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Item type:Publication, Access status: with files , Simulated ice loads on a ship propeller and comparison with full-scale measurements(Elsevier, 2025-10-15); ; ; ; A methodology to better estimate the loads of ice acting on the propeller of a ship is developed. Based on measurements conducted in the North Pole region, an existing failure model for ice based on the Mohr–Coulomb nodal split approach is modified to better represent the lower strength of polar ice compared to laboratory ice. The modified material model for the sea ice is used to compute the propeller torque and a load spectrum for the propeller-ice interaction of the research ship S.A. Agulhas II. To this end, a floe-ice breaking simulation is used to estimate the size and shape of the ice cusps hitting the propeller of this ship. In the next step, a set of finite element simulations of the propeller-ice interaction utilizing the modified Mohr–Coulomb nodal split model is conducted. Based on this, the load spectrum is computed and compared with the measured torque on the propeller shaft of the S.A. Agulhas II. The successful reproduction shows the applicability of the approach to better estimate the loads exerted by the ice on the propeller.Publicationtype: Journal Article54 29 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ice trails with “Le Commandant Charcot” for load assessment(Lulea University of Technology, 2025-07); ; The Arctic Ocean is in a process of significant changes, which also raises the interest in exploring these changes. This also concerns the performance of ships and how different operational profiles together with climate change are affecting current and future designs. This paper presents ice trials with a PC2 ice classed ship during a Trans-Arctic voyage, where continuously data such as ice thickness and accelerations are measured. From these data the number of ice impacts is determined which is used in a probabilistic extreme ice load assessment. The probabilistic ice pressures are compared with the design pressures from the Polar Ice Classes. The results indicate a significant loading of the structure with a potential to exceed Ice Class values. The analysis and results contain uncertainties, as the applied state of the art needs to be updated with new measurements and data accounting for climate change. A detailed analysis during one ice trail with constant power indicated that ridges contribute significantly to the number of impacts, while recent research on Arctic survey indicates that the ice surface becomes smoother and the number of ridges reduce.Publicationtype: Conference Paper100 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Reconstructing beam bending strength of arctic second year ice from small disk bending tests(American Society of Mechanical Engineers (ASME), 2025-06); The flexural strength of ice is one of the most significant strength parameters for the design of ships and marine structures in ice. By an unwritten convention the flexural strength refers to beam bending tests in ice. For this engineering formulas are derived that support engineering design. However, both climate and engineering fields are changing and ice properties still need to be assessed by in-situ measurements. Beam bending tests in full-scale, i.e. nature, are laborious and require both significant time and equipment. In the light of this an alternative method based on thin disk bending tests gained from drilled standard ice cores is presented. The method of testing small disks is introduced in the late 1960ies and has gained little attention in the community. The method presented utilizes tested disk samples throughout the entire ice thickness in order to assess the distribution of properties, while using this information reconstructing the global behavior of an ice cantilever beam in flexure. A numerical model of a virtual cantilever ice beam experiment is built from which the reference flexural strength of a cantilever beam is derived. The determined flexural strength is reduced by a stress concentration factor accounting for the notch effect in the beam-root transition. This stress concentration factor is determined numerically for different ratios of radius and beam width. Finally, the obtained strength value is scaled accounting for the increase of flaws in larger ice specimens. The approach is compared with literature data and evaluated in terms of its validity and robustness. The method also indicates the problem of missing standards for flexural strength determination.Publicationtype: Conference Paper39 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Einfluss von Minusgraden und variablen Lastamplituden infolge Seegangs- und Eislasten auf den Entwurf von Offshore Windenergieanlagen(2021-03); ; ; ; Publicationtype: Conference Paper58 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Development of a design load patch for the consideration of ice loadsShips operating in ice-covered waters may experience structural damage due to ice-induced loads. This can occur even though the ship structure is designed according to rules considering ice loading. The basis of these design rules can be empirical, e.g. measured loads from full-scale trials and observed damages or energy based, which is known as the Popov Method. The rules propose to apply the design ice load as a uniformly loaded rectangular pressure patch. This simplification is, however, not in line with spatial variations of local ice loads and does not account for high pressure zones directly. Therefore, this paper proposes a method for identifying a representative ice load distribution under consideration of local pressure maxima based on a spatial and temporal varying ice load sequence. This identified load is applied to an example structure and the response is compared to the response using a current rule-based patch load.Publicationtype: Journal Article109 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , State of the art and knowledge gaps on modelling structures in cold regions(American Society of Mechanical Engineers (ASME), 2019-06); ; ; ; The environment in cold regions undergoes significant changes that manifest in rising temperatures and melting ice caps. These processes allow access to new areas for shipping and the installation of structures. However, the occurring changes are not solely a reduction of ice, but also waves increasingly occur in cold regions contributing to ice break up in the Marginal Ice Zone (MIZ) and the transport of ice towards the open sea. Much work has been done to combine the single topic disciplines: wave-hydrodynamics, ice mechanics and structure mechanics to wave-structure (WSI) and ice-structure interaction (ISI). The changing environment in cold regions and the increased wave activity form a new combined discipline: wave-ice-structure interaction (WISI). This paper addresses existing knowledge gaps of the future loading scenario WISI that need to be addressed in engineering to ensure safety for future operations in Polar Regions. The knowledge gaps however, do not only refer to the discipline interfaces, i.e. challenges in combining them, but also to knowledge gaps within them. Wave statistics and the cross-effect between wave and ice are widely unknown which limits the definition of a design wavescenario. Structures in such environments are exposed to subzero temperatures and neither their impact on properties nor on fatigue life is fully understood. While most phenomena of these two disciplines and their implementation into numerical models are established the ice mechanics appear as the weakest link. Ice is a complex material and not all aspects of its mechanical behaviour are understood and if - the implementation into (numerical) models has not been successful yet. Ice pieces that are energetically charged by waves and collide with structures at high velocities and for such high impact loads the governing ice mechanics are hardly covered by the state of the art or not at all.Publicationtype: Conference Paper257