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Metal foams are highly useful in industries because of their lightweight, energy and vibration absorption properties. This study investigated the propagation of torsional waves in an elastic layer over a fluid-saturated fractured poroelastic half-space with a metal foam coated layer. It is assumed that the interfaces are in sliding contact with two different sliding parameters. The coated layer is closed-cell aluminium foam. We use the separation variable technique and the Bessel function to solve the equation of motion in different layers. The displacement components are written in terms of the second kind Whittaker functions. Using an asymptotic formulation of the Whittaker function and appropriate boundary conditions, the dispersion equation is derived in terms of the determinant. The control of the vibration due to the metal foam-coated layer is one of the important goals of this study. Also, numerical and graphical analyses have been done with the help of Mathematica software to see the effect of different parameters on torsional wave propagation. It is found that the presence of coated metal foam layer decreases the phase velocity of the torsional wave propagation. The work may be helpful in the seismology, automobile, and aerospace industries. [ABSTRACT FROM AUTHOR]

This paper investigates a quantitative comparison of the Love wave propagation due to traction-free and rigid boundary surfaces on the piezoelectric-dispersive layer over a non-dispersive initially stressed half-space. The model is considered (a) transversely isotropic piezoelectric material in the upper layer, (b) exponentially increasing dispersive (non-homogeneous) layer in the intermediate, and (c) initially stressed non-dispersive (homogeneous) medium in the lower half-space. Electrical potential fields in the piezoelectric layer are defined in terms of electrical potential function with open and short circuit piezoelectricity using the quasi-static Maxwell's equation. We have derived analytical dispersion relations for two cases of boundary conditions: (i) free surface with zero tractions and (ii) rigid boundary, in both the open and short circuit cases. The validities of the dispersion relations are shown by deriving some particular cases and compared with the classical dispersion relation of the Love wave. A novel numerical representation of changes in displacement amplitude with depth and comparative effect of various piezoelectric materials such as PZT-4, PZT-5A, PZT-7A, and BaTiO3 are shown using MATLAB software. The rigid boundary surface case is more effective than traction-free boundary surfaces in terms of electromechanical coupling factor. It is also identified that there are significant effects on the dispersion of the Love-type waves due to different boundary conditions on the upper surface of the model. These comparative studies highlight the present work and may be helpful in the fields of solid mechanics and material fabrication processes. [ABSTRACT FROM AUTHOR]