Granular micromechanics based continuum model for grain rotations and grain rotation waves

Abstract

Grain rotations are a key component of the grain-scale deformation kinematics of granular materials. For describing the deformation of these materials at large length scales, continuum description is efficient and desirable in spite of the current computational abilities. It is, however, clear that grain-scale deformation mechanisms have a profound impact upon the macro-scale behavior of these materials. Recently, the authors have presented an approach to account for the effects of grain rotations within the continuum description of these materials (Misra and Poorsolhjouy, 2017). Here, we further motivate and elaborate the approach to establish the needed constitutive relationships and variational principles. The derived model is then used to predict grain rotation waves and their dispersion. The occurrence of such waves and ability of this deformation mode to transmit energy within granular materials is supported by quasi-static measurements and simulations, and therefore cannot be discounted.