bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D Printing Miniature Marine Structures Models for Structural Analysis Purpose: Is it Possible?
Authors: Calle Gonzales Miguel Angel , Kujala Pentti 
Published: November 2019

Abstract
In the last few years, additive manufacture techniques — also known as 3d printing — are gaining more applications in the maritime sector including the production of functional large ship components in compliance with demanded operational and quality standards. By contrast, 3d printing miniature models of marine structures with the aim to reproduce structural responses brings along a higher degree of complexity. On the one hand, miniature thin-walled structures entails different manufacturing challenges when compared with large-size ship components. On the other hand, modeling structural events that comprise extreme reduction scales (around 1:100), material deformation and fracture at high loading rates, among other aspects, require purpose-designed scaling laws to handle all these effects adequately. The aim of this work is to present a wide panorama in the development of miniature 3d printed marine structures aiming to model experimentally ship collision and grounding events in reduced scale. Some preliminary experimental tests in miniature marine structures are also presented.
On the Selection of an Appropriate Consolidation Coefficient for Offshore Geotechnical Design
Authors: White David , Chen Jinbo , Gourvenec Susan , O’Loughlin Conleth 
Published: November 2019

Abstract
This paper addresses the selection of an appropriate consolidation coefficient for the analysis of drainage beneath foundations and pipelines in offshore geotechnical design. An emerging trend in the design of subsea infrastructure is the consideration of ‘whole life’ effects — namely the changes in soil properties and geotechnical capacity over the operating life.
Seabed pipelines that undergo repeated thermal expansion and contraction cause shearing and consolidation in the underlying soil, leading to significant changes in the available seabed friction. Also, foundations that are either fixed or designed to slide on the seabed, are subjected to intermittent loads interspersed with periods of consolidation. These also cause a change in seabed strength and geotechnical capacity.
To assess the time over which these effects occur, and therefore their influence on the response and the reliability of the system, it is necessary to perform consolidation calculations, using an appropriate consolidation coefficient. This paper presents observed operative consolidation coefficients drawn from recent model testing measurements and numerical analyses. It is shown that the consolidation rate can vary by more than an order of magnitude for the same soil profile under different loading conditions, due to the differences in stiffness and permeability. Meanwhile, design parameters are commonly drawn from one-dimensional oedometer compression tests.
This compendium of data highlights the potential variation in consolidation coefficient for different loading types and through the ‘whole life’ of infrastructure. A key conclusion is that consolidation effects generally occur faster than is commonly assumed, meaning that changes in strength and stiffness — that are commonly beneficial in design — may be more readily relied on than is done so in current practice.
Life Extension of Deepwater Risers Used for a Spar Application in Gulf of Mexico
Authors: Cheng Yongming , Yu Chenteh Alan , Yang Guangqiang , Carballo Manuel R. 
Published: November 2019

Abstract
Deepwater development in Gulf of Mexico (GoM) started about two decades ago. It is the time to evaluate the global integrity of the offshore production unit and riser system and explore the possibility of life extension. This paper investigates life extension of deepwater risers used for a spar application in GoM.
A spar in GoM has been put into service for the past 17 years since it was installed in 2000. It was expected to extend the riser design life of 20 years by 10 more years. This paper first introduces the configuration of Steel Catenary Risers (SCRs) and Top Tensioned Risers (TTRs) used for the Spar platform. It then discusses the philosophy for life extension of deepwater risers by assessing the integrity of the riser system. Latest technology and monitored data are used for the assessment.
The TTRs and SCRs are modelled using latest analysis programs that were not readily available when the risers were designed. The interaction between the TTR and buoyancy can tensioning system is modelled as a pipe-in-pipe system that considers the function of centralizers with a gap size. The contact interaction between buoyancy can / stem and supporting guides of the hull platform is modelled as non-linear spring elements. The spring elements connect normally to the hull centerline and allow vertical sliding movement of the buoyancy can tension / stem system with friction. The base line inspections of the vessel, SCRs, and TTRs was carried out in the same inspection campaign with the spar hull structure. As-built information, production and operational data was also used for a continuous service assessment. Environmental condition data to the state of the art, including measured spar VIM data, was used in the assessment of VIM fatigue damage to the risers. The investigation was based on the up-to-date analytical tools including latest FEA program ABAQUS and VIV prediction Shear7. It further computes the riser global performance including dynamic strength and fatigue damage with the contributions from wave fatigue, VIV and VIM. This paper finally draws a conclusion for the life extension of the risers for the application in GoM.
Explosion Response of Cold Bond Corrosion Repairs Applied to Offshore Living Quarters
Authors: Turner Trey N. , Kumar Abhimanyu 
Published: November 2019

Abstract
Maintaining the integrity of an aging offshore facility often requires the repair of corrosion. With advances in adhesive technology, epoxy adhesives (cold bond repairs) are increasingly being adopted to repair corrosion damage on offshore structures. Structural elements, protection barriers, and occupied buildings, for example a platform living quarters, designated as safety critical often must comply with project or facility performance standards that specify minimum design accidental loading (e.g., from fire, explosions, or impact). In addition to satisfying conventional structural design criteria, a corrosion repaired structure must also perform within acceptable limits when subjected to accidental loads. The present study outlines approaches to assess the performance of cold bond repairs subjected to accidental explosion loads. The living quarters considered in this study featured approximately 50 individual cold bond repairs; each arbitrarily located over the building’s external surfaces. Under accidental blast conditions, failure of a cold bond repair was deemed unacceptable due to the threat of pressure leakage into the building’s interior. As such, the study demanded an analysis capable of considering both the global response of the living quarters as well as the local response of cold bond repairs. There have been several studies conducted by researchers around the globe to evaluate the response characteristics of adhesive bonds. However, these studies are largely focused on experimental, local, and micromechanical analysis of adhesively bonded materials. Numerical analysis of adhesive bonds, for purposes of global structural system response assessments, especially in the case of accidental loading, appear to be nonexistent in available literature. Inspired by this gap, we present a case study involving an assessment of global structural performance of a living quarters building repaired with cold bond adhesives subject to loading due to accidental and rare events. In this study, the local behavior of cold bond adhesives was calibrated using numerical simulations of the ASTM tests specified by the adhesive vendor. The calibrated properties were implemented in finite element analyses used to validate cold bond seal plate repairs at various locations on the living quarters building. The study includes a discussion about the methods and approaches used to model cold bond repairs in a practical and efficient manner. The approach outlined herein provides a useful framework that can be adapted to similar assessments by a practicing engineer responsible for blast analysis of marine structures.
Control Strategy for a Point-Absorber Wave Energy Converter
Authors: Li Qiao , Murai Motohiko 
Published: November 2019

Abstract
Linear driving wave energy converter (WEC) system need to control the electric generator to obtain more power generation. Electric power is consumed by control, but it is possible to control the natural period of the floating motion. By resonating the movement of the float part with wave, it is possible to obtain the power generation more than the control power consumption, the total power generation performance will be improved.
In this study, to ensure the WEC safety and performance for various wave condition, especially high wave height, the electrical control algorithms are changed for different wave condition. A control strategy is proposed for various wave condition considering the control force limitation and motion amplitude limitation. Basis on the control strategy, the range of operation by electric control is estimated. In addition, by estimating the expected value of power generation in the set sea, the setting parameters of the WEC can be discussed according to the wave situation.
Experimental Study on the Mechanics of a Coiled Tubing Working Within a Marine Riser Under the Affection of Marine Loads
Authors: Chen Yingchun , Wang Chang , Wang Xinhua , Wang Wenming , Wang Wenda 
Published: November 2019

Abstract
Due to its unique advantages, coiled tubing is now widely used in marine oil and gas exploitation operations, while the mechanical behavior of coiled tubing working within a marine riser affected by marine loads is still unknown. By building an indoor simulation experimental system, the mechanics of this pipe-in-pipe system was studied, and the effect of the lateral excitation on the axial force transmission of inner pipe was clarified. It was found that, when the external excitation frequency was within the first natural frequency range of the outer pipe, the external excitation would increase the axial load transfer efficiency of the inner pipe, and the axial force transfer efficiency of the inner tube would reach the maximum when the resonance of out pipe occurred. The results can be helpful on the understanding of mechanics of a coiled tubing working within a marine riser.
Material Design of Offshore Linepipe Steels for Ultra Deep Water Application
Authors: Yasuda Kyono , Shimamura Junji , Igi Satoshi , Muraoka Ryuji 
Published: November 2019

Abstract
Offshore pipeline projects have been expanded to deeper water region and the linepipes are required to have higher resistance against collapse by external pressure. The collapse resistance is mainly dominated by pipe geometry and compressive yield strength. For deep water application, diameter to thickness ratio (D/t) and pipe roundness are key factors. On the other hand, the mechanical properties in each circumferential position is dramatically changed by cyclic deformation through a pipe forming process. Therefore, in order to improve compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. The mechanism of this effect is understood that internal stress is generated by accumulation of dislocation and it reduces reverse flow stress. In this study, the microscopic deformation behavior was analyzed from FEM calculation, it was found that multi-phases microstructure enhanced the microscopic heterogeneous deformation adjacent to the boundary between soft and hard phases. Therefore, homogenized microstructure inhibits the Bauschinger effect. In addition, the materials of offshore pipeline should have other properties such as low temperature toughness and sour resistance. It is well known that fine grained microstructure improves the lower temperature toughness. For achieving high compressive yield strength and good lower temperature toughness, the effect of chemistry and rolling condition were investigated to obtain fine and homogeneous microstructure. Based on laboratory results, mill trial tests were carried out for Grade X65 linepipes with heavy gauge by TMCP. Full scale collapse test was also conducted after pipe coating heating. In this paper, material design concept and its mechanical properties of developed pipes were introduced.
Numerical Analysis of Tidal Turbine Performance for Floating Platform
Authors: Xing Xiuqing , Kang Chang Wei , Xu George , Lou Jing , Takagi Ken , Sinclair Jarrod 
Published: November 2019

Abstract
A three dimensional Computational Fluid Dynamics (CFD) model solving Reynolds-averaged Navier-Stokes (RANS) equations with k-ε turbulence model has been developed based on OpenFoam to investigate a tidal turbine performance. The CFD model is validated by comparing the simulation results with the performance characteristic data. Simulation results match the measured data with discrepancies less than 5.4%. The well validated model is then adopted to predict the turbine performance with a current heading angle of 30 degree. The simulated turbine power coefficient and flow field details from OpenFoam are compared with those obtained from commercial software ANSYS FLUENT for verification. The two simulated results match each other with a difference of only 3%. Simulated results indicate that the turbine power output drops significantly when the tidal turbine operates with a current heading angle of 30 degree. The performance loss due to a misalignment between the current and the turbine axis is analyzed with the aim to identify main causes and provide recommendations to tidal turbine operation.
Experimental Study of Wave Loading by Internal Solitary Waves on a Semi-Submersible Platform
Authors: Zhang Jingjing , Chen Ke , You Yunxiang , Zhang Xinshu 
Published: November 2019

Abstract
The experimental measurements presented here describe the major features of the loads exerted by internal solitary waves (ISWs) on columns and caissons of a semi-submersible platform in a two-layer fluid system. Particular attention is paid on the forces acted on the platform under different layer thickness ratio. By use of the dynamometer for forces of three degree of freedom (DOF), the wave forces exerted by the ISWs on the columns and caissons of the model are measured quantificationally, so the variations of forces with ISW’s amplitude and upper layer depth are derived. Comparisons are made between the experimental results and calculations based on the modified Morison equation and pressure integral method. The calculated results are well consistent with the measurements, so the method is capable of providing satisfactory predictions on the forces. Besides, the results show that the wave height has a considerable influence on the wave loads produced by the ISWs, and the forces varies with the different locations of the interface between the upper and lower layer.
CFD Study of Propeller Cavitation With Hull-Propeller Interaction
Authors: Kang Chang Wei , Xing Xiuqing 
Published: November 2019

Abstract
Propeller cavitation is the root cause for noise, hull vibration, as well as erosion on the propeller blades and appendages. Although it is a common practice for marine industry to predict the propeller cavitation by model tests, numerical simulation of propeller performance and the hull-propeller interaction has become feasible with the advancement of high performance computing. In this study, numerical studies of the flow field details around the ship hull with a rotating propeller are performed using Computational Fluid Dynamics (CFD) method by solving the unsteady Reynolds Averaged Navier-Stokes (RANS) equations. The numerical model is developed with commercial software package STAR-CCM+ for the cavitation prediction by considering the hull/propeller interactions and the free surface. Rotating propeller is modeled with an overset mesh, while κ-ω turbulence model is chosen instead of large eddy simulation (LES) or detached eddy simulation (DES) for higher computational efficiency while maintaining satisfied simulation accuracy. Cavitation bubble growth and collapse are estimated using Schnerr-Sauer cavitation model based on Rayleigh-Plesset equation. Simulation results suggest that the model developed in this study is capable to capture the flow field details under the effect of hull-propeller interactions and the free surface. This includes the cavitation emerging position, extinction position, as well as the cavitation patterns on the blade surface at various angular positions. The cavitation induced pressure oscillations on the hull at 1st to 3rd harmonics of Blade Passing Frequency (BPF) are also analyzed. The pressure fluctuation result can provide pressure load information for hull vibration evaluations in future.
Fatigue Evaluation of Drill Pipes for Scientific Drilling Program by Applying Non-Stop Driller Concept
Authors: Inoue Tomoya , Fujikubo Masahiko , Nakano Kenji , Sakurai Noriaki 
Published: November 2019

Abstract
The scientific drilling vessel Chikyu is performing Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), a challenging deep drilling activity, for scientific purpose. We faced difficulty to drill deep during past NanTroSEIZE operations due to unstable sediments and insufficient cutting removal. Non-Stop Driller concept is, therefore, applied for the operation of NanTroSEIZE scheduled to start Oct. 2018 to enable continuous circulation of drilling fluid circulation. The Non-Stop Driller concept requires an additional, specially-designed sub called an “NSD sub” with a ball valve for drilling fluid inlet.
Generally, the fatigue strength of a drill pipe is a critical factor governing the performance of challenging deep drilling. This study, therefore, focused on the fatigue failure of the NSD sub due to the bending stress caused by interference with risers including flex joints, ship structure, or drilling equipment resulting from ship motions. The bending stress leads to cyclic stress caused by rotation of the drill pipe. This is especially the case at the Nankai Trough where ocean currents are very strong reaching or sometimes exceeding 4 knots, a high bending stress is assumed to be exerted on the NSD sub.
Full-scale fatigue tests of the NSD sub were first conducted to acquire the actual fatigue curve. Further, the bending stress distribution of a drill pipe, which refers to the locus of the bending stress during the drilling operation, was analyzed by considering interference of the drill string with the structure, drilling equipment, and risers that are deformed by the ocean current.
Time-series ship motions is prepared using the response amplitude operators of the Chikyu for the sea states at Nankai Trough area, and then time-series stress response is obtained by considering the operational conditions such as rate of penetration and rotational velocity of drill pipe. The numbers of occurrence of each stress amplitude can be counted from the time-series stress response. Consequently, the cumulative damage ratio is calculated for evaluating the fatigue of the NSD sub. The results confirmed that the cumulative fatigue is within a safe range.
This study focused on the evaluation of the fatigue strength of the specially designed NSD sub for the challenging scientific drilling operation at Nankai Trough, a harsh environment because of the presence of strong ocean currents. This paper presents the overview of NanTroSEIZE including the Non-Stop Driller concept, and the results of fatigue evaluations.
An Experimental Apparatus for Investigating the Unsteady Aerodynamics of a Floating Wind Turbine
Authors: Wen Binrong , Zhang Qi , Liu Haoxue , Tian Xinliang , Dong Xingjian , Peng Zhike , Zhao Yongsheng , Kou Yufeng 
Published: November 2019

Abstract
In our prior investigations, extensive numerical simulations have been conducted to reveal the unsteady aerodynamics of Floating Wind Turbine (FWT). To validate the simulation results and further deepen the corresponding topics, a dedicated experimental apparatus has been developed by the State Key Laboratory of Mechanical System and Vibration (SKL-MSV) and State Key Laboratory of Ocean Engineering (SKL-OE) at Shanghai Jiao Tong University (SJTU). The main modules of the test bed include a dedicated Wind Generation System (WGS), a Model Wind Turbine (MWT), a 6-DOF (Degree Of Freedom) Motion Control Platform (MCP) and an integrated measurement system. The WGS is able to generate controlled flows with different wind speeds, turbulence intensities, and horizontal/ vertical wind shears. The MWT is equipped with Fiber Bragg Grating (FBG) sensors on the blade surface to monitor the operating conditions. The MCP is developed to generate controlled oscillations to the MWT aiming to model the oscillation of the FWT in offshore environments. The measurement system includes a torque sensor, two 6-DOF load cells, a 3-DOF accelerator, 2 FBG-fibers each with 3 FBG sensors, and a Wake Detection System (WDS) consisting of 6 hot-wire probes. Extensive calibrations are conducted for the WGS and the transducers. Some primary results about the unsteady aerodynamics of the FWT are presented. In the future, the MCP will be replaced by a floating platform to conduct the tests in the wave tank at SKL-OE to reveal the fully coupled dynamics of FWTs.
An AIS-Based Multiple Trajectory Prediction Approach for Collision Avoidance in Future Vessels
Authors: Murray Brian , Perera Lokukaluge P. 
Published: November 2019

Abstract
This study presents a method to predict the future trajectory of a target vessel using historical AIS data. The purpose of such a prediction is to aid in collision avoidance in future vessels. The method presented in this study extracts all trajectories present in an initial cluster centered about a vessel position. Features for each trajectory are then generated using Principle Component Analysis and used in clustering via unsupervised Gaussian mixture modeling. Each resultant cluster represents a possible future route the vessel may follow. A trajectory prediction is then conducted with respect to each cluster of trajectories discovered. This results in a prediction of multiple possible trajectories. The results indicate that the algorithm is effective in clustering the trajectories, where at least one cluster corresponds to the true trajectory of the vessel. The resultant predicted trajectories are also found to be reasonably accurate.
Development of Wireless Control System With Underwater Fish-Eye Camera to Monitor Fish at the Test Site of Marine Renewable Energy
Authors: Yoshida Takero , Mizukami Yoichi , Zhou Jinxin , Kitazawa Daisuke 
Published: November 2019

Abstract
Environmental impact assessment is important when marine renewable energy device is installed. Fishermen concern the effect of device on local fish. To confirm the effect before and after installation of marine renewable energy device, we developed wireless monitoring system using an underwater fish eye camera. The camera system is composed of a dome-shaped fish eye lens, a container, and a float. Two thrusters are attached on the container to change the monitoring directions. In the current research, this system was developed to monitor underwater situation around device remotely and in real time. We tested to monitor a target and fish in a fish case at the site off Kamaishi city. The recorded video showed the target and fish. Effectiveness of this system was shown through the field test for real time monitoring around marine renewable energy device.