Author(s): Raed Lubbad; Geir Moe; Sveinung Loset
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Abstract: When level ice interacts with a sloping structure, or when a ship advances in level ice, the ice sheet may begin to fail by forming cracks in the radial direction. These radial cracks will be lengthened and increased in number until a circumferential crack is formed and consequently the ice sheet reaches its ultimate capacity. After the formation of the radial cracks the ice sheet can no longer be modelled as a continuum, instead it is common to use the model of adjacent wedges. This paper reviews the state-of-the-art in modelling the ultimate failure of an ice sheet using the model of adjacent wedge-shaped beams. In this paper, both the static and dynamic problems are formulated for a floating wedge-shaped beam interacting with a sloping structure. For the dynamic interaction, the results of the elastohydrodynamic approach are compared with the model of Winkler foundation combined with added mass and hydrodynamic damping. The comparison shows that the elastohydrodynamic model is more reliable than the Winkler approach. The breaking lengths of the ice wedges are also investigated and it is concluded that the breaking lengths increase with increasing ice thickness and/or axial compression in the ice; while increasing the drift acceleration will always decrease the breaking lengths. The static results match the results of the elastohydrodynamic solution for small ice drift accelerations. The calculations are performed using the commercial finite element program “Comsol Multiphysics”.
Year: 2008