Numerical Evaluation of the Effect of Gradient on Reflection Coefficient of Continuously Graded Layer

Abstract—This paper presents a numerical model, based on transfer matrix method, for modeling the propagation of surface acoustic waves at the interface formed by the coupling liquid and a continuously inhomogeneous thin layer on a semi-infinite substrate. The tow-dimensional spectrum of reflection coefficient computed by this model, allows determining the modes which propagate at the studied interface, this model treats different profile of gradients, and the numerical results obtained show that the reflection coefficient is sensitive to the variation of these gradients. Keywords—surface acoustic waves; nondestructive testing; functionally graded materials; dispersion curve; Lamb modes I