Author(s): Terrance D. Ralston
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Abstract: The indentation of an ice sheet by a flat indenter is of engineering interest because of its similarity to the crushing failure of ice moving against a vertical pier. Several experimental studies of ice sheet indentation have recently been discussed in the literature. A relationship between these results and more basic ice properties is established in this paper using the methods of plastic limit analysis. The strength of columnar-grained ice is rate-dependent, temperature dependent, anisotropic, sensitive to confining stress, and differs in tension and compression. An appropriate failure criterion that describes these effects can be used with the methods of plastic limit analysis to address various ice failure processes, such as the initial penetration of an ice sheet by a flat indenter. This problem has been addressed by others using material descriptions that were originally developed to describe plastic deformation of structural metals. However, metals are essentially isotropic, non-pressure sensitive, and do not differ significantly in tension and compression. The present analysis demonstrates how the basic strength properties of columnar-grained freshwater ice can be used to predict ice indentation forces.
Year: 1978