DEFINING RELATIONS FOR A VISCOELASTIC MEDIUM WITH MICROROTATIONS

The results of [1, 2] are extended to the case of a Cosserat medium wi th a memory (the force stress tensor and the couple stress tensor depe nd on the history of deformations and rotations of a particle in the m edium). In the linear approximation the defining relations have the fo rm of convolutions with some relaxation kernels with respect to time. Restrictions for the kernels are obtained, which follow from the gener al principles of thermodynamics. The propagation of weak perturbations is studied. The general functional form of the kernels corresponding to experimental data on the viscoelasticity of rock formations is give n. (C) 1998 Elsevier Science Ltd. All rights reserved.