Marine Structures最新文献

{"title":"Data-driven modelling of fully nonlinear wave loads on offshore wind-turbine monopiles at prototype scale","authors":"Weikai Tan ,&nbsp;Pu Ren ,&nbsp;Deping Cao ,&nbsp;Hui Liang ,&nbsp;Hao Chen","doi":"10.1016/j.marstruc.2024.103775","DOIUrl":"10.1016/j.marstruc.2024.103775","url":null,"abstract":"<div><div>Offshore wind energy constitutes a vital component of the renewable energy portfolio, and accurate and efficient prediction of nonlinear wave loads on monopile foundations is critical for ensuring structural integrity and prolonging wind turbines’ operational lifespans. Unlike large-volume marine structures, third-order and higher wave loading is important for such slender structures due to ringing response. Traditional approaches, such as the numerical wave tank based on the fully nonlinear potential flow theory and computational fluid dynamics (CFD), are often computationally expensive. This paper proposes data-driven approaches to model nonlinear wave loads using machine learning (ML) techniques. These approaches offer substantial reductions in computational cost while maintaining reasonable predictive accuracy for high-order wave loadings under a range of wave conditions. Two ML-based models are developed and trained based on high-fidelity CFD data to capture linear and nonlinear wave load components, where the CFD data are classified into clusters using the K-means algorithm, an unsupervised clustering technique to optimise the dataset. A representative subset of data is selected from each cluster to construct the training and testing datasets for the ML models, ensuring that sufficient patterns are captured to facilitate model training and generalisation. The first ML model implements a hybrid approach to predicting the nonlinear wave load in the time domain. It combines a physics-based linear predictor for the inline force with a long short-term memory (LSTM) predictor to estimate the residual between the linear model and CFD results. The second model adopts the spirit of reduced-order modelling by predicting the fundamental and higher-order harmonics of the nonlinear wave load in the frequency domain, which are subsequently reconstructed into the time domain. A comparative study of the two models reveals that the second ML-based approach is more robust for the present application, eliminating the trade-off between overfitting and underfitting high-frequency oscillations, an inherent issue in the first model. We also compare the performance of the ML model with the FNV wave load model (Faltinsen et al., 1995; Kristiansen and Faltinsen, 2017). The proposed ML model is applied to predict nonlinear wave loads under various wave conditions, and the variation of maximum force and force nonlinearity is investigated.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103775"},"PeriodicalIF":4.0,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147186","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}

{"title":"Optimization of structural configuration and analysis of dynamic response using Absolute Nodal Coordinate Formulation for flexible hoses in deep-sea mining system","authors":"Qi Guo ,&nbsp;Guoqing Jin ,&nbsp;Zongbing Yu ,&nbsp;Li Zou ,&nbsp;Jian Hu ,&nbsp;Haoyu Qian","doi":"10.1016/j.marstruc.2024.103774","DOIUrl":"10.1016/j.marstruc.2024.103774","url":null,"abstract":"<div><div>The arrangement of buoyancy materials significantly affects the spatial configuration of flexible hoses, influencing mining vehicle performance. This paper develops a mechanical model for geometrically nonlinear flexible hoses using the Absolute Nodal Coordinate Formulation (ANCF) and introduces an ANCF-GA (Genetic Algorithm) coupling algorithm to optimize buoyancy material arrangement for the hose. The study explores the impact of mining vehicle paths on geometric parameters (angles <span><math><mi>α</mi></math></span> and <span><math><mi>β</mi></math></span> between hose ends and the y-axis, and bending angle <span><math><mi>θ</mi></math></span>) and mechanical characteristics, including traction forces on the mining vehicle and intermediate warehouse. In static analysis, the ANCF-GA algorithm effectively optimizes the buoy material arrangement for flexible hoses with predefined material properties and geometric dimensions. In dynamic analysis, hydrodynamic forces significantly influence hose behavior. For a constant displacement, the vehicle’s trajectory and velocity minimally affect traction on the intermediate warehouse but strongly influence traction on the vehicle, increasing with speed. Geometric parameters <span><math><mi>α</mi></math></span> and <span><math><mi>θ</mi></math></span> exhibit consistent trends, with <span><math><mi>α</mi></math></span> decreasing and <span><math><mi>θ</mi></math></span> increasing as the vehicle moves, while higher speeds reduce their rate of change. In contrast, <span><math><mi>β</mi></math></span> is highly sensitive to trajectory and speed, showing accelerated growth at higher speeds.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103774"},"PeriodicalIF":4.0,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147798","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}

{"title":"Towing performance of mono-column composite bucket foundation in irregular waves","authors":"Conghuan Le,&nbsp;Xiling Qi,&nbsp;Puyang Zhang,&nbsp;Hongyan Ding,&nbsp;Yang Gao","doi":"10.1016/j.marstruc.2024.103771","DOIUrl":"10.1016/j.marstruc.2024.103771","url":null,"abstract":"<div><div>The mono-column composite bucket foundation (MCCBF) has many advantages, such as quick installation and good bearing performance. To explore the towing performance of the MCCBF when encountering different waves in practical engineering, model tests are carried out to analyze the effects of different peak shape parameters, significant wave heights, and peak periods on MCCBF. The results show that the pitch and heave of the MCCBF's natural period increase with the draft's increase. When the draft is 8 m, the natural period of the pitch is 9.11 s, and the natural period of the heave is 7 .91s. Under different peak shape parameters, the air pressure fluctuations in Compartment 1 and Compartment 4 are the largest, Compartment 2 and Compartment 3 are smaller, and Compartment 7 is the smallest. When the peak period is close to the natural period of the MCCBF, the MCCBF will resonate in the corresponding free degree, which should be avoided in practical towing operations. With the increase of the significant wave height, the contact area between the MCCBF and the wave increases, and the wave load on the structure increases, resulting in an increase in the air pressure of each compartment, the towing force, and the pitch fluctuation. During practical towing, the contact area between the MCCBF and the waves can be changed by adjusting the draft of the MCCBF to reduce the towing force required.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103771"},"PeriodicalIF":4.0,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147799","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}

{"title":"Dynamic similarity study of the truncated model test for submerged floating tunnels under wave actions","authors":"Weidong Chen ,&nbsp;Haikuo Zhang ,&nbsp;Gancheng Zhu ,&nbsp;Bing Ren ,&nbsp;Pengzhi Lin","doi":"10.1016/j.marstruc.2025.103777","DOIUrl":"10.1016/j.marstruc.2025.103777","url":null,"abstract":"<div><div>Conducting experiments on full-span submerged floating tunnels (SFTs) is challenging due to their extensive length and limitations in experimental conditions. Truncated models offer an alternative for studying SFTs' dynamic response under wave actions. This study investigates the dynamic similarity between the truncated model and full-span structure in regular waves. Modal similarity is utilized in designing the truncated models, along with proposing constraint stiffness for the truncated boundary. A numerical model for simulating the dynamic response of SFTs under wave actions is established using Ansys and validated by physical model tests of the SFT segment with a free boundary. Comparisons of the natural frequencies, motion amplitudes, and mooring forces between the truncated models and full structures are conducted through numerical calculations. The horizontal, vertical, and rotational stiffness of the truncated boundaries are determined, with observed coupling effects between the horizontal and rotational constraints. The analysis of displacement amplitude for different truncation lengths indicates that as the truncation length increases, the displacement of the truncated model gradually approaches that of the full structure. It is also found that the sway amplitude at the truncated boundary is about 0.8 - 1.2 times of the full structure, while the way amplitude at mid-span is about 0.78 - 0.85 times of the full structure. The displacement distribution along the tube suggests that neglecting the rotation angle around the Z-axis at the truncated boundary leads to this discrepancy. The analysis results of this paper show that the proposed truncated model can effectively represent the dynamic response of the full structure. The dynamic similarity method for truncated model serves as a valuable reference for experimental design of SFTs.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103777"},"PeriodicalIF":4.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147706","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}

{"title":"Fiber-reinforced polymers effect on the degree of bending in offshore cross-shaped tubular connections under out-of-plane bending","authors":"Pooya Rezadoost ,&nbsp;Behrouz Asgarian ,&nbsp;Hossein Nassiraei","doi":"10.1016/j.marstruc.2024.103776","DOIUrl":"10.1016/j.marstruc.2024.103776","url":null,"abstract":"<div><div>The degree of bending (DoB), representing the ratio of bending stress to total stress within the chord wall thickness, is crucial for predicting the fatigue life of tubular connections in offshore structures. This study investigates the influence of fiber-reinforced polymer (FRP) on DoB, hot spot stress, and stress distribution within the chord wall of cross-type tubular connections. Following the validation of a finite element model (FEM) against existing experimental and theoretical data, 166 FEMs were developed and analyzed under out-of-plane bending conditions to examine the effects of connection geometry ratios and FRP parameters (type, layer count, and layout). The findings indicate that FRP sheets significantly enhance connection fatigue performance, increasing DoB by 34.66 %. Furthermore, the application of FRP results in a 51.28 % reduction in bending stress, a 93.21 % reduction in membrane stress, and a decrease in hot spot stress of 54.58 % and 40.54 % on the outer and inner surfaces of the chord, respectively, compared to un-retrofitted connections. A novel parametric formula for estimating DoB in FRP-retrofitted connections under out-of-plane bending is introduced, addressing a significant gap in existing research. This formula provides a valuable tool for the design and analysis of retrofitted tubular connections in offshore structures.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103776"},"PeriodicalIF":4.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147707","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}

{"title":"Active anti-rolling characteristics of fluid momentum wheel for cylindrical FPSO under wave conditions","authors":"Ke-Dong Zhang ,&nbsp;Wen-Hua Wang ,&nbsp;Tai-Wei Piao ,&nbsp;Yi-Hua Liu ,&nbsp;Shu-Dong Leng ,&nbsp;Yuan-Bo Xiu ,&nbsp;Chao-Fan Tu ,&nbsp;Lin-Lin Wang ,&nbsp;Ya-Zhen Du ,&nbsp;Hong-Xia Li ,&nbsp;Yi Huang","doi":"10.1016/j.marstruc.2024.103773","DOIUrl":"10.1016/j.marstruc.2024.103773","url":null,"abstract":"<div><div>In complex sea conditions, floating platforms experience unavoidable roll and pitch motions that impact the efficiency and safety of the crew and equipment. To address the application limitations of gyrostabilizer, the fluid momentum wheel (FMW) based on the angular momentum and precession principle is proposed. The motion responses of a cylindrical floating body in the numerical wave tank are compared with those in an experimental tank to verify the accuracy of the numerical method. Additionally, the results for the coupling model of the floating platform and the FMW demonstrate that the FMW can achieve an effective response reduction, which can be up to 99.64 %. Next, the paper explores the anti-rolling characteristics of the FMW by examining various start-up strategies and arrangement locations, which indicate that the strategy of slow linear growth can enhance the anti-rolling stability and reduce costs. The arrangement location of FMW has a minor impact on the motion control process, highlighting its advantage in adjusting the center of gravity (COG) of the platform. Finally, the FMW demonstrates good applicability across different COGs and geometric configurations, effectively producing stabilizing effects on classic cylindrical platforms with various parameters. These findings evidence the ability of the FMW to reduce pitch motion responses of floating platforms, providing a basis for its potential application on offshore platforms.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103773"},"PeriodicalIF":4.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147708","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}

{"title":"Enhancing the real-time prediction of fatigue damage in offshore structures: A novel method integrating frequency-domain approaches","authors":"Haiyang Ge ,&nbsp;Xin Li ,&nbsp;Wenyue Lu ,&nbsp;Bo Wu ,&nbsp;Yunlong Jiang","doi":"10.1016/j.marstruc.2024.103772","DOIUrl":"10.1016/j.marstruc.2024.103772","url":null,"abstract":"<div><div>Offshore structures are continuously subjected to wideband random loads, rendering the real-time prediction and assessment of their fatigue life a challenge. Thus far, a high-confidence method for predicting fatigue damage, referred to as rain-flow counting (RFC), has failed to perform real-time damage prediction in actual offshore operation scenarios owing to its large computing time and input data size. In this study, an improved fatigue damage estimation method is proposed for real-time prediction in the frequency domain by constructing standard stress spectrum to determine the distribution parameters, weight factors, and distribution correction coefficients associated with the spectrum width parameters. A new assembly distribution is applied using a weighted combination of exponential, half-Gaussian, and two double-parameter Weibull distributions. Based on the established standard stress spectra, the proposed method was compared with RFC to preliminarily verify its prediction accuracy. Subsequently, the proposed method was applied to actual ship monitoring and compared with nine typical prediction methods; the results confirmed the satisfactory prediction accuracy and stability of the developed model. In conclusion, the high-precision predictions made by the developed method closely match the RFC results, significantly improving the fatigue damage prediction over various bandwidth processes.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103772"},"PeriodicalIF":4.0,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147800","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}

{"title":"A frequency-domain optimization procedure for catenary and semi-taut mooring systems of floating wind turbines","authors":"Serag-Eldin Abdelmoteleb,&nbsp;Erin E. Bachynski-Polić","doi":"10.1016/j.marstruc.2024.103768","DOIUrl":"10.1016/j.marstruc.2024.103768","url":null,"abstract":"<div><div>This work presents an efficient method for assessing mooring system designs for floating wind turbines (FWTs) based on frequency-domain analysis. The method is used to explore the design space and design-driving constraints for catenary and semi-taut mooring systems for semi-submersible FWTs with power ratings from 5 to 25 MW. The proposed method combines a previously presented model for low-frequency rotor-aero-servo dynamics in frequency-domain with a frequency-domain lumped mass model for estimating the wave-frequency dynamic tension, which has often been treated quasi-statically in previous studies. Multiple design constraints including ultimate limit state, fatigue limit state, and maximum allowable offset were considered in design space exploration and optimization. The main design-driving criteria were found to be the maximum offset and fatigue life. The resulting designs were tested using nonlinear coupled time-domain analysis and found to satisfy all the required design criteria. The frequency-domain model captures the main trends of the motion and tension statistics of the FWTs while providing conservative estimates for fatigue damage for most conditions. The discrepancies between the frequency- and time-domain results are mainly due to overestimation of the surge resonance response due to the linearization of aerodynamic damping in the frequency-domain model.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103768"},"PeriodicalIF":4.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147716","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}

{"title":"Ultimate bearing capacity and fatigue life analysis of marine sandwich composite bolted connection structure: Fatigue test and numerical simulation","authors":"Yu Qiu ,&nbsp;RenJun Yan ,&nbsp;Jiajing Lei ,&nbsp;Gongrong Li ,&nbsp;Wei Shen ,&nbsp;Yaoyu Hu","doi":"10.1016/j.marstruc.2024.103770","DOIUrl":"10.1016/j.marstruc.2024.103770","url":null,"abstract":"<div><div>Because of the great difference in performance between component materials, there are some problems in sandwich composite structures, such as complex fatigue failure mode and difficult observation of internal damage. The numerical simulation method of fatigue can effectively simulate the whole process of fatigue failure. At present, the fatigue failure prediction methods of reinforced fiber laminates and interlayer interfaces are effectively analyzed, but there is no relevant numerical simulation method that can consider the fatigue failure of core materials. Based on the fatigue test data of foam core materials, an improved fatigue life prediction method of foam core material with principal stress and Tresca stress as basic parameters is proposed, and a progressive failure fatigue analysis method of foam sandwich composite structure is formed by combining the stiffness/strength degradation model of fiber reinforced laminates and Shokrieh fatigue failure criterion. Based on the finite element calculation software ABAQUS, the corresponding UMAT subroutine is compiled and the fatigue life and damage mode prediction of the sandwich composite bolted connection structure are verified. Compared with the experimental results, it can be found that the proposed finite element fatigue analysis method has high calculation accuracy and can be used to guide the anti-fatigue design and optimization of sandwich composite structures.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103770"},"PeriodicalIF":4.0,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147715","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}

{"title":"Long-term cyclic performance of offshore jacked piles in structured clays: Insights from model testing","authors":"Pan Zhou ,&nbsp;Feng Dai ,&nbsp;Shanghui Yang ,&nbsp;Yi Liu ,&nbsp;Zelin Yan ,&nbsp;Mingdong Wei","doi":"10.1016/j.marstruc.2024.103769","DOIUrl":"10.1016/j.marstruc.2024.103769","url":null,"abstract":"<div><div>Marine soft clays are known for their poor engineering properties, which, when subjected to prolonged static and dynamic loading, can lead to excessive settlement of offshore pile foundations and subsequent structural instability, resulting in frequent engineering failures. This study examines the bearing and deformation behavior of jacked piles in these clay deposits under both static and cyclic loading conditions using a custom-designed model testing apparatus. Emphasizing the time-dependent load-carrying capacity and accumulated cyclic settlement of piles, the research uses artificially structured clay to more accurately simulate stratum conditions than traditional severely disturbed natural clays. Model pile testing was carried out to analyze the effects of soil structure and cyclic loading patterns on the long-term response of jacked piles. Key factors investigated include initial soil structure, pile jacking-induced destruction, soil reconsolidation post-installation, disturbed clay's thixotropic effects, and cyclic loading's impact during service. Results show that increasing the cement content within the clays from 0 % to 4 % nearly doubled pile penetration resistance, led to a more significant accumulation of excess pore water pressure (EPWP), and accelerated its dissipation rate. Additionally, the ultimate load-carrying capacity of jacked piles also doubled. Higher cement content slowed pile head settlement rates and reduced stable cumulative settlement values, requiring more cycles to reach instability. Under high-amplitude, low-frequency cyclic loads, hysteresis loops of the model piles became more pronounced and rapid. This study enhances understanding of the long-term cyclic behavior of jacked piles in soft soils, providing valuable insights for designing offshore piles.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"101 ","pages":"Article 103769"},"PeriodicalIF":4.0,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147664","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}