Pub Date : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119692
Di Zhang, Jin-ming Ye, Kai Liu, Wan-li Yang
As a new vibration and noise reduction measure, the twisted rudder in submarines improves propeller propulsion efficiency and reduces propeller excitation force. To fully understand the performance of the twisted rudder, the control force and propeller cavitation performance under small rudder angles were investigated. The propeller surface pressure pulsation was taken as a dipole sound source, and the low-frequency linear spectrum sound of the submarine propellers with conventional and twisted rudders under small rudder angles was numerically predicted employing an acoustic analogy method. The results showed that the twisted rudder improved the steering maneuverability and was beneficial for improving the cavitation performance of the propeller. The twisted rudder significantly reduced the main blade-passing frequency sound pressure level (1BPF SPL) of the propeller noise, which can reduce the average value of the 1BPF SPL of all monitoring points in the XY and XZ plane by more than 3.963 and 11.872 dB under different rudder angles, respectively. The results also exhibited a correlation between the reduction effect of the 1BPF SPL of the propeller and the reduction effect of the 1BPF amplitude of the unsteady force coefficient. The results have important military application value for submarine propeller noise reduction.
{"title":"Influence of twisted rudder on propeller line spectrum noise and rudder control force in submarines","authors":"Di Zhang, Jin-ming Ye, Kai Liu, Wan-li Yang","doi":"10.1016/j.oceaneng.2024.119692","DOIUrl":"10.1016/j.oceaneng.2024.119692","url":null,"abstract":"<div><div>As a new vibration and noise reduction measure, the twisted rudder in submarines improves propeller propulsion efficiency and reduces propeller excitation force. To fully understand the performance of the twisted rudder, the control force and propeller cavitation performance under small rudder angles were investigated. The propeller surface pressure pulsation was taken as a dipole sound source, and the low-frequency linear spectrum sound of the submarine propellers with conventional and twisted rudders under small rudder angles was numerically predicted employing an acoustic analogy method. The results showed that the twisted rudder improved the steering maneuverability and was beneficial for improving the cavitation performance of the propeller. The twisted rudder significantly reduced the main blade-passing frequency sound pressure level (1BPF SPL) of the propeller noise, which can reduce the average value of the 1BPF SPL of all monitoring points in the XY and XZ plane by more than 3.963 and 11.872 dB under different rudder angles, respectively. The results also exhibited a correlation between the reduction effect of the 1BPF SPL of the propeller and the reduction effect of the 1BPF amplitude of the unsteady force coefficient. The results have important military application value for submarine propeller noise reduction.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119692"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660408","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 : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119670
Yang Cao, Yu Zhang, Shengnan Wu, Chen An
The hydraulic systems of deepwater Blowout Preventers (BOPs) are crucial for ensuring the reliability and safety of offshore oil and gas extraction operations. A functional failure can lead to uncontrolled blowouts, resulting in casualties and significant economic losses on the rig. The Direct Drive Valve (DDV) and the Subsea Plated Mounted (SPM) valve are key components that help maintain the proper functioning of the hydraulic system in deepwater BOPs. This study begins by utilizing the Weibull analysis method to assess the reliability of the DDV and SPM valves using limited fault data samples. To enhance the accuracy of predictions, Weibull parameters are estimated through various methods, including Maximum Likelihood Estimation (MLE), Least Squares Estimation (LSE), and a combination of Correlation Coefficient Optimization with Support Vector Regression (CCO + SVR).Given the challenges in gathering extensive fault data for DDV and SPM valves—due to complex subsea environments, cost constraints, time limitations, and other factors—this study proposes a method employing a Back Propagation Neural Network (BPNN) model to augment the limited fault data samples. To ensure the reliable operation of the DDV and SPM valves, preventive maintenance cycles are established at 2840 and 7550 operations, respectively. At the same reliability level, as the number of operational cycles increases, the remaining service life of the valves gradually decreases, leading to a higher probability of failure over a shorter timeframe. The Mean Remaining Life (MRL) of the DDV and SPM valves, corresponding to different operational times, is analyzed, providing essential reference points for their usage and maintenance. When the extended data sample is utilized for reliability evaluation, the reliability characteristics of the small fault data samples are effectively reflected, and the parameter prediction error remains low. This indicates that the extended data sample is more suitable for reliability evaluation.
{"title":"Reliability analysis of DDV and SPM in BOP-based Weibull model and expand fault dataset using deep learning","authors":"Yang Cao, Yu Zhang, Shengnan Wu, Chen An","doi":"10.1016/j.oceaneng.2024.119670","DOIUrl":"10.1016/j.oceaneng.2024.119670","url":null,"abstract":"<div><div>The hydraulic systems of deepwater Blowout Preventers (BOPs) are crucial for ensuring the reliability and safety of offshore oil and gas extraction operations. A functional failure can lead to uncontrolled blowouts, resulting in casualties and significant economic losses on the rig. The Direct Drive Valve (DDV) and the Subsea Plated Mounted (SPM) valve are key components that help maintain the proper functioning of the hydraulic system in deepwater BOPs. This study begins by utilizing the Weibull analysis method to assess the reliability of the DDV and SPM valves using limited fault data samples. To enhance the accuracy of predictions, Weibull parameters are estimated through various methods, including Maximum Likelihood Estimation (MLE), Least Squares Estimation (LSE), and a combination of Correlation Coefficient Optimization with Support Vector Regression (CCO + SVR).Given the challenges in gathering extensive fault data for DDV and SPM valves—due to complex subsea environments, cost constraints, time limitations, and other factors—this study proposes a method employing a Back Propagation Neural Network (BPNN) model to augment the limited fault data samples. To ensure the reliable operation of the DDV and SPM valves, preventive maintenance cycles are established at 2840 and 7550 operations, respectively. At the same reliability level, as the number of operational cycles increases, the remaining service life of the valves gradually decreases, leading to a higher probability of failure over a shorter timeframe. The Mean Remaining Life (MRL) of the DDV and SPM valves, corresponding to different operational times, is analyzed, providing essential reference points for their usage and maintenance. When the extended data sample is utilized for reliability evaluation, the reliability characteristics of the small fault data samples are effectively reflected, and the parameter prediction error remains low. This indicates that the extended data sample is more suitable for reliability evaluation.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119670"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660402","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 : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119709
Zihang Li , Dan Hu , Fen Li , Wenlin Xiong
The prediction of time-dependent behavior of axial capacity for jacked piles are essential for coastal pile engineering. This study develops a numerical model to simulate the entire process of pile installation, soil consolidation, and loading, incorporating soil-pile interaction effects on excess pore pressure and effective stress distribution in the surrounding soil, which influence the bearing performance of jacked piles in saturated clay. The well consistency between the predictions from the presented approach and the experimental measurement data validate the applicability of the proposed model. The mechanism of set-up effects on the pile axial capacity is elucidated through the evolution of excess pore pressure. A parametric study is performed to assess the influence of the permeability coefficient (k) and length-to-diameter (L/De) ratio on the axial capacity of jacked piles. The findings demonstrate that the proposed model accurately predicts the set-up effects of jacked piles. Specifically, the permeability coefficient primarily impacts the rate of capacity increase, while the axial capacity exhibits a significant rise with an increase in L/De. The derived empirical formula can reasonably guide the design of the axial bearing capacity of piles in saturated clay.
{"title":"Numerical study of set-up effects on axial capacity of jacked piles in saturated clay","authors":"Zihang Li , Dan Hu , Fen Li , Wenlin Xiong","doi":"10.1016/j.oceaneng.2024.119709","DOIUrl":"10.1016/j.oceaneng.2024.119709","url":null,"abstract":"<div><div>The prediction of time-dependent behavior of axial capacity for jacked piles are essential for coastal pile engineering. This study develops a numerical model to simulate the entire process of pile installation, soil consolidation, and loading, incorporating soil-pile interaction effects on excess pore pressure and effective stress distribution in the surrounding soil, which influence the bearing performance of jacked piles in saturated clay. The well consistency between the predictions from the presented approach and the experimental measurement data validate the applicability of the proposed model. The mechanism of set-up effects on the pile axial capacity is elucidated through the evolution of excess pore pressure. A parametric study is performed to assess the influence of the permeability coefficient (<em>k</em>) and length-to-diameter (<em>L</em>/<em>D</em><sub>e</sub>) ratio on the axial capacity of jacked piles. The findings demonstrate that the proposed model accurately predicts the set-up effects of jacked piles. Specifically, the permeability coefficient primarily impacts the rate of capacity increase, while the axial capacity exhibits a significant rise with an increase in <em>L</em>/<em>D</em><sub>e</sub>. The derived empirical formula can reasonably guide the design of the axial bearing capacity of piles in saturated clay.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119709"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660405","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 : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119663
A.K. Kushwaha , V.K. Gupta , H. Behera , T.-W. Hsu
This study develops a theoretical model to analyze wave scattering between multiple floating flexible circular plates and water waves propagating over a porous bed. This boundary value problem is tackled using the eigenfunction expansion technique along with Graf’s addition theorem. Utilizing the relevant boundary conditions, the unknown velocity potentials for the outer area and the plate-covered regions are determined. In each region of the problem domain, the velocity potentials associated with the incident and scattered waves are expressed through an expansion utilizing Bessel and Hankel functions. The study incorporates three distinct edge boundary conditions: clamped, moored, and free. The effectiveness of this study in evaluating the influence of various parameters is assessed by analyzing the heave force acting on the circular plates. This study reveals a compelling trend: as the porous-effect parameter associated with the porous bottom increases, the heave force exerted on the circular plates exhibits a significant reduction. It is also observed that for an array of two, three, and four circular flexible plates, the heave force on each subsequent plate is reduced compared to the preceding plates. Furthermore, to clearly visualize the wave dynamics around the circular flexible plates over time, a time simulation of the fluid flow is provided for different porosity parameter values. This simulation shows a reduced wave amplitude in the lee-side zone. The flow distributions around the circular plates are illustrated both with and without single or multiple circular plates, indicating a lower amplitude in the lee-side zone. The porous bed significantly contributes to diminishing the wave force exerted on the circular plates and establishing a calm area on the back side of the structures.
{"title":"Wave scattering by multiple floating flexible circular plates over a porous bed","authors":"A.K. Kushwaha , V.K. Gupta , H. Behera , T.-W. Hsu","doi":"10.1016/j.oceaneng.2024.119663","DOIUrl":"10.1016/j.oceaneng.2024.119663","url":null,"abstract":"<div><div>This study develops a theoretical model to analyze wave scattering between multiple floating flexible circular plates and water waves propagating over a porous bed. This boundary value problem is tackled using the eigenfunction expansion technique along with Graf’s addition theorem. Utilizing the relevant boundary conditions, the unknown velocity potentials for the outer area and the plate-covered regions are determined. In each region of the problem domain, the velocity potentials associated with the incident and scattered waves are expressed through an expansion utilizing Bessel and Hankel functions. The study incorporates three distinct edge boundary conditions: clamped, moored, and free. The effectiveness of this study in evaluating the influence of various parameters is assessed by analyzing the heave force acting on the circular plates. This study reveals a compelling trend: as the porous-effect parameter associated with the porous bottom increases, the heave force exerted on the circular plates exhibits a significant reduction. It is also observed that for an array of two, three, and four circular flexible plates, the heave force on each subsequent plate is reduced compared to the preceding plates. Furthermore, to clearly visualize the wave dynamics around the circular flexible plates over time, a time simulation of the fluid flow is provided for different porosity parameter values. This simulation shows a reduced wave amplitude in the lee-side zone. The flow distributions around the circular plates are illustrated both with and without single or multiple circular plates, indicating a lower amplitude in the lee-side zone. The porous bed significantly contributes to diminishing the wave force exerted on the circular plates and establishing a calm area on the back side of the structures.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119663"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660512","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}
In this paper the CFD-FEM two-way coupled method is used to simulate the motions and wave loads on a 21000TEU containership subjected to freak waves. A numerical wave tank is established for the generation of long-crested freak waves by wave focusing method based on superimposing sinusoidal component waves. The ship hull is modeled with a backbone beam which reproduces the vertical bending vibration modal behaviour of real ship. The simulated freak waves are checked and the evolution of freak waves during propagation is analyzed first. The ship responses in regular waves at different wave heights and ship speeds are compared. The extreme responses of ship motion and sectional loads in freak waves are analyzed and compared with those in regular waves. The influence of ship forward speed and wave height of freak waves on ship motion and load responses are analyzed and discussed.
{"title":"Hydroelasticity of a 21000TEU containership under freak waves by fluid-flexible structure interaction simulations","authors":"Bowen Ma , Xing Chang , Zhenwei Chen , Jialong Jiao","doi":"10.1016/j.oceaneng.2024.119748","DOIUrl":"10.1016/j.oceaneng.2024.119748","url":null,"abstract":"<div><div>In this paper the CFD-FEM two-way coupled method is used to simulate the motions and wave loads on a 21000TEU containership subjected to freak waves. A numerical wave tank is established for the generation of long-crested freak waves by wave focusing method based on superimposing sinusoidal component waves. The ship hull is modeled with a backbone beam which reproduces the vertical bending vibration modal behaviour of real ship. The simulated freak waves are checked and the evolution of freak waves during propagation is analyzed first. The ship responses in regular waves at different wave heights and ship speeds are compared. The extreme responses of ship motion and sectional loads in freak waves are analyzed and compared with those in regular waves. The influence of ship forward speed and wave height of freak waves on ship motion and load responses are analyzed and discussed.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119748"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660533","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 : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119716
Yikang Wang , Chen Wang , Hao Zhang , Fayun Liang , Zhouchi Yuan
Tetrapod piled jacket (TPJ) foundations, featuring large-diameter semi-rigid piles have been employed to support offshore wind turbines (OWTs), but limited research exists on their dynamic response under seismic excitations in marine environments. Thus, this study employs advanced 3D finite element simulations to analyze and compare the seismic responses of flexible and semi-rigid piled TPJ systems under combined dynamic loads. Under seismic loads, the semi-rigid piled system experience higher compressive stress on the tower but lower maximum stress at X-brace and battered leg joints compared to flexible piled systems. Additionally, soil shear strain in the semi-rigid pile system displays a punch-through failure pattern at the pile end. The impacts of increasing scour depth and clay shear strength on semi-rigid-piled systems are distinctly characterized by greater pile top settlement, augmented bending moment responses, and diminished rotational deformation, compared to those of flexible ones. These findings offer valuable insights into semi-rigid-piled TPJ system dynamic response in complex marine environments.
以大直径半刚性桩为特点的四柱桩套（TPJ）地基已被用于支撑海上风力涡轮机（OWT），但有关其在海洋环境地震激励下的动态响应的研究却十分有限。因此，本研究采用先进的三维有限元模拟，分析和比较了柔性和半刚性桩 TPJ 系统在组合动荷载下的地震响应。与柔性桩基系统相比，在地震荷载作用下，半刚性桩基系统的塔身受到的压应力更大，但在 X 支撑和撞击腿连接处受到的最大应力较小。此外，半刚性桩系统的土壤剪切应变在桩端显示出一种冲穿破坏模式。与柔性桩系统相比，增加冲刷深度和粘土剪切强度对半刚性桩系统的影响表现为桩顶沉降增大、弯矩响应增强和旋转变形减小。这些发现为半刚性桩TPJ系统在复杂海洋环境中的动态响应提供了宝贵的见解。
{"title":"Comparative study of seismic response of offshore tetrapod jacket systems with semi-rigid and flexible piles under environmental loads","authors":"Yikang Wang , Chen Wang , Hao Zhang , Fayun Liang , Zhouchi Yuan","doi":"10.1016/j.oceaneng.2024.119716","DOIUrl":"10.1016/j.oceaneng.2024.119716","url":null,"abstract":"<div><div>Tetrapod piled jacket (TPJ) foundations, featuring large-diameter semi-rigid piles have been employed to support offshore wind turbines (OWTs), but limited research exists on their dynamic response under seismic excitations in marine environments. Thus, this study employs advanced 3D finite element simulations to analyze and compare the seismic responses of flexible and semi-rigid piled TPJ systems under combined dynamic loads. Under seismic loads, the semi-rigid piled system experience higher compressive stress on the tower but lower maximum stress at X-brace and battered leg joints compared to flexible piled systems. Additionally, soil shear strain in the semi-rigid pile system displays a punch-through failure pattern at the pile end. The impacts of increasing scour depth and clay shear strength on semi-rigid-piled systems are distinctly characterized by greater pile top settlement, augmented bending moment responses, and diminished rotational deformation, compared to those of flexible ones. These findings offer valuable insights into semi-rigid-piled TPJ system dynamic response in complex marine environments.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119716"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660543","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 : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119656
Wei Dai , Tianyun Li , Lin Wang , Xiang Zhu , Baiyang Shi , Jian Yang
This paper proposes a nonlinear vibration isolator with hybrid passive elements to mitigate the vibration transmission in floating raft systems. The proposed isolator employs a combination of a geometrically nonlinear linkage mechanism, an inerter, and a motion constraint. Analytical and numerical methods are applied to determine the responses. Given the presence of multiple transmission paths and excitations, power flow indices serve as primary metrics for performance assessment. The results show that the constraint can prevent the folding problem of the linkage mechanism. This, in turn, provides 1) flexibility in the parameter design to achieve quasi-zero dynamic stiffness and 2) protection for geometrically nonlinear systems under extreme operating conditions. The proposed element introduces an anti-peak into the response and power transmission curves, effectively shifting the resonance peaks to lower frequencies. The desired low-frequency isolation performance can be achieved through a coordinated parameter design. This would provide an ultralow response as well as force and energy transmission near the original resonant peaks of the linear system. Furthermore, the proposed design exhibits enhanced performance across diverse operational conditions including multiple frequency excitations and varying mass ratios and forcing amplitudes. These observations demonstrate the potential of utilizing hybrid nonlinear elements in ocean engineering applications.
{"title":"Performance enhancement of floating raft system by exploiting geometric nonlinearity and motion constraint in vibration isolators","authors":"Wei Dai , Tianyun Li , Lin Wang , Xiang Zhu , Baiyang Shi , Jian Yang","doi":"10.1016/j.oceaneng.2024.119656","DOIUrl":"10.1016/j.oceaneng.2024.119656","url":null,"abstract":"<div><div>This paper proposes a nonlinear vibration isolator with hybrid passive elements to mitigate the vibration transmission in floating raft systems. The proposed isolator employs a combination of a geometrically nonlinear linkage mechanism, an inerter, and a motion constraint. Analytical and numerical methods are applied to determine the responses. Given the presence of multiple transmission paths and excitations, power flow indices serve as primary metrics for performance assessment. The results show that the constraint can prevent the folding problem of the linkage mechanism. This, in turn, provides 1) flexibility in the parameter design to achieve quasi-zero dynamic stiffness and 2) protection for geometrically nonlinear systems under extreme operating conditions. The proposed element introduces an anti-peak into the response and power transmission curves, effectively shifting the resonance peaks to lower frequencies. The desired low-frequency isolation performance can be achieved through a coordinated parameter design. This would provide an ultralow response as well as force and energy transmission near the original resonant peaks of the linear system. Furthermore, the proposed design exhibits enhanced performance across diverse operational conditions including multiple frequency excitations and varying mass ratios and forcing amplitudes. These observations demonstrate the potential of utilizing hybrid nonlinear elements in ocean engineering applications.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119656"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660528","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}
Pub Date : 2024-11-12DOI: 10.1016/j.oceaneng.2024.119710
Yunling Ye , Jin Gan , Weiguo Wu , Shan Wang , C. Guedes Soares
The study aims to study the bending and failure behaviour of the inflated membrane beams under floating conditions to support their application in floating platforms. Bending tests are conducted to assess the structural stiffness and ultimate bearing capacity of the beam with various diameters and inflated pressures. With the elastic modulus determined through four-point bending tests, a new analytical formula based on Winkler elastic foundation theory is then developed to predict the deflection of the beams. The results revealed that the beams initially undergo total submersion, followed by end turn-up and anti-arching deformation in the loaded section. The bearing capacity of the beams increases with the increase in internal pressure and diameter. Localised wrinkling is a typical failure mode at low internal pressures, while at high pressures, the failure mode shifts to boundary failure, characterised by submerging in water. The experimental and analytical results show quite good agreement, confirming the accuracy of the current analysis. Overall, this paper contributes to understanding the bending and failure behaviour of inflated membrane beams under floating conditions and supports the offshore structure safety design.
{"title":"Experimental and analytical assessment of the bending behaviour of floating inflated membrane beams","authors":"Yunling Ye , Jin Gan , Weiguo Wu , Shan Wang , C. Guedes Soares","doi":"10.1016/j.oceaneng.2024.119710","DOIUrl":"10.1016/j.oceaneng.2024.119710","url":null,"abstract":"<div><div>The study aims to study the bending and failure behaviour of the inflated membrane beams under floating conditions to support their application in floating platforms. Bending tests are conducted to assess the structural stiffness and ultimate bearing capacity of the beam with various diameters and inflated pressures. With the elastic modulus determined through four-point bending tests, a new analytical formula based on Winkler elastic foundation theory is then developed to predict the deflection of the beams. The results revealed that the beams initially undergo total submersion, followed by end turn-up and anti-arching deformation in the loaded section. The bearing capacity of the beams increases with the increase in internal pressure and diameter. Localised wrinkling is a typical failure mode at low internal pressures, while at high pressures, the failure mode shifts to boundary failure, characterised by submerging in water. The experimental and analytical results show quite good agreement, confirming the accuracy of the current analysis. Overall, this paper contributes to understanding the bending and failure behaviour of inflated membrane beams under floating conditions and supports the offshore structure safety design.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119710"},"PeriodicalIF":4.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660529","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}
Pub Date : 2024-11-09DOI: 10.1016/j.oceaneng.2024.119728
Chenxu Gu , Chengjie Cao , Yongjin Li , Liyu Ye , Chao Wang
To integrate high-performance GPU parallel computing with the peridynamics method and enhance the computational efficiency of numerical simulations for ice-propeller milling, thus providing better data support for the design of propellers in ice-covered areas, a GPU-based parallel peridynamics computational approach was developed on CUDA in this study. The approach was built upon the bond-based peridynamics theory and CUDA programming framework, and its validity was confirmed using test cases involving an airfoil cutting ice and an ice ball impacting a rigid wall. A corresponding three-dimensional GPU parallel computational program was created for the ice-propeller milling process, and the computational code was optimized, resulting in a 24-fold increase in computational efficiency. Utilizing the high-performance computational code, the influence of sea ice elastic modulus and propeller pitch on the mechanical performance of the blades was investigated. The computational results revealed that the ice loads on the blades increased with rising elastic modulus and decreased with increasing pitch, and a larger pitch led to more sea ice being milled away.
为了将高性能 GPU 并行计算与周流体力学方法相结合，提高冰-螺旋桨铣削数值模拟的计算效率，从而为冰覆盖地区的螺旋桨设计提供更好的数据支持，本研究在 CUDA 上开发了一种基于 GPU 的并行周流体力学计算方法。该方法建立在基于键的周流体力学理论和 CUDA 编程框架之上，其有效性通过涉及机翼切冰和冰球撞击刚性壁的测试案例得到了证实。针对冰桨铣削过程创建了相应的三维 GPU 并行计算程序，并对计算代码进行了优化，使计算效率提高了 24 倍。利用高性能计算代码，研究了海冰弹性模量和螺旋桨螺距对叶片机械性能的影响。计算结果表明，叶片上的冰载荷随着弹性模量的增加而增加，随着螺距的增大而减小，螺距越大，铣去的海冰越多。
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Pub Date : 2024-11-09DOI: 10.1016/j.oceaneng.2024.119733
Bin Zhu , Yuan Sun , Tao Wang , Pinqiang Mo , Yunrui Han , Yubin Ren , Jiabo Li
A comprehensive examination of the wave-induced oscillatory response of seabeds around structures is of great significance for ensuring the safe operation of marine engineering projects and enhancing the efficiency of marine resource development. Soil properties in nature exhibit spatial variability due to various geological processes, which should be considered in seabed stability analysis. An integrated CFD-SFEM is proposed for spatially heterogeneous seabeds, incorporating multi-physical solvers for nonlinear wave motion and poroelastic seabed response within a unified framework through a one-way coupling procedure. The wave sub-model for nonlinear fluid flow is based on RANS equations, with an internal wave-maker and absorbing layers realized by employing a momentum source function and damping source terms. The spatially heterogeneous seabed sub-model is based on Biot's poroelastic theory and the random field method. We have implemented the integrated model and automated the iterative algorithm for MCS using MATLAB codes, assisted by the LiveLink platform. The proposed method has been validated from various perspectives and applied to a study of soil response around a partially buried pipeline to demonstrate its practical utility. This study offers a novel framework and perspective for the probabilistic evaluation of oscillatory responses in spatially varied seabeds surrounding structures.
{"title":"Oscillatory responses of a spatially random seabed in the vicinity of structures: Validation and application of the integrated CFD-SFEM","authors":"Bin Zhu , Yuan Sun , Tao Wang , Pinqiang Mo , Yunrui Han , Yubin Ren , Jiabo Li","doi":"10.1016/j.oceaneng.2024.119733","DOIUrl":"10.1016/j.oceaneng.2024.119733","url":null,"abstract":"<div><div>A comprehensive examination of the wave-induced oscillatory response of seabeds around structures is of great significance for ensuring the safe operation of marine engineering projects and enhancing the efficiency of marine resource development. Soil properties in nature exhibit spatial variability due to various geological processes, which should be considered in seabed stability analysis. An integrated CFD-SFEM is proposed for spatially heterogeneous seabeds, incorporating multi-physical solvers for nonlinear wave motion and poroelastic seabed response within a unified framework through a one-way coupling procedure. The wave sub-model for nonlinear fluid flow is based on RANS equations, with an internal wave-maker and absorbing layers realized by employing a momentum source function and damping source terms. The spatially heterogeneous seabed sub-model is based on Biot's poroelastic theory and the random field method. We have implemented the integrated model and automated the iterative algorithm for MCS using MATLAB codes, assisted by the LiveLink platform. The proposed method has been validated from various perspectives and applied to a study of soil response around a partially buried pipeline to demonstrate its practical utility. This study offers a novel framework and perspective for the probabilistic evaluation of oscillatory responses in spatially varied seabeds surrounding structures.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119733"},"PeriodicalIF":4.6,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660523","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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