The nonlinear viscoelastic Cosserat model for the wave propagation with generation of subharmonics (Q1282745)

A Cosserat model is developed in nonlinear form to describe the appearance of lower frequencies in seismic wave spectra. The translational degrees of freedom are described by linear elasticity, but the rotational kinematically independent motion is governed by the nonlinear elastic potential and linear viscosity. The dynamics of linear perturbations show that the longitudinal translations and rotations both decouple completely from other motions. These rotations represent local oscillations due to the existence of the potential, and they do not propagate. However, the linear transverse translations and microrotations are coupled. It is shown that they describe seismic and acoustic waves.