Plane waves in linear viscoelastic materials
In this paper we discuss the propagation of plane sinusoidal waves in linear viscoelastic materials, both anisotropic and isotropic. Unlike the usual discussions (see, for example, [1]), we do not here assume that the planes of constant amplitude and constant phase are parallel. We do, however, assume that the imaginary parts of the complex moduli are small compared with their real parts and that correspondingly the magnitude of the imaginary part of the slowness vector is small compared with that of the real part. This implies that the attenuation of the wave is small in distances of travel of the order of a wavelength.