Study of the SH-wave propagation in an FGPM layer imperfectly bonded over a microstructural coupled stress half-space

In this paper, SH-wave propagation in a composite structure having an FGPM (functionally graded piezomagnetic material) layer overlying a microstructural coupled stress half-space is investigated by the WKB (Wentzel-Kramers-Brillouin) asymptotic approach. The interface between these two mediums is considered mechanically and magnetically imperfect. The dispersion equation is derived for both magnetically open and short conditions. The effect of magnetic boundary conditions at the free surface and the imperfect interface between the layer and half-space is considered in detail. For results and discussion, two different materials CoFe_2O_4 and Terfenol - D are taken as a layer. Graphs are plotted in terms of dimensionless phase velocity and dimensionless wave number to show the sustainable effect of different parameters of the above-mentioned conditions. Results show that the elastic parameters and density varying along the propagation direction obviously influence the variation of phase velocity. Some variations due to gradient, microstructural, and imperfection parameters also affect the phase velocity, but the effects are more significant for CoFe_2O_4 than for Terfenol - D. This work may provide theoretical guidance for the analysis and design of SAW devices constructed from piezomagnetic materials. This study will also be helpful in the fields of material engineering, seismology, geophysics, and many more.