Author(s): A. Cormeau; I. J. Jordaan; M. Nessim; H. Tomin
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Keywords: No Keywords
Abstract: Loading of fixed offshore structures by ice results from a variety of situations, typical of which are impacts by discrete features (floes, icebergs) and continuously moving ice. In the case of discrete impacts, the ice feature will arrive with a given kinetic energy (including added mass) and in the case of continuously moving ice, one can think of energy dissipated per unit time (power). The key features are dissipation of energy either at constant or variable rates of movement. It is important to identify the important energy sinks. The interaction problem given a loading scenario is studied and attention is concentrated on the dissipation of energy within the ice feature, for structures with vertical faces. Energy transformations are intimately related to the constitutive equations used to model the ice. Elastic energy is stored in the ice and this is dissipated as creep movements and consumed in the fracture process (creation of new surfaces). Crushing in compression involves the creation of numerous crack surfaces and can be an important energy sink. In the event that an ice feature breaks into pieces, these may attain energies of translation and rotation. For oblique impacts, translational kinetic energy is converted to rotational energy. Examples of the formulation of typical problems are given, including the finite-element analysis of the splitting of an ice floe with initial (pre-existing) cracks. These are shown to propagate at much lower loads than these corresponding to crushing of the ice.
Year: 1984