A constitutive model for isotropic freshwater ice

Abstract

A three-dimensional constitutive model is developed to describe the stress–strain behaviour of isotropic freshwater ice. The model consists of two sets of equations. The first set deals with the behaviour of intact ice (undamaged material), and the second set accounts for the effect of damage (microcracking) on the overall stress–strain behaviour of ice. The intact-ice model (the first set of equations) is developed on the basis of the traditional viscoelasticity and viscoplasticity theories, whereas the damaged-ice model (the second set of equations) is developed using the rate theory for crack kinetics. The results of several uniaxial and triaxial tests are used to evaluate the accuracy of the model predictions. The comparisons between the predicted and measured stress–strain curves indicate that the model predicts reasonably well the strength of ice, the effect of damage, and the postpeak behaviour (including softening) of ice subjected to monotonic loading and unloading–reloading cycles.Key words: isotropic freshwater ice, constitutive model, damaged ice, crack kinetics, cyclic loading, softening.