The influence of ice classification on design of an LNG tanker (2013)

The influence of ice classification on design of an LNG tanker (2013)

– Roy Andre Pedersen

This thesis seeks to identify the influence of the target ice class on the hull production cost, steel structural weight and arrangement. Therefore, the following aspects shall be considered for the study: Sensitivity in cost, mass and steel structural arrangement to the choice of ice class and finally the identification of the optimum steel structural arrangement for the target ice class.

An Offshore Supply Base (OSB) concept for the Barents Sea (2013)

An Offshore Supply Base (OSB) concept for the Barents Sea (2013)

– Sunniva Fossen Haugen

This thesis is concerning with the development of a new type of Offshore Supply Base (OSB) to be used as a bridge element to overcome the large distance from the oil and gas fields to shore. Therefore, the following aspects shall be considered for the OSB concept: Offshore Supply Bases (OSB) that combines transhipment functionality, oil spill response centres and eventual emergency repair yard capabilities; Development of advanced position floating OSB structures in high seas close to field operation, including storage and SAR with offshore/near shore helicopter services; Integration into land-to-base and base-to-base transport and logistic solutions and models and identification of the optimum location and base density and Impact of the harsh environment.

Risk Based Design Methodology for a Multipurpose Ice Classed OSV (2013)

Risk Based Design Methodology for a Multipurpose Ice Classed OSV (2013)

– A.D.M. Abdur Rahman

The focus of this project is the development of a risk-based design methodology for a multipurpose ice-classed OSV. To do so, three points will be focused on. At first, the challenges offered by the Barents Sea, such as harsh weather conditions, infrastructure and communication problems will be identified. Secondly, the relevant literature for OSV and risk based design will be studied for ice class vessel for specified area. At last the cost assessment of the OSV will be done to understand the economic viability for the alternatives vessels. In conclusion, these aspect will contribute to the development a risk-based design methodology.

The influence of ice classification on design of an offshore supply vessel (2013)

The influence of ice classification on design of an offshore supply vessel (2013)

– David André Molnes

This thesis will investigated the influence of the choice of ice classification on the design of offshore supply vessels. Therefore, the ice conditions to be encountered are assessed to further investigate how the hull design of the ship must be carried out accordingly. Reviews of how the hull interacts with the ice and how to make a strong enough hull to withstand the ice loading will be given. This is to get a better understanding of how the classification societies have built up their rules for classification of ice going ships. As a result, a sensitivity analysis will be performed for different ice classes and rules using optimization-based algorithms to enable most feasible compliance of the steel structural arrangement and scantlings.

An economic transport system of the next generation – integrating the northern and southern passages (2012)

An economic transport system of the next generation – integrating the northern and southern passages (2012)

– Anette Omre

The global climate change continues to increase the marine transport in the Arctic Sea as a result of decreasing ice extends. However, the distinct conditions of the Arctic Sea, such as remoteness or the lack of marine infrastructure, represent a challenge to be surpassed in order to ensure safe and economic feasibility.

Additionally, the Arctic Sea may not be seen as a substitute for marine transport, but as an integral member of new transport systems as part of a global fleet- and supply chain management system. Therefore, the purpose of this work is to identify an assessment framework to integrate the northern and southern passages together in an economically feasible transport system. Hence, the methodology needs to be capably to assess this economic feasibility for the different routing and scheduling options to be made considering the distinct requirements of the Arctic sea. This assessment shall include the assessment of the feasibility of different ice classed vessels for the possible ice conditions to be encountered. The results shall be presented both on a generally applicable level as well as with the use of a case study, also discussing the assumptions and limitations of the study.

Numerical simulations of ice loads on conical wind turbine foundation in the eastern Baltic Sea (2012)

Numerical simulations of ice loads on conical wind turbine foundation in the eastern Baltic Sea (2012)

– Rando Rosenthal (Cooperation with Aalto and Tallinn University)

Sea ice interaction with offshore structures is important engineering concern in ice infested areas. The present thesis deals with interaction between level ice and fixed, conical structure using explicit finite element code LS–DYNA. The aim of the thesis was to implement numerical Baltic Sea ice model in ice–structure problem and to study effects of structure slope angle and ice velocity. The thesis focuses on developing contact options between ice and structure as well as ice fragments which induce similar flexural failure as seen in natural environment.

The ice is treated as an isotropic, brittle material described by separate stress–strain curves for compression and tension. The failure of the ice is defined by pressure. When the state of pressure is exceeded at the ice material point, the element is eroded but the mass will remain active in the simulation. The buoyancy force is accounted by defining restoring motion for nodes depending on gravity, specific weight of water and effective area

In this thesis, ice loads on conical structure were calculated considering sea ice conditions in the eastern Baltic sea, including the mean level ice thickness and approaching ice velocities. In addition, the effect of slope angle of the wind mill foundation was studied. Numerically obtained ice forces were compared with analytical methods for calculation of ice sheet forces on conical structure presented by Croasdale and Ralston.

The results of numerical simulations showed lower maximum forces than analytical methods. The deviation increased as the sloping angle increased. However, considering nonlinearities disregarded in analytical methods, lower forces were expected. On the other hand, simulations showed that the ice velocity has an effect on ice loads. Ice forces on the structure become higher when the ice had a velocity of 0.3 m/s.

A Decision Support Model for Merchant Vessels Operating on the Arctic Sea (2012)

A Decision Support Model for Merchant Vessels Operating on the Arctic Sea (2012)

– Svenn Sørstrand

The objective of this work has been to assess design aspects for vessels using the Northern Sea Route (NSR) in addition to the Suez Canal Route (SCR). Followed by development of a decision support model (DSM) to assess the potential financial benefit of using the NSR taking into account the costs of ship requirements to be fulfilled, encountered ice and the vessels performance thereafter with resulting fuel consumption and cost, in addition to operational and voyage expenses.

Numerical simulations of a sea ice beam in four-point bending (2011)

Numerical simulations of a sea ice beam in four-point bending (2011)

– Tanel Soa (Cooperation Aalto University)

The goal of this thesis was to study the possibilities of modeling sea ice using the explicit finite element code LS-DYNA. Therefore, this study utilizes the experimental findings by Kujala et al. (1990) together with unpublished results from those experiments for sea ice four-point bending tests to derive the material input for comparative numerical simulations. Two different LS-DYNA material models are identified to be suitable numerical models. The descriptions of the experimental tests and numerical models are presented. The comparisons of experiments to calculations are presented.

Contact

Contact

Sören Ehlers
 
Professor, D.Sc. (Tech.)
 
Department of Marine Technology
 
Phone: +4773595596
Mobile: +4791897748
Email: soren.ehlers@ntnu.no
Marinteknisk senter, room E2.232
Otto Nielsens veg 10, 7491 Trondheim