Ice edge failure process and modelling ice pressure

Abstract

Ice action on ships and offshore structures is commonly determined by calculating the contact ice pressure. The aim of this paper is to describe the empirical background for determining the ice pressure. This review article describes six different test series where ice edge indentation and contact ice pressure have been investigated. These test series are ice pressure measurements onboard IB Sisu in the Baltic in 1977, pendulum tests carried out at Arctec in Ottawa, Canada, in 1979, laboratory and full scale ice crushing tests at WARC in 1988 and onboard IB Sampo 1989, medium scale indentation tests on Hobson's Choice Ice Island 1990, ice crushing tests at NRC, Ottawa 1992 and the JOIA tests in Hokkaido 1996–1999. These tests were selected as at each series a new phenomenon was observed. The aim of the paper is to introduce the main features for ice–structure contact empirically through the description of tests. The paper is concluded with a short description of the existing models for ice pressure, especially to gain an insight and highlight the main observations in each test series and how the models for ice pressure have developed based on the observations.This article is part of the theme issue ‘Modelling of sea-ice phenomena’.

Shared-Energy Prediction Model for Ship-Ice Interactions

“…Ice-crushing occurs over an area and is typically modelled as a contact pressure instead of a contact force [15]. Ice exerts pressure through both direct contact and a layer of extruded crushed ice material [16].…”

“…If restricted, the crushed ice can result in increased confinement and contact pressure. Likewise, if the crushed ice is allowed to extrude and not accumulate, this decreases the contact pressure [15,17].…”

“…Depending on the loading rate, crushed ice behaviour can be ductile or brittle [6,15]. At slower loading rates, the ice has a ductile response and a more uniform pressure.…”

Numerical simulation of ship performance in level ice: A framework and a model

“…One demanding aspect of this is the estimation of nominal pressure on the contact area, which affects the resisting moment considerably, but is still understood only to a limited extent. This, however, has been known as a difficult problem throughout the experimental investigations and theoretical modelling during the past decades (Varsta, 1983;Riska, 1987;Riska, 2018). Consequently, the uncertainty associated with pressure estimation will probably remain in such numerical models for a long time until a satisfactory solution is reached.…”

Analysis of a Collision-Energy-Based Method for the Prediction of Ice Loading on Ships

“…The maximum force generated by ice acting upon a structure depends on the strength of the ice in the relevant mode of failure [29]. Because in ship-ice interactions, the ice often fails by crushing, ice crushing strength is an important factor for estimating ice loading on ships [30]. As pointed out by Kujala [8], the crushing strength of ice depends on multiple parameters, including ice salinity, ice temperature and loading rate, but all of this is not fully understood.…”