bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Evaluation on Lateral Impact Resistance of Thermoplastic Composite Pipes in Terms of Internal Pressure Capacity
Authors: Wang J. , Shi C. , Fu G. , Liu Z. , Bao X. , Li H. 
Published: December 2020

Abstract
Subsea pipelines are prone to be damaged by the falling objects from ships or offshore platforms, which may result in economic losses and pollution. The dimensions of dent were commonly used to evaluate the impact resistance of pipes made from carbon steel. Thermoplastic composite pipes (TCPs), due to their superior properties including corrosion resistance, thermal insulation, fast installation, etc., are increasingly used as the subsea pipelines. The TCP is made from thermoplastic resins and reinforced by continuous fibers. Because of the brittle nature of carbon fibers and glass fibers, the dimensions of dent are not suitable for assessment of impact resistance of a TCP. In the present work, a procedure was proposed using the internal pressure capacity as an indicator to evaluate the lateral impact resistance of a TCP. First, the internal pressure capacity of an intact TCP was evaluated. Second, a quasi-static simulation was conducted by applying a lateral compression force on the intact TCP using a rigid ball, until one of the composite plies in the reinforcement layer failed. The quasi-static simulation provided an initial estimate of the minimum energy that causes the start of damage of the TCP. Third, the impact simulations were performed by using a rigid ball hitting the TCP and, then, the internal pressure capacity of the damaged TCP was evaluated. Finally, the internal pressure capacity of the damaged pipe, compared with that of the intact pipe, was used as an indicator to evaluate the lateral impact resistance of the TCP. In this study, a glass-fiber reinforced polyethylene (PE) pipe of an inner diameter of 150 mm was modeled by ABAQUS to illustrate the procedure. A theoretical method was proposed to calculate the impact energy of a dropped object in a shallow water. The example studied in the present work showed that the modeled TCP was not strong enough to survive the lateral impact caused by the dropped object and should be buried to a certain depth beneath the seabed if used as a subsea pipeline.
Software Application Based on Subsea Engineering Design Codes
Authors: Gullaksen Joannes 
Published: December 2020

Abstract
Development of software application for subsea engineering design and analysis is to a large extent based on codes and standards used in the offshore industry when considering subsea pipelines. In this paper a software is described which main purpose is to facilitate the design and analysis process and such that results and documentation are automatically generated to increase quality of documentation. Current scope is a standard calculation tool covering different aspects of design in compliance with relevant offshore codes. A modularization technique is used to divide the software system into multiple discrete and independent modules based on offshore codes, which are capable of carrying out task(s) independently. All modules in range operate from a project model that is accessed directly by other modules for analysis and performance prediction and allows design changes to flow through automatically to facilitate smooth communication and coordination between different design activities. All the modules have a number of common design features. The quality of an implementation of each offshore code in independent software modules is measured by defining the level of inter-dependability among modules and their interaction among them, and by defining the degree of intra-dependability within elements of a module. This modularization technique also includes other benefits, such as ease of maintenance and updates. The improvements are related to the objectives of a state-of-the-art procedure of performing engineering, design and analysis by use of offshore codes implemented in a software application. The application is developed in .NET C# language with MS Visual Studio Technology that provides a powerful graphical user interface well integrated in windows environment.
Integrity Management for Steel Catenary Risers With Design Life of 30 Years
Authors: Song Hao , Yu Chenteh Alan , Cheng Yongming , Hou Jing 
Published: December 2020

Abstract
The riser is a critical element in a subsea production system for transporting hydrocarbons from the seafloor to the surface. The track record of existing riser systems worldwide has shown that risers tend to be designed conservatively to accommodate dynamic loads, strength and fatigue requirements, and corrosion/erosion provision needs. Among all the riser types, the steel catenary riser (SCR) is the most installed riser configuration for deepwater oil and gas production worldwide in the last two decades. This is mainly because of their simple configuration and relatively low manufacturing and installation cost.
As riser technology advances, SCRs are designed to tackle more challenging environments and longer service lives. For the riser life extension applications, regulatory bodies prefer riser operations to be managed through an integrity management program, demonstrating that a robust framework with detailed records on the conditions of the risers is in place. This paper studies an integrity management program for SCRs with a 30-year design life in a harsh environment.
The planned riser integrity management program is based on successful industry practice and the newly published riser integrity management standard API RP 2RIM [4]. It starts with a review of the riser design basis and as-built data, continuing with key field data measurement and production fluid sampling. A digital model, continuously calibrated with the measured data, is established to assess the integrity of the riser system.
Key physical quantities are selected to monitor the structural health of the SCRs, including vessel motion measurement, measurement of SCR top hang-off angles and tensions, and full water column current measurement. The relationship between the measurement data and the riser strength and fatigue performance is established. Details of the riser integrity assessment in a digital model utilizing the measurement data are presented. The implemented proposed riser integrity management program is expected to provide a more focused and efficient method with a higher level of confidence in operating the SCRs during the design life and potentially beyond.
Fatigue Performance of Thick Section Titanium Grade 29 Girth Welds
Authors: Rombado Gabriel , Baker David A. , Haldorsen Lars M. , Macdonald Kenneth , Walker Heath , Caldwell Chris , He Binyan , Johnston Carol 
Published: December 2020

Abstract
Design of Steel Catenary Risers (SCRs) requires the use of specialized connection hardware to mitigate the high dynamic bending moments at the hang-off location induced by host floater motion. Reliability of this connection hardware is imperative, especially in those applications involving high tension loads, high pressure and elevated fluid temperature. One option for connection hardware is a monolithic, metallic tapered stress joint. Because of its inherent density, strength, and stiffness properties, steel is not well suited for these applications due to excessive stress joint length and weight requirements. Titanium Grade 29 has been identified as an attractive material candidate for demanding service applications due to its unique mechanical properties including increased flexibility, excellent fatigue performance and corrosion resistance to sour fluids. This technology is well established in the offshore industry and utilized in over 60 SCR installations with operating lives exceeding 20 years of continuous subsea operation.
Large titanium stress joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot volume limitations thus making one or more intermediate girth weld(s) necessary to satisfy the overall length requirements. Fatigue testing of 38 mm (1.5-in) wall thickness girth welds, utilizing an optimized GTAW welding procedure to limit defect sizes to sub-millimeter, has previously been performed in seawater (OD exposure) under cathodic protection potentials and sour service (ID exposure) under galvanic potentials. Fatigue testing results fully verified the vendor S-N fatigue design curve, in addition, no appreciable differences in fatigue performance in environments were observed allowing project-specific testing to be limited to in-air testing.
This paper presents in-air fatigue testing results of 51 mm (2.0-in) wall thickness Grade 29 girth welds, using the same optimized welding procedure, to assess thickness size effect on the vendor S-N fatigue design curve. Verification of the vendor fatigue design curve was demonstrated by testing curved dog-bone specimens, extracted longitudinally across the girth weld, with production level surface finishes on inner and outer surfaces in-air up to a predefined S-N fatigue target curve with 95% confidence level.
Using Isotropic and Anisotropic Models to Determine Solar Module Tilt to Maximize Incident Energy and PV Electricity Output on the Alaska North Slope
Authors: Wurthmann Kurt 
Published: December 2020

Abstract
The Alaska North Slope is a pristine and fragile arctic environment that needs protection. The present article illustrates the application of isotropic and anisotropic models for predicting solar radiation on photovoltaic (PV) modules (and, hence, potential electricity output) for different angles of inclination (or tilt) in Utqiagvik Alaska. The anisotropic model is shown to provide higher, albeit more accurate, predictions of solar radiation since it includes all of the measures used in the isotropic model, but provides a more comprehensive representation of the diffuse component. Specifically, the anisotropic model includes not only the isotropic part of diffuse radiation, but also the circumsolar and horizon brightening parts. A PV array angle of tilt of 55 degrees is shown to provide the greatest total amount of incident solar radiation for the entire year, based on both the isotropic and anisotropic models. However, both models also indicate that angles of tilt that are steeper than 55 degrees result in slightly greater amounts of incident solar radiation during the late-winter, early-spring, and mid-fall months; while angles of tilt that are flatter than 55 degrees result in slightly greater amounts of incident solar radiation during the summer and early-fall months. It is shown that a PV system with a moderately sized array, tilted at the fixed angle of 55 degrees, could provide more than 50 percent of the total annual electricity needs for homes in Utqiagvik Alaska.
Investigation of a Novel Wave Energy Generator Using Dielectric Elastomer
Authors: Jiang Changqing , Chiba Seiki , Waki Mikio , Fujita Koji , el Moctar Ould 
Published: December 2020

Abstract
The type of electroactive polymer, known as dielectric elastomers, has shown considerable promise for harvesting energy from environmental sources such as ocean waves, wind, and human motions, etc. The high energy density and conversion efficiency of dielectric elastomers (DEs) can allow for very simple and robust “direct drive” generators. In such generators, a DE transducer is directly driven by the up and down motions of waves. These generators can be simple, low-cost and robust. The efficiency of a wave energy convertor using DEs was confirmed by our previous experimental work.
In this study, a wave energy convertor using DEs was numerically investigated as a moored floating body. First, the numerical model is validated against existing benchmark experiments. Then the moored floating body is numerically modelled, and the simulated results are compared to physical wave tank tests. The analyzed conditions vary from single body, two bodies with different intervals, and three bodies. The fluctuation, energy absorption efficiency, as well as the influence of multiple moored floating bodies on each other are discussed. The purpose of present work is to clarify the influence of floating body intervals and number of floating bodies on the motions, the mooring tensions, as well as the power generation efficiencies for a plurality of floating bodies arranged in a series in head seas. This kind of optimal arrangement is expected to be popularized in the future, which may contribute to the increasing demand of renewable energy solutions.
Numerical Analysis of a Floating Fish Cage With Feeding Systems
Authors: Li Lin , Bruset Mathias , Ong Muk Chen , Wu Xiaopeng 
Published: December 2020

Abstract
A modern marine-based fish farm normally consists of a feeding barge, several fish cages, and feeding tubes. Although many studies, both experimental and numerical, are available in the literature to investigate the global responses of the fish cages under wave and current conditions, research on the coupled system including both the fish cage and the feeding system is very limited. This paper presents a numerical study on the coupled system with a floating fish cage and the feeding system. The purpose is to study the dynamic responses of the coupled system under different environmental conditions and configurations of the fish farm. A numerical model is firstly established in the numerical program OrcaFlex, comprising of a feeding barge, a gravity-based floating fish cage with mooring systems, and a feeding tube between the barge and the cage. Time-domain simulations of this coupled system are then performed under environmental conditions corresponding to 1-year and 50-year return periods for a reference site. The deformation of the fish cage, the tensions in the anchor lines and in the feeding tube are compared under various conditions. Sensitivity studies on the solidity ratio of the fish net as well as the lengths of the feeding tube are addressed, and their influences on the responses of the coupled system are also discussed.
Model Updating of Soil-Structure Interface of Monopiled Offshore Wind Turbines
Authors: Cong Shuai , Hu Sau-Lon James , Li Hua-Jun 
Published: December 2020

Abstract
As the vibration analysis of an offshore wind turbine (OWT) system should consider its soil-structure interaction, a recent article proposed a simple soil-structure interface model. It includes a horizontal spring, a rotational spring and a rotational dash-pot at the interface. Developing a finite element model updating method on correcting the soil-structure interface coefficients based on the true response measurements is highly desired. This paper develops an accurate and efficient model updating method for simultaneously updating the stiffness and damping parameters of the soil-structure interface of a monopiled offshore wind turbine, when only a few measured modal frequencies and damping ratios are available. The performance of the proposed method is numerically demonstrated through a simulated National Renewable Energy Laboratory 5-MW (NREL 5-MW) reference turbine.
Coupled Dynamic Analyses of Deep-Water Semi-Submersible With New Spread Mooring System
Authors: Chandrasekaran S. , Jain Arvind Kumar , Uddin Syed Azeem 
Published: December 2020

Abstract
Offshore complaint structures dominate the deepwater oil exploration and production due to their adaptive geometric form and well-established construction practices. Semi-submersible is one of the widely preferred, floating production systems due to its form-dominant ability, better stability characteristics, and best constructional features. It is usually position-restrained using a dynamic-positioning system (active-restraining) or mooring system (passive-restraining); being less-sensitive to freak ocean environment is an added advantage. The Semi-submersible, chosen for the present study is based on a similar configuration of a 6th generation deep-water Hai Yang Shi You (HYSY) – 981 platforms, commissioned by the China National Offshore Oil Corporation (CNOOC) in 2012. A sixteen-point, spread catenary-mooring without submerged buoy (case-1) in the form of chain-wire-chain type configuration is used for position-restraining. Response behavior of the semi-submersible with a conventional spread catenary-mooring system with a submerged buoy (case-2) is compared. API spectrum is used for computing wind loads, while the JONSWAP spectrum is used to represent irregular waves for various directions of wave heading. The effect of non-linearly varying current is considered up to 10% of water depth. Numerical analyses of the semi-submersible are carried out under 10-years, and 100-years return period events using Ansys Aqwa. Under wind, wave, and current loads, motion responses of the Semi-submersible at 1500 m and 2000 m water depths are investigated for both the cases in time-domain. Dynamic mooring tension variations arise from the environmental loads are further investigated for a fatigue failure using the S-N curve approach. It is found that the fatigue life of the mooring lines after the inclusion of the buoy is enhanced. It was also observed that, during failure of mooring lines there is an increase in tension of the mooring lines which are adjacent to the failed mooring lines and this is due to the transfer of mooring load and hence reducing their fatigue life.
Cavitation Performance of Low Speed Ice-Classed Propeller
Authors: Wan Churui , Liu Zhenghao 
Published: December 2020

Abstract
In the ice breaking condition, on account of the low speed and heavy propeller load, the ship resistance is large, which will aggravate the propeller cavitation and the propeller-induced pressure. In this paper, the cavitation performance of the ice-classed propeller is analyzed by numerical simulation and model experiment. Commercial CFD software was used for the numerical simulations, in which the cavitation flow is solved by Schneer & Sauer cavitaiton model based on a single-fluid multiphase mixture flow approach. Model tests to measure cavitation flow on an ice-classed propeller were carried out in SSSRI K15 Cavitation Tunnel. The size of the test section of SSSRI K15 Cavitation Tunnel is 600mm*600mm. The propeller performances in uniform flow over a range of advance coefficients were carried out in open water test in a towing tank. The diameter (D) of the model propeller was 248mm in this research. Firstly, the open water performance of propeller is numerically studied. Near the design conditions, the numerical results are almost consistent with the test results, with an error of less than 1%. In the case of ice breaking, the blocking effect of ice in front of a propeller is studied. The experiment results show that with the ice block close to the propeller, one or more vortex tube structures are generated between the propeller blade and the ship bottom while the vortex cavitation occurs. Such phenomenon is also found between the propeller and the ice block. When the blocking effect is significant, the stable vortex tube structure will appear and significantly change the cavity shape near the blade. When the distance between the ice and the blade disc exceeds 0.72D, the vortex tube structure will disappear.
Reliability Analysis of FPSO Oil and Gas Processing System Based on Petri Net
Authors: Kang Jichuan , Geng Xinyuan , Sun Liping , Jin Peng 
Published: December 2020

Abstract
This paper aims to introduce a novel method in terms of risk analysis and control of FPSO oil and gas processing system. The Failure Mode and Effect Analysis (FMEA) is implemented to identify the critical equipment and typical failure modes, in order to improve the accuracy and pertinence of model establishment. A Petri Net model is then developed based on FMEA results and the correlation analysis between different components. The input reliability data are primarily collected from Offshore and Onshore Reliability Data (OREDA), and the maintenance information is assessed by industry experts, using fuzzy synthetic evaluation method. This paper focuses on the accuracy, rapidity and feasibility in the modeling and solution process, and considers the influence of weather factors on the maintenance operation and limited maintenance crew number, forming a complete set of reliability and maintenance strategy optimization analysis method of FPSO oil and gas processing system. The results contain system reliability, availability, and maintenance information. The proposed approach can reveal the risk feature of the system and provide corresponding risk control scheme.
Innovative Mooring in the Port of the Future: Scale Model Testing of the ShoreTension System
Authors: Reijmerink S. P. , Bruinsma N. , van der Hout A. J. , de Jong M. P. C. , Clement C. 
Published: December 2020

Abstract
Moored vessels often experience low-frequency vessel motions when moored in a port due to wave excitation. Under such conditions the loading and offloading of vessels may be hampered when these movements become too large [1,2,3]. Innovative mooring techniques can be used for reducing issues with excessive motions of moored vessels in waves [4,5,6]. Considering applying such techniques as part of the design of mooring facilities and ports is expected to make different approaches to port or mooring facility designs possible. Such techniques, like the ShoreTension (ST) system, are already applied successfully worldwide in ports [7,8,9], however the application and performance limits of such systems under extreme conditions are not well known.
This paper describes the results of a research project using physical scale modelling to systematically verify and extend the applicability and performance limits of innovative mooring systems. It resulted in a solid validation database for validating numerical models. The knowledge developed in this research will benefit developers of mooring facilities (including ports) to significantly reduce costs by limiting the need for structures providing shelter from waves. Furthermore, this may also help lowering the impact of port infrastructure on the coastal system when using less invasive infrastructure.
Rig-Assisted Snubbing: Drillpipe Pressure Control in MPD/UBD
Authors: Aasen Jan Aage , Svensson Joakim Haram 
Published: December 2020

Abstract
An important pressure control issue during live well work is the expulsion force acting on the drillpipe. Wellhead pressure multiplied by drillpipe sealing area in the blowout preventor must be overcome before entering the well. The highest snubbing force (compression) is applied when running the first joint into the well since pipe weight is at its lowest at this time. Focus of this paper is the mechanical analysis of the drillpipe as a well barrier element during live well entry. We look at normal operation (primary well barrier) and contingency (secondary well barrier). Load cases include critical unsupported buckling, helical buckling inside tubing guide, collapse and burst. In critical unsupported buckling there is no radial confinement of the pipe and the critical buckling limit is determined at the onset of lateral deflection. On the other hand, inside the tubing guide the pipe is allowed to buckle into a helix and the buckling limit is related to permanent corkscrewing of the pipe.
Technical contributions in this paper include engineering design formulas for unsupported buckling and helical buckling. Also presented are experimental buckling results from pipe up to 3½ inch (8.9 cm) diameter. Design calculations for primary and secondary well barriers are explained and analyzed using a field case. All load calculations are based on zero neutral axial stress as stress reference datum, which produces a yield circle that is conveniently deployed for three-dimensional well tubular design. The use of the dimensionless yield circle is found to be an efficient method to assess helical buckling loading and the combined effects of pressure and axial stresses.