods is presented and the multimodal approach is compared to the finite element method with respect to its efficiency.
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