Marine Structures最新文献

Multiple-arc cylinder under flow: Vortex-induced vibration and energy harvesting 流动下的多弧圆柱体：涡流诱导振动和能量收集

IF 4 2区工程技术

Marine Structures Pub Date : 2024-10-01 DOI: 10.1016/j.marstruc.2024.103699

{"title":"Multiple-arc cylinder under flow: Vortex-induced vibration and energy harvesting","authors":"","doi":"10.1016/j.marstruc.2024.103699","DOIUrl":"10.1016/j.marstruc.2024.103699","url":null,"abstract":"<div><div>The shape of a cylindrical cross-section affects the vibrational performance. The vortex-induced vibration (VIV) phenomena of multiple-arc cylinders were numerically investigated to assess their impact on hydrodynamic energy harvesting and potential vibration suppression across a flow velocity range of 0.2 m/s to 1.4 m/s (1.767 × 10<sup>4</sup><<em>R</em>e < 1.237 × 10<sup>5</sup>). The study involves five types of multiple-arc cylinders: 4-arc, 8-arc, 16-arc, 24-arc, and circular cylinders. The accuracy of the numerical method was validated through comparison with experimental data. Specifically, increasing the number of arcs generally enhances overall energy conversion efficiency. Then, the VIV response and energy conversion results of the 24-arc cylinder are similar to those of the circular cylinder with maximum efficiency. Notably, the 4-arc cylinder achieves a global maximum amplitude of 0.074 m (<em>A</em>∗ = 0.83) and a power output of 4.4 W with the new P + T mode, making it the most effective configuration for flow velocities between 0.7 and 0.9 m/s. For vibration suppression of multiple-arc cylinders, the appropriate arc structure effectively reduces amplitudes. The small vortices generated by the arc structures disrupt the separation of normal vortices from the boundary layer, leading to approximately a 50 % reduction in amplitude responses for 8-arc and 16-arc cylinders.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analysis of tubular joints in marine structures: A comprehensive review 海洋结构中的管状连接分析：全面回顾

IF 4 2区工程技术

Marine Structures Pub Date : 2024-09-28 DOI: 10.1016/j.marstruc.2024.103702

引用次数: 0

A study on the mechanical behavior of umbilical cables under impact loads using experimental and numerical methods 利用实验和数值方法研究冲击载荷下脐带缆的机械行为

IF 4 2区工程技术

Marine Structures Pub Date : 2024-09-27 DOI: 10.1016/j.marstruc.2024.103700

引用次数: 0

Numerical and experimental investigation on active hydraulic tensioner system for a TLP under tether fails condition 系绳失效条件下 TLP 的主动液压拉伸器系统的数值和实验研究

IF 4 2区工程技术

Marine Structures Pub Date : 2024-09-15 DOI: 10.1016/j.marstruc.2024.103693

{"title":"Numerical and experimental investigation on active hydraulic tensioner system for a TLP under tether fails condition","authors":"","doi":"10.1016/j.marstruc.2024.103693","DOIUrl":"10.1016/j.marstruc.2024.103693","url":null,"abstract":"<div><p>In this paper, a new active control system for hydraulic tensioners is proposed. Based on the three-dimensional potential flow theory, the dynamic response of TLP-riser-tensioner under tether fails is studied. It is found that when the tension-leg platform’ tethers fail instantaneously, not only the six-degree-of-freedom motion response of TLP will change, but also the tension 'jump' phenomenon will occur in the tension-riser (TTR). The experiment of the active control scheme based on the platform motion response is designed, and the stability of tension output of hydraulic tensioner under normal working conditions is verified by scale model experiment. Based on the joint simulation of AMESim and Simulink, the designed active hydraulic tensioner and its control strategy are effective for the tension control under the condition of second-order wave force failure. In the case of tethers fail, the fuzzy PID control method of active hydraulic tensioner designed in this paper has stronger robustness than the traditional PID control method.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0951833924001217/pdfft?md5=da7f6e65a43c3306a2c07e9fcbad831c&pid=1-s2.0-S0951833924001217-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Assessment of internal defects in flush ground butt welds in marine structures 评估海洋结构中齐平地面对接焊缝的内部缺陷

IF 4 2区工程技术

Marine Structures Pub Date : 2024-09-11 DOI: 10.1016/j.marstruc.2024.103696

{"title":"Assessment of internal defects in flush ground butt welds in marine structures","authors":"","doi":"10.1016/j.marstruc.2024.103696","DOIUrl":"10.1016/j.marstruc.2024.103696","url":null,"abstract":"<div><p>In this paper, acceptance criteria of internal planar defects for the highest design S-N curve for surface ground butt welds in fatigue design standards has been assessed based on fatigue tests of tethers containing internal defects. The results from crack growth analysis from defects placed close to the surface are compared with test data from constant amplitude testing of tethers with circumferential welds that includes flaws or small planar defects close to the surface. Floating structures and support structures are subjected to variable loads and the calculated response leads to a long-term stress range distribution with many small stress ranges. This means that if the cracks are small, the resulting stress intensity may be less than the threshold stress intensity factor and the crack does not grow for this stress cycle, or it grows at a reduced crack growth rate in the near threshold region. A methodology to account for this is presented based on a two-parameter Weibull long-term stress range distribution that is representative for load response of floating structures and for support structures for wind turbines. It is shown that the threshold value and the reduced crack growth rate in the near threshold region for small internal defect heights can be used to lift the fatigue test data from constant amplitude testing to be in better correspondence with a higher S-N curve when considering an actual long-term loading.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0951833924001242/pdfft?md5=c245ce826f2f883b5717b98b652dcbe1&pid=1-s2.0-S0951833924001242-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Polyester mooring system design and evaluation of a semi-platform in south China sea 中国南海半平台聚酯系泊系统的设计与评估

IF 4 2区工程技术

Marine Structures Pub Date : 2024-09-08 DOI: 10.1016/j.marstruc.2024.103686

{"title":"Polyester mooring system design and evaluation of a semi-platform in south China sea","authors":"","doi":"10.1016/j.marstruc.2024.103686","DOIUrl":"10.1016/j.marstruc.2024.103686","url":null,"abstract":"<div><p>Polyester rope offers numerous advantages over traditional steel catenary mooring systems and is considered an appealing option for deep-water mooring systems. In this paper, the design and evaluation procedure of the polyester mooring system for a semi-submersible platform located in the South China Sea is presented. A fully coupled numerical model of the semi-submersible platform, including all risers and mooring lines, has been established and calibrated through wave basin testing. To simulate the elongation behavior of polyester, a static-dynamic stiffness model is employed, and the corresponding procedure for mooring evaluation is established to simulate the mooring response under extreme environmental conditions. A comprehensive fatigue analysis is also conducted for the polyester mooring system using time domain dynamic theory. The effects of Vortex-Induced Motion (VIM) on mooring fatigue damage are also considered. The results indicate that the polyester mooring system could be safely operated at the target offshore field throughout its service life. Additionally, model test calibration is a crucial procedure during the entire mooring evaluation process, and the numerical model should be adjusted appropriately to accurately reflect the dynamic behavior of the coupled system. This study also illustrates that the stiffness of the rope plays a crucial role in polyester mooring design and global performance calculations. The proposed evaluation methodology can provide a foundation for the design of polyester mooring systems and for evaluating their safety and reliability in engineering practice.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S095183392400114X/pdfft?md5=92a28346c33576dbea09f15f007502fd&pid=1-s2.0-S095183392400114X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corrosion-fatigue damage identification in submerged mooring chain links using remote acoustic emission monitoring 利用远程声发射监测识别水下系泊链节的腐蚀疲劳损伤

IF 4 2区工程技术

Marine Structures Pub Date : 2024-08-31 DOI: 10.1016/j.marstruc.2024.103685

引用次数: 0

Structural strength and fatigue analyses of large-scale underwater compressed hydrogen energy storage accumulator 大型水下压缩氢储能蓄能器的结构强度和疲劳分析

IF 4 2区工程技术

Marine Structures Pub Date : 2024-08-30 DOI: 10.1016/j.marstruc.2024.103684

{"title":"Structural strength and fatigue analyses of large-scale underwater compressed hydrogen energy storage accumulator","authors":"","doi":"10.1016/j.marstruc.2024.103684","DOIUrl":"10.1016/j.marstruc.2024.103684","url":null,"abstract":"<div><p>Underwater compressed hydrogen energy storage (UWCHES) is a potential solution for offshore energy storage. By taking advantage of the hydrostatic pressure of deep seawater, the compressed hydrogen can be isobarically stored in underwater artificial energy storage accumulators. The accumulator should withstand high pressure and large buoyancy and possess reliable anchoring to the seabed. In this study, the structural strength analysis and fatigue life of the large-scale accumulator is conducted employing the finite element method (FEM). The dimensionless stress prediction model and dimensionless fatigue life prediction model are developed through dimensional analysis and multivariate regression analysis. The performance of the accumulator with operating water depth of 100∼300 m, gas storage volume of 1081∼10128 m³, and concrete wall thickness of 0.1∼0.63 m is investigated. The results show that with an operating water depth of 100 m, gas storage capacity of 10,128 m<sup>3</sup>, and concrete wall thickness of 0.63 m, the maximum compressive stress is 1.43 MPa (yield strength is 60 MPa) and the maximum tensile stress of the accumulator is 2.55 MPa (yield strength is 6 MPa). The design fatigue life is 10<sup>6</sup> cycles which is larger than the expected service life of 10<sup>4</sup> cycles. Therefore, the accumulator structure meets the static strength and fatigue life. As the operating water depth increases with a consistent gas storage capacity, a transition in the stress state shifts from primarily tensile stress to predominantly compressive stress. The accuracy of the dimensionless stress prediction model and the dimensionless fatigue life prediction model were verified, with maximum deviations of 10.3 % and 13.7 %, respectively. Furthermore, the anchoring factor of safety of 1.12 is achieved.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Predicting heave and pitch motions of an FPSO using meta-learning 利用元学习预测浮式生产储油轮的倾斜和俯仰运动

IF 4 2区工程技术

Marine Structures Pub Date : 2024-08-29 DOI: 10.1016/j.marstruc.2024.103681

{"title":"Predicting heave and pitch motions of an FPSO using meta-learning","authors":"","doi":"10.1016/j.marstruc.2024.103681","DOIUrl":"10.1016/j.marstruc.2024.103681","url":null,"abstract":"<div><p>Real-time motion prediction is helpful in guaranteeing the operation stability of a Floating Production Storage Offloading (FPSO) unit. Recurrent neural networks (RNNs) are becoming feasible alternatives to numerical simulations for motion prediction as artificial intelligence develops rapidly. In this study, model-agnostic meta-learning (MAML) is combined with RNNs to deterministically predict the heave and pitch motions of a ship-shaped FPSO. This approach is motivated by the fact that MAML improves training efficiency without losing accuracy. The data came from a scaled model test conducted at Shanghai Jiao Tong University’s deepwater wave basin. Before introducing MAML, we verified that long short-term memory (LSTM) and gated recurrent unit (GRU) could accurately predict the heave and pitch of about 7.68 s into the future. With fewer learnable parameters than LSTM, GRU demonstrates slightly better accuracy. Therefore, this study focuses particularly on the combination of GRU and MAML. The parameters of MAML, including order of derivative, step size, number of adaption gradient updates, and batch size of the tasks, are evaluated systemically in terms of accuracy and training efficiency. With the assistance of MAML, GRU’s training efficiency for heave and pitch has significantly improved, increasing by approximately 65% and 55%, respectively. Meanwhile, the prediction error for both has decreased by about 10%. Notably, MAML’s performance is minimally affected by variations in incoming wave direction and sea state, as well as the randomness and temporal variability of the motion. MAML is a powerful tool that enables RNNs to achieve real-time prediction of FPSO motion.</p></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Insights into the scale effects on ship motions and wave loads considering hydroelasticity 考虑到水弹性，洞察船舶运动和波浪载荷的尺度效应

IF 4 2区工程技术

Marine Structures Pub Date : 2024-08-26 DOI: 10.1016/j.marstruc.2024.103683

引用次数: 0