No abstract

The paper deals with 3D analysis of the near-resonant regimes of a point load, moving steadily along the surface of a coated elastic half-space. The developed approach relies on a specialized hyperbolic-elliptic formulation for the wave field earlier established by the authors. Straightforward integral solutions of the 2D perturbed wave equation describing wave propagation along the surface are derived along with their far-field asymptotic expansions obtained using the uniform stationary phase method. Both sub-Rayleigh and super-Rayleigh cases are studied. It is shown that the singularities arising at the contour of the Mach cones typical of the super-Rayleigh case, are smoothed due to a dispersive effect of the coating.

An explicit hyperbolic-elliptic formulation for surface Rayleigh waves is analysed with an emphasis on the causality of obtained results. As an example, a 3D moving load problem for a distributed vertical load is considered. A simple approximate solution is derived for a near-resonant regime, and the related point load solution is recast as a limiting case. It is shown that causality is characteristic only for the longitudinal wave potential along the surface, where it is governed by a hyperbolic equation modelling the small dilatation disturbances propagating at the Rayleigh wave speed.