Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Mechanical properties of ice

Constitutive relations describing major features of fabric evolution (induced anisotropy) as ice is sheared during its flow through an ice sheet have been constructed. These are the necessary ice properties which must be incorporated into the physical balances of momentum and energy which govern the flow of ice in the sheet as it involves under climatic forcing. Correlations with experimental and field data have been made, and some simple predictions calculated for idealised flows. Responses of different classes of relation have been compared.

The theoretical constrauctions of the two classes of constitutive realtion both formulate frame-indifferent relations between shear stress, sheer strain-rate and strain which describes evolving orthotropic (anisotropic) responses. One approach is based on an Orientation Distribution Function which defines the current weighting of a preferred direction in the polychrystal, while the second is a direct formulation of a general law. The realtions contain general functions depending on invariants of the evolving strain-rate, strain and stress, which can be constructed to correlate response in uni-axial and shear tests with laboratory data. The influence of idealised model realtions on simple ice sheet flows is assessed by comparison with the corresponding conventional isotropic viscous fluid solutions.

Reported by

University Plain
United Kingdom