Acceleration waves, flutter instabilities and stationary discontinuities in inelastic porous media (Q1196441)

Coupled constitutive equations for a saturated porous medium are developed in the frame of the theories of mixtures: the fluid constituent is elastic and the solid skeleton behaves as a rate-independent elastic- plastic solid. Then the existence of real acceleration wave-speeds is considered: actually the analysis centers on the modes in which these wave-speeds cease to be real. An explicit criterion indicating the critical value of the plastic modulus at the onset of a stationary discontinuity (one wave-speed is zero) is derived in both cases where the fluid and solid constituents are compressible and where they are not.