Rayleigh–Lamb waves in a microstretch elastic plate cladded with liquid layers

Propagation of Rayleigh–Lamb waves in an infinite plate of finite thickness and composed of microstretch elastic material is considered. The top and bottom of the plate are cladded with finite layers of a homogeneous and inviscid liquid (non-micropolar and non-microstretch). There exist two sets of boundary conditions at solid/liquid interface and the choice on these sets of boundary conditions is arbitrary. Frequency equations are derived for symmetric and antisymmetric modes of propagation for Rayleigh–Lamb waves propagation. It is found that the frequency equations for both the modes of propagation are dispersive in nature and the presence of microstretch has negligible effect on the dispersion curves. However, the attenuation coefficient is found to be influenced by the presence of microstretch in the plate with free boundaries. Considerable effect of the liquid layers is noticed on the dispersion curves. Numerical computations are performed for a specific model to compute the phase velocity and attenuation coefficient for different values of wavenumber, for both symmetric and antisymmetric vibrations. Results of some earlier workers have been deduced as special cases.