Abstract
ABSTRACTExperimental data from creep tests on polycrystalline ice samples highlight not only the non-Newtonian behavior of ice but also suggest a critical dependence of the various rheological parameters upon the applied hydrostatic pressure. We propose a new modeling framework, based on implicit theories of continuum mechanics, that generalizes two well-known constitutive models by taking into account the effect of the pressure in the description of ice in creep. To ascertain the validity of the proposed models, we fit the physical parameters with experimental data for the elongational flow of ice samples. The results show good agreement with the experimental creep curves. In particular, the proposed generalized models reproduce the increase of the creep rate due to the presence of hydrostatic pressure.
Highlights
An understanding of the physical processes that take place within glaciers requires information about the plastic deformation behavior of ice at high pressures. Jones and Chew (1983) and Mctigue and others (1985) reported creep experiments on polycrystalline ice subject to a combination of uniaxial compression and hydrostatic pressure
Barrette and Jordaan (2003) investigated the compressive behavior of laboratory-produced ice as well as genuine iceberg ice subjected to constant confinement pressure
As the first constitutive model, we generalize the basic second-grade fluid model proposed in Mctigue and others (1985), assuming that the characteristic constitutive parameters depend on the pressure p, the mean normal stress (Rajagopal and others (2012, 2015); Rajagopal (2015); Rajagopal and Saccomandi (2016)): p
Summary
An understanding of the physical processes that take place within glaciers requires information about the plastic deformation behavior of ice at high pressures. Jones and Chew (1983) and Mctigue and others (1985) reported creep experiments on polycrystalline ice subject to a combination of uniaxial compression and hydrostatic pressure. Mctigue and others (1985) showed that these constitutive parameters exhibit a non-negligible dependence on the applied hydrostatic pressure (the confining pressure) They ascribed this phenomenon to a partial inadequacy of the second-grade fluid model. We present a similar analysis for both models (i) and (ii), showing how the dependence of the rheological parameters on pressure has nonnegligible qualitative and quantitative effects on the flow Both models describe quite well the experimental results presented in Jones and Chew (1983), Mctigue and others (1985) and Barrette and Jordaan (2003), and capture the increase in the creep rate caused by the increasing pressure.
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