The anisotropic contact response of viscoplastic monocrystalline ice particles

The contact between two particles of ice is studied experimentally and modeled. Experiments on the gradual indentation of a single or on two monocrystalline cylinders of ice demonstrate the effect of the relative orientation of their basal planes with the loading axis. Using polarized light and Digital Image Correlation, the main deformation mechanisms are documented. Experimental observations show the strong anisotropy of deformation, with strain localization into shear bands, corresponding to basal gliding of dislocations. When the rotation of cylinders is hindered by a large initial contact size, a simple model is proposed. It is based on indentation theory and takes into account the preferential viscoplastic deformation on the basal plane. The model form is validated by experimental data and by finite element simulations that incorporate the transverse isotropic law of an ice crystal.

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