A Study of New Nondispersive SH-SAWs in Magnetoelectroelastic Medium of Symmetry Class 6 mm

Abstract

Two additional solutions of new shear-horizontal surface acoustic waves (SH-SAWs) are found in this theoretical report. The SH-SAW propagation is managed by the free surface of a solid when it has a direct contact with a vacuum. The studied smart solid represents the transversely isotropic piezoelectromagnetic (magnetoelectroelastic or MEE) medium that pertains to crystal symmetry class 6 mm. In the developed theoretical treatment, the solid surface must be mechanically free. Also, the magnetic and electrical boundary conditions at the common interface between a vacuum and the solid surface read: the magnetic and electrical displacements must continue and the same for the magnetic and electrical potentials. To obtain these two new SH-SAW solutions, the natural coupling mechanisms such as e h µ α − and 2 εµ α − present in the coefficient of the magnetoelectromechanical coupling (CMEMC) can be exploited. Based on the obtained theoretical results, it is possible that a set of technical devices (filters, sensors, delay lines, lab-on-a-chip, etc.) based on smart MEE media can be developed. It is also blatant that the obtained theoretical results can be helpful for the further theoretical and experimental studies on the propagation of the plate SHwaves and the interfacial SH-waves in the MEE (composite) media. The most important issue can be the influence of the magnetoelectric effect on the SH-wave propagation. One must also be familiar with the fact that the surface, interfacial, and plate SH-waves can frequently represent a common tool for nondestructive testing and evaluation of surfaces, interfaces, and plates, respectively.

Dramatic Influence of the Magnetoelectric Effect on the Existence of the New SH-SAWs Propagating in Magnetoelectroelastic Composites

“…In definition (2) one can find the following independent nonzero material constants: the stiffness constant C, piezomagnetic coefficient h, piezoelectric constant e, dielectric permittivity coefficient ε, magnetic permeability coefficient μ, and electromagnetic constant α [5] [10]- [12].…”

“…It is a natural choice to compare the velocity behaviors of the eighth and tenth new SH-SAWs recently discovered in papers [11] and [12], respectively, with the SH-BAW V tem and SH-SAW V BGM . This is constructive because there is an assumption that the new SH-waves can propagate even slower than the surface BGM wave in dependence on the electromagnetic constant α.…”

“…The second new wave for comparison called the tenth new SH-SAW [12] is characterized by the following propagation speed:…”

“…The surface BGM wave [5] [10] can actually propagate significantly slower than the corresponding piezoelectromagnetic SH-BAW. In this paper, the eighth and tenth new PEM SH-SAWs discovered in papers [11] and [12], respectively, are studied to record the possible fact that these new waves can propagate (significantly) slower than the BGM wave. These new waves can propagate under the following boundary conditions applied to the suitable free surface of a PEM solid (interface between the solid and a vacuum): mechanically free surface, continuity of both the electrical (φ) and magnetic (ψ) potentials, and the continuity of both the electrical (D 3 ) and magnetic (B 3 ) displacement components that are normal to the surface.…”

“…The following section acquaints the reader with the analytical study of the nondispersive SH-waves. The main purpose is to investigate the eighth [11] and tenth [12] new PEM SH-SAWs in comparison with the other known SH-SAW called the surface BGM wave and the corresponding SH-BAW. These SH-waves are treated as functions of the electromagnetic constant α to record possible peculiarities.…”