Marine Structures最新文献

{"title":"Ultra-low cycle fatigue of ship hull structure – an alternately-cyclically loaded four-point bending test of a large box girder","authors":"Shi Song ,&nbsp;Sören Ehlers ,&nbsp;Franz von Bock und Polach ,&nbsp;Moritz Braun","doi":"10.1016/j.marstruc.2024.103732","DOIUrl":"10.1016/j.marstruc.2024.103732","url":null,"abstract":"<div><div>Ultra-low cycle fatigue (ULCF) refers to material failure at small number of loading cycles. For large complex structures like ships, the damage from ULCF can bring hazardous consequences. In this study, an alternately-cyclically loaded four-point bending test of a large box girder is introduced as the specimen to represent the ULCF of ship hull structure. In every load during the test, large deformation is applied to the specimen even after reaching its ultimate hull girder strength (UHGS), thus extensive plastic deformation and obvious fracture can occur in the specimen. The severely damaged specimen is further tested until 1.5 cycles of bending are finished, thus the test of post-damage box girder is realized. Moreover, the box girder is divided into 3 sub-sections, which show different but still interacting structural behavior. The result of the test shows the structural behavior of a large complex structure suffering severe damage during alternate hogging and sagging after reaching its UHGS, which corresponds to the consequence of ULCF. The presented ULCF test also provides experiences for investigations of large complex structures with existing damages or after accidental loads. Considering the number of cycles in the test, this study can bridge the gap between monotonic overload and ultra-low cycle fatigue.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103732"},"PeriodicalIF":4.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745634","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":"Upper bound solution of the vertical bearing capacity of the pile-bucket composite foundation of offshore wind turbines","authors":"Guangsi Chen,&nbsp;Hao Gu,&nbsp;Run Liu,&nbsp;Tianliang Li,&nbsp;Chao Liang","doi":"10.1016/j.marstruc.2024.103728","DOIUrl":"10.1016/j.marstruc.2024.103728","url":null,"abstract":"<div><div>Pile-bucket composite foundations are regarded as a promising solution for offshore wind power infrastructure. However, accurately assessing their vertical ultimate bearing capacity remains a technical challenge. Therefore, establishing an upper bound solution of the ultimate bearing capacity of the composite foundations is of significant importance for their promotion and application. This study begins with small-scale model tests, using Abaqus for modeling based on the relevant test conditions. Next, following model validation, the vertical bearing capacity of the composite foundations under different <em>H/D</em> ratios and the corresponding soil failure modes are investigated. According to the upper limit method and the ultimate equilibrium theory, the kinematic velocity field is subsequently constructed to derive the upper bound solution of the vertical bearing capacity. Finally, the effectiveness and accuracy of the proposed theoretical upper bound solution are verified against the results of model tests, and this study hopes to provide a reference for the future design of vertical bearing capacity of pile-bucket composite foundations.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103728"},"PeriodicalIF":4.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699126","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":"Impact of hull flexibility on the global performance of a 15 MW concrete-spar floating offshore wind turbine","authors":"Ikjae Lee ,&nbsp;Moohyun Kim ,&nbsp;Chungkuk Jin","doi":"10.1016/j.marstruc.2024.103724","DOIUrl":"10.1016/j.marstruc.2024.103724","url":null,"abstract":"<div><div>In this study, we investigated the impact of the hull flexibility of 15MW spar-type FOWT (floating offshore wind turbine) on the global dynamics/performance analysis. Until recently, the rigid hull (floating foundation) model with flexible tower and RNA (rotor-nacelle assembly) has been used as industry standard procedure in the global performance analysis of FOWTs. Since the FOWT size continues to increase beyond 20MW, there has been increasing concern of the effect of hull flexibility on its global performance. The present study is intended to provide representative insights on this subject. Global performance analysis of the 15MW WindCrete spar is examined based on the conventional hull-rigid and the DMB (discrete-module-beam) models including hull flexibility. Coupled aero-hydro-servo-elastic-mooring dynamic simulations were carried out with the rigid-hull and DMB (discrete-module-beam) models under various combinations of irregular waves, sheared currents, and full-field turbulent winds. The lowest fore-aft bending-mode natural frequency is shifted toward lower frequency from 0.52 to 0.41 Hz after including hull flexibility. Platform rigid 6-DOF (degree-of-freedom) motions and mooring tensions by the DMB model are little changed but nacelle horizontal accelerations and tower-base bending moments may be appreciably increased compared to the rigid-hull model.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103724"},"PeriodicalIF":4.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699164","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":"Non-linear dynamic behavior of T0 and T90 mesopelagic trawls based on the Hilbert–Huang transform","authors":"Bruno Thierry Nyatchouba Nsangue ,&nbsp;Hao Tang ,&nbsp;Ruben Mouangue ,&nbsp;Wei Liu ,&nbsp;Achille Njomoue Pandong ,&nbsp;Liuxiong Xu ,&nbsp;Fuxiang Hu ,&nbsp;Leopold Tcham","doi":"10.1016/j.marstruc.2024.103727","DOIUrl":"10.1016/j.marstruc.2024.103727","url":null,"abstract":"<div><div>Although adopting the T90 mesh orientation on the trawl net can improve the selectivity of the trawl codend, it is unknown whether the T90 mesh orientation influences the dynamic behavior of the trawl system. Therefore, this study uses non-linear dynamic analysis to examine the effect of mesh orientations, mesh size, and twine diameter on the mesopelagic trawls' fluttering motions and hydrodynamic force responses. Three trawls are designed with different mesh orientations (T0 and T90), mesh sizes (40 mm and 60 mm), and twine diameters (0.96 mm and 1.11 mm) on the codend and codend extension sections of the trawl model based on Tauti's law. These trawls are tested in a flume tank under various flow velocities and catch sizes. A time-frequency analysis method based on the Hilbert–Huang transform is utilized to analyze each trawl's dynamic responses, including motions and drag force responses. The results are compared with those obtained through Fourier analysis using power spectral density. The results highlight that the oscillation amplitude of the surge motion of the T90 trawl is higher than that of the T0 trawl. In contrast, the T90 trawl's heave motion oscillation amplitude is smaller. The dominant frequency of the periodic high-energy coherent structures of the surge and heave motions are detected at a low frequency. The surge and heave motions of the T0 trawl have a greater response to the current components with lower frequencies than that of the T90 trawl. An increase in mesh size, a decrease in twine diameter, and a change in mesh orientation decrease the drag force. The inherent characteristic oscillations of the drag force response for the three trawl models are synchronized with the low-frequency characteristic of surge and heave motions. The gravity periods of the low-frequency mode components of drag force, surge motion, and heave motion for the T90 trawl are higher than those for the T0 trawls. In other words, the T90 trawl is more stable and selective than the T0 trawl. The findings of this study offer important information for comprehending and enhancing the selectivity of trawls in marine mesopelagic fisheries, particularly for exposing the effects of mesh orientation and design parameters on trawl performances.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103727"},"PeriodicalIF":4.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699163","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":"Further development of offshore floating solar and its design requirements","authors":"Arefeh Emami ,&nbsp;Madjid Karimirad","doi":"10.1016/j.marstruc.2024.103730","DOIUrl":"10.1016/j.marstruc.2024.103730","url":null,"abstract":"<div><div>Floating solar platform (FSP) installations in coastal waters provide a significant energy source for reaching the goal of global net-zero emissions by 2050. These alternative and beautiful green energy installations offer substantial renewable energy generation potential. However, developing robust design solutions is crucial for fully exploiting such potential in offshore environments. This review explores the fundamental requirements for designing FSPs in offshore settings from an engineering perspective. A primary focus is on the hydrodynamic and aerodynamic characteristics, stochastic behaviours, and nonlinear phenomena associated with these structures. Key design parameters such as geometry, modularity, connectivity, and mooring systems are subjected to comprehensive analysis. The interaction between wind, waves, and FSP dynamics is examined, with particular attention to wind-wave coupling. Additionally, complex nonlinear wave phenomena, such as slamming, overtopping, green water, sloshing, ringing, and springing, are thoroughly discussed. The review also highlights the application of previous fluid-structure interaction research in FSP design and development, addressing challenges and variations encountered in this field. Furthermore, the role of data-driven approaches, particularly machine learning, in enhancing the design and development of FSPs is illustrated. This comprehensive examination provides a more delicate understanding of the design challenges and requirements inherent in this rapidly evolving technological field.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103730"},"PeriodicalIF":4.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699123","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 analysis in polar exploration: Fluid-structure interaction modeling of projectile colliding with floating ice during water entry","authors":"Xinyu Hu,&nbsp;Yingjie Wei,&nbsp;Cong Wang","doi":"10.1016/j.marstruc.2024.103729","DOIUrl":"10.1016/j.marstruc.2024.103729","url":null,"abstract":"<div><div>In polar resource exploration, the interaction between polar detectors and floating ice, as well as their water entry mechanisms, are crucial for ensuring effective detector operation and data collection. This study developed a fluid-structure interaction (FSI) model to simulate the water entry of the projectile in a multidegree motion state upon collision with the floating ice, and the numerical method was validated through experiments. This study analyzes the mechanisms of cavity evolution and the laws of cavity pinch-off. This analysis further explores the motion states and dynamic characteristics under the interaction between the projectile and the floating ice. Additionally, this study also considers the influence of structural parameters of the floating ice, including thickness (<em>L_t</em>), width (<em>L_w</em>), and collision position (<em>S_d</em>), on the water entry process. The study reveals that increasing the submergence depth of the floating ice enhances the stability between the floating ice and water, and can mitigate flow separation phenomena generated by passive motion under inertial effects. Variations in the floating ice thickness significantly affect the cavity evolution and the projectile's underwater motion state. Conversely, variations in the floating ice width notably affect the liquid level disturbances, the development of splash crowns, and the evolution of passive water entry cavities. In specific multidegree motion states, various collision positions do not alter the evolution form of water entry cavities, yet the variation in collision positions notably affects floating ice displacement. As the collision position shifts from the center to the side edge of the floating ice, both the hydrodynamic forces on the projectile and the stress on the floating ice gradually decrease, with the decrease in hydrodynamic forces being the most significant, reaching up to 58%. This study is important for enhancing multi-body fluid-structure interaction algorithms and advancing polar exploration engineering development.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103729"},"PeriodicalIF":4.0,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699125","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 analysis of breaking wave impact on a floating offshore wind turbine via smoothed particle hydrodynamics","authors":"Shengzhe Wang ,&nbsp;Wei-Liang Chuang","doi":"10.1016/j.marstruc.2024.103731","DOIUrl":"10.1016/j.marstruc.2024.103731","url":null,"abstract":"<div><div>This work leverages Lagrangian smoothed particle hydrodynamics (SPH) to explore the structural and hydrodynamic response of floating offshore wind turbines (FOWT) subject to impulsive breaking waves. The SPH formulation was first validated against breaking wave impact on a model tension leg platform (TLP) which demonstrated good consistency with experimental results. Following validation, wave focusing was utilized to generate both breaking and nonbreaking extreme waves impacting a moored semi-submersible FOWT at full scale. Impulsive forces and accelerations resulting from the plunging breaker were observed to exceed that of nonbreaking waves by up to 70 % and 230 %, respectively, and were highly sensitive to the wave impingement location relative to the FOWT. However, wave breaking did not appear to significantly influence rigid body motions and yielded lower mooring tensions than its nonbreaking counterpart due to the short duration of impact. This work ultimately demonstrates the applicability of SPH for the simulation of breaking wave interactions with floating bodies and provides further impetus towards the study of FOWTs under such conditions.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103731"},"PeriodicalIF":4.0,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699165","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":"Experimental and numerical investigation on the influence of bilge keel shape on roll damping","authors":"Hasan Islam Copuroglu ,&nbsp;Emre Pesman ,&nbsp;Toru Katayama","doi":"10.1016/j.marstruc.2024.103725","DOIUrl":"10.1016/j.marstruc.2024.103725","url":null,"abstract":"<div><div>Excessive roll amplitudes due to roll motion are undesirable in marine ships. Consequently, it is imperative to conduct a detailed analysis of roll motion and the associated roll damping characteristics. This study experimentally and numerically investigates the roll damping characteristics of bilge keels with various geometric shapes on a ship model under different roll amplitudes. By comparing the non-dimensional roll damping coefficients obtained from experiments and numerical analyses, it is observed that bilge keels with geometries differing from the conventional plate shape exhibit distinct roll damping coefficients. Specifically, bilge keels with sharper tip ends demonstrate higher roll damping coefficients. Based on these findings, it is recommended that the corners and tip end of bilge keels be sharpened to enhance the roll damping coefficient.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103725"},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699124","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":"Design of a quick-connection device for installing pre-assembled offshore wind turbines","authors":"Behfar Ataei ,&nbsp;Zhengru Ren ,&nbsp;Karl Henning Halse","doi":"10.1016/j.marstruc.2024.103720","DOIUrl":"10.1016/j.marstruc.2024.103720","url":null,"abstract":"<div><div>Higher wind velocities and lower wind shear are two motivations driving the development of floating offshore wind turbines (OWTs). However, such designs suffer from high expenses and complicated installation scenarios. Installation of offshore wind turbines is challenging due to the unpredictable nature of the environment and the technical complexities, especially at offshore sites. Mating of OWT on top of the pre-installed substructure is one of the critical stages of the installation operation. Grouted, welded, and bolted connections are utilized conventionally, but all have shortcomings. Welded and grouted connections suffer from fatigue forces, while a bolted connection requires minimal installation tolerances and sensitivity to impact forces. The design of a quick connection device (QCD) is expected to reduce the installation time, expand the operational weather window, and overcome the limitations of the earlier connection devices.</div><div>The QCD described here comprises conic cross-sections, circular plates, and stiffeners connected to the floating substructure and OWT. This research uses a global model to estimate the relative velocities and displacements between the OWT and spar buoy. Furthermore, a local finite element model is developed to assess the influence of the impact forces and the design of the connection device. Implementing the hydrostatic stiffness of the floating spar within the impact simulations improved the simulation fidelity and reduced the impact damage. Different impact scenarios are performed, and the sensitivity of impact damage concerning the distribution of impact initiation points is assessed. Furthermore, an active control mechanism is used to reduce the relative motions between the installation vessel and the floating substructure. It is concluded that utilizing the anti-swing active control system minimizes the impact velocity and impact damage. This research can be extended by optimizing the design of the quick connection device.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103720"},"PeriodicalIF":4.0,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655179","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":"An ULS reliability-based design method for mooring lines using an efficient full long-term approach","authors":"Marina Leivas Simão ,&nbsp;Luis Volnei Sudati Sagrilo ,&nbsp;Paulo Maurício Videiro ,&nbsp;Mauro Costa de Oliveira","doi":"10.1016/j.marstruc.2024.103718","DOIUrl":"10.1016/j.marstruc.2024.103718","url":null,"abstract":"<div><div>In the long-term scenario, the environmental actions to which floating offshore structures are subjected to, such as waves, wind and current, are non-stationary stochastic processes. However, this long-term behavior is usually modeled as a series of short-term stationary conditions. In a full long-term analysis approach, an estimate of the N-year response can be obtained through a multi-dimensional integration over expected short-term environmental conditions. An innovative and more efficient long-term integration approach based on the Importance Sampling Monte Carlo Simulation (ISMCS) method is presented, where the uniform distribution over an environmental contour is used as the sampling function. In parallel, a multi-dimensional joint environmental model that statistically describes all relevant environmental parameters is employed, contemplating linear and directional variables, and thoroughly accounting for the occurrences of wind waves and swell. The methodology is applied to two FPSOs systems installed in Brazilian ultradeep waters. Ultimately, a design-oriented procedure based on the developed methodologies is provided, using an Ultimate Limit State (ULS) reliability-based design with calibrated safety factors in an LRFD (Load and Resistance Factors Design) format. It is shown that the developed procedures can be powerful tools to account for the simultaneous occurrence of wind sea and swell waves in offshore system response evaluations required in the design and life extension analyses.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103718"},"PeriodicalIF":4.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661842","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}