MODELING OF CONTINUOUS CRUSHING OF ICE IN FRONT OF OFFSHORE STRUCTURES

A one-dimensional finite element is developed to represent the continu ous crushing and extrusion of ice in interactions with offshore struct ures. The element is developed with the objective of providing a model for the analysis of dynamic ice-structure interactions in which both nonsimultaneous and phase-locked behaviours occur. The element has two components: one to model the damage accumulation in intact ice and on e to model the extrusion of pulverized ice between the intact ice and the structure. The intact but damaging ice behaviour is based on a rat e theory approach to crack density and damaged material compliance whi ch is a function of stress and damage. The extrusion component models a viscous-plastic material which is modelled using a Tresca failure cr iterion and viscous now. The element is developed as part of an existi ng finite element package (Abaqus) through its user material and user element capabilities. The paper describes in detail the development an d implementation of the element and presents sample results of its per formance in continuous crushing interactions with a rigid structure. T he results show that the element can be used as the interface between moving intact ice sheets and offshore structures modelled using the fi nite element method.