A review of ice rheology for ice sheet modelling

The mechanical properties of ice and snow are reviewed. The tensile strength of ice varies from 0.7–3.1 MPa and the compressive strength varies from 5–25 MPa over the temperature range −10°C to −20°C. The ice compressive strength increases with decreasing temperature and increasing strain rate, but ice tensile strength is relatively insensitive to these variables. The tensile strength of ice decreases with increasing ice grain size. The strength of ice decreases with increasing volume, and the estimated Weibull modulus is 5. The fracture toughness of ice is in the range of 50–150 kPa m1/2 and the fracture-initiating flaw size is similar to the grain size. Ice-soil composite mixtures are both stronger and tougher than ice alone. Snow is a open cellular form of ice. Both the strength and fracture toughness of snow are substantially lower than those of ice. Fracture-initiating flaw sizes in snow appear to correlate to the snow cell size.

Review Mechanical properties of ice and snow

Brittle failure of ice

The present work uses a micromechanical force apparatus to directly measure cyclopentane clathrate hydrate cohesive force and hydrate-steel adhesive force, as a function of contact time, contact force and temperature. We present a hydrate interparticle force model, which includes capillary and sintering contributions and is based on fundamental interparticle force theories. In this process, we estimate the cyclopentane hydrate tensile strength to be approximately 0.91 MPa. This hydrate interparticle force model also predicts the effect of temperature on hydrate particle cohesion force. Finally, we present the first direct measurements of hydrate cohesive force in the gas phase to be 9.1 ± 2.1 mN/m at approximately 3 °C (as opposed to 4.3 ± 0.4 mN/m in liquid cyclopentane).

Interfacial mechanisms governing cyclopentane clathrate hydrate adhesion/cohesion.

This review deals with properties of sea ice that are relevant to mechanical behavior on a fairly small scale. The main concern is with polycrystalline ice that is more or less intact. This sets the lower limit of scale not far below 0.1 m, and the upper limit around 10 m. However, the discussion is extended to cover the behavior of fragmented ice over broader areas. The latter discussion is intended to bridge the gap between this review, which relates to small-scale natural processes and engineering problems, and companion reviews, which deal with the mechanics of sea ice over very large areas.

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Mechanical behavior of sea ice

The tensile strength of ice as a function of grain size

: An analysis of ice fracture that incorporates dislocation mechanics and linear elastic fracture mechanics is discussed. The derived relationships predict a brittle to ductile transition in polycrystalline ice under tension with a Hall-Petch type dependence of brittle fracture strength on grain size. A uniaxial tensile testing technique, including specimen preparation and loading system design was developed and employed to verify the model. The tensile strength of ice in purely brittle fracture was found to vary with the square root of the reciprocal of grain size, supporting the relationship that the theory suggests. The inherent strength of the ice lattice and the Hall-Petch slope are evaluated and findings discussed in relation to previous results. Monitoring of acoustic emissions was incorporated in the tests, providing insights into the process of microfracture during ice deformation.

A Study on the Tensile Strength of Ice as a Function of Grain Size

: A procedure is described for testing ice in tension. It incorporates a one-piece lucite mold, two carpeted Synthane end-caps and a pair of yokes and ball joints. Use of the procedure has resulted in a successful test rate greater than 80%. Originator supplied keywords include: Ice; Tensile tests; Testing; Laboratory procedures.

J. H. Currier

Papers

The tensile strength of ice as a function of grain size

A Study on the Tensile Strength of Ice as a Function of Grain Size

A procedure for testing polycrystalline ice in uniaxial tension