INHOMOGENEOUS WAVES IN VISCOELASTIC MEDIA

Inhomogeneous, plane, monochromatic waves travelling in viscoelastic media are considered. Through a description in terms of complex potentials, detailed expressions of phase speed and attenuation are derived by having recourse to thermodynamic restrictions and to the properties of the complex propagation vector under inversion of the frequency. The complex amplitude vector for transverse and longitudinal waves is also discussed. Next, reflection and refraction at the common boundary of different types of media are investigated. As an application, the problem of a longitudinal wave propagating within an inviscid fluid and entering a viscoelastic solid is analyzed numerically. In particular it is shown that an analysis of the dependence of the reflected wave on the frequency leads to the determination of the relaxation time for an exponential-type relaxation function. © 1990.