Pub Date : 2026-01-17DOI: 10.1016/j.marstruc.2026.104012
Shi Guijie , Cao Jiajun , Gao Dawei , Wan Zhong , Wang Deyu
Membrane-type corrugated sheets have been used as the primary barriers for LNG carriers to reduce thermal and mechanical stress level. A small failure in primary barrier could cause severe leakage consequences. As the ship capacity increases, the action loads on the primary barrier also rise, making the corrugated sheets more prone to structural failure. This paper focuses on the buckling strength of a corrugated sheet under hydrostatic pressure. In this research, a series of symmetric and asymmetric hydrostatic pressure tests were carried out on a new type of corrugated sheets. Displacement, strain, and hydrostatic pressure were measured to provide comprehensive data on the weak parts of the corrugated sheet. Three-dimensional scanning revealed the deformation mode of the specimens after the test. FEM simulations were conducted to analyze the Mises stress distribution on the midspan section. Six different buckling criteria are defined, differing in physical quantity and buckling point selection. Their advantages, disadvantages, and applicability are discussed, providing the estimation of critical buckling strength from conservative to radical.
{"title":"Experimental and numerical analysis of critical buckling strength for a corrugated sheet under hydrostatic pressure","authors":"Shi Guijie , Cao Jiajun , Gao Dawei , Wan Zhong , Wang Deyu","doi":"10.1016/j.marstruc.2026.104012","DOIUrl":"10.1016/j.marstruc.2026.104012","url":null,"abstract":"<div><div>Membrane-type corrugated sheets have been used as the primary barriers for LNG carriers to reduce thermal and mechanical stress level. A small failure in primary barrier could cause severe leakage consequences. As the ship capacity increases, the action loads on the primary barrier also rise, making the corrugated sheets more prone to structural failure. This paper focuses on the buckling strength of a corrugated sheet under hydrostatic pressure. In this research, a series of symmetric and asymmetric hydrostatic pressure tests were carried out on a new type of corrugated sheets. Displacement, strain, and hydrostatic pressure were measured to provide comprehensive data on the weak parts of the corrugated sheet. Three-dimensional scanning revealed the deformation mode of the specimens after the test. FEM simulations were conducted to analyze the Mises stress distribution on the midspan section. Six different buckling criteria are defined, differing in physical quantity and buckling point selection. Their advantages, disadvantages, and applicability are discussed, providing the estimation of critical buckling strength from conservative to radical.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104012"},"PeriodicalIF":5.1,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976619","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}
Pub Date : 2026-01-16DOI: 10.1016/j.marstruc.2026.104015
Tae Hee Lee , Mujong Kim , Yena Lee , Sangmin Lee , Jung-Wuk Hong
Dynamic responses of a scaled segmental submerged floating tunnel (SFT) subjected to pendulum-type impact loadings are investigated through a combination of experimental tests and numerical simulations. In the experimental program, displacement responses of the moored SFT model were first examined under impacts applied at the upper, central, and lower parts of the tunnel. Additional tests were conducted by releasing the tension in the mooring lines. The scaled tunnel was fixed at the top and subjected to twelve cases combining three different impactor masses with four initial pendulum angles, enabling direct measurement of impact forces. Structural displacements, mooring line tensions, and impact forces were systematically analyzed to evaluate the dynamic behavior of the SFT under various loading conditions. For the numerical modeling of pendulum impact tests, appropriate buoyancy representation and fluid mesh discretization were identified as critical parameters. Different modeling strategies were assessed, and the most effective combination was selected to obtain accurate results. To ensure accurate contact modeling under diverse impact conditions, the penalty scale factor was calibrated by comparing predicted impact forces with experimental measurements. A cubic polynomial relationship between the penalty scale factor and initial impact velocity was established and extended to the full-scale prototype to provide a practical guideline for contact parameter selection. The calibrated numerical model reproduced the observed responses with prediction errors consistently below 7%. A reliable approach for assessing SFT impact behavior is established by the experimental methodology and verified simulation framework presented in this study. These methodologies not only enhance the efficiency of SFT design and safety evaluation but also provide a foundation for impact studies of other submerged buoyant structures.
{"title":"Effects of impact loadings on a submerged floating tunnel: Experimental and numerical investigations","authors":"Tae Hee Lee , Mujong Kim , Yena Lee , Sangmin Lee , Jung-Wuk Hong","doi":"10.1016/j.marstruc.2026.104015","DOIUrl":"10.1016/j.marstruc.2026.104015","url":null,"abstract":"<div><div>Dynamic responses of a scaled segmental submerged floating tunnel (SFT) subjected to pendulum-type impact loadings are investigated through a combination of experimental tests and numerical simulations. In the experimental program, displacement responses of the moored SFT model were first examined under impacts applied at the upper, central, and lower parts of the tunnel. Additional tests were conducted by releasing the tension in the mooring lines. The scaled tunnel was fixed at the top and subjected to twelve cases combining three different impactor masses with four initial pendulum angles, enabling direct measurement of impact forces. Structural displacements, mooring line tensions, and impact forces were systematically analyzed to evaluate the dynamic behavior of the SFT under various loading conditions. For the numerical modeling of pendulum impact tests, appropriate buoyancy representation and fluid mesh discretization were identified as critical parameters. Different modeling strategies were assessed, and the most effective combination was selected to obtain accurate results. To ensure accurate contact modeling under diverse impact conditions, the penalty scale factor was calibrated by comparing predicted impact forces with experimental measurements. A cubic polynomial relationship between the penalty scale factor and initial impact velocity was established and extended to the full-scale prototype to provide a practical guideline for contact parameter selection. The calibrated numerical model reproduced the observed responses with prediction errors consistently below 7%. A reliable approach for assessing SFT impact behavior is established by the experimental methodology and verified simulation framework presented in this study. These methodologies not only enhance the efficiency of SFT design and safety evaluation but also provide a foundation for impact studies of other submerged buoyant structures.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104015"},"PeriodicalIF":5.1,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976743","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}
Pub Date : 2026-01-16DOI: 10.1016/j.marstruc.2026.104014
Qi Zhang, Ould el Moctar, Changqing Jiang
Offshore wind turbines consist of slender cylindrical members whose fatigue and ultimate strength govern both structural safety and cost. Accurate design requires reliable prediction of wave–structure interactions, including hydroelastic effects, which are often neglected in traditional rigid-body or decoupled analyses. This study implements a fully coupled CFD-FEM framework to investigate hydroelastic responses of a top-fixed flexible cylinder, representative of offshore wind turbine foundations. The framework combines a finite-volume Navier–Stokes solver with a nonlinear structural dynamics solver, validated against benchmark experiments for both rigid hydrodynamics and flexible structural behavior. Results demonstrate that structural flexibility fundamentally alters wave-induced loads, particularly when wave excitation frequencies approach the cylinder’s natural modes. Spectral analysis shows that rigid assumptions overpredict higher-order harmonics in short waves but underpredict key harmonics (2nd, 3rd) in long waves, leading to potentially non-conservative fatigue estimates. Increasing wave steepness amplifies nonlinear interactions and higher-order vibrations, which dominate fatigue-critical responses. These findings highlight the necessity of accounting for hydroelasticity in the design and lifetime assessment of offshore wind support structures to ensure both safety and cost efficiency.
{"title":"Hydroelasticity effects on wave-induced loads for flexible slender components in offshore wind turbines","authors":"Qi Zhang, Ould el Moctar, Changqing Jiang","doi":"10.1016/j.marstruc.2026.104014","DOIUrl":"10.1016/j.marstruc.2026.104014","url":null,"abstract":"<div><div>Offshore wind turbines consist of slender cylindrical members whose fatigue and ultimate strength govern both structural safety and cost. Accurate design requires reliable prediction of wave–structure interactions, including hydroelastic effects, which are often neglected in traditional rigid-body or decoupled analyses. This study implements a fully coupled CFD-FEM framework to investigate hydroelastic responses of a top-fixed flexible cylinder, representative of offshore wind turbine foundations. The framework combines a finite-volume Navier–Stokes solver with a nonlinear structural dynamics solver, validated against benchmark experiments for both rigid hydrodynamics and flexible structural behavior. Results demonstrate that structural flexibility fundamentally alters wave-induced loads, particularly when wave excitation frequencies approach the cylinder’s natural modes. Spectral analysis shows that rigid assumptions overpredict higher-order harmonics in short waves but underpredict key harmonics (2nd, 3rd) in long waves, leading to potentially non-conservative fatigue estimates. Increasing wave steepness amplifies nonlinear interactions and higher-order vibrations, which dominate fatigue-critical responses. These findings highlight the necessity of accounting for hydroelasticity in the design and lifetime assessment of offshore wind support structures to ensure both safety and cost efficiency.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104014"},"PeriodicalIF":5.1,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976742","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}
This work develops an experimentally validated multi-faceted fluid–structure interaction (FSI) model using LS-DYNA to investigate sequential sympathetic implosion of metallic cylinders in semi-confined underwater environments. The numerical model was first validated using experiments in which sequentially arranged aluminum cylinders underwent hydrostatic collapse in a semi-confined chamber, with transient pressure sensors capturing key response metrics. Numerical simulations replicated the observed collapse sequence. They matched the dynamic pressure–time response in both magnitude and timing, reinforcing confidence in the accuracy and predictive capability of the FSI framework. Following this successful validation, a series of parametric studies was conducted by varying the secondary cylinder’s length-to-diameter (L/D) ratio to investigate its influence on sympathetic implosion dynamics, energy absorption, and pressure wave evolution. Results show that increasing the L/D ratio of the secondary cylinder from 4 to 6 leads to earlier sympathetic collapse, greater than 14 % increase in kinetic energy absorption, and strain energy surpassing that of the primary cylinder. Pressure recordings and FSI profiles reveal peak overpressures escalating by 10–15 %, fluid jet velocities doubling (from ∼65 to ∼130 m s-1), and more coherent pressure rebound patterns as slenderness increases. These findings reveal key relationships, including that higher L/D ratios accelerate energy transfer, amplify collapse intensity, and produce stronger, more focused pressure waves. Conversely, shorter cylinders exhibit delayed, impulsive collapse with reduced energy uptake. Overall, this work establishes a predictive framework for designing resilient clustered subsea systems by linking structural geometry, fluid–structure interaction, and shock dynamics to informed mitigation of cascading failure risks.
本文利用LS-DYNA建立了一个实验验证的多面流固相互作用（FSI）模型，用于研究半密闭水下环境中金属圆柱体的顺序交感内爆。数值模型首先通过实验进行验证，在实验中，顺序排列的铝瓶在半密闭腔室中进行静压坍塌，瞬态压力传感器捕获关键响应指标。数值模拟再现了观测到的崩塌顺序。他们在量级和时间上与动态压力-时间响应相匹配，增强了对FSI框架准确性和预测能力的信心。在成功验证后，通过改变次级柱的长径比（L/D）进行了一系列参数研究，以研究其对交感内爆动力学、能量吸收和压力波演变的影响。结果表明，将次柱的L/D比值从4提高到6，交感神经塌陷提前，动能吸收增加14%以上，应变能超过主柱。压力记录和FSI剖面显示，峰值超压上升了10 - 15%，流体喷射速度翻倍（从~ 65到~ 130 m s-1），并且随着细细的增加，压力反弹模式更加一致。这些发现揭示了关键关系，包括更高的L/D比加速了能量传递，放大了坍塌强度，并产生了更强、更集中的压力波。相反，较短的圆柱体表现出延迟的脉冲坍缩，能量摄取减少。总的来说，这项工作通过将结构几何、流固耦合和冲击动力学联系起来，为设计弹性集群海底系统建立了一个预测框架，以减轻级联故障风险。
{"title":"Sympathetic hydrostatic implosions and fluid-structure interaction of metallic cylinders in a semi-confined environment","authors":"Bolaji Oladipo , Helio Matos , Arun Shukla , Sumanta Das","doi":"10.1016/j.marstruc.2026.104010","DOIUrl":"10.1016/j.marstruc.2026.104010","url":null,"abstract":"<div><div>This work develops an experimentally validated multi-faceted fluid–structure interaction (FSI) model using LS-DYNA to investigate sequential sympathetic implosion of metallic cylinders in semi-confined underwater environments. The numerical model was first validated using experiments in which sequentially arranged aluminum cylinders underwent hydrostatic collapse in a semi-confined chamber, with transient pressure sensors capturing key response metrics. Numerical simulations replicated the observed collapse sequence. They matched the dynamic pressure–time response in both magnitude and timing, reinforcing confidence in the accuracy and predictive capability of the FSI framework. Following this successful validation, a series of parametric studies was conducted by varying the secondary cylinder’s length-to-diameter (L/D) ratio to investigate its influence on sympathetic implosion dynamics, energy absorption, and pressure wave evolution. Results show that increasing the L/D ratio of the secondary cylinder from 4 to 6 leads to earlier sympathetic collapse, greater than 14 % increase in kinetic energy absorption, and strain energy surpassing that of the primary cylinder. Pressure recordings and FSI profiles reveal peak overpressures escalating by 10–15 %, fluid jet velocities doubling (from ∼65 to ∼130 m s<sup>-1</sup>), and more coherent pressure rebound patterns as slenderness increases. These findings reveal key relationships, including that higher L/D ratios accelerate energy transfer, amplify collapse intensity, and produce stronger, more focused pressure waves. Conversely, shorter cylinders exhibit delayed, impulsive collapse with reduced energy uptake. Overall, this work establishes a predictive framework for designing resilient clustered subsea systems by linking structural geometry, fluid–structure interaction, and shock dynamics to informed mitigation of cascading failure risks.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104010"},"PeriodicalIF":5.1,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976618","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}
Pub Date : 2026-01-11DOI: 10.1016/j.marstruc.2026.104009
Ramy Gadallah, Masakazu Shibahara
Local weld geometry is a critical factor that strongly influences the fatigue behavior of welded joints. The stress concentration factor (SCF) is a key parameter that quantifies the notch effect caused by such geometry. This study numerically investigates the combined influence of multi-pass welding and phase-transformation-induced welding residual stress (WRS) on SCF behavior at the weld root of butt-welded joints, with particular emphasis on the role of low transformation temperature (LTT) weld material. WRS distributions were simulated for different welding scenarios, including partial and full LTT welds, with a fully conventional multi-pass weld included for comparison. The SCF along the weld root was then evaluated under a range of nominal stress levels by incorporating the WRS from each scenario. The results show that LTT weld material effectively reduced tensile longitudinal WRS at the weld root but introduced unfavorable tensile transverse WRS in and around the root region. Among the investigated cases, the full LTT multi-pass welds provided the greatest benefit, significantly reducing the SCF compared with the full conventional welds, particularly at lower stress levels. In contrast, partial LTT welds placed at the weld root did not yield comparable SCF reductions. The findings indicate that to maximize the benefit of LTT welds, the primary service loading should not be aligned with the unfavorable transverse WRS component. The role of WRS in the evaluated SCF was also quantified and discussed to support the study findings.
{"title":"Influence of low transformation temperature welds on stress concentration at the weld root of multi-pass butt-welded joints","authors":"Ramy Gadallah, Masakazu Shibahara","doi":"10.1016/j.marstruc.2026.104009","DOIUrl":"10.1016/j.marstruc.2026.104009","url":null,"abstract":"<div><div>Local weld geometry is a critical factor that strongly influences the fatigue behavior of welded joints. The stress concentration factor (SCF) is a key parameter that quantifies the notch effect caused by such geometry. This study numerically investigates the combined influence of multi-pass welding and phase-transformation-induced welding residual stress (WRS) on SCF behavior at the weld root of butt-welded joints, with particular emphasis on the role of low transformation temperature (LTT) weld material. WRS distributions were simulated for different welding scenarios, including partial and full LTT welds, with a fully conventional multi-pass weld included for comparison. The SCF along the weld root was then evaluated under a range of nominal stress levels by incorporating the WRS from each scenario. The results show that LTT weld material effectively reduced tensile longitudinal WRS at the weld root but introduced unfavorable tensile transverse WRS in and around the root region. Among the investigated cases, the full LTT multi-pass welds provided the greatest benefit, significantly reducing the SCF compared with the full conventional welds, particularly at lower stress levels. In contrast, partial LTT welds placed at the weld root did not yield comparable SCF reductions. The findings indicate that to maximize the benefit of LTT welds, the primary service loading should not be aligned with the unfavorable transverse WRS component. The role of WRS in the evaluated SCF was also quantified and discussed to support the study findings.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104009"},"PeriodicalIF":5.1,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976741","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}
Pub Date : 2026-01-10DOI: 10.1016/j.marstruc.2026.104008
Kai Hong , Jiazhen Zhan , Yuhao Guo , Gang Liu
With the expansion of offshore wind farms into deeper and more remote seas, the operational environment for offshore wind turbine structures is becoming increasingly harsh. Consequently, ensuring the long-term safety of the tower structure—which supports the entire unit—under complex marine conditions is of critical importance. The Inverse Finite Element Method (iFEM) can reconstruct the full-field deformation of the tower structure in real time, thereby providing a crucial guarantee for real-time structural health monitoring. However, the classical iFEM requires the back-to-back installation of triaxial strain sensors on both sides of the element. This significantly increases the complexity and economic cost of sensor deployment. To address this limitation, this paper proposes a One-Sided Uniaxial Strain-based iFEM (OSUS-iFEM). Then, an optimization method for the weighting coefficients utilizing the Multi-Island Genetic Algorithm has been developed to enhance the reconstruction performance. The proposed method significantly reduces the requirements for sensor configuration by reformulating the error functional. Numerical results demonstrate that the OSUS-iFEM supports flexible selection of in-plane strain measurement schemes (uniaxial, biaxial, or triaxial). Compared to the classical iFEM, this approach significantly reduces the number of sensors required (by up to 83.3%) and simplifies installation complexity. Furthermore, the method demonstrates good robustness even with sparse sensor configurations and a coarse mesh. Even in an extremely sparse configuration (using only 24 sensors), the MAE and RMSE remain within 8.5 mm and 9.5 mm, respectively. After optimization, the MAE and RMSE values are consistently maintained below 2.4 mm and 4.1 mm, respectively.
{"title":"An inverse finite element method for full-field deformation reconstruction of wind turbine towers using one-sided uniaxial strain","authors":"Kai Hong , Jiazhen Zhan , Yuhao Guo , Gang Liu","doi":"10.1016/j.marstruc.2026.104008","DOIUrl":"10.1016/j.marstruc.2026.104008","url":null,"abstract":"<div><div>With the expansion of offshore wind farms into deeper and more remote seas, the operational environment for offshore wind turbine structures is becoming increasingly harsh. Consequently, ensuring the long-term safety of the tower structure—which supports the entire unit—under complex marine conditions is of critical importance. The Inverse Finite Element Method (iFEM) can reconstruct the full-field deformation of the tower structure in real time, thereby providing a crucial guarantee for real-time structural health monitoring. However, the classical iFEM requires the back-to-back installation of triaxial strain sensors on both sides of the element. This significantly increases the complexity and economic cost of sensor deployment. To address this limitation, this paper proposes a One-Sided Uniaxial Strain-based iFEM (OSUS-iFEM). Then, an optimization method for the weighting coefficients utilizing the Multi-Island Genetic Algorithm has been developed to enhance the reconstruction performance. The proposed method significantly reduces the requirements for sensor configuration by reformulating the error functional. Numerical results demonstrate that the OSUS-iFEM supports flexible selection of in-plane strain measurement schemes (uniaxial, biaxial, or triaxial). Compared to the classical iFEM, this approach significantly reduces the number of sensors required (by up to 83.3%) and simplifies installation complexity. Furthermore, the method demonstrates good robustness even with sparse sensor configurations and a coarse mesh. Even in an extremely sparse configuration (using only 24 sensors), the MAE and RMSE remain within 8.5 mm and 9.5 mm, respectively. After optimization, the MAE and RMSE values are consistently maintained below 2.4 mm and 4.1 mm, respectively.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104008"},"PeriodicalIF":5.1,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938755","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}
Pub Date : 2026-01-09DOI: 10.1016/j.marstruc.2025.104004
Afolarinwa David Oyegbile , Michael Muskulus , Athanasios Kolios
This article presents a practical framework for minimizing the mass of offshore wind jacket structures under fatigue constraints with fully discrete design variables. The Heuristic Particle Elimination Optimization (HPEO) algorithm is employed to navigate a predefined catalogue of tubular diameters and wall thicknesses, ensuring manufacturable solutions without continuous relaxation or rounding. The framework integrates detailed fatigue verification with catalogue-based discrete sizing and explicit modelling of conical transition joints. The effectiveness of this approach is demonstrated on a jacket support structure for an offshore wind turbine under requirements related to natural frequencies, ultimate strength, and fatigue life. A coupled aero–hydro–servo–elastic model is used to compute the dynamic response under wind and wave loading. Stress concentration factors (SCFs) are obtained using Efthymiou parametric expressions, and hot-spot stresses at eight chord and brace locations are evaluated through superposition of axial, in-plane, and out-of-plane components; additional hot-spot stresses at conical transitions are also included. Fatigue damage is computed using rainflow counting and Miner’s rule. Results show that conical transitions can govern fatigue, highlighting the need to model them explicitly. Refining the design discretization from a coarse model (six pipe families) to a fine model (32 members with explicit cans and stubs) reduced the optimized jacket mass by up to 26.5%, with all natural-frequency, strength, and fatigue constraints still satisfied. Despite large initial particle pools, fewer than 5% in the coarse and in the fine discretization required full analyses, demonstrating computational savings of several orders of magnitude compared with population-based heuristics. By discarding non-promising candidates early, the HPEO framework converges to optimal or near-optimal designs that satisfy both mass reduction and fatigue life requirements.
{"title":"Fatigue-constrained jacket optimization using Heuristic Particle Elimination Optimization algorithm with catalogue-discrete variables and conical joint modelling","authors":"Afolarinwa David Oyegbile , Michael Muskulus , Athanasios Kolios","doi":"10.1016/j.marstruc.2025.104004","DOIUrl":"10.1016/j.marstruc.2025.104004","url":null,"abstract":"<div><div>This article presents a practical framework for minimizing the mass of offshore wind jacket structures under fatigue constraints with fully discrete design variables. The Heuristic Particle Elimination Optimization (HPEO) algorithm is employed to navigate a predefined catalogue of tubular diameters and wall thicknesses, ensuring manufacturable solutions without continuous relaxation or rounding. The framework integrates detailed fatigue verification with catalogue-based discrete sizing and explicit modelling of conical transition joints. The effectiveness of this approach is demonstrated on a jacket support structure for an offshore wind turbine under requirements related to natural frequencies, ultimate strength, and fatigue life. A coupled aero–hydro–servo–elastic model is used to compute the dynamic response under wind and wave loading. Stress concentration factors (SCFs) are obtained using Efthymiou parametric expressions, and hot-spot stresses at eight chord and brace locations are evaluated through superposition of axial, in-plane, and out-of-plane components; additional hot-spot stresses at conical transitions are also included. Fatigue damage is computed using rainflow counting and Miner’s rule. Results show that conical transitions can govern fatigue, highlighting the need to model them explicitly. Refining the design discretization from a coarse model (six pipe families) to a fine model (32 members with explicit cans and stubs) reduced the optimized jacket mass by up to 26.5%, with all natural-frequency, strength, and fatigue constraints still satisfied. Despite large initial particle pools, fewer than 5% in the coarse and <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup><mtext>%</mtext></mrow></math></span> in the fine discretization required full analyses, demonstrating computational savings of several orders of magnitude compared with population-based heuristics. By discarding non-promising candidates early, the HPEO framework converges to optimal or near-optimal designs that satisfy both mass reduction and fatigue life requirements.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104004"},"PeriodicalIF":5.1,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938800","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}
Pub Date : 2026-01-09DOI: 10.1016/j.marstruc.2026.104007
Hao Chen , Jisheng Zhang , Jianjian Zhao , Yu Zhang , Yakun Guo , Hao Hu , Yiming Ji , Yanhong Wang
The continuous development of clean energy and the growing demand for environmentally friendly power generation have made vertical-axis tidal turbines an important choice. These turbines have advantages because they can adapt to complex marine flow environments and areas with a wide range of flow velocity. Operational safety of the tidal stream energy system is important in the development of tidal energy, while tidal flow induced scour around the vertical-axis tidal turbine is one of factors causing the instability of the system. To this end, physical laboratory experiments are conducted in this study to evaluate the influences of flow intensity, tip clearance, tip speed ratio and water depth on the scour evolution around the tidal stream energy system foundation. The equilibrium scour topography is analyzed. The impact of the turbine rotor operation on the foundation erosion is examined by comparing the scour topography around the monopile foundation without turbine structure. Results show that the maximum scour depth and the scour extent around the foundation increase with the increase of flow intensity and tip speed ratio, but decrease with the increase of tip clearance and water depth. It is found that the rotor rotation significantly enhances sediment transport and scour around the foundation.
{"title":"On seabed scour around the vertical-axis tidal turbine under unidirectional flow loading","authors":"Hao Chen , Jisheng Zhang , Jianjian Zhao , Yu Zhang , Yakun Guo , Hao Hu , Yiming Ji , Yanhong Wang","doi":"10.1016/j.marstruc.2026.104007","DOIUrl":"10.1016/j.marstruc.2026.104007","url":null,"abstract":"<div><div>The continuous development of clean energy and the growing demand for environmentally friendly power generation have made vertical-axis tidal turbines an important choice. These turbines have advantages because they can adapt to complex marine flow environments and areas with a wide range of flow velocity. Operational safety of the tidal stream energy system is important in the development of tidal energy, while tidal flow induced scour around the vertical-axis tidal turbine is one of factors causing the instability of the system. To this end, physical laboratory experiments are conducted in this study to evaluate the influences of flow intensity, tip clearance, tip speed ratio and water depth on the scour evolution around the tidal stream energy system foundation. The equilibrium scour topography is analyzed. The impact of the turbine rotor operation on the foundation erosion is examined by comparing the scour topography around the monopile foundation without turbine structure. Results show that the maximum scour depth and the scour extent around the foundation increase with the increase of flow intensity and tip speed ratio, but decrease with the increase of tip clearance and water depth. It is found that the rotor rotation significantly enhances sediment transport and scour around the foundation.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 104007"},"PeriodicalIF":5.1,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938793","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}
Pub Date : 2026-01-07DOI: 10.1016/j.marstruc.2025.104005
Arun Rajput , Harikrishna Chavhan
The elastic properties of honeycomb structures are determined by the foil thickness (FT) and cell size (CS), which significantly influence their mechanical behavior. In present study, comparison of energy absorption capacity and specific energy absorption of different shapes of honeycombs (Hexagonal, Square and Triangular) sandwich composites has been presented. Initially, experiments were performed on a pair of hexagonal honeycomb sandwich composites using a Charpy impact testing machine in accordance with ASTM E23 standards. The experimental results were validated through numerical simulations conducted using the commercially available software Abaqus, showing good agreement. Subsequently, numerical simulations were extended to various honeycomb sandwich structure geometries. Energy absorption and specific energy absorption (SEA) values were extracted at the time steps corresponding to the detachment of the specimen from the supports. A comparison of the energy absorbed by different honeycomb shapes was carried out. Furthermore, the influence of FT, CS, and core height (CH) on the SEA of various honeycomb geometries was examined through detailed numerical analysis.
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Ships can suffer impact injuries when they are impacted by underwater explosions. Currently, the impact injury studies of seated crew members are mostly focused on lumbar-pelvic and neck whiplash injuries, and there is a lack of analysis of secondary collision injuries in the absence of seatbelt restraints. In this paper, an impact injury analysis of seated shipmates was carried out based on a multibody dynamics human model, and the accuracy of the model was verified by experimental comparison. Head Injury Criterion (HIC), Neck Injury (NIJ), Dynamic Response Index (DRI) and other injury guidelines were used to evaluate the impact damage in various parts of the human body. Sensitivity analysis was conducted for two parameters, namely impact factor and angle of attack, comparing the damage patterns of the human body with and without seat belt restraints. The results showed that the crew with a seatbelt produced a four-cycle whiplash motion, and the crew without a seatbelt would produce three phases: flight phase, deck-head collision phase, and deck-torso collision phase. These findings can guide the development of impact injury protection strategies for shipmates.
当船只受到水下爆炸的冲击时，可能会受到撞击伤。目前，对坐式乘员的碰撞损伤研究多集中在腰骨盆和颈部颈部鞭打伤，缺乏对无安全带约束的二次碰撞损伤的分析。本文基于多体动力学人体模型对坐式船友的碰撞损伤进行了分析，并通过实验对比验证了模型的准确性。采用Head Injury Criterion （HIC）、Neck Injury （NIJ）、Dynamic Response Index （DRI）等损伤指南对人体各部位的冲击损伤进行评价。对冲击系数和迎角两个参数进行敏感性分析，比较有无安全带约束时人体的损伤模式。结果表明，系安全带的机组人员产生了4个周期的鞭动，而不系安全带的机组人员产生了3个周期的鞭动：飞行阶段、甲板头部碰撞阶段和甲板躯干碰撞阶段。这些发现可以指导船员碰撞伤害保护策略的制定。
{"title":"Research on impact damage of ship crew with sitting posture","authors":"Wenqi Zhang , Shenhe Zhang , Zhifan Zhang , Guiyong Zhang , Ying Li","doi":"10.1016/j.marstruc.2025.103996","DOIUrl":"10.1016/j.marstruc.2025.103996","url":null,"abstract":"<div><div>Ships can suffer impact injuries when they are impacted by underwater explosions. Currently, the impact injury studies of seated crew members are mostly focused on lumbar-pelvic and neck whiplash injuries, and there is a lack of analysis of secondary collision injuries in the absence of seatbelt restraints. In this paper, an impact injury analysis of seated shipmates was carried out based on a multibody dynamics human model, and the accuracy of the model was verified by experimental comparison. Head Injury Criterion (HIC), Neck Injury (NIJ), Dynamic Response Index (DRI) and other injury guidelines were used to evaluate the impact damage in various parts of the human body. Sensitivity analysis was conducted for two parameters, namely impact factor and angle of attack, comparing the damage patterns of the human body with and without seat belt restraints. The results showed that the crew with a seatbelt produced a four-cycle whiplash motion, and the crew without a seatbelt would produce three phases: flight phase, deck-head collision phase, and deck-torso collision phase. These findings can guide the development of impact injury protection strategies for shipmates.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"107 ","pages":"Article 103996"},"PeriodicalIF":5.1,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884568","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}
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