Marine Structures最新文献

{"title":"Degradation mechanisms of axial compressive performance in defective unbonded flexible pipes","authors":"Yu Liu,&nbsp;Yanfei Chen,&nbsp;Keyang Tan,&nbsp;Mingchang He,&nbsp;Rongfeng Zhong,&nbsp;Xin Wang,&nbsp;Ruihao Liu,&nbsp;Rui Li","doi":"10.1016/j.marstruc.2025.103862","DOIUrl":"10.1016/j.marstruc.2025.103862","url":null,"abstract":"<div><div>As a critical conduit connecting offshore oil and gas fields to marine platforms, the unbonded flexible pipe plays a vital role in offshore production. The tensile armor, as one of the primary load-bearing components of the flexible pipe, is crucial to the structural integrity of the pipeline system, and its failure poses a significant threat. Therefore, investigating the influence mechanisms of various defects on the mechanical properties of the tensile armor and analyzing its mechanical behavior are of great theoretical and engineering significance. A numerical simulation approach was employed to study the axial compression performance of the tensile armor in unbonded flexible pipes with defects. A five-layer finite element model of the unbonded flexible pipe under axial compression was established to examine the effects of defects in the non-metallic layer, interlayer friction coefficient, and wires fracture on the axial compression stiffness and critical buckling load. The results indicate that a decrease in the friction coefficient due to increased annular water content significantly reduces the critical buckling load, while defects in the non-metallic layer and fracture of the wires substantially decrease both axial compression stiffness and critical buckling load. These findings emphasize the necessity of monitoring annular water content and ensuring the structural integrity of each layer in engineering applications. By constructing a critical buckling load degradation model and a nonlinear axial stiffness degradation model considering defects in both non-metallic and metallic layers, as well as a degradation model for the critical buckling load and stiffness that accounts for the differences between internal and external fracture of the metal layer, this study reveals the scale-separation characteristics of interlayer mechanical transmission in unbonded flexible pipes. A key innovation of this work is the development of a dual-scale coupled axial compression degradation model. By introducing a novel degradation factor (<span><math><mrow><mi>β</mi><mo>(</mo><mi>θ</mi><mo>,</mo><mi>L</mi><mo>)</mo></mrow></math></span>) linking non-metallic defect severity to metallic layer buckling sensitivity and a nonlinear weighted degradation term (<span><math><mrow><mi>ψ</mi><mo>(</mo><msub><mi>n</mi><mrow><mi>o</mi><mi>u</mi><mi>t</mi></mrow></msub><mo>,</mo><msub><mi>n</mi><mtext>int</mtext></msub><mo>)</mo></mrow></math></span>) capturing the accelerated stiffness loss due to wire fracture interactions, this model explicitly quantifies the synergistic effects between non-metallic and metallic defects, which have largely been treated in isolation previously. This provides a more comprehensive and physically grounded framework for evaluating the axial compression performance of unbonded flexible pipes with complex, co-existing defects.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103862"},"PeriodicalIF":4.0,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242154","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":"Thermal buckling of aluminum conductors in submarine cables","authors":"Haolin Li ,&nbsp;Zhenkui Wang ,&nbsp;Yifan Wang ,&nbsp;Hongyu Wang ,&nbsp;Xiaowei Huang ,&nbsp;Zhen Guo","doi":"10.1016/j.marstruc.2025.103860","DOIUrl":"10.1016/j.marstruc.2025.103860","url":null,"abstract":"<div><div>The conductor is a key component in submarine cables for power transmission. During the operation of the cable, the transmission of current results in an increase in the conductor's temperature. Due to initial imperfections caused by welding, the aluminum conductor at the joint may experience buckling failure under the compressive load induced by thermal loading. In this study, a finite element model is developed to investigate the thermal buckling of the wire in the conductor, and the model is validated against theoretical formulas within the elastic stage. The welding effect is considered in the finite element model, including the mechanical strength reduction, length, and initial deformation of the heat-affected zone (HAZ). The typical buckling mechanism of the conductor wire is analyzed, and a sensitivity analysis of the welding effect on the buckling behavior is also conducted. The results indicate that the conductor wire in the HAZ undergoes snap-through buckling under thermal loading during the plastic stage. This buckling behavior causes a sudden and significant increase in displacement and stress in the HAZ, which may lead to structural failure. Moreover, both the critical buckling temperature and critical buckling axial force are negatively correlated with the magnitude of the mechanical strength reduction, length, and out-of-straightness of the HAZ.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103860"},"PeriodicalIF":4.0,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144223252","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":"Theoretical and data-driven methods to predict the mechanical response of flexible pipe carcass under radial compression","authors":"Wenbo Li ,&nbsp;Hailong Lu ,&nbsp;Murilo Augusto Vaz ,&nbsp;Jun Yan","doi":"10.1016/j.marstruc.2025.103857","DOIUrl":"10.1016/j.marstruc.2025.103857","url":null,"abstract":"<div><div>The carcass layer is the innermost structure of flexible pipes and is primarily designed to resist radial loads. Flexible pipes are subjected to compression by tensioners during installation, and excessive radial loads can lead to plastic deformation and premature material yielding, consequently diminishing the structural load-bearing capacity. Despite the critical role of the carcass layer, limited research has been performed on the plastic analysis of its complex cross-section under symmetric radial compression. This study applied the plastic-hinge theory to a planar circular ring, considering factors such as ellipticity and material hardening, and introduced the concept of equivalent radial stiffness for the carcass layer to predict the load-displacement curve during the plastic phase of the carcass layer under radial compression. Simultaneously, owing to the challenge of uneven stress distribution caused by a complex cross-section, this study adopts a combined approach of the attention mechanism and Long Short-Term Memory (LSTM) neural network. By inputting the structural ellipticity, inner diameter, and load–displacement response, the method aims to accurately predict the stress in the carcass layer. This conclusion indicates that the theoretical model exhibits a higher prediction accuracy when material hardening is considered. Errors arise when material hardening is ignored, as the theoretical model fails to account for the deformation of nonuniform cross-sections. By contrast, the data-driven models demonstrated high precision in predicting both radial and circumferential stresses in the carcass layer under radial compression.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103857"},"PeriodicalIF":4.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213255","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":"Numerical simulation of ship hydroelastic responses in short-crested irregular waves","authors":"Zhenwei Chen ,&nbsp;Jialong Jiao ,&nbsp;Wenhua Xu ,&nbsp;Caixia Jiang ,&nbsp;Shuai Chen","doi":"10.1016/j.marstruc.2025.103858","DOIUrl":"10.1016/j.marstruc.2025.103858","url":null,"abstract":"<div><div>In this paper a two-way CFD-FEM fluid-structure coupled method is developed to simulate ship motions and wave load responses in short-crested irregular waves. First, a segmented ship model is established in FEM solver, and a numerical tank is established in CFD solver to reproduce short-crested irregular waves. Then, the simulation of 3D irregular waves is illustrated, and the time series of simulated waves and the estimated directional spectra are analyzed. The simulation results of ship motions and sectional loads in 3D waves are illustrated and analyzed. The asymmetric motions and loads for ship with and without forward speed are comprehensively analyzed and cross-spectral method is used for correlation analysis between different signals. This paper has potential application values in the prediction of ship seakeeping and hydroelastic responses in realistic sea states.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103858"},"PeriodicalIF":4.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204367","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":"Large static deformation analysis of thin cylindrical shells with different moduli in tension and compression: An application in pressure hulls","authors":"Xiao-Ting He ,&nbsp;Jun-Song Ran ,&nbsp;Xin Wang ,&nbsp;Jun-Yi Sun","doi":"10.1016/j.marstruc.2025.103859","DOIUrl":"10.1016/j.marstruc.2025.103859","url":null,"abstract":"<div><div>Bimodular materials have different moduli of elasticity in tension and compression. In existing studies, the bimodular effect of materials is rarely considered due to the complexity of the analysis. This paper presents a theoretical study of large static deformation problems of thin circumferentially-closed cylindrical shells with bimodular effect in an underwater environment. First, the geometrical and physical equations of large axisymmetric deformation of bimodular thin cylindrical shells are established, and the total strain energy of the cylindrical shell is obtained. Based on variation principle, the Ritz method is used for the obtainment of the important relationship between external pressure and deformation. The numerical simulation based on ABAQUS also validates the analytical relation. As an application example, the underwater pressure hulls considering the bimodular effect and large deformation is analyzed. Results show that the bimodular effect change the stiffness of shells to some extent, thus leading to changes in deformation. The cylindrical shell is more sensitive to the bimodular effect at higher loads. In addition, the change of radius-to-thickness ratios of shells will strengthen bimodular effect on deformation while the change of length-to-radius ratios will influence the bending configurations of shells. In the design of pressure hulls, considering the bimodular effect will play a positive role in materials saving.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103859"},"PeriodicalIF":4.0,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195203","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":"Model tests of a stiffness-similar jack-up, Part 1: Model design, fabrication and structural pre-tests","authors":"M. Cai,&nbsp;S. Zhang,&nbsp;C. Zhang,&nbsp;W.K. Chen,&nbsp;M. Yu,&nbsp;C.K. Yeo,&nbsp;H.J. Soo,&nbsp;J. Cao,&nbsp;Y.Z. Law,&nbsp;B.V.E. How,&nbsp;H. Santo,&nbsp;A.R. Magee,&nbsp;M. Si","doi":"10.1016/j.marstruc.2025.103846","DOIUrl":"10.1016/j.marstruc.2025.103846","url":null,"abstract":"<div><div>This paper forms Part 1 of a paper series on jack-up model tests describing model design, fabrication and an extensive set of structural pre-tests. The model tests were aimed to provide high quality data-sets for the development of structural digital twin, therefore realistic and representative model of a jack-up platform at model-scale would be essential. In this regard, a generic jack-up model at 1:30 scale was designed such that the dynamic behaviour at full-scale was representative of actual jack-ups as reported in the literature. The main novelty was the use of Polycarbonate (PC) material to construct the leg structure, such that stiffness-similarity at model-scale could be achieved, both in terms of bending and axial rigidity. The benefits are two-fold. First, this allows direct strain/stress measurements along the legs to obtain axial member forces. Second, foundation fixity and leg-to-hull fixity at model-scale can also be representatively modelled such that the measured boundary forces were meaningful. The design and structural pre-tests of the key components of the jack-up model, which included the legs, spudcan, leg-to-hull connection, hull and cantilever, are thoroughly described in this paper. In general, good linear behaviours were observed, although small non-linear behaviour was noted for the spudcan module at lower loading amplitude. Additional pre-tests of the assembled jack-up model were also conducted prior to the start of model tests, and similar observations were drawn. A numerical Finite Element model of the jack-up was set up using ABAQUS, and in general, good agreement was achieved between measurements and numerical simulations for the boundary forces, moments and strains, as well as the overall dynamic characteristics. The numerical model could form the basis for development of structural digital twin tapping on the model test results for validation and proof-of-concept.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103846"},"PeriodicalIF":4.0,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184598","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":"Numerical study for elastic floating structures coupled with nonlinear mooring system in irregular waves, including a multi-unit floating offshore wind turbine platform","authors":"HeonYong Kang","doi":"10.1016/j.marstruc.2025.103848","DOIUrl":"10.1016/j.marstruc.2025.103848","url":null,"abstract":"<div><div>To understand interactions of an elastic floating structure with nonlinear mooring dynamics and multiple wind turbines dynamics especially in irregular waves, the elastic mode expansion of Cummins’ equation for an elastic structure in irregular waves is strongly coupled with nonlinear rod element method for the nonlinear mooring lines through Jacobian matrix formed in a time-domain predictor and corrector solver up to the second order. The multiple wind turbines dynamics is resolved by load mapping of stress resultants at wind turbines into the hosting structure. Three numerical studies are presented to investigate linear elastic mode resonance interacting with both of nonlinear mooring excitation and higher elastic modes with the second order irregular waves, nonlinear elastic mode resonance with higher order harmonic excitation from various mooring lines, and three-dimensional elastic deformation interacting with multiple wind turbines dynamics in combination with nonlinear mooring excitation in irregular wave loads. The numerical study further identifies three-dimensional deformation can have substantial interactions with multiple wind turbine dynamics, influenced by outstanding rigid modes, while analogous symmetry in modes imposes strong coupling between elastic and rigid modes as well. Moreover, the relative configuration between mode shapes, mooring, and wind turbines can determine the coupled hydroelastic responses.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103848"},"PeriodicalIF":4.0,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144147180","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 review on fluid-sediment and foundation-sediment coupling mechanisms and anti-scour countermeasures","authors":"Fei Sha,&nbsp;Jingze Xu,&nbsp;Shijiu Gu,&nbsp;Yulong Dong,&nbsp;Wenwen Xiao","doi":"10.1016/j.marstruc.2025.103843","DOIUrl":"10.1016/j.marstruc.2025.103843","url":null,"abstract":"<div><div>Offshore wind turbines (OWTs) have development prospects in the world energy supply system, and the local scour of the foundation of such turbines is an issue that may hinder their normal operation. Based on existing research, local scour characteristics based on fluid-sediment coupling are presented. At the individual soil particles or groups of particles level, the initiation mechanism of foundation scour is explained based on the force equilibrium of seabed particles, whereas at the scour hole level, the shapes and maximum scour depths are considered. Second, the local scour effects based on foundation-seabed coupling are discussed in terms of the lateral bearing capacity, p-y curve, and natural frequency. The study of fluid-sediment and foundation-sediment coupling mechanisms can clarify the protection mechanism of scour protection measures as well as the enhancement of protection. From the perspective of foundation scour control, different scour monitoring methods are analysed. The effects of different types of scour protection are also emphasised. Finally, the current problems and future research directions are presented. This paper provides insights into reducing the occurrence of the scour phenomenon, realising prevention and control of local foundation scour, and ensuring the normal and safe operation of OWTs.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103843"},"PeriodicalIF":4.0,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144147179","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 response and performance of subsea sandwich pipelines with various interlayers subjected to underwater collision","authors":"Hong Lin ,&nbsp;Longcheng Wei ,&nbsp;Hao Xu ,&nbsp;Hassan Karampour ,&nbsp;Mahmoud Alrsai ,&nbsp;Qi Fan ,&nbsp;Lei Yang","doi":"10.1016/j.marstruc.2025.103853","DOIUrl":"10.1016/j.marstruc.2025.103853","url":null,"abstract":"<div><div>Compared to single-layer pipelines, sandwich pipelines exhibit superior resistance to accidental collisions caused by falling objects. However, previous research has rarely examined sandwich pipelines with different interlayer materials under underwater collisions. This study developed an Arbitrary Lagrangian-Eulerian (ALE) based numerical model to predict the behavior of the sandwich pipe when subjected to complex underwater collision scenarios, considering the fluid-structure interaction (FSI) effects. Subsequently, comparative simulations were performed using the Lagrange method to evaluate its feasibility and accuracy. The results indicate a good agreement between the ALE and Lagrange models. A sensitivity analysis was conducted based on the Lagrange collision model, and investigated the effect of collision velocity, collision angle, seabed properties and interlayer medium on the responses of the sandwich pipeline including deformation, stress, and energy properties. It is concluded that increasing the collision angle, decreasing the collision velocity, and enhancing the seabed stiffness reduce pipeline damage. The inner pipe deformation was more sensitive to the density of the interlayer foam than the outer pipe. Additionally, the water-filled interlayer exhibited superior resistance to collision loads compared to the air-filled interlayer.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103853"},"PeriodicalIF":4.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144135143","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":"Ultimate strength of sandwich elliptical pressure hulls: experimental, numerical and analytical investigations","authors":"Yinhui Tang ,&nbsp;Jian Zhang ,&nbsp;Huifeng Jiao ,&nbsp;Yunsen Hu ,&nbsp;Xiaozhi Hu","doi":"10.1016/j.marstruc.2025.103855","DOIUrl":"10.1016/j.marstruc.2025.103855","url":null,"abstract":"<div><div>This study investigates the buckling resistance of sandwich elliptical pressure hulls using experimental, numerical, and analytical methods. The hull, composed of two thin stainless steel faces bonded to a resin core, was fabricated through shell hydroforming. Geometric and thickness measurements confirmed manufacturing accuracy, and hydrostatic testing was performed to evaluate its structural performance. Nonlinear finite-element analysis (FEA) was used to examine the buckling mechanisms and ultimate strength of the hull. The results reveal that the sandwich structure significantly enhances ultimate strength and stability compared to single-layer elliptical pressure hulls. Specifically, the resin core functions as a barrier and stabilizes the structure by redistributing stresses between the external steel faces, which act as the primary load-bearing components. A semi-analytical equation was also developed and validated to predict the ultimate strength of the sandwich hull under hydrostatic conditions, providing a useful tool for structural design.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"103 ","pages":"Article 103855"},"PeriodicalIF":4.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114939","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}