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Modelling Brittle Failure of Ice

Presented by: 
Kari Kolari VTT Technical Research Centre of Finland
Thursday 9th November 2017 - 16:00 to 17:00
INI Seminar Room 1
The modeling of physics and mechanics of compressive failure is of importance in the ice-structure interaction modelling. Horizontal splitting of ice (termed spalling), has been observed in several ice-structure interaction experiments when drifting ice is failed by crushing in the interaction with vertical structure.

One of the greatest challenges of material failure analysis is the modelling of brittle failure. Materials like natural ice and rock are heterogeneous and crystalline, containing pores and flaws and other weaknesses. When these materials are subjected to compressive loading in the brittle regime, they are known to fail by splitting along the loading direction. Formation, growth and interaction of (micro)cracks due to material inhomogeneities and external force are considered to be the mechanism of brittle failure.

In this presentation, I will review three approaches applied in the modelling of brittle failure of ice: 1) Breakable/cohesive bond model; 2) Continuum damage mechanics (CDM) model, starting from Helmholz free energy; 3) WC-CMD-model, where the damage evolution is based on the observed micro-mechanism termed sliding wing crack mechanism.

The WC-CMD-model predicts axial splitting failure mode of granular ice under uniaxial and biaxial compression, and tensile splitting under tension. It also links grain size and strength of granular ice: the model is able to predict Hall-Petch relationship between grain diameter and strength, both under compression and tension. In addition, the model predicts experimentally observed increase in compressive strength with decrease in temperature.

Related Links
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons