Dissipation and dispersion properties of microinhomogeneous media

The propagation of a harmonic elastic wave in a microinhomogeneous (defect- containing) medium is considered in the framework of the rheological model that reperesents the medium in the form of a one-dimensional chain of masse s connected by purely elastic elements and by Kelvin-Voigt viscoelastic ele ments. Analytical expressions are derived for the dissipation and dispersio n characteristics of this medium for various distributions of the parameter s of the viscoelastic elements. The dissipation and dispersion properties a re found to obey the Kramers-Kronig relations. It is also shown that the da mping decrement of the wave is almost constant, and the phase velocity mono tonically increases in a sufficiently wide range of parameters of the visco elastic elements in a wide frequency band. The derived expressions for the dispersion and dissipation are used to simulate the propagation of broadban d pulses in this kind of medium. (C) 2000 MAIK "Nauka/Interperiodica".