  The numerical analysis of elastic wave propagation in unbounded media may be
difficult due to spurious waves reflected at the model artificial boundaries.
This point is critical for the analysis of wave propagation in heterogeneous or
layered solids. Various techniques such as Absorbing Boundary Conditions,
infinite elements or Absorbing Boundary Layers (e.g. Perfectly Matched Layers)
lead to an important reduction of such spurious reflections. In this paper, a
simple absorbing layer method is proposed: it is based on a Rayleigh/Caughey
damping formulation which is often already available in existing Finite Element
softwares. The principle of the Caughey Absorbing Layer Method is first
presented (including a rheological interpretation). The efficiency of the
method is then shown through 1D Finite Element simulations considering
homogeneous and heterogeneous damping in the absorbing layer. 2D models are
considered afterwards to assess the efficiency of the absorbing layer method
for various wave types and incidences. A comparison with the PML method is
first performed for pure P-waves and the method is shown to be reliable in a
more complex 2D case involving various wave types and incidences. It may thus
be used for various types of problems involving elastic waves (e.g. machine
vibrations, seismic waves, etc).
