Author(s): Ian J. Jordaan; Richard F. Mckenna

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Keywords: No Keywords

Abstract: The formulation of equations for the creep of ice is addressed. The starting point is taken as Sinha's relationship. An approach based on a strict analysis of viscoelastic models is proposed using a Burgers model with stress-dependent elastic and viscous behaviour. Based on Sinha’s model, non-linearity of the viscous components are required. The components of the model can be related in general to observed physical behaviour of ice in terms of its structure, for example, grain boundary sliding. The use of the concept of "reduced time", based on the Biot-Schapery analysis of the thermodynamics of irreversible processes, is introduced in the above analysis. The results of the thermodynamic theory are briefly summarised. The resulting equations have a form similar to linearly superimposed creep compliance (Laplace transformable), yet include nonlinearities, e. g. Glen's law. Two implications of this are found: first, the structure of the equations results in a natural summary of past history in terms of current state. This is a logical consequence of the formulation: the second implication is that computer calculations are simplified since storage of past stress states can be obviated. Initial fits of curves using the proposed model are given.

DOI:

Year: 1988