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Rayleigh wave[′rā·lē ‚wāv]
an elastic disturbance that propagates along the free boundary of a solid body and is attenuated with depth. The existence of such waves was predicted by Lord Rayleigh in 1885.
Rayleigh waves occur on the earth’s surface during earthquakes. Ultrasonic waves used to check the surface layer of various device components and specimens are another example of Rayleigh waves. The thickness of the layer where the waves are localized is (1–2)λ, where λ is the wavelength. At a depth λ the energy density in a wave is ~0.05 of the density at the surface. Particles in Rayleigh waves move in elliptical trajectories whose semimajor axis is perpendicular to the surface of the body and whose semiminor axis is parallel to the direction of wave propagation. The phase velocity of Rayleigh waves is less than the phase velocities of longitudinal and shear waves and is equal to the group velocity.
In anisotropic media the structure and properties of Rayleigh waves depend on the type of anisotropy and the direction of wave propagation. There exist media, such as triclinic crystals, in which Rayleigh waves cannot exist at all. Sometimes, the term “Rayleigh waves” is applied to surface waves of a more general type that arise at the interface between a solid and a liquid or at the boundary of a system of solid or liquid layers with a solid half space.
REFERENCESKol’skii, G. Volny napriazheniia v tverdykh telakh. Moscow, 1955. (Translated from English.)
Landau, L. D., and E. M. Lifshits. Teoriia uprugosti, 3rd ed. Moscow, 1965. (Teoreticheskaia fizika, vol. 7.)
Viktorov, I. A. Fizicheskie osnovy primeneniia ul’trazvukovykh voln Releia i Lemba v tekhnike. Moscow, 1966.