Rayleigh-Like Waves in Coated Elastic Half-Space with Voids: Use of Effective Boundary Condition Method

Propagation of Rayleigh-like surface waves in a linear, homogeneous, and isotropic elastic solid half-space coated with a thin isotropic elastic solid layer has been studied. The interface between the half-space and the layer is assumed to be in smooth contact with each other. Both the layer and the half-space contain uniform distribution of small void pores. The effective boundary conditions are derived that replace the entire effect of the thin layer to the interface. These conditions are then utilized to derive the approximate secular equations of second-order, third-order, and fourth-order for Rayleigh-like wave propagation in terms of dimensionless wavenumber. The corresponding secular equations are solved numerically to obtain the speed of propagating Rayleigh-like wave for a particular model. The presence of voids in the model is found to influence the speed of Rayleigh-like wave theoretically and verified numerically. However, the void parameters of the half-space (and not of the layer) are found to affect the propagation of Rayleigh-like wave. In the absence of voids from the model, the resulting secular equation is found to be in complete agreement with the corresponding model available in literature. The nature of contact interface between layer and the half-space affects the propagation speed of Rayleigh-like waves. The thickness of the coating/layer also affects the speed of propagation in the considered model.