Abstract
Abstract. The critical fracture toughness is a material parameter describing the resistance of a cracked body to further crack extension. It is an important parameter for simulating and predicting the breakup behavior of ice shelves from the calving of single icebergs to the disintegration of entire ice shelves over a wide range of length scales. The fracture toughness values are calculated with equations that are derived from an elastic stress analysis. Additionally, an X-ray computer tomography (CT scanner) was used to identify the density as a function of depth. The critical fracture toughness of 91 Antarctic bubbly ice samples with densities between 840 and 870 kg m−3 has been determined by applying a four-point bending technique on single-edge v-notched beam samples. The examined ice core was drilled 70 m north of Kohnen Station, Dronnning Maud Land (75°00' S, 00°04' E; 2882 m). Supplementary data are available at doi:10.1594/PANGAEA.835321.
Highlights
In order to simulate and predict the calving of icebergs or the disintegration and breakup of ice shelves, the deformation and stress states within ice shelves need to be identified and related to material properties
91 failed due to a crack emanating from the notch; the other samples broke at another position away from the notch, most likely due to a local defect that resulted in a higher stress intensity factor than at the notch
Rist et al (1999) measured the critical fracture toughness in an ice lab at −20 ◦C and stated “we believe that within experimental error, temperature would have no significant effect on our measured values of fracture toughness for shelf ice” (Rist et al, 1999)
Summary
In order to simulate and predict the calving of icebergs or the disintegration and breakup of ice shelves, the deformation and stress states within ice shelves need to be identified and related to material properties. Deformation and stress states, vary with location within an ice shelf. Knowledge of material data is crucial for numerical simulations. Depending on the timescale under consideration, one has to distinguish the material response of ice as viscous or elastic. A material model according to Glen is used, in which the important parameters are the shear viscosity and stress exponent; see Glen (1958) and Greve and Blatter (2009). The elastic response is valid on short timescales and the relevant parameters are fracture and rupture. Measured velocity fields can be used to compute the strain and stress state locally
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