Creep Behavior Of Ice Research Articles

An Experimental Investigation of the Effect of Grain Size on “Dislocation Creep” of Ice

AbstractThe creep behavior of ice is believed to be dominated by dislocation creep at high stresses (1 MPa) and high homologous temperatures (0.9). Dislocation creep of ice is often described by the Glen law, , with a canonical value of 3, and is independent of grain size. Laboratory studies of ice deformation at elevated pressures, however, suggest that dislocation creep of ice is characterized by a value of 4. Here, we deformed ice samples with initial grain sizes of 0.23 and 0.63 mm, at 263 K and confining pressures of 10 or 20 MPa. The experiments yield a value of 3.6 using the peak stresses obtained at a strain 0.02, and reveal a marked dependence of the stress on initial grain size. The nominally constant flow stresses at larger strains, up to 0.2, yield a value of 3.9, and no influence of the initial grain size on the stress is observed. The lower value of at peak stresses and the decrease in peak stress with decreasing initial grain size suggest a contribution to the strain rate from a grain‐size‐sensitive process, such as grain boundary sliding. Our data yield two flow laws, one for isotropic ice and one for highly anisotropic ice deformed to large strains, the latter of which may be used to model flow in high‐strain natural environments.

A three dimensional anisotropic constitutive model for ductile behaviour of columnar grained ice

A three dimensional constitutive model for the ductile behaviour of fresh water columnar grained ice is developed. The model is capable of describing the inherent anisotropy, the crack evolution, the opening and sliding of cracks, the grain size effect on material behaviour, and the effect of cracks on viscous strain. The model is used to predict the dependence of strength on the angle between the mean c-axis and loading direction for S3 ice and the magnitude of the anisotropic deformation of transversely isotropic S2 ice. The model predictions are compared with experimental results on S2 ice. Good agreement is achieved for (1) time dependence of axial and lateral strains in constant load tests, (2) strain rate dependence of strength in the ductile range, and (3) the effect of grain size on creep behaviour of ice.

Grain growth and the creep behavior of ice

Grain growth and the creep behavior of ice

The time-dependent deformation of ice domes

Thin shells of ice, constructed by spraying water onto an inflated membrane, could provide inexpensive winter shelters in the arctic. The major design consideration must be the creep behaviour of ice. In the present paper some time-dependent deformations of the proposed ice dome are obtained for the unloaded and snow-loaded situations.

Process of failure in ice

Information is presented on the failure behavior of columnar-grained ice during compressive creep and constant strain rate tests. The role of crack formation in establishing the failure condition is briefly described. Breakdown of structure is responsible for a marked change in the creep behavior of ice in the stress range of 10 to 12 kg/cm2. A ductile-to-brittle transition is observed at a strain rate of about 5 × 10−3 min−1. The upper yield stress in constant strain rate tests is shown to increase with increase in rate of strain up to the ductile-to-brittle transition.