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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 , Ice pressure measurements with tekscan sensors-behaviour, calibration and application limits(American Society of Mechanical Engineers (ASME), 2022-06); ; ; ; Ships and offshore structures operating in ice-covered sea areas have to withstand ice loads. In particular, the distribution of ice pressure in the contact area is critical. The pressure dis-tribution changes temporally and spatially and depends on the ice failure behaviour. Experimental measurements of ice pres-sures are possible with pressure mapping systems. A commonly used system in academia uses sensors manufactured by TekScan. The resulting measurements can be used to gain insight into ice failure behaviour, to establish design pressure patches, and to develop numerical models. However, various issues emerge when using these pressure measurement systems, e.g., equilibra-tion and calibration, which result in measurement uncertainties. Hence, this paper summarize and discuss possible issues and gives recommendations to address them.Publicationtype: Conference Paper39 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Scenario-based risk management for arctic waters(American Society of Mechanical Engineers (ASME), 2022-06); ; ; ; Arctic shipping is growing driven by a demand for natural resources, climate change, and technological development, among other factors. While this provides many benefits for society, it also entails risks for people, the environment, and property. The purpose of this article is to assist ship designers, operators, owners, and other stakeholders in managing those risks by defining a comprehensive approach to scenario-based risk management for Arctic waters. The approach covers both the management of short-Term operational risks, as well as of risks related to a ship's long-Term extreme (design) ice loads and structural response. For operational risk management, a further developed version of the established Polar Operational Limitations Assessment Risk Indexing System (POLARIS) method is defined. In contrast to the established method, the further developed version considers the consequences of potential accidental events. For managing risks related to a ship?s long-Term extreme ice loads and structural response, guidelines are provided for the application of existing methods of assessing ice loads, including analytical, numerical, and semiempirical methods. In addition, to support the design of ice class ship structures, a new approach based on closed-form expressions is defined that can be used in the conceptual design phase to determine preliminary scantlings of primary hull structural members (e.g., transverse web frames).Publicationtype: Conference Paper24 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A comprehensive approach to scenario-based risk management for Arctic waters(Taylor & Francis, 2022-03-22); ; ; ; While 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.Publicationtype: Journal ArticleScopus© Citations 11 46 272 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Long term measurements of internal level ice pressure in vicinity of structures or (Land) fast ice(2021-06); ; Due to the interaction with land or other (larger) ice masses, high internal stress can occur inside sea ice. During the MOSAiC Expedition the level ice pressure in the vicinity of the research vessel Polarstern was measured over a time period of six months by three pressure panels frozen into the ice. The objective is to investigate the relationship of changing level ice conditions and the internal ice pressure in the vicinity of structures.Publicationtype: Conference Paper71 - 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 Article107 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The ice extrusion test: a novel test setup for the investigation of ice-structure interaction–results and validationUnderstanding ice-structure interaction is critical for an efficient and safe design of offshore structures and ships in ice-covered waters. During the last decades a variety of field experiments, full-scale measurements on ships and laboratory tests have been conducted. Within this paper, a novel experimental setup of the ice extrusion test for the investigation crushing loads is proposed. Due to the flexible design of the experiment brittle and ductile ice loads can be investigated in the laboratory at different load levels. A comprehensive test series with more than 350 tests has been carried out to investigate the system behaviour. The failure mode of the ice is mostly determined by the test speed. The ratio of gap height and sample diameter is the most important parameter for the load level. A validation against full-scale data showed that with this experimental setup it is possible to generate relevant nominal local ice pressures.Publicationtype: Journal Article102