EFFECTIVE BOUNDARY CONDITION METHOD AND APPROXIMATE SECULAR EQUATIONS OF RAYLEIGH WAVES IN ORTHOTROPIC HALF-SPACES COATED BY A THIN LAYER

In this paper, the effective boundary condition method for deriving approximate secular equations of Rayleigh waves propagating in elastic half-spaces coated by a thin layer is introduced. Then, the method is used to obtain approximate secular equations of Rayleigh waves in compressible (incompressible) orthotropic half-spaces covered by a thin incompressible (compressible) orthotropic layer. Approximate secular equations of third order have been derived and it is shown that they have high accuracies. Some numerical examples are carried out to evaluate the effect of incompressibility on the Rayleigh wave propagation. It is shown that the incompressibility affects considerably on the Rayleigh wave velocity.