Experiments on Anisotropic and Rate-Sensitive Strain Ratio and Modulus of Columnar-Grained Ice

Anisotropic and rate-sensitive characteristics of the ratio of lateral strain to axial strain in addition to the rate-sensitive effective modulus for columnar-grained freshwater ice and sea ice from the Arctic, have been investigated. Tests were carried out at −20°C, for conditions of no microcracking under uniaxial loads (normal to the length of the grains) in the stress rate range of 1 × 10⁻³ MN · m⁻² s⁻¹ to 1 × 10²MN · m⁻² s⁻¹ or an equivalent strain rate range of 1 × 10⁻⁷ s⁻¹ to 1 × 10⁻² s⁻¹. With increase in stress rate, the ratio increased from about 0.2 to 0.3 in the plane parallel to the columns, whereas it decreased from about 0.65 to 0.3 in the plane normal to the columns. A closed-loop controlled test system in association with foil gages, mounted directly on the specimen, was used. A clip-on displacement gage was used to evaluate the accuracy of the foil gages.