bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Analysis of Non-Welded Wrapped Composite Joints Versus Welded Joints Under Multi-Axial Load Conditions in Offshore Wind Turbine Supporting Structures: A Fatigue Performance Evaluation
Authors: Koetsier Mathieu , Mylonopoulos Vasileios , Wolters Mees , Pavlović Marko 
Published: August 2024

Abstract
Offshore multi-membered structures, such as wind turbine support systems, frequently use Circular Hollow Sections (CHS). These structures face loading scenarios from wind, waves, and tides, resulting in axial forces and bending moments in the connections. Traditional welding methods introduce stress concentrations in the material, necessitating the consideration of Stress Concentration Factors (SCF) in fatigue design and the incorporation of stubs and cans to enhance fatigue life. An innovative alternative, as proposed by TU Delft, involves the use of non-welded Wrapped Composite joints. These joints rely on the interfacial bonding between the composite wrap and the hollow section members to transfer loads. This paper presents a comparative analysis of fatigue performance between experimentally tested wrapped composite joints and the fatigue lifetime prediction of their welded counterparts, addressing combined load conditions. At full-scale and 1/4th of full-scale. The study uses a Hexapod testing machine to evaluate various load scenarios on 1/4th of full-scale, including out-of-plane bending, and combinations of axial tension with bending. Full-scale wrapped composite joint in out-of-plane bending is tested in Cronos at OCAS N.V. Belgium. Results reveal exceptional fatigue resistance of wrapped joints to combined loading when compared to welded joints, showcasing their potential for offshore applications.
Investigation Into Sloshing-Induced Fatigue of Inter-Array Cables Inside a Fixed Offshore Wind Turbine Monopile Foundation
Authors: Siddiqui Mohd Atif , Li Henan , Farnes Knut-Aril , Midttveit Steinar 
Published: August 2024

Abstract
Offshore wind offers a great potential to replace fossil fuel energy sources, the latter being the major source of greenhouse gas emissions contributing to global warming. Size of offshore turbines is increasing (better efficiency), with it the size of supporting monopile (MP) structure increases, and turbines are being installed further offshore (stronger and sustained winds available). These factors can cause water motion of the internal free surface (sloshing) inside the MP to be relatively strong. Here, a 3D sloshing analysis is performed to study the effect on the MP and on internal structures such as inter-array cables (IACs) using a Computational Fluid Dynamics (CFD) solver. Sloshing resonance periods/frequencies are calculated using a theoretical formulation. Forced oscillatory motions of the MP in surge direction are simulated at selected sloshing resonance periods to obtain pressure and velocity on the internal free surface. It is found that loads on the MP and internal structures are within limits. A check for IACs fatigue due to sloshing-induced velocities is performed. Fatigue analysis is performed using an in-house tool Flexstress for Umbilicals (FFU). FFU calculates fatigue by combining global analysis from a specialized slender structures time-domain solver (OrcaFlex) for the IAC with a local cross-section analysis of IAC (UFLEX2D). It is found that sloshing has little effect on cable fatigue life (high fatigue life found).
Ship Manoeuvring Study of a Vessel Transiting a Ship Tunnel
Authors: Ross Andrew , Bruyat Anne , Aspelund Leiv , Hassani Vahid , Simanesew Abushet 
Published: August 2024

Abstract
We present an extensive simulation study focused on the approach to, and transit through, the Stad Ship Tunnel. The study incorporates innovative developments in a simulator tool, utilising results from geospatial modelling of the fjords and tunnel, shallow-water and confined-water hydrodynamics, extended modelling of ship hydrodynamics, both seakeeping and manoeuvring, and incorporating collision-dynamics all in one time-domain code, for the calculation of a diverse set of simulation results that can still be synthesised into manageable results.
Combined High and Low Cycle Fatigue Assessment of Tubular K-Joints With Consideration of Plasticity Accumulation
Authors: Xia Yuxuan , Yue Jingxia , Hu Yuhua 
Published: August 2024

Abstract
Various types of marine engineering structures, such as offshore platforms, often use intersecting tubular joints and are prone to initiate fatigue crack under cyclic loadings. Considering that the actual service process may encounter extreme sea conditions, the fatigue of the tubular joints is often not a simple fatigue problem, but a more complex combined high and low cycle fatigue (CCF) one that should take plasticity accumulation into account.
The traditional hot spot stress (HSS) method often fails to achieve satisfactory results when local stress exceeds yield strength. In this paper, a new CCF model considering the accumulation of plasticity is proposed. A nonlinear kinematic hardening material model of Chaboche was used to characterize the hardening behavior of materials under cyclic loadings. The damage under various loadings is calculated based on the new CCF model. And an assessment of a tubular K-joint was made under extreme loadings with the help of FEM.
Compared with the traditional HSS method, this method takes into account the interaction between various loadings, reflects the material’s kinematic hardening behavior, and can predict the fatigue performance of tubular joints more accurately under potentially extreme sea conditions. This method is also applicable to other forms of marine engineering structures.
Physics-Informed Neural Networks for Modeling Linear Waves
Authors: Sheikholeslami Mohammad , Salehi Saeed , Mao Wengang , Eslamdoost Arash , Nilsson Håkan 
Published: August 2024

Abstract
Numerical simulation of water waves is of essential importance for ships and offshore structures design. One promising new method is the training of Physics-Informed Neural Networks (PINNs) for these simulations. The current study is an attempt to train a PINN architecture to analyze the velocity potential of the flow beneath periodic linear waves. It is shown that the developed PINN architecture predicts the pattern of velocity potential distribution near the free surface. The average error of the predicted pattern compared to the results of the analytical solution is 4.34%. The standard deviation of the error after 10 times retraining of the model is found to be 2.79%. The velocity field of the flow can be calculated by the spatial derivation of the velocity potential field. Therefore, the developed PINN can predict the velocity field of the flow beneath the given free surface with the same accuracy. A sensitivity study revealed that the average error and the standard deviation of the error in the prediction of the velocity potential field are highly influenced by the number of neurons, layers, and collocation points of the PINN architecture. The increase in the number of neurons and number of layers is found to have different effects on the average error and the standard deviation of the error.
The Effect of High Triaxiality in HPHT Polymers Used in Flexible Pipes
Authors: Bonanni Michele , Mintzas Angelos , O’Donnell Brendan , Johnsen Joakim , Roberts Andrew 
Published: August 2024

Abstract
The increasing trend for higher temperature and higher pressure developments places more demanding design requirements on flexible pipes. More sophisticated polymer modelling becomes important in these conditions.
The inner pressure sheath or barrier is the critical pressure containing layer in unbonded flexible pipe. At high temperatures, these materials soften significantly whilst retaining sufficient toughness for standard operation. However, this may result in significant plastic deformation in partially constrained scenarios such as at interfaces between metallic and polymer layers.
Traditionally, inner pressure sheath integrity is managed by limiting global strain and ensuring sufficient remaining barrier layer thickness, as specified in API 17J, or through the addition of additional sacrificial layers (tapes or extrusions) where required. Highly localized polymer strains are not normally considered a risk to product integrity.
A large local plastic deformation in a relatively thick layer may result in significant residual triaxial tension at the interface between the plastic zone and the elastic zone within the polymer. At low temperatures, the normal polymer material stiffening exacerbates the triaxial stress state, potentially creating the conditions for fracture nucleation.
Similar effects may be observed in highly dynamic events, such as rapid decompressions, where the strain rate variation can result in changes in material stiffness analogous to temperature effects.
In this paper this phenomenon is discussed further, describing how Enodo and Baker Hughes have performed material testing, developed material models, finite element simulations and defined failure criteria to predict such failures and provide a safe operating envelope for inner pressure sheath design in high temperature and high pressure scenarios.
Experimental Investigation of Nonlinear Forces on a Monopile Offshore Wind Turbine Foundation Under Directionally Spread Waves
Authors: Ding Haoyu , Zang Jun , Zhao Guangwei , Tang Tianning , Taylor Paul H. , Adcock Thomas A. A. , Dai Saishuai , Ning Dezhi , Chen Lifen , Li Jinxuan , Wang Rongquan 
Published: August 2024

Abstract
Accurate prediction of nonlinear wave loading is crucial for designing marine and offshore structures, yet it remains a challenging task. Prior research has primarily focused on uni-directional extreme sea states, revealing that linear loading cannot accurately represent the total wave forces acting on offshore wind turbine foundations, with significant contributions from high-order harmonics. This study broadens the scope to include multi-directional and bi-directional wave interactions with monopile offshore wind turbine foundations. We use a phase-based harmonic separation method to isolate harmonic components in the presence of complex wave scenarios. This approach allows for the clear delineation of individual harmonics from the total wave force by controlling the phase of incident focused waves. Remarkably, this method shown effective even with multi-directional and bi-directional spreading. The clean separation of individual harmonics enables the estimation of contributions from each harmonic. Our findings are in line with previous research, showing that nonlinear loading can constitute up to 40% of the total under certain wave conditions. We have also observed that wider wave spreading reduces nonlinear high-order harmonics, and uni-directional waves induce the most severe nonlinear forces. These insights emphasize the importance of accounting for high-order nonlinear wave loading in offshore structure design.
Finite Element Analysis of Collapse in Thermoplastic Composite Pipes Under External Pressure
Authors: Freitas Inês S. G. , Sousa José R. M. , C. e Gama Winston , O. de Souza Charlton 
Published: August 2024

Abstract
Rising demand for thermoplastic composite pipes (TCPs) in the oil and gas industry is due to their lightweight, strength, and resistance to stress corrosion cracking (SCC). TCPs are utilized in hybrid flexible pipes, replacing steel armors, particularly in the central core, to withstand pressure in deepwater operations. In this context, this study proposes a finite element model to predict the potential collapse of TCPs under external pressure. The finite element (FE) model was developed using ANSYS®, employing three-dimensional solid elements to represent the layers of the pipes. Parametric analyses were conducted to assess the effects of initial ovalities and explore some laminate combinations. Additionally, some failure criteria for composite materials are employed to predict collapse pressure and compare it with the results derived from the finite element model. In these analyses, lay-ups with higher winding angles have shown improved performance. However, it notes that axial resistance decreases with higher winding angles, emphasizing the importance of fiber orientations due to complex loads in risers. Initial ovality impacts deformation more than the capacity for collapse loads. Finally, the failure criteria aligned well with the FE model, with Tsai-Wu demonstrating better accuracy.
Optimization of Segmented Wave-Maker Control to Generate Spatially Uniform Regular Waves in a Wave Basin by Parallel Simulated Annealing Algorithm
Authors: Ota Daichi , Houtani Hidetaka 
Published: August 2024

Abstract
To ensure the accuracy of the seakeeping test of a model ship, the spatial distribution of regular wave heights generated in a wave basin should be uniform. However, the cylindrical propagation property of the waves generated by the segmented wave maker causes non-uniformity. This study aims to suppress such non-uniformity by optimizing the control amplitudes of the wave makers using “Temperature Parallel Simulated Annealing”. The proposed method was numerically validated for wave generation under three different wave direction conditions in the Actual Sea Model Basin at the National Maritime Research Institute. This basin has a rounded-rectangular shape and is equipped with flap-type wave makers all around the perimeter. The proposed method demonstrates a 57% improvement in the mean absolute error of wave amplitudes at a test zone located in the basin for a wave direction of 90° (generated using flaps arranged at the long side of the basin), 26% improvement for a wave direction of 120° (oblique wave), and 25% improvement for a wave direction of 180° (using the short side flap array) compared to wave generation by the conventional “snake motion” principle.
Experimental Study of the Hydrodynamic Characteristics of the Raft Aquaculture Facilities Around a Windfarm Monopile
Authors: Ai Qing , Cao Jinchao , Jin Lei , Chen Deming , Tang Yanli , Zhao Fenfang , Sheng Huaxiang , Wang Xinxin 
Published: August 2024

Abstract
The hydrodynamic attributes of aquaculture structures play a crucial role in ensuring stability and reliability within complex marine environments. This study focuses on raft aquaculture structures situated in offshore wind farms, with a focus on their interaction with the wind farm monopile. Mooring line tension for these raft aquaculture facilities is investigated under various wave conditions, both with and without the presence of wind farm monopile, utilizing physical model experiments conducted in a wave flume. The study employs physical model experiments to assess the hydrodynamic performance of two prevalent raft aquaculture facilities: the longline raft aquaculture and pontoon raft aquaculture facilities, exposed to varying wave conditions. The experimental results show that the maximum mooring line tension diminishes with lengthening wave periods and increases with higher wave height. Notably, the windfarm monopile exerts a pronounced dampening on wave propagation. In the case of single-row aquaculture facilities utilizing windfarm monopile foundation as the mooring anchor, the mooring line tension of pontoon aquaculture facility experiences a reduction ranging from 16% to 65 %, peaking at a wave steepness of 0.037. Meanwhile, the mooring line tension of the longline aquaculture facility is reduced by 71–82 %, reaching its maximum at a wave steepness of 0.041. Moreover, it is observed that the maximum mooring line tension in multiple-row raft aquaculture facilities is smaller than that in the single-row raft aquaculture facility. This research on the hydrodynamic characteristics of raft aquaculture structures aims to provide scientific guidance for selecting aquaculture structure types in offshore wind farms.
Characterization and Performance Evaluation of Various Types of Polymers Based Latexes for Cementing Application
Authors: Al-Yami Abdullah , Khan Majad , Tahir Muhammad Nawaz , Alsafran Ali , Wagle Vikrant , Almulhim Sara 
Published: August 2024

Abstract
Gas migration through cemented casings may introduce a risk for wellbore integrity if cement formulations do not contain additives such as polymer latex. Polymer latex have been used to help reduce the fluid loss to minimize gas migration, improve wellbore integrity, and aid in the mixing ability of cement slurries. Many theories and mechanisms have been detailed to prevent annular gas flow through a cement column. Cement slurry loses its ability to transmit hydrostatic pressure during the transition from liquid phase to semi-solid phase until complete loss of hydrostatic pressure as cement slurry sets. In high pressure formation, gas or liquids can travel up through cement matrix due to lost hydrostatic pressure. This migration of liquid or gas can cause high surface pressure that may prevent us from fully utilization of these wells.
Similar produced latex is employed as a binding agent in cement used primarily for construction applications. The construction cement is, however, exposed to ambient temperature and pressure conditions. Thus, it is proposed to study the performance of latex used in construction industry for cementing applications at elevated temperature and pressure conditions.
Analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared analysis (FTIR), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA) were used to help in elucidating the structures and physical properties of different latexes. Tests such as thickening time test, fluid loss test, and rheology measurement test were conducted to compare the performance of different latexes in cement slurries.
Different concentrations of polymer latex based on emulsion of polyvinyl acetate were used without success resulting in extreme fluid loss. So, we had to increase the concentration of polyvinyl alcohol in the local PVA by conducting in-situ hydrolysis. We have utilized lime or Ca (OH)2 to achieve this. The result was polyvinyl alcohol and calcium acetate. Treating styrene butadiene polymer-based latex with citric acid extended the thickening time of cement slurries beyond 6 hours which is enough to perform cementing operations for oil and gas wells. As the pH is reduced by the addition of citric acid, thickening time will be longer and fluid loss will be lower. The ability of forming a film to reduce filtration is improved by reducing the deprotonation of the latex in basic solution (less interaction with calcium ions).
Effect of Forward Speed on Hydrodynamic Responses and Structural Responses of a Benchmark Vessel
Authors: Cheng Zhiping , Chen Yingying , Cai Minbo 
Published: August 2024

Abstract
This study first validates the Rankine source model with experimental data, subsequently, conducts hydrodynamic analyses of KVLCC2 at four forward speeds. The effect of forward speed on hydrodynamic responses is evaluated by comparing long-term extreme responses of 6-DOF motions and global section loads. There is a notable increasing trend of surge motion and yaw motion as forward speed increases. Whereas the pitch motion demonstrates the opposite tendency. The influence of forward speed on other motion modes is negligible. As for global section loads, the impact of forward speed on vertical shear forces and vertical bending moments is not significant. While the horizontal shear forces, horizontal bending moments and torsional moments show a downward trend with an increment of forward speed. Whereafter, this paper performs global FE analyses of KVLCC2 at zero forward speed and the design speed (15.5 knots). The comparisons of stress RAO amplitudes of typical structural members indicate that the effect of forward speed on stress amplitudes does not show a consistent trend in different wave conditions. The long-term stochastic analysis and fatigue assessment results reveal that most of the selected structure members experience larger extreme stress responses and more severe fatigue damage in stationary state than in navigating state with the design speed. Whereas, the bulbous bow suffers more severe fatigue damage in navigating state with the design speed.
Dynamic Response of a Steel Catenary Riser at Touch Down Zone With Seabed Trenching Development Considered Under Irregular Waves
Authors: Gao Zhenguo , Zhou Zefeng , Wang Weichen 
Published: August 2024

Abstract
The steel catenary riser (SCR) serves as a primary solution for deep-water oil and gas field development, but it encounters complex dynamics due to forced oscillations induced by wave-driven floater motions, especially at the touch-down zone (TDZ). Traditional pipe-soil models often fail to address these challenges, as they do not account for soil remoulding and the impact of irregular motion. This is particularly relevant in real sea states characterized by irregular waves, where the floater’s movements have a significant impact on seabed trenching, thus complicating the dynamic responses of the SCR. To address these issues, this study integrates an innovative effective-stress-based pipe-soil interaction model into a global SCR analysis to explore its dynamic response and fatigue damage under irregular waves. The irregular movements of the floater, derived from response amplitude operator (RAO) data and wave spectra, are applied to the SCR’s top end after a translation to the hang off location. This allows for dynamic simulations that consider the evolution of the seabed and the process of trenching. The study focuses on deriving the dynamic stresses experienced by the SCR at the TDZ and evaluating fatigue damage using the S-N curve method. It also examines the seabed interaction, including the evolution of trenching, changes in seabed stiffness, and soil resistance at various SCR locations. By considering real sea conditions, this study yields insights into trenching and seabed-SCR interactions, promising to enhance design methodologies and bolster offshore infrastructure performance and safety.
Experimental and Numerical Investigation on Ship Rolling Motion Response Coupled With Liquid Sloshing
Authors: Wang Yunhe , Jiang Shengchao , Zhou Tongming 
Published: August 2024

Abstract
This paper investigates the coupled dynamics of a ship carrier with sloshing inside three liquid tanks at varying filling depths, employing both experimental and numerical methods. Two obvious peaks for ship rolling motion are captured when sloshing exists in the liquid tank. One peak occurs earlier and the other occurs later than the peak of ship rolling motion without sloshing. The coupling motion results reveal the existence of the natural period of sloshing and the natural periods of ship-tank system rolling motion. The natural period of sloshing always corresponds to the trough between the first and the second peak. The biggest difference between the two peaks is the opposite phase relationship between ship-tank motion and the fluid motion inside tanks. The experimental free decay test can only predict one of the two periods (corresponding to the two peaks) of ship rolling motion. A new numerical coupling model is developed and it can simulate the ship motion coupled sloshing precisely.