78 research outputs found
Limit mechanisms for ice loads: FEM-DEM and simplified load models
Get PDFThis work summarizes our recent findings on mechanisms and limits for the ice loads on wide inclined Arctic marine structures, like drilling platforms or harbour structures. The fresults presented are based on hundreds of two-dimensional combined finite-discrete element method (FEM-DEM) simulations on ice-structure interaction pro- cess. In such processes, a floating sea ice cover, driven by winds and currents, fails against a structure and fragments into a myriad of ice blocks which interact with each other and the structure. The ice load is the end result of this interaction process. Using the simu- lation data, we have studied the loading process, analysed the
statistic of ice loads, and recently introduced a buckling model [1] and extended it to a simple probabilistic limit load model and algorithm [2], which predict the peak ice load values with good accuracy. These models capture and quantify the effect of two factors that limit the values of peak ice loads in FEM-DEM simulations: The buckling of force chains and local ice crush- ing in ice-to-ice contacts. The work here describes the models and demonstrates their applicability in the analysis of ice-structure interaction
Ship resistance when operating in floating ice floes: a combined CFD&DEM approach
Get PDFWhilst climate change is transforming the Arctic into a navigable ocean where
small ice floes are floating on the sea surface, the effect of such ice
conditions on ship performance has yet to be understood. The present work
combines a set of numerical methods to simulate the ship-wave-ice interaction
in such ice conditions. Particularly, Computational Fluid Dynamics is applied
to provide fluid solutions for the floes and it is incorporated with the
Discrete Element Method to govern ice motions and account for ship-ice/ice-ice
collisions, by which, the proposed approach innovatively includes wave effects
in the interaction. In addition, this work introduces two algorithms that can
implement computational models with natural ice-floe fields, which takes
randomness into consideration thus achieving high-fidelity modelling of the
problem. Following validation against experiments, the model is shown accurate
in predicting the ice-floe resistance of a ship, and then a series of
simulations are performed to investigate how the resistance is influenced by
ship speed, ice concentration, ice thickness and floe diameter. This paper
presents a useful approach that can provide power estimates for Arctic shipping
and has the potential to facilitate other polar engineering purposes.Comment: 26 pages 18 figures, submitted journal pape
A comprehensive approach to scenario-based risk management for Arctic waters
Get PDFWhile society benefits from Arctic shipping, it is necessary to recognize that ship operations in Arctic waters pose significant risks to people, the environment, and property. To support the management of those risks, this article presents a comprehensive approach addressing both short-term operational risks, as well as risks related to long-term extreme ice loads. For the management of short-term operational risks, an extended version of the Polar Operational Limit Assessment Risk Indexing System (POLARIS) considering the magnitude of the consequences of potential adverse events is proposed. For the management of risks related to long-term extreme ice loads, guidelines are provided for using existing analytical, numerical, and semi-empirical methods. In addition, to support the design of ice class ship structures, the article proposes a novel approach that can be used in the conceptual design phase for the determination of preliminary scantlings for primary hull structural members.Peer reviewe
Jään murtumissitkeys ja sen vaikutus jään mallittamiseen sekä eräisiin laivan ja jään vuorovaikutustilanteisiin
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Experimental observations of the brittle failure process of ice and ice-structure contact
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