Finite element model for waves guided along solid systems of arbitrary section coupled to infinite solid media

The Semi-Analytical Finite Element (SAFE) method is becoming established as a convenient method to calculate the properties of waves which may propagate in a waveguide which has arbitrary cross-sectional shape but which is invariant in the propagation direction. A number of researchers have reported work relating to lossless elastic waves, and recently the solutions for nonpropagating waves in elastic guides and for complex waves in viscoelastic guides have been presented. This paper presents a further development, addressing the problem of attenuating waves in which the attenuation is caused by leakage from the waveguide into a surrounding material. This has broad relevance to many practical problems in which a waveguide is immersed in a fluid or embedded in a solid. The paper presents the principles of a procedure and then validates and illustrates its use on some examples. The procedure makes use of absorbing regions of material at the exterior bounds of the discretized domain.