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Item type:Publication, Access status: without files , Linking fault tree analysis to probabilistic damage stability calculationTraditional damage stability assements focus on ship stability after damage has occurred. Certain regulations may also require redundancies, such as Safe Return to Port. To date, a comprehensive assessment of damage stability has been decoupled from other redundancy requirements in regulatory terms, possibly allowing initially non-critical damages to cause an impermissible deterioration of the system despite the redundancy measures. Linking probabilistic damage stability calculation with damage-based functional chain evaluation would enable a more comprehensive assessment of ship safety, particularly in the passenger ship sector and in the field of naval vessels. This paper shows how a probabilistic damage stability calculation based on the Monte Carlo principle is extended with a fault tree analysis for functional chain evaluation, using an in-house developed code. Particular attention is paid to the modelling and information allocation to the basic events, as well as their evaluation and integration into the existing safety index. By linking basic fault tree events with compartments, a connection is established between damage cases and possible failures of the functional chain. The results show, using a modelled example, that integrating functional chain evaluation into probabilistic damage stability calculation can lead to a significantly lower attained index, indicating potential failure of critical ship functions post-damage and highlighting the importance of ship layout beyond initial damage. Concepts traditionally used in naval shipbuilding, such as section self-sufficiency, may also be relevant for passenger ships in a less pronounced form. The current modeling of ship safety using a required subdivision index already provides a basic assessment. Traditional approaches to requiring a certain level of resilience, such as Safe Return to Port regulations, are not sufficient to demonstrate this beyond doubt because of their deterministic nature, demanding essentially a one compartment status for functions. Therefore, the required subdivision index for certain ship types should also include an assessment of the vulnerabilities of critical functional chains.Publicationtype: Conference Paper5 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Data-driven gust modeling and adaptive wind tunnel control using offshore field data from the Baltic Sea(American Society of Mechanical Engineers (ASME), 2026-06); ; 8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Development and validation of a local fatigue design concept for welded joints in offshore structures subjected to multi-axial and variable loading(American Society of Mechanical Engineers (ASME), 2026-06); ; ; ; Fatigue assessment of welded maritime structures is vital for safe, cost-effective offshore design. Conventional methods struggle with complex loading, variable amplitudes, and thick sections, often leading to overly conservative designs. In the joint industry research project SMATRA, a novel local approach combining notch stress analysis and fracture mechanics was developed, accounting for weld geometry, post-weld treatments, and multi-axial loading. By integrating 3D surface scans, automated FEM modeling, and a two-phase life prediction model (initiation and growth), prediction accuracy improved by 24–77% over IIW, Eurocode 3, and FKM standards. Validation on small-scale specimens and a full-scale double-Y-joint confirmed accurate crack initiation prediction. A practical design tool reduced assessment time by 80% and enabled seamless workflow integration. Material savings exceeded 25% in weld volume and plate thickness while maintaining safety. The project outcomes enable more efficient, safe, and sustainable offshore structures and establishes a foundation for industrial standardization of local fatigue assessment methods in the offshore industry.Publicationtype: Conference Paper15 2 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , On the alignment of Ice observation data and ship-Ice simulations(American Society of Mechanical Engineers (ASME), 2026-06); The warming Arctic becomes more popular for shipping. With thinning ice thickness and shrinking ice covered areas in summer, the northern sea routes are becoming more accessible to both, ice going and conventional vessels. To determine the loads on and performance of these different vessels in ice-covered areas, simulations are used. Additionally, the performance assessment relies strongly on ice model tests. For both, the results can only be as good or accurate as the input parameters are, e.g. the ice conditions. To obtain reliable results, simulations have to be validated, which requires detailed ice descriptions as well. As shown in previous research, a simple ice observation protocol based on ice concentration, thickness and floe diameters in the surrounding area is not sufficient to represent a specific ice situation. This work describes and evaluates a new, more detailed approach of ice condition monitoring, based on a combination of shipborne video image data as well as written protocols. By evaluating the image data frame by frame with known vessel positions of each frame, a full image of the ice conditions is stacked together. The ship machinery and navigational data are used to verify the stacked ice images along the ship’s transect.Publicationtype: Conference Paper8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Dynamic analysis of variable depth sonar systems under realistic sea conditionsUnderwater detection is an important capability for many vessels, particularly naval and research ships, where accurate and reliable data is essential. To enable this capability, vessels are often equipped with variable depth sonar (VDS) systems that are typically towed behind the ship. The deployment and retrieval of such towed bodies can exhibit complex and potentially uncontrolled dynamic behaviour—not only while entering or exiting the water but also in the underwater near-field of the vessel. For instance, if the towed body enters the propeller wash, it may experience uncontrollable oscillations, making a safe retrieval impossible. Therefore, calculating and predicting the motion behaviour and the influence of external forces acting on the system during deployment and retrieval is of great importance. This paper presents a comprehensive and modular approach for modelling the dynamic motion behaviour of a VDS system deployed from a shipborne crane. The model accounts for ship-induced excitations, external forces and the complex oscillatory motion of the towed body. Ship motions are simulated using the E4-ROLLS method, while the VDS dynamics are formulated within a multi-coordinate framework based on the system’s differential equations of motion. The model combines ship-induced excitations at the deployment point as well as hydrodynamic damping effects due to water resistance. Furthermore, external forces acting on the VDS during underwater operation are considered, particularly those arising from interactions with the vessel’s propeller wash and surrounding environment. The proposed approach provides a valuable tool for enhancing the deployment strategies and operational performance of variable depth sonar systems under realistic sea conditions.Publicationtype: Conference Paper5 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Assessment of wind gust effects on the flow around offshore helidecks using RANS simulations(American Society of Mechanical Engineers (ASME), 2026-06); ; ; Wind gusts can significantly affect the flow characteristics above offshore helidecks, with direct implications for the operability and safety of helicopters. In this paper, RANS simulations using k–ω SST turbulence model are performed to investigate the influence of wind gusts on the mean flow field above a converter platform helideck. Idealized gusts are defined using field-measured characteristics from the Baltic Sea, and the gust response is analyzed through phase-interval averaged quantities and assessed using relevant metrics. The results show that gust forcing induces an increase in the mean turbulence kinetic energy and flow velocity magnitude with respect to the baseline mean flow. Across the investigated wind directions, turbulence kinetic energy generally increases over gust phases, with the strongest response occurring during the phase following the gust peak velocity. Critical wind directions for helicopter operations are identified for the configurations in which the helideck is located in the flow stagnation region, and the separated shear layer from the helideck interacts with the wakes from the surrounding superstructures. The results also highlight the importance of accounting for unsteady inflow conditions, showing that steady inflow simulations can lead to differences in the estimated kinetic energy values of turbulence during gust events.Publicationtype: Conference Paper13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Influence of artificial seawater corrosion on the fatigue strength of 40 mm thick welded details for offshore wind support structures(American Society of Mechanical Engineers (ASME), 2026-06); ; ; Offshore wind support structures are exposed to cyclic loading and harsh environmental conditions that can promote corrosion and potentially affect fatigue performance. This study investigates the influence of long-term artificial seawater corrosion on the fatigue strength of thick welded steel details representative of offshore applications. Butt-welded and fillet-welded joints with plate thickness of 40 mm were exposed to artificial seawater for 12 months and subsequently tested under four-point bending fatigue loading. Changes in weld geometry induced by corrosion were quantified using optical 3D surface scans. The results show that artificial seawater does not reduce the characteristic fatigue strength of the investigated joints. While butt welds exhibit comparable fatigue performance before and after corrosion, fillet welds show an increase in fatigue strength due to corrosion-induced smoothing of the weld toe geometry. These findings indicate that corrosion-induced surface modifications should be considered in fatigue assessment and lifetime extension strategies for offshore wind support structures.Publicationtype: Conference Paper14 3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Predicting route-specific fuel consumption with wind propulsion systemsThis paper presents a novel approach for assessing the effectiveness of wind propulsion systems through an integrated simulation framework combining a four degrees of freedom (4 DoF) Performance Prediction Program (PPP)/Velocity Prediction Program (VPP) with route-based voyage simulations incorporating environmental conditions and conventional engine usage. The methodology leverages the SAIL module within an in-house software environment, which calculates aerodynamic forces on individual wind propulsion elements—such as Dynarigs—using experimentally derived wind tunnel force coefficients. These aerodynamic forces are integrated into the route simulation tool, enabling voyage simulations that include detailed weather data, ocean currents, and conventional engine power. By simulating a defined route with given environmental inputs, the framework computes the vessel’s optimal equilibrium speed and propulsion power distribution. The WPS sail area is adjusted dynamically in response to wind speed and direction to maximize thrust contribution while ensuring safe vessel operation. The simulation iteratively balances wind propulsion input with conventional engine output to maintain target speeds along the route, facilitating direct comparisons of fuel consumption and emissions with and without wind assistance. Furthermore, the modular nature of the simulation allows for future incorporation of additional factors such as sail maneuvers and route optimization.Publicationtype: Conference Paper6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Experimental evaluation of data-driven deterministic wave generation(American Society of Mechanical Engineers (ASME), 2026-06); ; ; ; This paper explores the applicability of data-driven deterministic wave generation in an experimental environment. Various datasets that comprise different combinations of experimental- and synthetic data are used to train a fully convolutional neural network on the task of predicting the wave-maker control signal associated to a desired target wave sequence at a predefined target location in the wave tank. The trained models are evaluated in an experimental program, where the predicted control signals are executed in a wave tank, the actual wave is measured and compared against the predefined target wave. The standard wave modeling approach for the generation of tailored wave sequences, which is based on linear theory, is conducted for reference. The test dataset contains 950 irregular sea states with a wide range of characteristic sea state parameters, as well as seven tailored extreme waves, including the well-known “Draupner Wave”. It is shown that the data-driven approach consistently outperforms the standard method in accuracy across the studied range of sea states, emphasizing its effectiveness as a flexible and precise alternative for wave basin experiments.Publicationtype: Conference Paper29 5