bluuebunny/crossref_metadata_2025_split huggingface dataset:
Torsion Failures in Handling Operations for Power Cables, Umbilicals and Flexible Pipes
Authors: Mainçon Philippe , Longva Vegard 
Published: October 2021

Abstract
Over the past 10 years, SINTEF has investigated, or been informed about, a range of torsion failures in cables, umbilicals or flexible pipes. These failures have occurred while the flexible products were being transported along a route during production, loadout, installation. One failure occured during operation. There are no guidelines on how to minimize the risk of such failures. This may be attributed to a lack of knowledge in the industry about the mechanisms that cause torsional moments to appear. Further, some buckling patterns of the components of a flexible product under excessive torsion, closely resemble patterns caused by excessive bending or compressive load, so that some torsion-induced failures are wrongly attributed. Hence, there is a need to increase the knowledge and awareness of torsion failures in the industry. Previous papers by the authors have considered some of the mechanisms that lead to the appearance of torque in handling operations. The present paper is a continuation which focuses on torque-induced failure modes. It begins by providing a systematic nomenclature for the description of torsion kinematics. It then provides a qualitative description of known torque-induced failure modes. The literature provides some models for torque-induced failures, as well as models of component failures due to excessive bending or compression of the flexible product, which are also relevant for the study of torsion. These are reviewed, and their relevance to torsion-induced failures are discussed. Knowledge gaps and challenges are highlighted.
A Scheme of Radial Basis Function Interpolation Based on Partition of Unity Method for FSI Boundary Data
Authors: Min Yu , Xuan Zhang , Tingqiu Li , Yongou Zhang 
Published: October 2021

Abstract
For Fluid-Structure Interaction (FSI) analysis, Radial Basis Functions (RBF) interpolation is very effective for data transfer between fluids and structures because it can avoid interface mesh mismatches that make it difficult to transfer data. However, one of the main drawbacks of conventional RBF interpolation is the computational cost associated with solving linear equations, as well as the corresponding running times. In this paper, a scheme of RBF interpolation based on the Partition of Unity Method (RBF-PUM) is proposed to handle a large amount of FSI boundary data with the aim of striking a balance between computational accuracy and efficiency. And a cross-validation technique is coupled with RBF-PUM, for the purpose of searching for the optimal value of shape parameter related to RBF interpolation. The scheme basically focuses on two parts, one of which is how to partition the fluid domain of node points into a number of subdomains or patches, and the other is how to efficiently exploit the techniques that are applied to reduce the interpolation error locally and globally. Numerical experiments show that compared to the CSRBF method and the greedy algorithm-based RBF method, RBF-PUM significantly improves the computational efficiency of the interpolation and the computational accuracy is relatively competitive.
Failure Modes and Rules Related to the Yield-to-Tensile Strength Ratio in Steel Structures
Authors: Wong Wei Jun , Walters Carey L. 
Published: October 2021

Abstract
Upper limits on the ratio of the yield strength to the tensile strength (σy/σu ratio) and lower limits on the fracture elongation εf are present in various offshore, maritime and civil engineering rules, standards and specifications for steel structures as a provision for the minimum material ductility and toughness which ensures sufficient structural ductility. In other instances, the design yield stress to be adopted in strength calculations is reduced from its nominal value if the σy/σu ratio exceeds a certain limit. Such requirements deter the use of high strength steels (nominal σy higher than 690 MPa), which inherently have a high σy/σu ratio. To guide subsequent efforts towards optimised and scientifically grounded σy/σu limits and wider application of high strength steels, this paper first presents an overview of the current provisions in engineering practice relating to the σy/σu ratio and structural ductility, and it then discusses the key underlying failure mechanisms to which these ductility requirements are relevant: tensile strain localization, yielding and localization precipitated by stress concentrations, localization of plastic bending hinges and ductile fracture. The reasoning behind the current provisions, the findings of previous research concerning the requirements, and the key potential areas for future research are highlighted.
Assessment of Wind and Wave High-Resolution Forecasts During High-Energy Weather Events in the Brazilian Coast
Authors: Chagas F. M. , Rachid B. R. F. , Ambrosio B. G. , Luz A. A. , Gramcianinov C. B. , Serrao P. F. , Camargo R. , Siegle E. 
Published: October 2021

Abstract
We present a high-resolution metocean forecast model (Aimar), which provides 24/7 results for the Brazilian coast. The model integrates global model boundary conditions and detailed coastal models, especially for complex geometry areas near ports and major coastal cities. The aim of this paper is to assess the forecast reliability and to present model data compared to in-situ measurements under high energy weather events. Mean wind velocity and direction were investigated during the occurrence of an extratropical cyclone near Brazilian coast. The model has been assessed by comparing its results to two specific events, one for winds and one for waves. Results of the tested wind event show that Aimar results predict the high energy winds in advance of 5 days, while NCEP’s Global Forecast System Ensemble (GFSe) predicted the same event in advance of 2–3 days, for the region of Santos city. Results of the tested wave event show that Aimar forecasts properly represent the wave propagation for complex geometry coasts. The high-resolution coastal model could predict the nearshore state of sea agitation caused by the passage of a cold front. Model agreement with in-situ wave measurements adjacent to Rio de Janeiro-RJ city were considered Excellent and Good, according to statistical parameters R and RMAE. These results show that high-resolution coastal forecast models can be applied to increase the efficiency, resource uses and reduce the risks for marine operations and engineering works.
An Experimental and Numerical Analysis of Gap Resonance Applicable for FLNG Side-by-Side Offloading
Authors: Nwafor Jideofor Collins , Hu Zhiqiang 
Published: October 2021

Abstract
The present research focuses on the experimental and numerical analysis of nonlinear gap resonance which can occur for two side-by-side configured vessels during the offloading operation of Liquified Natural Gas (LNG). The proximity of the FLNG (Floating Liquefied Natural Gas) facility and LNGC (Liquified Natural Gas Carrier) brings about the formation of a long narrow gap region between the two vessels. The model test was carried out in a wave flume with vessels of different sizes to obtain the resonance response at different locations in the gap region with the effects of gap distances and vessel drafts in incident waves of different wave frequencies and wave directions analysed. It was found that certain model configurations produce increased wave amplification between the vessels, these were highlighted and presented and have the possibility of being predicted to prevent the occurrence. The numerical analysis was carried out with the potential flow solver SIMA in the time domain and a calibrated damping factor was assigned to suppress the overestimated wave elevation in the narrow gap region.
Hull Form Optimization for a 62000DWT Heavy Lift Multi-Purpose Vessel
Authors: Jiang Shuhui , Zhang Li , Chen Weimin 
Published: October 2021

Abstract
A new optimized hull form was proceeded based on a parent ship 60000 DWT bulk carrier. The goal of optimization is to obtain better resistance performance in the loading conditions of scantling draught and design draught. Firstly, the numerical simulation of the parent ship was carried out, the flow field information around the hull was analyzed, the area of high or low pressure was checked, and the area was optimized to make the pressure distribution more uniform. At the same time, the bow entrance section was optimized to reduce the wave-making resistance, and the length of the run body was lengthened to reduce the flow separation area and the viscous pressure resistance. Aiming at these above optimization objectives, the deformation range of hull form was set by commercial software CAESES, and the total resistance of generated optimized cases was solved by SHIPFLOW and evaluated by STARCCM+ software. To grantee the resistance reduction at both design draught and scantling draught, by using the operation profile optimization method, the resistance weights of scantling draught and design draught were set as 50% respectively, that is, the total resistance of optimized hull form equals 50% resistance of design draught condition and 50% resistance of scantling draught condition. The optimization results of total resistance were compared and analyzed, and the cases with relatively minimum total resistance were obtained. On this basis, the wake field at the propeller disk was optimized either, and finally, the target optimization of hull form was obtained. The numerical results showed that, compared with the parent ship, the total resistance at the design speed of the design draught was reduced by about 1.64%, about 2.10% at the design speed of the scantling draught. The wake distribution on the propeller area was more uniform. The final optimized hull form meets the target requirements.
Development of a Simulation System for Estimating the Impact Force of Tsunami Drift Using the Explicit MPS Method
Authors: Aida Yasuhiro , Ikoma Tomoki , Masuda Koichi 
Published: October 2021

Abstract
When a large-scale tsunami occurs, structures in the coastal area will be destroyed by the impact of tsunami drifts. In the design of tsunami evacuation facilities and petroleum complexes, it is necessary to estimate the impact force of tsunami drift, which varies in size, shape and mass. Although some design equations have been proposed to estimate the impact force of tsunami drift, the impact force varies depending on various conditions such as the draft of the tsunami drifts, the attitude of the collision, the condition of the surrounding flow field, and the rigidity of the structure, etc. No reasonable design equation has been developed yet to meet all these conditions. Therefore, it is necessary to estimate the impact force of tsunami drift by water tank experiments and numerical simulations. In order to simulate the impact of a tsunami drift on a structure by numerical simulation, it is necessary to solve the coupling of fluid, floating object and structure. In this study, we have developed a simulation system that can simulate the impact force of a tsunami drift with the MPS method, which is a kind of particle method. This simulation system introduces an explicit method for pressure calculation, which allows for relatively large scale numerical calculations. In addition, the system is able to reproduce the deformation of structures as an elastic body due to the impact of tsunami drift. In particular, we have introduced an analytical method that allows us to set the computational time step that satisfy the CFL conditions for elastic and fluid particles, respectively, for stable simulation even when there is a large difference between the velocity of fluid particles and the velocity of structural particles caused by elastic waves. As a result of the comparison of the impact force on the cantilevered beam of the tsunami drift with the simulation and the water tank test, the deformation of the structure at the time of impact was reproduced with more than 90% accuracy.
Offshore Wind Turbine Mono-Bucket Foundations in Sand
Authors: Low Han Eng , Zhu Fangyuan , Mohr Henning , Watson Phillip , Erbrich Carl , O’Loughlin Conleth , Bransby Fraser , Randolph Mark , Travasarou Thaleia , O’Connell Daniel 
Published: October 2021

Abstract
Single (or mono) suction buckets have been put forward by others as possible offshore wind turbine (OWT) foundations. This paper presents a series of centrifuge model tests conducted in dense sand to investigate their monotonic response for a range of drainage conditions. The results from the centrifuge tests suggest that the mono-bucket rotational response at large rotation in dense sand is dependent on drainage conditions but does not seem to be affected by the contact condition between the bucket invert and the seabed. A final comparison between results from an equivalent set of uplift tests suggests, however, that multi-bucket foundation systems are likely to be more efficient foundation solutions, although suggestions are made which might improve mono-bucket foundation response.
Cathodic Protection Design Consideration for an Offshore Flexible Riser Connected to an Impressed Current System
Authors: Dequin Thierry , Weldon Clark , Hense Matthew 
Published: October 2021

Abstract
Flexible risers are regularly used to produce oil and gas in subsea production systems and by nature interconnect the subsea production system to the floating or fixed host facilities. Unbonded flexible pipes are made of a combination of metallic and non-metallic layers, each layer being individually terminated at each extremity by complex end fittings. Mostly submerged in seawater, the metallic parts require careful material selection and cathodic protection (CP) to survive the expected service life. Design engineers must determine whether the flexible pipe risers should be electrically connected to the host in order to receive cathodic protection current or be electrically isolated. If the host structure is equipped with a sacrificial anode system, then electrical continuity between the riser and the host structure is generally preferred. The exception is often when the riser and host structure are operated by separate organizations, in which case electrical isolation may be preferred simply to provide delineation of ownership between the two CP systems.
The paper discusses these interface issues between hull and subsea where the hull is equipped with an impressed current cathodic protection (ICCP) system, and provides guidance for addressing them during flexible pipe CP design, operation, and monitoring. Specifically, CP design philosophies for flexible risers will be addressed with respect to manufacturing, installation and interface with the host structure’s Impressed Current Cathodic Protection (ICCP) system. The discussion will emphasize the importance of early coordination between the host structure ICCP system designers and the subsea SACP system designers, and will include recommendations for CP system computer modeling, CP system design operation and CP system monitoring.
One of the challenges is to understand what to consider for the exposed surfaces in the flexible pipes and its multiple layers, and also the evaluation of the linear resistance of each riser segment. The linear resistance of the riser is a major determinant with respect to potential attenuation, which in turn largely determines the extent of current drain between the subsea sacrificial anode system and the hull ICCP system.
To model the flexible riser CP system behavior for self-protection, linear resistance may be maximized, however the use of a realistic linear resistance is recommended for evaluation of the interaction between the host structure and subsea system. Realistic flexible linear resistance would also reduce conservatism in the CP design, potentially save time during the offshore campaign by reducing anode quantities, and also providing correct evaluation of drain current and stray currents.
Lateral Buckling Mitigation of Subsea Pipeline by Temporary Winch Pull
Authors: Le Maout Yann , Cerulli Michele 
Published: October 2021

Abstract
The design process of lateral buckling has gained in maturity over the last ten years. However the design of any required engineered trigger to control the formation of lateral buckles remains open to a wide range of design concepts (like sleeper, buoyancy modules, snake lay or residual curvature method) with sometimes increasing complexity in either engineering, fabrication or installation.
This paper will describe how a lateral deflection initiated by a temporary subsea winch after pipelay can be used as a reliable mitigation with limited impact on the project execution.
The interaction between the winch pull and the pipe soil interaction and the consequences on both the post buckle behaviour and reliability design of the mitigation architecture will be presented. The advantages of this technique (decoupling of construction activities between pipelay and lateral buckling mitigation, standard engineering process, no offset from seabed, no additional permanent equipment) and its limitations (stiff pipeline, detailed pipe soil interaction) will be discussed.
The operational feedback from several flowlines designed, installed and operated with this winch pull mitigation will be reviewed and the main lessons learnt will be highlighted.
It can be concluded that this temporary subsea winch pull is an interesting and cost effective option for lateral buckling initiation of subsea pipelines.
Experimental Study of Hydraulic Sealability and Shear Bond Strength of Cementitious Barrier Materials
Authors: Kamali Mohammadreza , Khalifeh Mahmoud , Eid Elsayed , Saasen Arild 
Published: October 2021

Abstract
In this experimental study, two different cementitious materials including (i) a class of expansive cement that is currently used for P&A operations, and (ii) a non-cement-based naturally occurring rock, known as geopolymer are selected to examine the hydraulic bond strength and shear bond strength. Clean machined steel and rusty corroded steel were selected to represent the casing. The test samples were cured at 90 °C, which is considered as bottom-hole static temperature (BHST), and under elevated pressure of 17.2 MPa for one week.
The hydraulic sealability of the barrier materials tested up to 3.4 MPa of differential pressure. The results indicated that additives used in slurry preparation have an impact on the hydraulic sealability of the material. Additionally, the rusty corroded streel provided a better hydraulic sealability comparing to the clean machined steel for the same cementitious material.
The shear bond strength test was performed by running the push-out test. According to the present test observations, no correlation was found between the shear bond and hydraulic bond strength of different barrier materials. The geopolymer showed the lowest shear bond strength, while it provided the highest hydraulic sealability.
Possibility of Reducing Spar-Type FOWT Hydrodynamic Response Using a Torus Structure With Annular Flow
Authors: Murai Motohiko , Liu Xiaolei 
Published: October 2021

Abstract
Gyroscopic motion is considered as an appropriate approach to suppress the shaking motion of rigid bodies. Its spatial orientation is also used to make gyro compasses in the marine industry. In this paper, the floating offshore wind turbine (FOWT) was designed based on potential theory and gyroscopic effect and rotational axis retention effect were also considered, so that FOWT could obtain better hydrodynamic response. However, gyroscopic motion was generated through an annular flow in the internal torus instead of rigid body rotation. The scale of torus and the angular velocity of the annular flow were the design parameters that this article was eager to understand obviously. By vast quantity of calculations, the suitable range of design parameters was obtained.
Comparative Study of Drilling Riser Running/Retrieving Analysis Methodologies
Authors: Vale Leandro , Gallagher Conor , Souza Marcelo , Carneiro Daniel 
Published: October 2021

Abstract
Drilling risers are key components in offshore oil exploration and are present in most of the well construction phases (drilling, casing, cementing and completion). Mobile offshore drilling units can operate in different sites exposed to a range of environmental loadings and water depths. Global riser analyses based on the FE (finite element) method are performed to assess the system feasibility and operating envelopes. In harsh environment and ultradeep water scenarios, the riser running/retrieving operation is one of the most critical due to top-angle limits and riser stress as a result of either contact with the inside of the diverter housing/substructures or loading at the gimbal-spider (API-RP-16Q [1], ISO 13624-1 [2]).
The use of beam-column elements is satisfactory for modelling the riser global response, however it may lead to result uncertainty in terms of local response associated with complex geometry, over-stress, stress concentration and contact modelling (DNV-ST-F201 [3], DNVGL-RP-F203 [4], ISO 13628-7 [5]). The objective of this paper is to compare riser analysis results from a global and a local FE analysis. This comparison is used to identify any limitations associated with the use of a global riser analysis approach for determining structural limits for the riser during deployment/retrieving operations. Several recommendations are also provided regarding the use of the global analysis approach.
System Uncertainty Effects on the Wave Frequency Response Of Floating Vessels Based on Polynomial Chaos Expansion
Authors: Radhakrishnan Gowtham , Han Xu , Sævik Svein , Gao Zhen , Leira Bernt Johan 
Published: October 2021

Abstract
From a mathematical viewpoint, the frequency domain analysis of vessel motion responses due to wave actions incorporates the integration of system dynamics idealized in terms of response amplitude operators (RAOs) for 6 DOF rigid body motions and an input wave spectrum to yield the response spectrum. Various quantities of interest can be deduced from the response spectrum and further used for decision support in marine operations, extreme value and fatigue analysis. The variation of such quantities, owing to the uncertainties associated with the vessel system parameters, can be quantified by performing uncertainty propagation (UP) and consequent sensitivity analysis (SA). This study, emphasizes and proposes a computational-efficient way of assessing the sensitivity of the system model output with respect to the uncertainties residing in the input parameters by operating on a surrogate model representation. In this respect, the global sensitivity analysis is effectively carried out by deploying an efficient non-intrusive polynomial chaos expansion (PCE) surrogate model built using a point collocation strategy. Successively, the coherent and effective Sobol’ indices are obtained from the analytical decomposition of the polynomial coefficients. The indices, eventually, are employed to quantitatively gauge the effects of input uncertainties on the output 6 DOF vessel responses.