Author(s): Ian J. Jordaan; Sanjay K. Singh
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Keywords: No Keywords
Abstract: It is essential to the understanding of ice interaction with ships and structures that the spatial heterogeneity of the ice failure process be appreciated. In the paper, compressive failure of an ice sheet or other feature against such a structure is considered. The principal processes are macrofractures, which result in spalls and consequent reduction in the contact area, and a damage process adjacent to this area which leads to considerable modification of the microstructure of the material. The action of the two processes results in regions of extremely high pressure, through which most of the load is transferred to the structure. These correspond to regions with high confinement and flaw structures in the ice that result in minimal spalling, i. e. zones where flaws do not propagate into macrocracks, at least for a period of time. The zones of high pressure contain a layer of ice, the microstructure of which is substantially modified as a result of prior stress and strain history. The localisation of damage results from the concurrent spalling activity. The deformational behaviour of the macrostructural modified ice is very different from the virgin ice, with much enhanced deformational response. Critical zones also offer an explanation of "phase-lock" as observed in the Molikpaq structure during the interaction events of 1986. If the individual critical wnes begin to act together, as a result of the influence of structural compliance, then the vibration of the wnes will be in phase. Thus, an increasing "zone of influence" is possible with more and more critical zones participating in phase.
Year: 1994