bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds in Tapered Stress Joints
Authors: Rombado Gabriel , Baker David A. , Haldorsen Lars M. , Craidy Pedro , Feiger Jim H. , Hudak Stephen J. 
Published: November 2019

Abstract
Design of steel catenary risers (SCRs) requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is imperative, especially in those applications involving high pressure and temperature fluids. One option for connection hardware is the metallic tapered stress joint. Because of its inherent density, strength and stiffness, steel is not well suited for these applications as it would result it excessive length and weight for deepwater applications. Titanium grade 29 (Ti 29) has been identified as an attractive material candidate for demanding stress joint applications due to its unique mechanical properties including greater flexibility, excellent fatigue performance, and high resistance to sour fluids. Industry has successfully used this technology in over 60 SCR applications.
Titanium stress joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot/billet volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. Fracture and fatigue performance of these welds in the presence of cathodic potential in seawater and galvanic potentials in sour production fluids that may produce hydrogen embrittlement effects must be assessed to ensure long term weld integrity. This paper describes a joint industry project (JIP) performed to qualify titanium stress joints welds for ultra-deep water applications under harsh service and environmental conditions. Fatigue crack growth rate (FCGR) results for Ti 29 1G/PA gas tungsten arc welding (GTAW) specimens in air, seawater under cathodic potential and sour brine environments under galvanic potentials are presented and compared to vendor recommended design curves.
Experimental Study on Bubble Size Measurement for Development of Seafloor Massive Sulfides
Authors: Imai Seira , Nakajima Yasuharu , Murai Motohiko 
Published: November 2019

Abstract
Seafloor Massive Sulfides have been expected to be future mineral resources. To promote the development of Seafloor Massive Sulfides, Seafloor Mineral Processing, a method of extracting valuable minerals from the ores on deep seafloor using flotation to reduce the lifting cost of ores from the seafloor to the sea surface, was proposed. To apply flotation for the seafloor mineral processing, a measurement method of bubble size applicable to deep-sea conditions has been desired because it is necessary to generate fine air bubbles suitable to flotation under pressure conditions on deep seafloor. Then, the authors have studied on bubble size measurement by image analysis, which is expected to be applicable to deep-sea conditions. At the first phase of this study, photographic conditions suitable to image analysis of air bubbles were distinguished. Air bubbles were generated by using a porous nozzle at some air flow rates in a bubble column with a rectangular cross-section. Video images of air bubbles were taken by using both high-speed camera and video camera with a low frame rate. Bubble size was measured by binarizing the video images of bubbles. Under optimal photographic conditions, bubble size was obtained from not only the high-speed camera but also the video camera; and both size data agreed relatively well, which implies that bubble size measurement by using image analysis would be applicable to deep-sea conditions. At the second phase, experiments were carried out under high-pressure conditions up to 2.4 MPa. Single bubble generation by using a capillary nozzle in a small pressure chamber with a sight glass was observed by using a digital microscope. Bubble size measurement by image analysis was carried out by the procedure established at the first phase. While the process of bubble generation at the high pressures was similar to that at the atmospheric pressure, the bubble size was decreased as the pressure rose. The result implies there is a strong correlation between the pressure and the bubble size.
Numerical Simulation and Analysis of Phase Focused Breaking and Non-Breaking Wave Impact on Fixed Offshore Platform Deck
Authors: Moideen Rameeza , Behera Manasa Ranjan , Kamath Arun , Bihs Hans 
Published: November 2019

Abstract
Extreme wave impact due to tsunamis and storm surge create large wave heights causing destruction to coastal and offshore structures. These extreme waves are represented by focused waves in the present study and the impact on offshore deck is studied. Numerical wave tank used is modelled using open-source software REE3D, where the level set method is used to capture the air-water interface. Vertical impact force on offshore deck is computed and compared with the experimental results to validate the numerical model. Focused wave is generated by phase focusing a group of waves at a particular position and time. The nonlinearity of focused wave and its effect on the vertical impact force is quantified for different airgap and increasing wave heights. The steepness of this focused wave is increased to initiate phase focused breaking in the numerical wave tank, which is validated with experimental results of Ghadirian et al., 2016. The main purpose of this paper is to examine breaking focused wave group loads on the offshore deck and to study the impact on deck at different breaking locations. The positioning of the deck with respect to breaker location have shown that the maximum horizontal impact force due to breaking wave occurs when the plunging crest hits the deck side.
Model Experiments of Floating Side-by-Side Barges
Authors: Chua Kie Hian , de Mello Pedro Cardozo , Nishimoto Kazuo , Choo Yoo Sang 
Published: November 2019

Abstract
The interaction between two floating vessels has been a subject of much study in recent years due to its relevance to floating liquefied natural gas (FLNG) developments. The safety and operability of these facilities are directly influenced by the wave elevation in the gap between the two vessels as well as the relative motions between the vessels. In the industry, it is common practice to use potential flow models to calculate free-surface responses under various wave conditions. Given that these numerical models are inviscid, calibration of additional damping terms are usually carried out using model tests to in order to account for the viscous dissipation on the gap hydrodynamics. However, it is known that the dissipative effects of viscosity may be nonlinear and thus, model test data obtained using one set of wave conditions may not be suitable for use in another scenario. In this paper, model experiments of two identical side-by-side barges of 280m (length) × 46m (breadth) × 16.5m (draught) under various wave excitation are described. The experiments considered a range of parameters such as gap width, wave heights, periods and wave directions. The results obtained for each set of these parameters are discussed and compared between the two types of incident waves (regular and irregular).
Experimental Study of the Effect of the Pontoon Presence on the Flow-Induced Motion of a Semi-Submersible Platform With Four Square Columns
Authors: Gonçalves Rodolfo T. , Suzuki Hideyuki , Cenci Fredi , Fujarra André L. C. , Hirabayashi Shinichiro 
Published: November 2019

Abstract
The Flow-Induced Motions (FIM) is an essential topic on multi-column platforms due to the effect on the mooring line fatigue life. Vortex-Induced Motions (VIM) or galloping behavior can be observed for an array of four columns with square sections. The presence of pontoons showed to be important for changing the flow around the array and promote different amplitude behavior of the motions in the transverse direction mainly. This article aims to understand the effect of the presence of two pontoons on the FIM of a semi-submersible platform (SS) with four columns and square sections. Model tests of a floating system supported elastically utilizing four springs were performed in a towing tank. Five different pontoon ratios were tested, namely P/L = 0, 0.25, 0.50, 0.75 and 1.00; where P is the pontoon height, and L is the length of the square column face. The draft condition was kept constant as H/L = 1.5; where H is the draft of the platform. The spacing ratio of the columns was S/L = 4; where S is the distance between column centers. Three incidence angles of the current were carried out, i.e., 0-deg incidence represents the condition in which the two pontoons are aligned to the current, 45-deg incidence represents the non-symmetric condition in which the pontoons are 45 degrees positioned to the current, and 90-deg incidence represents the condition in which the two pontoons are perpendicular to the current. The transverse amplitudes decreased with increasing the pontoon ratio for 0 and 45-deg incidences. On the other hand, the transverse amplitudes increased with increasing the pontoon ratio for 90-deg incidence. The pontoon presence needs to be well investigated to choose the best condition to avoid raising the FIM.
Study on Pipe Wear Evaluation Based on Large Scale Experiment for Deep Sea Mining
Authors: Takano Satoru , Sato Hirotaka , Terao Takashi , Masanobu Sotaro , Kawano Seiya 
Published: November 2019

Abstract
Japan Oil, Gas and Metals National Corporation (JOGMEC) has been conducting R&D of production system for Seafloor Massive Sulfides (SMS) mining. In order to reach commercialization stage in SMS development, the pipe wear due to slurry flow is one of many technical issues to be solved.
In the present paper, the authors conducted the large scale experiment using full scale pipes to obtain the various data on pipe wear, and investigated the pipe wear amount in commercial operation. In the experiment, SUS 304 and UHPE were used for the inner materials of test pieces. In addition, the test pieces were installed in the vertical, horizontal and inclined section. Then the authors estimated the thickness reduction of pipe due to slurry flow based on the experimental results.
Magnetoelastic Characteristics of Pipeline Steel Under Tensile Stress
Authors: Bao Sheng , Jin Pengfei , Mustapha Ashri , Zhao Zhengye 
Published: November 2019

Abstract
This research is to investigate the stress-induced magnetic fields surrounding initially undemagnetized pipeline steel specimen. A series of tensile tests were carried out. The variations of magnetic fields at different positions of the specimen were measured. Analysis of the results indicates that the specimen tends to be magnetized as a magnet with a N pole and S pole at two ends with the increase of load. The possible reasons underlying the experimental results are discussed on the basis of the theory of the interaction between dislocation and domain.
Submerged Production Unit: Design and Method for Launch and Tow to Field
Authors: Arumugam Elumalai Venkatesan , Daasvatn Sigbjørn , Karunakaran Daniel , Larsen Kjell , Leira Bernt Johan 
Published: November 2019

Abstract
The requirement for fossil fuels expedites for an advancement in the existing subsea technology. The developments evolved as the search for hydrocarbons moved from onshore to offshore, followed by a transition from shallow to deep and ultra-deep waters. Another huge milestone was achieved, when production systems made a transition from topsides to subsea units for efficiency. Currently, there is an enormous drive to minimize the operational costs involved in the processing of hydro-carbons. Researches are underway towards what would be yet another significant feat in the oil and gas industry, which is by moving the processing systems to subsea. One such impressive concept, which is being developed, is the Submerged Production Unit (SPU). This study is an initial attempt to investigate the challenges associated with the SPU focusing on the factors influencing design, launching and towing. A design concept that goes back and forth from performance and design spaces was used in modelling the SPU, solving the complexity that revolved around assembling the hollow Glass Reinforced Plastic (GRP) beams with subsea buoyancy materials. Submerged Tow Method (STM), an adaptation of Controlled Depth Tow Method (CDTM) was used instead of the conventional way of lifting the equipment using cranes of heavy lift vessels or construction vessels on site during deployment considering cost and safety. OrcaFlex software was used for towing analysis. End force in global X direction on towline, obtained from static analysis was used to identify the Bollard Pull (BP) required for towing the SPU. Dynamic analysis was performed for different environmental conditions to identify the maximum effective tension on the towline. BP requirement of 100t was estimated from the towing analysis. This study was carried out by author as a master’s thesis [1].
Sensitivity Analysis of a Bottom Fixed Offshore Wind Turbine Using the Environmental Contour Method
Authors: Barreto David , Moghtadaei Abdolmajid , Karimirad Madjid , Ortega Arturo 
Published: November 2019

Abstract
In the field of stochastic dynamics of marine structures, environmental conditions play a vital role. Considering wind and waves as random processes, determining the environmental parameters which correspond to an annual exceedance probability for a certain structural concept is of vital importance for the respective assessment of the loads and their effects. The accuracy in predicting the conditions, especially those corresponding to the sea, is of a great relevance when a probabilistic design is performed in order to ensure the structural integrity of an offshore wind turbine. In particular, models are not always completely perfect and accurate data is not always available. The Environmental Contour Method (ECM), which is based on the IFORM methodology, is one of the most popular methods in the offshore industry when determining the environmental conditions, for a given annual exceedance probability, is required. The ECM allows analysing proper sea states for operational and extreme conditions with lower computational efforts than the most accurate method (Full Long-Term Analysis). In the present study, effects of progressive variations (uncertainties) of the sea states parameters (i.e. significant wave height, spectral peak period) on the dynamic response of a Monopile Wind Turbine (NREL 5MW) are analysed. Two operative conditions are considered: rated wind and cut-out wind speed. In each case, the 50-year environmental contour (EC) is plotted for a site located in the North Sea. Some sea states are selected from the EC (base cases) and then derived cases with percentage variations are generated. All the cases are simulated in FAST (NREL) and the standard deviations of the time series are compared with its respective values of base cases. The results for the dynamic responses at mudline (e.g. overturning moments and shear forces) are presented as the most important parameters governing the design of the monopile. In this analysis, the wave height shows more influence on the response variation percentage than the peak period. This work shows the importance of accurately setting up the input parameters and their impact on the calculation of the dynamic responses.
Experimental Evaluation of Wave Impact Loads on Semi-Submersible Structure According to Trim Angle
Authors: Seo Min-Guk , Ha Yoon-Jin , Kim Nam-Woo , Nam Bo Woo , Lee Kang-Su 
Published: November 2019

Abstract
This study considers the wave impact loads on the semi-submersible structure. To evaluate wave impact loads on the semi-submersible structure, a series of experiments are conducted in a 2D wave flume. In the experimental test, the semi-submersible half model is used, and 11 uniaxial force sensors are installed in deck side, column side, and deck bottom. Wave probes are, also, attached in the test model to measure the relative wave elevation. To generate horizontal and bottom wave impact on the test model, focusing wave is applied. The test model is fixed without any motion during each test, while the trim angle of the test model is changed to examine the effect of trim angle on wave impact load. Through this, the characteristics of the wave impact force at each position were investigated.
Introduction of Virtual Structural Boundary for Collision Force Analysis of Tsunami Drifting Objects in Particle Method
Authors: Aida Yasuhiro , Masuda Koichi , Ikoma Tomoki , Eto Hiroaki 
Published: November 2019

Abstract
One of the reasonable methods to analyze the collision force of a tsunami drifting object against a structure is a particle method. However, when both the structure and the drifting body are composed of particles, there are various problems such as particles of the collision object slipping through particles of the structure. Therefore, the authors have constructed a particle method - analytical solution hybrid method which can analyze the collision force of a tsunami drifting object to an elastic member by constructing a structure as a boundary condition acting on a drifting object. However, since this boundary was introduced as a virtual boundary that acts only on drifting particles, the collision force of the tsunami drifting object to the structure can be analyzed, but the fluid force can’t be analyzed. Therefore, in this study, in addition to the boundary condition as the structure, we further reconstructed the collision force and the fluid force as a method that can analyze the collision force and the fluid force simultaneously by setting the mirror particle boundary condition for the fluid particle. By developing this method, it became possible to calculate the collision force in a situation where a stagnation point occurs like a flow field at the front of the wall type structure, and the drifting object is decelerating.
RANS Based Calm Water Resistance Prediction for Tumblehome Hull With Different Bow Appendages
Authors: Sun Shuzheng , Zhao Xin 
Published: November 2019

Abstract
The calm water resistance of the models a bare tumblehome hull and with 3 different bow appendages (triangle fins, rectangular foil, and semi-submerged body) are predicted based on RANS and k-ε turbulence model using STAR CCM+ software. VOF method is used for the 2-phases simulation. The resistance calculation results of the bare hull are validated against model test data. The verification and convergence studies are carried out on the grid size and time step. The validation studies show that the relative changes of the resistance calculation results compared with the model test data for Fr = 0.294 are 5–6%. The results of resistance prediction for the hulls with 3 bow appendages show that the bow fin configuration shows the best performance at Fr = 0.220, and the semi-submerged body configuration shows the best performance at Fr = 0.367. The details of flow field of different hulls will be analysed in this paper.
Spring-Dashpot Simulations of Polyester Ropes: Validation of the Syrope Model
Authors: Falkenberg Erik , Yang Limin , Åhjem Vidar 
Published: November 2019

Abstract
The way polyester ropes change their length in response to tension is often represented using a static-dynamic model with parameters for dual linear stiffness, based on testing according to defined procedures. This may not be sufficient for the mooring analysis since the stretch response to tension of fiber ropes is nonlinear. In the Syrope Joint Industry Project, a model to be used in mooring analyses was developed together with a test procedure to obtain the parameters for this model. Based on these parameters and experience from the testing, an equivalent non-linear spring-dashpot model was developed. This model can predict the response in the rope also for other test procedures than those used for establishing the parameters in the analysis model. This demonstrates the validity of this Syrope analysis model.
Integrity Assessment of Subsea Pipeline Dent / Buckle Using ILI Data
Authors: Kagita Gurumurthy , Achary Gudimella G. S. , Addala Mahesh B. , Srinivasan Balaji , Pottem Penchala S. K. , Gupta Deepak , Sripada Subramanyam V. R. 
Published: November 2019

Abstract
Mechanical damage in subsea pipelines in the form of local dents / buckles due to excessive bending deformation may severely threaten their structural integrity. A dent / buckle has two significant effects on the pipeline integrity. Notably, residual stresses are set up as result of the plastic deformation and stress concentrations are created due to change in pipe geometry caused by the denting / buckling process. To assess the criticality of a dent / buckle, which often can be associated with strain induced flaws in the highly deformed metal, integrity assessment is required. The objective of this paper is to evaluate the severity of dent / buckle in a 48” subsea pipeline and to make the rerate, repair or replacement decision. This paper presents a Level 3 integrity assessment of a subsea pipeline dent / buckle with metal loss, reported in in-line inspection (ILI), in accordance with Fitness-For-Service Standard API 579-1/ASME FFS-1. In this paper, the deformation process that caused the damage (i.e. dent / buckle) with metal loss is numerically simulated using ILI data in order to determine the magnitude of permanent plastic strain developed and to evaluate the protection against potential failure modes. For numerical simulation, elastic-plastic finite element analyses (FEA) are performed considering the material as well as geometric non-linearity using general purpose finite element software ABAQUS/CAE 2017. Based on the numerical simulation results, the integrity assessment of dented / buckled subsea pipeline segment with metal loss has been performed to assess the fitness-for-service at the operating loads.