Ocean EngineeringPub Date : 2025-06-04DOI: 10.1016/j.oceaneng.2025.121577
Daoming Pan, Honglei Sun, Tingyu Wu
{"title":"Dynamic behavior and stiffness degradation of fine-grained gassy soils under cyclic loading","authors":"Daoming Pan, Honglei Sun, Tingyu Wu","doi":"10.1016/j.oceaneng.2025.121577","DOIUrl":"10.1016/j.oceaneng.2025.121577","url":null,"abstract":"<div><div>The dynamic behavior of fine-grained gassy soils under cyclic loading remains unclear, particularly regarding small-strain properties and stiffness degradation. This study investigates the effects of gas content, cyclic stress ratio (CSR), and frequency on these responses using triaxial tests and bender element measurements. Results show gas content significantly influences strain accumulation: higher gas levels exacerbate permanent axial strain and pore pressure buildup under increased CSR, with stiffness degradation accelerating as stress amplitude rises. Both dynamic elastic modulus and small-strain shear modulus (<em>G</em><sub>max</sub>) decrease with CSR, though <em>G</em><sub>max</sub> degrades less prominently, highlighting distinct deformation mechanisms across strain scales. Gas presence amplifies modulus reduction, especially at low frequencies, due to restricted bubble mobility. This work underscores gas content as a critical factor in modulating cyclic response, revealing that even moderate gas inclusion alters soil stiffness and strain behavior. Findings advance understanding of gassy soil dynamics, informing offshore foundation design in gas-rich environments.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121577"},"PeriodicalIF":4.6,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204852","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}
Ocean EngineeringPub Date : 2025-06-04DOI: 10.1016/j.oceaneng.2025.121699
Baoyin Sun , Long Gao , Kai Wang , Jinzhe Ye , Jiaheng Xuan , Yongxin Wu , Jinping Ou
{"title":"A practical multi-scale simulation framework for high-cycle fatigue analysis of wind turbines","authors":"Baoyin Sun , Long Gao , Kai Wang , Jinzhe Ye , Jiaheng Xuan , Yongxin Wu , Jinping Ou","doi":"10.1016/j.oceaneng.2025.121699","DOIUrl":"10.1016/j.oceaneng.2025.121699","url":null,"abstract":"<div><div>Wind turbines (WTs) are vulnerable to high-cycle fatigue, especially in welded or structurally weak regions, leading to crack initiation and propagation. Existing fatigue assessment methods based on monitoring are limited by sensors and data integrity issues, thereby impeding their extensive utilization in engineering practice. While finite element methods (FEM) can address some of these challenges, accurately simulating fatigue cracks remains difficult. This study proposes a novel coupled analysis framework integrating FEM and peridynamics (PD), offering an effective approach for simulating high-cycle fatigue behavior in WTs. It begins with an introduction to the fundamental concepts of PD theory, the surface softening effect correction method, and a fatigue model tailored for the PD framework. A robust coupling strategy is developed and implemented in the OpenSees platform, ensuring displacement continuity and force equilibrium between solid elements and the PD model. Furthermore, an integrated simulation framework combining Matlab and OpenSees is established for multiscale, high-cycle fatigue analysis of WT structures. The proposed methodology is validated through three numerical case studies, demonstrating its effectiveness in assessing wind-induced fatigue damage. The framework proves especially effective in modeling crack propagation in complex welded regions, underscoring its potential for practical applications in the fatigue analysis of WT structures.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121699"},"PeriodicalIF":4.6,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204502","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121507
Wanwan Zhang, Jørn Vatn, Adil Rasheed
{"title":"A differential evolution based approach for short-term predictive maintenance optimization of an offshore wind turbine","authors":"Wanwan Zhang, Jørn Vatn, Adil Rasheed","doi":"10.1016/j.oceaneng.2025.121507","DOIUrl":"10.1016/j.oceaneng.2025.121507","url":null,"abstract":"<div><div>Offshore wind energy is growing rapidly but faces high maintenance costs. To implement predictive maintenance (PdM) in this field, this paper proposes a novel optimization approach for short-term PdM of a single offshore wind turbine (OWT). It combines an adaptive differential evolution algorithm with optional archive (JADE) and Gaussian process regression (GPR) models through a reinforcement learning (RL) framework. Temperatures from four OWTs are processed by an autoencoder to create a database. Using this database, a case study involving an OWT with five components is conducted. First, GPR models generate probabilistic remaining useful life (RUL) predictions for each component. An RL agent then simulates future degradation trajectories based on these predictions. JADE is applied across different scenarios to optimize maintenance by interacting with the virtual environment, considering external factors such as electricity and component prices, wind speeds, and maintenance duration. Results show that the maintenance plan based on pessimistic RUL forecasts exhibits the highest robustness across scenarios. This approach delivers highly precise and robust PdM schedules under prognostic uncertainty. It bridges a critical gap in integrating failure prognostics with maintenance optimization for OWTs.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121507"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195236","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 reinforcement learning-based control approach with lightweight feature for robotic fish heading control in complex environments: Real-world training","authors":"Xing Chen , Xinliang Tian , Jingpu Chen , Qiong Hu , Binrong Wen , Xiyang Liu , Yu Chen , Siyu Tang","doi":"10.1016/j.oceaneng.2025.121667","DOIUrl":"10.1016/j.oceaneng.2025.121667","url":null,"abstract":"<div><div>In complex and unpredictable ocean environments, reinforcement learning (RL) based intelligent control strategy holds significant potential for enhancing the survival and operation performance of robotic fish. Although it is well known that training RL-based control strategy in real-world environments possesses numerous advantages, yet achieving it remains significant challenges such as training approach and computational power. This paper proposes a RL-based lightweight control strategy for robotic fish heading direction control, which can be implemented on a compact control system (72 MHz) in the physical world. The control strategy integrates RL with a central pattern generator (CPG). Specifically, RL is employed for decision-making processes, whereas CPG plays a crucial role in action execution. Functional segregation within this framework enables low computational consumption while facilitating rapid convergence. The proposed control strategy is validated through the conduction of diverse directional swimming tests in a wire-driven robotic fish that is trained in a circulating water channel. The complex flow environment and the damaged caudal fin are incorporated into the tests, demonstrating the satisfactory generalization performance, robustness, and adaptability to unknown control scenarios in practical applications. The proposed control strategy exhibits approximately a <span><math><mrow><mn>50</mn><mspace></mspace><mo>%</mo></mrow></math></span> enhancement in control accuracy and a notable improvement in stability compared to the traditional PID approach. This study offers a valuable reference for the development and implementation of RL-based control strategy in robotic fish, specifically for physical training and directional control during swimming.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121667"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204498","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121545
Nitin Gupta, Barun Pratiher
{"title":"Hydrodynamic modeling with cascade PID control and experimental realization of a two-link flexible underwater robotic manipulator","authors":"Nitin Gupta, Barun Pratiher","doi":"10.1016/j.oceaneng.2025.121545","DOIUrl":"10.1016/j.oceaneng.2025.121545","url":null,"abstract":"<div><div>Flexible robotic manipulators play a vital role in underwater exploration, but fluid-structure interactions and link elasticity pose significant dynamic challenges. This study presents a novel dynamic model incorporating key hydrodynamic effects, including added mass, viscous damping, and drag forces. The model accurately characterizes natural frequencies, mode shapes, and vibration response using extended Hamilton’s principle and the assumed mode method (AMM). The coupled nonlinear partial differential equations (PDEs) are systematically reduced to ordinary differential equations (ODEs) with well-defined boundary conditions, enhancing analytical and computational efficiency. A two-stage cascade Proportional—Integral—Derivative (PID) controller is designed to independently regulate the rigid-body and flexible-link dynamics, ensuring precise motion control and improved stability. The underwater environment’s influence on vibration characteristics is analyzed through modal studies, revealing a significant reduction in eigenfrequencies. Comparative experimental and analytical investigations in air and water demonstrate a substantial decrease in tip displacement and vibrational peak amplitude in submerged conditions. MATLAB simulations and experimental validation confirm the proposed control strategy effectively suppresses vibrations, with faster damping in water. This research establishes a comprehensive framework for modeling, analyzing, and controlling underwater flexible manipulators, contributing to their stability and efficiency for critical marine applications such as inspection, intervention, and maintenance.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121545"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204853","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121706
Kang Cheng , Chen Xu , Min Liu , Yongqi Zhang , Yijun Mao
{"title":"Comparative study of tonal noise prediction methods for stator-rotor interaction","authors":"Kang Cheng , Chen Xu , Min Liu , Yongqi Zhang , Yijun Mao","doi":"10.1016/j.oceaneng.2025.121706","DOIUrl":"10.1016/j.oceaneng.2025.121706","url":null,"abstract":"<div><div>Tonal noise radiated from the periodic flow induced by stator-rotor interaction has attracted considerable attention as a primary noise component in pump-jet propulsors. This paper explores a multi-phase, multi-reference frame method (MMFM) for the fast prediction of the periodic flow in pump-jet propulsors. The method quickly extracts periodic features by simulating the steady flow at different relative circumferential positions between the rotor and the stator, thereby avoiding the computational inefficiency of the time-domain numerical method (TDNM). Using TDNM as a benchmark, a comparative analysis is conducted between MMFM and the nonlinear harmonic method (NLHM) to evaluate their computational accuracy and cost in predicting the periodic flow and associated tonal noise. The results show that NLHM outperforms MMFM in capturing the periodic flow. The maximum errors in predicting the sound pressure level of MMFM and NLHM are 2.2 dB and 3.6 dB, respectively, over 488 spherical observer points, with 20.5 % and 73.6 % of the points having errors within ±1 dB. Their computational times are 5.6 % and 4.7 % of TDNM, while their computational costs are 16.7 % and 1.2 % of TDNM, respectively. Both methods significantly reduce computational cost while maintaining acceptable accuracy, providing efficient tools for predicting the tonal noise of pump-jet propulsors.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121706"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204854","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121657
Tao Zhao , Li Zou , Zongbing Yu , Guoqing Jin , Xinyu Ma
{"title":"Numerical investigation of internal waves generated by submerged bodies with different aspect ratios in stratified flow","authors":"Tao Zhao , Li Zou , Zongbing Yu , Guoqing Jin , Xinyu Ma","doi":"10.1016/j.oceaneng.2025.121657","DOIUrl":"10.1016/j.oceaneng.2025.121657","url":null,"abstract":"<div><div>Understanding the characteristics of internal waves generated by submerged bodies in a density-stratified environment is essential for clarifying their formation and propagation mechanisms. This knowledge provides a scientific basis for optimizing submerged body design and enhancing navigation trajectory inversion strategies. This study uses a numerical method incorporating a linear pycnocline. It analyzes the spatial characteristics of internal waves generated by submerged bodies with varying aspect ratios (<span><math><mrow><mi>ϑ</mi></mrow></math></span>), and their relationship with wake centerline velocity. Increasing <span><math><mrow><mi>ϑ</mi></mrow></math></span> significantly raises the wave height of the generated internal waves, showing a nearly linear trend at higher velocities. Wave height is mainly controlled by the Froude number (Fr), with <span><math><mrow><mi>ϑ</mi></mrow></math></span> having a more pronounced effect than velocity. The wavelength of the generated internal waves shows a critical <span><math><mrow><mi>ϑ</mi></mrow></math></span>, at which it reaches its minimum. Although velocity significantly impacts the wavelength, its effect diminishes as <span><math><mrow><mi>ϑ</mi></mrow></math></span> increases. The vertical velocity along the wake centerline is closely related to the generated internal waves. Submerged bodies with larger <span><math><mrow><mi>ϑ</mi></mrow></math></span> exhibit a broader wake evolution region and a longer evolution time.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121657"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195749","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121673
Chun Bao Li , Xiaomei Li , Jianhua Zhang , Mingsheng Chen , Wei Shi
{"title":"Yielding strength assessment of a 15 MW offshore floating wind turbine substructure with a fully coupled approach","authors":"Chun Bao Li , Xiaomei Li , Jianhua Zhang , Mingsheng Chen , Wei Shi","doi":"10.1016/j.oceaneng.2025.121673","DOIUrl":"10.1016/j.oceaneng.2025.121673","url":null,"abstract":"<div><div>With the development of large-scale floating offshore wind turbines (FOWTs), the structural integrity of the floating support structures has become increasingly critical for ensuring operational reliability. The objective of the present study is to carry out a comprehensive dynamic response analysis of a 15 MW FOWT substructure under extreme loads specified by the International Electrotechnical Commission (IEC), with particular focus on yield strength evaluation at critical locations. A framework was proposed to simulate the stress time history of the floating support structure under combined wave, wind, and current actions using a fully coupled approach. The proposed method was validated through a representative case study involving the UMaine VolturnUS-S platform substructure. The potential damage locations were identified by screening regions exhibiting the highest Von Mises stress concentrations at the incident wave frequency corresponding to the peak surge acceleration Response Amplitude Operator (RAO). The proposed method was subsequently employed to systematically investigate wave-wind-current interactions and their effects on local stress characteristics in the time domain. Statistical analysis was conducted to quantify the influence of varying wave heights and wind speeds on stress distributions at identified critical locations. Finally, the yielding strength assessment was performed to assess the possibility of structural collapse at the potential damage locations. The findings showed that the total stress response is predominantly governed by Rotor Nacelle Assembly (RNA) excitation and wave actions. As wind speeds increase, the mean value of the total stress response presents explicit offsets from the zero averages. Conversely, while wave height variations minimally affect mean stress values, they substantially amplify stress fluctuation amplitudes.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121673"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195234","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121708
Chenxuan Jing , Shengguo Shi , Xuezhi Li , Song Li , Jiangyi Zhang , Desen Yang
{"title":"Scattering modulation of sound waves by underwater oscillating cylinder and surrounding perturbed flow","authors":"Chenxuan Jing , Shengguo Shi , Xuezhi Li , Song Li , Jiangyi Zhang , Desen Yang","doi":"10.1016/j.oceaneng.2025.121708","DOIUrl":"10.1016/j.oceaneng.2025.121708","url":null,"abstract":"<div><div>Numerical and experimental investigations are conducted to analyze the modulation of sound wave scattering caused by the underwater oscillating cylinder and its surrounding perturbed flow. A numerical analysis method is developed, comprising four steps: (1) simulating the perturbed flow field generated by oscillating cylinder; (2) mapping flow data to the acoustic domain via spatial interpolation; (3) simulating the scattered sound field at various times under the quasi-static assumption by solving the convected wave equation; (4) performing temporal interpolation on the time-discretized sound field to analyze time-frequency characteristics. Additionally, the theoretical analysis elucidates the modulation mechanism of acoustic scattering. The theoretical analysis and numerical results demonstrate that the acoustic scattering by the oscillating cylinder and its surrounding perturbed flow induces a modulation effect, with modulation sideband harmonics appearing on both sides of the incident acoustic wave frequency. The modulated sidebands contain the target's oscillation frequency, which is significant for underwater target identification. Experiments conducted in an anechoic water tank validated the scattering modulation effect and the numerical prediction.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121708"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204595","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}
Ocean EngineeringPub Date : 2025-06-03DOI: 10.1016/j.oceaneng.2025.121726
Ze Chen , Yandong Gu , Weigang Lu , Lin Zhang , Dongdong Zhu , Zhiqiang Zhou
{"title":"Characterization of solid-liquid two-phase flow in a canned-motor pump for marine vehicles based on the Euler-Lagrange method","authors":"Ze Chen , Yandong Gu , Weigang Lu , Lin Zhang , Dongdong Zhu , Zhiqiang Zhou","doi":"10.1016/j.oceaneng.2025.121726","DOIUrl":"10.1016/j.oceaneng.2025.121726","url":null,"abstract":"<div><div>Canned motor pumps are critical components in marine liquid cooling systems, directly impacting operational safety. However, in practical applications, trace impurities accumulate within the system and prolonged operation may lead to wear of the hydraulic components in canned motor pumps, resulting in performance degradation. Complex internal structures hinder particle motion prediction. This research employs the Euler-Lagrange method to simulate solid-liquid two-phase flow. By comparing simulation and experimental results, the accuracy of the simulation model was confirmed. Furthermore, the Stokes number is introduced to analyze the influence of particle trajectories, solid-liquid two-phase velocity and external characteristics under varying particle counts and sizes. Results show that the Stokes number effectively characterizes particle motion. Increasing particle count or size, particle trajectories exhibit pronounced deflection toward the blade pressure surface and accumulate along the volute periphery. Simultaneously, both the head coefficient and efficiency decrease accordingly. An increasing in particle count or decrease in particle size enhances the likelihood of particles entering the motor gap. Moreover, particle velocity within the flow field increases, whereas the liquid phase velocity remains largely unaffected by particle phase. These findings on solid-liquid two-phase flow characteristics provide insights for optimizing marine cooling system performance and extending service life.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"335 ","pages":"Article 121726"},"PeriodicalIF":4.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195235","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}