Modelling of continuous crushing of ice in front of offshore structures

Abstract

A one-dimensional finite element is developed to represent the continuous crushing and extrusion of ice in interactions with offshore structures. 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 one to model the extrusion of pulverized ice between the intact ice and the structure. The intact but damaging ice behaviour is based on a rate theory approach to crack density and damaged material compliance which is a function of stress and damage. The extrusion component models a viscous-plastic material which is modelled using a Tresca failure criterion and viscous flow. The element is developed as part of an existing finite element package (Abaqus) through its user material and user element capabilities. The paper describes in detail the development and implementation of the element and presents sample results of its performance in continuous crushing interactions with a rigid structure. The results show that the element can be used as the interface between moving intact ice sheets and offshore structures modelled using the finite element method. Key words: ice, structures, dynamics, finite elements, rheology.

Seismic performance analysis of a wind turbine with a monopile foundation affected by sea ice based on a simple numerical method

“…Shi et al (2001), Yue et al (2003) and Wang (2014) improved the governing ice force function and the parameters of the ice force model, but they did not consider the physical and mechanical properties of ice when determining the ice crushing length. Xiangjun et al (2006), Brown and Morsy (1995) and Bouaanani et al (2004) improved the substructure model based on different crushing models and sea-ice criteria; however, there is no uniform formula for calculating the ice force in these models. In fact, the dynamic ice force models mentioned above are relatively simple and are a feasible method of simulating the mechanical behavior of ice, but they cannot be used to simulate the influences of the three-dimensional geometric characteristics (ice boundary range and thickness) on the wind turbine under earthquake activity.…”

Experimental and analytical study of thermal stresses during pipe freezing

“…Ice interacting with other solids has been analysed by the nite element method (FEM) but within engineering contexts and conditions imposing very different modelling requirements on the respective formulations. Recent examples of such applications include simulations of ice indentations [7,8] and interactions with offshore structures [9,10]. Common characteristics of these problems are predominantly compressive stresses, relatively high temperatures, viscoelastic ice behaviour and, possibly, strength-reducing damage due to crack formation.…”