Surface acoustic waves in an infinite plate covered by a viscoelastic layer

In order to understand the characteristics of the viscoelastic coating and evaluate adhesive quality, we analyzed the effect of a thin viscoelastic layer on the propagation of surface acoustic waves in an infinite plate, which can be isotropic or anisotropic. Based on an introduction of potential functions of wave propagation in the viscoelastic layer, we started from the interaction of a thin viscoelastic layer and surface acoustic waves in an isotropic infinite plate, and obtained the relationship between wave velocity and the thickness of viscoelastic layer. Numerical results shown when the thickness of the viscoelastic layer is zero, surface acoustic waves will have the same velocity as the case of corresponding infinite plate; with the increase of the thickness of the viscoelastic layer, both mass and attenuation effect will have more influence on wave velocity. Finally, we analyzed the effect of a thin viscoelastic layer on the propagation of surface acoustic waves in a quartz crystal plate. It is observed from an ST-cut quartz crystal plate that there are many vibration modes and corresponding velocities due to the interaction of waves in the plate and viscoelastic layer. All these results and method could provide potential applications for estimation of viscoelastic parameters or evaluation of quality of adhesion.