Finite-Element Simulation of Ice-Sheet Indentation

A nonlinear phenomenological constitutive law for ice developed previously by the writers is implemented in a finite-element procedure. The features of the iterative time-stepping algorithm that are specific to this constitutive law are described. The finite-element formulation is used in a series of simulations of plane stress indentation of ice sheets using both rectangular and cylindrical indentors. Numerical results are presented for peak average indentor stress versus indentation rate, average indentor stress versus indentor displacement, and stress distribution in the vicinity of the indentor. Where possible, comparisons are made with published experimental data. It is found that for simulations in the regime of ductile behavior, the agreement with experimental results is good. Predictions for problems in the transition and brittle regimes are unreliable due to the limitations of the constitutive model at higher strain-rates.