bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the Sliding and Penetrating Resistances of a Mobile Subsea Mudmat Accounting for Maintained Load, Shearing and Reconsolidation
Authors: Liu Kehan , Wang Dong , Fu Dengfeng 
Published: August 2024

Abstract
Subsea mudmats are employed extensively as a shallow foundation on soft clay to support the seabed structures for offshore oil and gas developments. Compared with a conventional fixed mat, an emerging concept of the tolerably mobile mudmat, which is to allow foundations sliding with the pipeline supported to accommodate the periodic thermal expansion and contraction, is a potential solution to reduce the foundation sizes and then the installation cost. In this paper, the performance of a tolerably mobile subsea mudmat subjected to maintained load and periodic sliding events with intervening consolidation during its whole life is investigated. A series of coupled large-deformation finite-element (LDFE) analyses were carried out. LDFE results of several typical field scenarios are used to develop an extended effective stress framework, which is capable of predicting the changes in sliding and penetrating resistances of the mobile mudmat due to maintained and cyclic loads. An extended reconsolidation solution within the framework was proposed to simulate the coupled dissipation response of excess pore pressures that remaining from partial installation consolidation and generating progressively from cyclic shearing. The proposed framework is validated by the existing centrifuge tests. Variations in stress state and strength profile are discussed to interpret the changing sliding and penetrating resistances. The LDFE and framework analyses provide insights that a shorter installation period and frequent slide events are contributed to a rapid hardening of resistance.
A Coupled CFD-FEM Study on Slamming Loads and Structural Dynamic Responses of a Simplified Ro-Ro Ship
Authors: Gao Ziyu , Yue Jingxia , Zhao Xiaosa , Zhang Chi 
Published: August 2024

Abstract
Roll-on/Roll-off (Ro-Ro) ships with small deadrise angles may subject to substantial hydrodynamic loads, particularly during slamming events in adverse sea conditions. While existing studies have primarily focused on slamming loads and structural dynamics in the bow flare region, a notable research gap persists in understanding these phenomena when the bow doors are open — a critical scenario during emergencies or abrupt landings.
This paper explores the specified scenario using a simplified model of a Ro-Ro ship — a symmetrical wedged grillage structure with two stiffened plates representing the bow doors. Numerical analysis based on a coupled CFD-FEM method is employed, and the slamming event is modeled as a free-fall water entry process. Validation is performed through simulations on a wedged grillage structure with a vertical bow plate and comparing results with available experimental studies. Subsequently, case studies are conducted for the simplified Ro-Ro ship with the bow doors in open and closed states, respectively, to assess the influence of the door status on slamming and structural responses. Additionally, four different current velocities are considered to investigate the effect of forward speed on slamming loads and dynamic responses of Ro-Ro ships.
The study reveals that opening bow doors results in negative slamming pressure on the bow door structure, contrasting with positive values when doors are closed. Moreover, the strains (representing structural deformation) in the connection region between the doors and the hull structure is positive in the door-open state, in contrast to the negative strain observed when the doors are closed. A peak in the time history of strain is detected only when the doors are open. The study also shows that slamming occurs more rapidly with the increase of current velocity. As the current velocity increases, the amplification of maximum strain in the connection area also increases when the bow doors are open. These findings could be useful for the design of bow doors and the operation of Ro-Ro ships.
Crack Propagation Test of Stiffened Panel in Low Temperature
Authors: Feng Guoqing , Yang Xuanyu , Li Songcheng , Li Kaiyan 
Published: August 2024

Abstract
With the increasing exploration of polar regions, the problem of fatigue crack propagation during ice-breaking operations of ships in polar low-temperature environments has received more and more attention, which has put forward higher requirements on the mechanical properties of high-strength steels used in hulls in low-temperature environments and the fatigue crack propagation properties of typical details of hulls in low-temperature environments. In this context, the study of fatigue crack propagation of typical details of hulls in low-temperature environment is caried out. The main contents of this paper are as follows:
The Test specimens with a through-thickness initial crack are designed based on the bow stiffened plate structure of the hull, and fatigue crack propagation tests of the bow stiffened plate structure in a low-temperature environment are conducted. It was found that with the gradual propagation of the fatigue crack, the fatigue crack propagation rate gradually increased and the fatigue crack tip gradually expanded in the direction away from the inter-reinforcement welds. Then, the finite element simulation of fatigue crack propagation test of stiffened panel of hull under low temperature environment is carried out, and the accuracy of the simulation results is verified by comparing the simulation results with the test results.
A Power Estimation Method for Hybrid Contra-Rotating Propeller Propulsion System
Authors: Wakabayashi Tomoki , Katsui Tokihiro 
Published: August 2024

Abstract
Due to the recent high level of environmental regulations, there has been increasing of the attention to Energy Saving technics. One of the developing energy saving technics is the Hybrid Contra-Rotating Propeller (HCRP) propulsion system. To date HCRP propulsion system has been applied to limited numbers of ships which has special order like domestic liners in Japan [1][2]. However, HCRP is promising system to be built in major ships like bulk carriers, tankers or container ship which are operated around the world in the future because of its high propulsion efficiency. One practical subject of HCRP is a power estimation method for this complex propulsion system. In these decades, several research projects treated HCRP. TRIPOD project [3][4] treated wide range of topics, which included tank test method, numerical analysis and concept validation adopting HCRP to an existing cargo ship. The mainstream of a power estimation method for HCRP is the way how a total force of two propeller acting as a CRP are treated as pseudo one propeller [5][6]. The feature of HCRP is that two propellers can act independently. It means there exists infinity numbers of rotational speed rate of two propellers and a propulsion performance and a maneuvering performance depends on it [5]. If we use a propeller open water characteristics of a CRP as pseudo one propeller, we can estimate only very limited conditions which are tested in a towing tank. This paper shows the newly developed powering method which use characteristics of individual two propellers and a mutual interaction of propellers acting as a CRP. This method can estimate every condition of revolution rate which made with a feature of HCRP propulsion system. The scope of this research is constructing a tank test method and a powering method and reviewing them with surveying of an actual ship performance.
Research on the Application of Gyrostabilizer in the Motion Control of Floating Offshore Wind Turbine
Authors: Zhang Yu , Yang Xiaolong , Deng Shi , Yang Liang , Zhang Fafu 
Published: August 2024

Abstract
Usually, the floating offshore wind turbine (FOWTs) are linked to the seabed by catenary mooring system, and its motion amplitude is significant under the action of wind and wave. If the pitch angle of FOWTs is too large, the efficiency of power generation will be reduced. Thus, it is necessary to study how to decrease the motion response amplitude of FOWTs. In this paper, a time domain coupled numerical simulation program for FOWTs is developed using the vector form intrinsic finite element (VFIFE) method. The program is composed of the aerodynamics module, hydrodynamics module, dynamic mooring module and core solver module (central difference scheme). In program framework, the partitioned bidirectional weak coupled strategy is used to exchange data between each module, and finally the unified coupled calculation in time domain is realized. Based on the established FOWT model, a gyrostabilizer is proposed to control the motion of the FOWT. Firstly, the coupled governing equation of motion of the FOWT and the gyrostabilizer is derived theoretically, then the control performance of the gyrostabilizer on the motion response of the FOWT is evaluated. The simulation results show that the gyrostabilizer to reduce the motion amplitude of the platform is significantly, but has little effect on reducing the mooring tension.
Offshore Infrastructure Disaster Ontology Construction Based on Feature Engineering
Authors: Li Yi-Lin , Loh Ching Wah , Li Sunwei , Hu Zhen-Zhong 
Published: August 2024

Abstract
In recent years, the South China Sea has faced a surge in marine meteorological disasters, causing substantial financial impacts across Asia and threatening the livelihoods of coastal communities. Despite earnest disaster prevention and mitigation efforts, formidable challenges persist in offshore engineering.
This study conducts a comprehensive analysis of potential transformations, structural failures, and collapses in offshore infrastructure under specific marine and meteorological conditions. It aims to deepen the understanding of the complex and dynamic mechanisms underlying marine disasters. To achieve this, a bottom-up multidimensional feature extraction approach is employed from historical data, considering temporal, spatial, and textual dimensions. Parameters such as spatial-temporal data, physical characteristics, geographical locations, meteorological conditions, and marine environmental factors are meticulously considered. The identified multidimensional features are then analyzed and integrated into an ontology representation, describing the intricate relationship between properties and marine infrastructure disasters. This comprehensive disaster ontology is structured using ontological and feature engineering, encompassing both ontology and epistemological data layers.
In conclusion, this study contributes to improving disaster preparedness and response strategies in the South China Sea and similar regions. By addressing offshore engineering intricacies during marine disasters, it offers valuable insights for more effective risk management and mitigation measures in the future.
Numerical Validation of Second-Order Wave Drift Forces Calculation for Floating Structures
Authors: Ramachandran Krishnavelu , Somayajula Abhilash 
Published: August 2024

Abstract
Accurate estimation of second-order wave drift forces is imperative for predicting the responses of offshore structures, mooring systems, and vessel motions in ocean waves, especially in adverse wave conditions. These wave drift forces are derived from non-linear wave potential effects. Precise estimation of wave drift forces is vital for the design and analysis of offshore platforms, moored structures, and ships operating in challenging wave conditions to ensure safety, stability, fatigue resistance, and long-term structural integrity. This study presents a comprehensive derivation and implementation of second-order wave drift forces for an in-house numerical tool, Hydrodynamic Response Analysis (HydRA). The HydRA program has been developed using a Green function-based 3-D potential flow theory-based panel method code. The numerical investigation focuses on the Benchmark KRISO Container ship (KCS) for this study. The HydRA tool accurately calculates wave drift forces at zero speed case. This numerical simulation tool is capable of accurately assessing rigid body motions and loads in all six degrees of freedom. Validation of the second-order drift forces at zero speed will be conducted against the MDLHydroD and WAMIT programs. This research contributes to the advancement of understanding and predicting second-order wave drift forces, offering valuable insights into the field of fluid-structure interaction and hydrodynamics analysis.
Simplified Fatigue Load Cases Assessment in Tension Leg Platform Floating Offshore Wind Structural Analysis
Authors: Meng Xun , Wang Zhaoyue , Lu Qing , Rawlinson-Smith Robert , Greaves Deborah , Wang Wenping , Fu Qiang 
Published: August 2024

Abstract
Floating offshore wind turbines (FOWTs) are considered a promising solution for wind energy harvesting in deep water, and optimized designs will bring the costs of FOWTs down and increase profitability. However, verifying the fatigue lifetime for the FOWT optimization model requires a large number of loading situations with computationally expensive response analyses. Fatigue damage calculated for six sets of simplified fatigue load cases (FLCs), with different combinations of turbine loads and wave loads, were compared using time-domain simulations in combination with Miner’s Rule, which allows for the identification of optimal parameters in a lifetime perspective, and fair comparisons between the different contribution from loading of the wind turbine and environmental waves. The chosen FLC for fatigue damage verification of the floater scantling model in the present work is applicable for the preliminary design of Tension Leg Platform (TLP) FOWTs, where they can provide a starting design for the detailed design phases. The methodologies can be further extended to account for different FOWT concepts, additional design parameters, and other load combination cases.
Simulating Waves at the Beaches of the Ericeira World Surfing Reserve
Authors: Gomes Tiago , Bihs Hans , Wang Widar , Vaz Guilherme 
Published: August 2024

Abstract
In an attempt to develop a forecast model for surfing waves, the fully nonlinear potential flow code REEF3D::FNPF is applied in the Ericeira World Surfing Reserve. Open-source bathymetry datasets, available in EMODNet, are used to define the domain. After a grid refinement study, simulations with irregular waves are performed, with varying heading directions. These waves are defined through the means of a JONSWAP spectrum, to model the effect of incoming swell. The wave spectrum and several significant wave height definitions are used to assess the impact that swell direction has on the waves of each beach. Moreover, the breaking wave detection algorithm incorporated in REEF3D::FNPF is combined with the Iribarren number to classify the type of breaking wave. This way, the model is able to predict the spatial location of plunging waves, one of the most appropriate types for surfing. Overall, North-South swell conditions produce the least amount of breaking waves, yet some of the beaches in the reserve still present potential for surf given the selected wave conditions.
Experimental Study on Hydrodynamic Damping of an Oscillating Cylinder Under Small Keulegan-Carpenter Numbers
Authors: Dong Guanning , Cheng Liang , Ren Chengjiao , Tong Feifei 
Published: August 2024

Abstract
This paper presents an experimental study on the hydrodynamic drag and inertia coefficients, which were decomposed from the total measured force through Morison equation, of an oscillating cylinder in quiescent water under small Keulegan-Carpenter number (K) conditions. The objective of this study is to address a discrepancy demonstrated by Ren et al. (J. Fluid Mech., vol. 913, 2021, A36) where drag coefficients determined in experiments under small K conditions deviated significantly from those of the analytical solution and direct numerical simulations (DNS). Two experimental inaccuracies responsible for this deviation are identified. The first one is associated with the additional inertia force induced by the oscillating load cell, leading to an overestimation of the inertia coefficient. The second is related to the non-synchronized measurements of signals by multiple sensors. A tiny phase difference between the force (recorded by the load cells) and motion (recorded by the accelerometer) signals is demonstrated to cause significant change in the drag coefficient. Finally, a post-processing strategy is proposed in this study to reduce these inaccuracies. After implementing this strategy, the calculated force coefficients agree well with those obtained from the analytical solutions and DNS.
Application of Irregular Frequency Removal Feature in Capytaine for Anode Cage Installation Over a Monopile Wind Turbine
Authors: Herdayanditya Ivandito , Baert Benjamin , Stempinski Florian , Rauwoens Pieter , Lataire Evert 
Published: August 2024

Abstract
Marine operations in offshore wind farms require hydrodynamic information to perform the operability analysis. An anode cage installation over a monopile wind turbine, an example of marine operations, needs the vessel hydrodynamic parameters and the flow field information around the monopile to perform time domain analysis to estimate the sling tensions during the installation. Capytaine, an open-source Linearized Potential Flow (LPF) solver, is utilized to compute the hydrodynamic parameters and the flow field around the monopile. However, the original version of Capytaine suffers from the irregular frequency problem. An existing method of applying a lid on the free surface is applied to remove this problem. The lid also appears to remove the oscillation of the hydrodynamic solutions in the high frequency. The results are validated by a well-established LPF solver, ANSYS AQWA. Afterward, two numerical model configurations of only the vessel and the vessel with the monopile are investigated where it is seen that the flow field around the monopile is sensitive to the multibody modeling. Therefore, the anode cage installation stages that do not require flow information (e.g. lifting in the air) can be done in single-body simulation, while multibody is inevitable if the flow field starts to play a significant role (e.g. lifting in the splash zone).
Probabilistic Approach of Lateral Buckling Analyses for HPHT Pipelines With Buckle Mitigators
Authors: Bai Qiang , Moura Endryws , Primieri Rodrigo , Brunner Mark , Wang Lijuan 
Published: August 2024

Abstract
This paper presents a probabilistic approach for lateral buckling analysis based on a global FE model via a case study of a 5km long subsea flowline with sleeper mitigators on an undulating seabed. In the case study, axial/lateral pipe-soil interaction (PSI), pipe/sleeper friction factors, and horizontal out-of-straightness (OOS) of flowline at seabed and sleepers are defined as stochastic parameters, while other parameters, including flowline as-laid vertical OOS, pipe section and operating parameters, are defined as deterministic variables. First, the response surfaces for lateral buckling of the full-length flowline due to the stochastic parameters are created through FE analyses based on a load case matrix selected by the Design of Experiments approach. Then, Monte Carlo simulations based on the response surfaces are performed to obtain the distributions of lateral buckling responses, including parameters such as the limit-states for post-buckle, buckle amplitudes, walking speed or end pile loads, rogue and engineered buckle locations. Lastly, the probability distributions of the limit-state unity checks are compared with the target failure probabilities.
This probabilistic approach will require more simulation time compared to the deterministic approach but can provide more detailed probability ranges for the lateral buckling responses and save the project on total cost. This approach can be used to assess the reliability of lateral buckling responses during the detailed design phase of subsea pipelines susceptible to lateral buckling.
Effects of Varying Breadth Ratios on Fluid Resonance in a Narrow Gap Formed Between Two Boxes in Close Proximity
Authors: Gong Shukai , Gao Junliang , Song Zhiwei 
Published: August 2024

Abstract
Fluid resonance within a narrow gap between two boxes in close proximity is investigated based on the open-source CFD package, OpenFOAM. The upstream box keeps fixed but with varying breadths, the downstream box heaves freely under wave actions and has a constant breadth. For comparison, a two-stationary box system is also considered. The aims of this work are to study the effects of the breadth ratio of the two boxes, i.e., the ratio of the breadth of the upstream box to that of the downstream box, on the hydrodynamics of the resonant fluid inside the gap and the motion of the downstream box. It has been found that the amplification of resonant wave height in the gap decreases significantly with the increase of the breadth ratio and the incident wave height, while the fluid resonant frequency seems insensitive to the breadth ratio. Compared with the two-stationary case, the fluid resonant frequency for the two-box system with the downstream box heaving freely shifts towards higher values. Furthermore, for the cases with a smaller incident wave height or a larger breadth ratio, there usually exists a local peak in the curve of the heave displacement versus the incident wave frequency. A larger breadth ratio leads to a smaller heave motion of the downstream box.
Short-Term Extreme Value Prediction for the Dynamical Responses of a Semi-Submersible Platform in Harsh Environment
Authors: He Lin , Chai Wei , Gu Jian , Sinsabvarodom Chana , Chen Junfeng , Shi Wei 
Published: August 2024

Abstract
Deep-sea platforms play a crucial role in the exploration of oil and gas resources. Ensuring the safety of semi-submersible platforms in challenging marine environments is of paramount importance. Consequently, this research is dedicated to the estimation of extreme values for motion responses and the mooring loads of a deep-water semisubmersible platform in the South China Sea. Specifically, numerical simulations are carried out by using commercial software, and the accuracy of the numerical results is verified with experimental data. To assess the safety of mooring systems with multipoint configurations under extreme sea conditions, the environmental contour method (ECM) is applied to select the most severe sea state. For a given sea state, short-term extreme value analysis is performed by using the average conditional exceedance rate (ACER) method. Finally, an analysis of the extreme value predictions is performed in compliance with relevant regulations to evaluate the safety of the mooring system.