Mohr-Coulomb yield curve and non-normal flow rule for sea ice viscous-plastic models

Abstract

<p>Deformation in sea ice takes the shape of narrow lines of high deformation, called the Linear Kinematic Features or LKFs. The distribution of intersection angles between LKFs indicates that the yield curve of sea ice is closer to the shape of a Mohr-Coulomb criterion than the commonly used elliptical yield curve, and that the flow rule of sea ice is most probably not normal to the yield curve. Thus, having Mohr-Coulomb yield curves in sea ice viscous-plastic models could improve the orientation and localization of LKFs in high-resolution sea ice models. In this work, we define multiple implementations of the Mohr-Coulomb yield criterion with different flow rules and test them in uniaxial compressive tests. We observe that the intersection angles are not the same as we expect from theory and previous experiments with the elliptical yield curve. To further the investigation, we define new rheologies with different yield curves and plastic potentials to study the effect of non-normal flow rules with different yield curve shapes, with the goal to finally be able to define a Mohr-Coulomb yield curve and flow rule that accurately models the creation of LKFs and their intersection angles.</p>