Three-dimensional Green’s function for time-harmonic dynamics in a viscoelastic layer

This paper presents Green’s function for time-harmonic elastodynamic problems for a single layer domain (three-dimensional region bounded by two parallel planes with traction-free boundary conditions). The semi-analytic solution is built in three steps: (a) potential displacement representation; (b) angular Fourier series; (c) radial Hankel transform. Reflection matrices are presented for the plate domain. Kernels are integrally split into a singular closed-form term (the static half-space solution) plus an incremental solution. In order to compute the inverse Hankel transform for displacements and stress components, a modified complex integration path is required. Theoretical considerations allow an adequate delimitation of such a complex path. A specific treatment is proposed for low excitation frequencies where asymmetric Lamb waves play a major role. A series of numerical benchmarks are presented to validate the implementation of the functions (displacements and tractions).