Pub Date : 2024-04-09DOI: 10.1177/14750902241242248
Wen Jiang, jin Zhao, Tao Bian, Wuxin Yu
This paper studies the effect of the duct geometry on the hydrodynamic performance of rim-driven thruster (RDT) based on Computational Fluid Dynamics (CFD) method. The effect of the thickness of the duct, the radius of the leading edge of the duct and the geometry of the trailing edge of the duct on the thrust coefficient, torque coefficient and efficiency are investigated and analyzed. The conclusion shows the thrust coefficient increases with the thickness of the duct decreasing, however the torque coefficient increases with the increase of the thickness of the duct, so the efficiency increasing with the decrease of the thickness of the duct. On the other hand, the radius of the leading edge of the duct has no significant effect on the thrust coefficient of the RDT. However, the torque coefficient of RDT decreases with the increase of the radius of the leading edge of the duct, so the efficiency of RDT increases with the increase of the radius of the leading edge of the duct. A comprehensive comparison shows that the RDT 15-0.5 (the duct thickness is 15 mm, the ratio of the radius of the leading edge of the duct and the duct thickness is 0.5) has the best hydrodynamic performance among the investigated RDT models in this work.
{"title":"Numerical analysis of the effect of the duct geometry on the hydrodynamic performance of rim-driven thruster","authors":"Wen Jiang, jin Zhao, Tao Bian, Wuxin Yu","doi":"10.1177/14750902241242248","DOIUrl":"https://doi.org/10.1177/14750902241242248","url":null,"abstract":"This paper studies the effect of the duct geometry on the hydrodynamic performance of rim-driven thruster (RDT) based on Computational Fluid Dynamics (CFD) method. The effect of the thickness of the duct, the radius of the leading edge of the duct and the geometry of the trailing edge of the duct on the thrust coefficient, torque coefficient and efficiency are investigated and analyzed. The conclusion shows the thrust coefficient increases with the thickness of the duct decreasing, however the torque coefficient increases with the increase of the thickness of the duct, so the efficiency increasing with the decrease of the thickness of the duct. On the other hand, the radius of the leading edge of the duct has no significant effect on the thrust coefficient of the RDT. However, the torque coefficient of RDT decreases with the increase of the radius of the leading edge of the duct, so the efficiency of RDT increases with the increase of the radius of the leading edge of the duct. A comprehensive comparison shows that the RDT 15-0.5 (the duct thickness is 15 mm, the ratio of the radius of the leading edge of the duct and the duct thickness is 0.5) has the best hydrodynamic performance among the investigated RDT models in this work.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"2 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140568452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-04-02DOI: 10.1177/14750902241240210
Chen Huang, Jijun Gu, Jichuan Jia, Leilei Chen, Shujiang Wang
DSR (Deep steep riser) is a new riser structure that reduces the ultra-high-tension load caused by the riser self-weight. In this paper, the mechanical behavior of DSR under different buoyancy module configurations and different ocean currents is studied. The finite element model of DSR is established based on co-rotational coordinate method. The model is solved by arc length method. The accuracy of the numerical method is verified by Abaqus software. Then, the effects of buoyancy module length and buoyancy factor on DSR are analyzed. Finally, the influence of different current incidence angles and velocities on DSR is evaluated. The results show that the DSR model based on the co-rotational coordinate method can effectively simulate the nonlinear behavior of large deformation of DSR. The method is simple, flexible and computationally efficient. This method can quickly improve the efficiency of numerical calculation in static analysis of deepwater riser. And DSR is feasible under certain conditions.
{"title":"Feasibility analysis of deep steep riser based on co-rotational coordinate method","authors":"Chen Huang, Jijun Gu, Jichuan Jia, Leilei Chen, Shujiang Wang","doi":"10.1177/14750902241240210","DOIUrl":"https://doi.org/10.1177/14750902241240210","url":null,"abstract":"DSR (Deep steep riser) is a new riser structure that reduces the ultra-high-tension load caused by the riser self-weight. In this paper, the mechanical behavior of DSR under different buoyancy module configurations and different ocean currents is studied. The finite element model of DSR is established based on co-rotational coordinate method. The model is solved by arc length method. The accuracy of the numerical method is verified by Abaqus software. Then, the effects of buoyancy module length and buoyancy factor on DSR are analyzed. Finally, the influence of different current incidence angles and velocities on DSR is evaluated. The results show that the DSR model based on the co-rotational coordinate method can effectively simulate the nonlinear behavior of large deformation of DSR. The method is simple, flexible and computationally efficient. This method can quickly improve the efficiency of numerical calculation in static analysis of deepwater riser. And DSR is feasible under certain conditions.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"92 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140568160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-03-28DOI: 10.1177/14750902241239361
Jiarui Huang, Lei Song, Zhuoyi Yang, Qilong Wu, Xiaochen Jiang, Cheng Wang
The motion response of offshore floating wind turbines significantly influences their structural integrity, power generation efficiency, operational complexity, safety, and stability. Therefore, predicting the motion response of offshore floating wind turbines is of paramount importance. In engineering practice, especially in extreme marine environments, the motion of wind turbines becomes more complex, making accurate prediction more challenging. In this era of rapid development in deep learning technology, some solutions have emerged for this problem. In this paper, we propose a hybrid model, namely the OVMD-FE-PSO-LSTM model. We begin by conducting numerical simulations of a 5 MW-OC4 semi-submersible floating wind turbine in extreme sea conditions, obtaining motion data for the turbine’s six degrees of freedom. We then decompose the initial motion data using an optimized traditional VMD method, assess the modal complexity with the FE method, combine modal components with similar complexity to reduce computational load, and make predictions using the PSO-LSTM model. Finally, we analyze and compare the predictive results of different models. The results demonstrate that the proposed hybrid model outperforms other comparative models in terms of accuracy, providing new insights into the prediction of the motion response of offshore floating wind turbines.
{"title":"Prediction of 6-DOF motion response of semi-submersible floating wind turbine in extreme sea conditions using OVMD-FE-PSO-LSTM methodology","authors":"Jiarui Huang, Lei Song, Zhuoyi Yang, Qilong Wu, Xiaochen Jiang, Cheng Wang","doi":"10.1177/14750902241239361","DOIUrl":"https://doi.org/10.1177/14750902241239361","url":null,"abstract":"The motion response of offshore floating wind turbines significantly influences their structural integrity, power generation efficiency, operational complexity, safety, and stability. Therefore, predicting the motion response of offshore floating wind turbines is of paramount importance. In engineering practice, especially in extreme marine environments, the motion of wind turbines becomes more complex, making accurate prediction more challenging. In this era of rapid development in deep learning technology, some solutions have emerged for this problem. In this paper, we propose a hybrid model, namely the OVMD-FE-PSO-LSTM model. We begin by conducting numerical simulations of a 5 MW-OC4 semi-submersible floating wind turbine in extreme sea conditions, obtaining motion data for the turbine’s six degrees of freedom. We then decompose the initial motion data using an optimized traditional VMD method, assess the modal complexity with the FE method, combine modal components with similar complexity to reduce computational load, and make predictions using the PSO-LSTM model. Finally, we analyze and compare the predictive results of different models. The results demonstrate that the proposed hybrid model outperforms other comparative models in terms of accuracy, providing new insights into the prediction of the motion response of offshore floating wind turbines.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"26 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140322515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-02-28DOI: 10.1177/14750902241231349
Xinxin Wei, Tianhong Yan, Tao Sun, Shulin Liu, Hongyi Du
The phenomenon of oblique water inflow is widespread in the operation of thrusters, which will cause adverse effects on the hydrodynamic performance of thrusters. In order to investigate the hydrodynamic performance and stress variation of the propeller in oblique flow, based on computational fluid dynamics theory, this paper takes the DTMB4119 propeller as the research object and conducts numerical simulation research on the propeller in oblique flow by solving the RANS equation. By calculating the open water performance curve and surface pressure distribution of the propeller, the rationality of the numerical method and the meshing are verified. Considering the flow field information such as velocity, oblique flow angles, flow line distribution, and pressure distribution, the changes in hydrodynamic characteristics of the propeller are simulated and analyzed. The results show that the uneven distribution of pressure on the propeller blade surface increases with a decrease in the advance coefficient. The force pulsation amplitude of a single blade increases with an increase in oblique flow angles. With the increase in oblique flow angles, the thrust, torque, and efficiency of the propeller show different increasing trends. With the increase in propeller advance coefficient, propeller thrust and torque decrease gradually, and propeller efficiency increases gradually. By using mature propellers, this paper has more reference value for studying the flow field around the ship hull and the hydrodynamic performance of propellers in the process of ship maneuvering.
{"title":"Research on the hydrodynamic performance of propellers under oblique flow conditions","authors":"Xinxin Wei, Tianhong Yan, Tao Sun, Shulin Liu, Hongyi Du","doi":"10.1177/14750902241231349","DOIUrl":"https://doi.org/10.1177/14750902241231349","url":null,"abstract":"The phenomenon of oblique water inflow is widespread in the operation of thrusters, which will cause adverse effects on the hydrodynamic performance of thrusters. In order to investigate the hydrodynamic performance and stress variation of the propeller in oblique flow, based on computational fluid dynamics theory, this paper takes the DTMB4119 propeller as the research object and conducts numerical simulation research on the propeller in oblique flow by solving the RANS equation. By calculating the open water performance curve and surface pressure distribution of the propeller, the rationality of the numerical method and the meshing are verified. Considering the flow field information such as velocity, oblique flow angles, flow line distribution, and pressure distribution, the changes in hydrodynamic characteristics of the propeller are simulated and analyzed. The results show that the uneven distribution of pressure on the propeller blade surface increases with a decrease in the advance coefficient. The force pulsation amplitude of a single blade increases with an increase in oblique flow angles. With the increase in oblique flow angles, the thrust, torque, and efficiency of the propeller show different increasing trends. With the increase in propeller advance coefficient, propeller thrust and torque decrease gradually, and propeller efficiency increases gradually. By using mature propellers, this paper has more reference value for studying the flow field around the ship hull and the hydrodynamic performance of propellers in the process of ship maneuvering.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"14 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140007289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-02-24DOI: 10.1177/14750902241232445
Dechun Zhang, Peng Li, Haoran Chen, Hong Yin, Yiren Yang
To overcome the difficulties of time-consuming and inefficient in the response calculations of the submerged cylindrical shell with internal substructures, this paper firstly presents a refined mode superposition method. In view of the necessity and difficulties of directly and quickly obtaining the frequencies and modes of structures submerged in fluid (named the wet modes), the wet modes are expanded by the modes in vacuum (dry modes) and solved by the energy method. The added kinetic energy of the fluid is calculated via boundary integration, and the Lagrange equations of the second kind is applied to the fluid-structure coupling equations. Then the wet modes are solved by eigenvalue calculation and the modal mass and stiffness of each order wet mode are obtained. Finally, they are used for establishing a mode superposition approach for response calculations. The accuracy of the present method is verified by ANSYS software. In this method, all the required data are obtained from the structural analysis and the traditional complicated fluid force modeling is no longer required. Thus it has the advantages of high computational efficiency and applicability. Compared to the traditional semi-analytic model, this modeling methodology has broad application potential for vibration problems of complex underwater structures since the structural dry modes can be solved efficiently by commercial software. It also has practical value as a theoretical reference for developing mode-superposition-based calculations for fluid-structure problems using commercial software.
{"title":"A refined mode superposition method for dynamical responses of an underwater cylindrical shell with substructures","authors":"Dechun Zhang, Peng Li, Haoran Chen, Hong Yin, Yiren Yang","doi":"10.1177/14750902241232445","DOIUrl":"https://doi.org/10.1177/14750902241232445","url":null,"abstract":"To overcome the difficulties of time-consuming and inefficient in the response calculations of the submerged cylindrical shell with internal substructures, this paper firstly presents a refined mode superposition method. In view of the necessity and difficulties of directly and quickly obtaining the frequencies and modes of structures submerged in fluid (named the wet modes), the wet modes are expanded by the modes in vacuum (dry modes) and solved by the energy method. The added kinetic energy of the fluid is calculated via boundary integration, and the Lagrange equations of the second kind is applied to the fluid-structure coupling equations. Then the wet modes are solved by eigenvalue calculation and the modal mass and stiffness of each order wet mode are obtained. Finally, they are used for establishing a mode superposition approach for response calculations. The accuracy of the present method is verified by ANSYS software. In this method, all the required data are obtained from the structural analysis and the traditional complicated fluid force modeling is no longer required. Thus it has the advantages of high computational efficiency and applicability. Compared to the traditional semi-analytic model, this modeling methodology has broad application potential for vibration problems of complex underwater structures since the structural dry modes can be solved efficiently by commercial software. It also has practical value as a theoretical reference for developing mode-superposition-based calculations for fluid-structure problems using commercial software.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"70 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-02-22DOI: 10.1177/14750902241230354
Siljung Yeo, Jeong Kuk Kim, Jae-Hyuk Choi, Won-Ju Lee
The shipping sector is one of the major contributors to greenhouse gas (GHG) emissions. We aimed to calculate GHG emissions categorized by ship type for all vessels registered in South Korea. Hence, for the first time in South Korea, a bottom-up method based on ship activity data was employed, estimating energy consumption and emissions by ship type. Data from ships registered from 2019 to 2021 were collected and reclassified by ship type, and operational profiles were developed. Based on these profiles, the emissions of major GHGs, including CO2, CH4, and N2O, were estimated for the 3-year period. Cargo ships accounted for the highest percentage of annual fuel consumption, approximately 62.7%–64.7% of the total fuel consumption for all ships. The GHG emissions were calculated to be an average of 4.644 million tonCO2e, which is approximately 6.5 times higher than those from oil tankers (0.710 million tonCO2e), the second-highest emitter. This highlights the need for intensified GHG reduction measures specifically targeting cargo ships, providing clear evidence for prompt and enhanced implementation. The research findings are expected to be utilized as substantiated data for developing specific and systematic GHG reduction policies tailored to each ship type.
{"title":"Estimation of greenhouse gas emissions from ships registered in South Korea based on activity data using the bottom-up approach","authors":"Siljung Yeo, Jeong Kuk Kim, Jae-Hyuk Choi, Won-Ju Lee","doi":"10.1177/14750902241230354","DOIUrl":"https://doi.org/10.1177/14750902241230354","url":null,"abstract":"The shipping sector is one of the major contributors to greenhouse gas (GHG) emissions. We aimed to calculate GHG emissions categorized by ship type for all vessels registered in South Korea. Hence, for the first time in South Korea, a bottom-up method based on ship activity data was employed, estimating energy consumption and emissions by ship type. Data from ships registered from 2019 to 2021 were collected and reclassified by ship type, and operational profiles were developed. Based on these profiles, the emissions of major GHGs, including CO<jats:sub>2</jats:sub>, CH<jats:sub>4</jats:sub>, and N<jats:sub>2</jats:sub>O, were estimated for the 3-year period. Cargo ships accounted for the highest percentage of annual fuel consumption, approximately 62.7%–64.7% of the total fuel consumption for all ships. The GHG emissions were calculated to be an average of 4.644 million tonCO<jats:sub>2</jats:sub>e, which is approximately 6.5 times higher than those from oil tankers (0.710 million tonCO<jats:sub>2</jats:sub>e), the second-highest emitter. This highlights the need for intensified GHG reduction measures specifically targeting cargo ships, providing clear evidence for prompt and enhanced implementation. The research findings are expected to be utilized as substantiated data for developing specific and systematic GHG reduction policies tailored to each ship type.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"1 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-02-22DOI: 10.1177/14750902241230351
Yujun Liu, Jing Liu, Guang Pan, Qiaogao Huang
Periodic isolation system is effectively applied in broadband vibration control. To further enhance the broadband vibration attenuation effect, the paper proposes a two-stage periodic isolation system for an underwater glider. The analytical model of the one-dimensional two-stage periodic isolation system is developed through the multi-degree of freedom spring mass model method. For illustrating the superiority of the proposed two-stage periodic isolator, the force transmission ratio and the wave propagation constant of the SDOF isolator, the single-stage periodic isolator, and the two-stage periodic isolator are calculated and compared. In order to obtain the dynamic parameter influences on the vibration isolation performances as the design guidelines of the two-stage periodic isolator, the parametrical study is carried out based on the analytical model. Furthermore, a two-stage periodic isolator is designed for an underwater glider. The application effect of the two-stage periodic isolator is investigated through analytical modeling and finite element method, comparing to the single-stage periodic isolator. The research results from the analytical models show the proposed two-stage periodic isolator could strength the broadband vibration suppression. The parametrical study results demonstrate the vibration attenuation bandgap and attenuation amount are greatly influenced by the designed dynamic parameters, such as the mass unit and the spring unit of the periodic isolator, the intermediate mass of the two-stage isolator, and the number of the periodic cells. In application study of an underwater glider, the finite element results verify that the two-stage periodic isolator has more vibration attenuation effect than the single-stage periodic isolator. The vibration isolation assessment according to the proposed analytical model gives good predictive performance before the finite element model verification.
{"title":"An analytical vibration model of a one-dimensional two-stage periodic isolation system for the broadband vibration suppression of an underwater glider","authors":"Yujun Liu, Jing Liu, Guang Pan, Qiaogao Huang","doi":"10.1177/14750902241230351","DOIUrl":"https://doi.org/10.1177/14750902241230351","url":null,"abstract":"Periodic isolation system is effectively applied in broadband vibration control. To further enhance the broadband vibration attenuation effect, the paper proposes a two-stage periodic isolation system for an underwater glider. The analytical model of the one-dimensional two-stage periodic isolation system is developed through the multi-degree of freedom spring mass model method. For illustrating the superiority of the proposed two-stage periodic isolator, the force transmission ratio and the wave propagation constant of the SDOF isolator, the single-stage periodic isolator, and the two-stage periodic isolator are calculated and compared. In order to obtain the dynamic parameter influences on the vibration isolation performances as the design guidelines of the two-stage periodic isolator, the parametrical study is carried out based on the analytical model. Furthermore, a two-stage periodic isolator is designed for an underwater glider. The application effect of the two-stage periodic isolator is investigated through analytical modeling and finite element method, comparing to the single-stage periodic isolator. The research results from the analytical models show the proposed two-stage periodic isolator could strength the broadband vibration suppression. The parametrical study results demonstrate the vibration attenuation bandgap and attenuation amount are greatly influenced by the designed dynamic parameters, such as the mass unit and the spring unit of the periodic isolator, the intermediate mass of the two-stage isolator, and the number of the periodic cells. In application study of an underwater glider, the finite element results verify that the two-stage periodic isolator has more vibration attenuation effect than the single-stage periodic isolator. The vibration isolation assessment according to the proposed analytical model gives good predictive performance before the finite element model verification.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"61 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-01-30DOI: 10.1177/14750902241227301
Honggen Zhou, Chaojie Bao, Bo Deng, Lei Li
Due to the advantages such as high efficiency, high precision, and the ability to reduce welding distortion, the block assembly method in shipbuilding possesses currently holds a dominant position in shipbuilding engineering. However, some key issues including low adjustment precision and slow control response speed urgently need to be resolved for the block assembly adjustment technology. This paper committed to solving the problems of inaccurate tracking of target displacement and slow control response speed in the vertical motion axis of the ship block joining equipment. A docking equipment control method based on the RBF neural network coupled with adaptive sliding mode algorithm was proposed. Firstly, an overview of the overall mechanics and control architecture of the ship block joining equipment was provided. Subsequently, a mathematical model for the transmission at the lifting mechanism was established. A sliding mode controller based on position control for the ship block joining equipment was designed for the transmission system. Then, the RBF neural network was employed to adjust the switching gain of the sliding mode controller and develop a self-adaptive sliding mode controller. Finally, simulations and verifications were conducted for multiple sets of input trajectories with different types. The results demonstrated that the combination of the neural network algorithm and the sliding mode control algorithm model presented in this paper reduces the system response time by 28.125% and improves the average motion tracking accuracy by 30.76%.
{"title":"Modeling and controlling of ship general section attitude adjustment process based on RBF neural network coupled with sliding mode algorithm","authors":"Honggen Zhou, Chaojie Bao, Bo Deng, Lei Li","doi":"10.1177/14750902241227301","DOIUrl":"https://doi.org/10.1177/14750902241227301","url":null,"abstract":"Due to the advantages such as high efficiency, high precision, and the ability to reduce welding distortion, the block assembly method in shipbuilding possesses currently holds a dominant position in shipbuilding engineering. However, some key issues including low adjustment precision and slow control response speed urgently need to be resolved for the block assembly adjustment technology. This paper committed to solving the problems of inaccurate tracking of target displacement and slow control response speed in the vertical motion axis of the ship block joining equipment. A docking equipment control method based on the RBF neural network coupled with adaptive sliding mode algorithm was proposed. Firstly, an overview of the overall mechanics and control architecture of the ship block joining equipment was provided. Subsequently, a mathematical model for the transmission at the lifting mechanism was established. A sliding mode controller based on position control for the ship block joining equipment was designed for the transmission system. Then, the RBF neural network was employed to adjust the switching gain of the sliding mode controller and develop a self-adaptive sliding mode controller. Finally, simulations and verifications were conducted for multiple sets of input trajectories with different types. The results demonstrated that the combination of the neural network algorithm and the sliding mode control algorithm model presented in this paper reduces the system response time by 28.125% and improves the average motion tracking accuracy by 30.76%.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"255 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139951889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-01-29DOI: 10.1177/14750902241227254
Shen Li, Feargal Brennan
This paper presents a critical review of literature on the emerging technology known as digital twin and its application in structural integrity management for marine structures. The review defines digital twin in relation to structural integrity management as a virtual representation of a physical structure that mirrors the same structural conditions in real time. Twinning is a dynamic process that involves reducing the discrepancy between the virtual representation and physical structure, which is achieved with the aid of monitored data. Regarding the state-of-the-art concerning marine structure applications, all require the creation of a finite element model to represent the physical structure. Several practical schemes for physical to virtual interconnection have been proposed, but few researchers have concentrated on virtual to physical feedback. In addition, most works have focused only on assessing the current states of structures. To address this, a digital twin-based monitoring framework is proposed and three key enabling technologies, namely model updating, real-time simulation, and data-driven forecasting are demonstrated using a numerical case study. Such technologies enable structural diagnostics, as well as prognostics, to support decision making such as inspection/maintenance planning. Based on the case study, the opportunities and associated challenges of digital twin are discussed. For instance, to fully exploit the potential of digital twin, challenges related to monitoring systems such as standardisation, enhanced redundancy for long-term application, and monitored data quality assurance need to be addressed. Further, because digital twin can avail a vast amount of data, a dedicated data mining capability should also be incorporated.
{"title":"Digital twin enabled structural integrity management: Critical review and framework development","authors":"Shen Li, Feargal Brennan","doi":"10.1177/14750902241227254","DOIUrl":"https://doi.org/10.1177/14750902241227254","url":null,"abstract":"This paper presents a critical review of literature on the emerging technology known as digital twin and its application in structural integrity management for marine structures. The review defines digital twin in relation to structural integrity management as a virtual representation of a physical structure that mirrors the same structural conditions in real time. Twinning is a dynamic process that involves reducing the discrepancy between the virtual representation and physical structure, which is achieved with the aid of monitored data. Regarding the state-of-the-art concerning marine structure applications, all require the creation of a finite element model to represent the physical structure. Several practical schemes for physical to virtual interconnection have been proposed, but few researchers have concentrated on virtual to physical feedback. In addition, most works have focused only on assessing the current states of structures. To address this, a digital twin-based monitoring framework is proposed and three key enabling technologies, namely model updating, real-time simulation, and data-driven forecasting are demonstrated using a numerical case study. Such technologies enable structural diagnostics, as well as prognostics, to support decision making such as inspection/maintenance planning. Based on the case study, the opportunities and associated challenges of digital twin are discussed. For instance, to fully exploit the potential of digital twin, challenges related to monitoring systems such as standardisation, enhanced redundancy for long-term application, and monitored data quality assurance need to be addressed. Further, because digital twin can avail a vast amount of data, a dedicated data mining capability should also be incorporated.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"23 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-01-29DOI: 10.1177/14750902241228153
Hao Yan, Tengzhou Xie, Fei Wang, Yishan Zeng, Jiaqiu Ai
A hydrofoil is a basic shape of fluid machinery blades, and its drag reduction performance is an important reference index in the field of fluid transportation. When fluid flows around a hydrofoil, it generates friction drag and pressure drag, greatly reducing the hydrofoil’s hydraulic performance. This study designs a bionic drag reduction structure by arranging fish scales on a Clark-Y hydrofoil. The overlapping size, thickness, and coverage area of fish scales are taken as design parameters, and the optimal design scheme is attained by using the Taguchi method. Large eddy simulation is used to numerically simulate various schemes. Results show that when the overlapping size O is 2.00 mm, the thickness h is 0.36 mm, the initial position x/C of the fish scale covering is 0 (where C is the chord length of the hydrofoil), and the hydrofoil exhibits excellent drag reduction performance. The total drag reduction rate of the hydrofoil is up to 35.15%, and the drag reduction rate of friction drag and pressure drag is up to 39.56% and 25.64%, respectively. The lift–drag ratio of the hydrofoil increases by 18.04%. The bionic fish scale structure effectively inhibits turbulence, thereby reducing the drag caused by the transformation of laminar flow to turbulence.
水翼是流体机械叶片的一种基本形状，其减阻性能是流体运输领域的一项重要参考指标。当流体围绕水翼流动时，会产生摩擦阻力和压力阻力，大大降低水翼的水力性能。本研究通过在克拉克-Y 型水翼上排列鱼鳞，设计了一种仿生减阻结构。以鱼鳞的重叠尺寸、厚度和覆盖面积为设计参数，采用田口方法获得最佳设计方案。采用大涡模拟对各种方案进行数值模拟。结果表明，当重叠尺寸 O 为 2.00 mm、厚度 h 为 0.36 mm、鱼鳞覆盖的初始位置 x/C 为 0（其中 C 为水翼的弦长）时，水翼表现出优异的减阻性能。水翼的总阻力降低率高达 35.15%，摩擦阻力和压力阻力的阻力降低率分别高达 39.56% 和 25.64%。水翼的升阻比提高了 18.04%。仿生鱼鳞结构有效地抑制了湍流，从而减少了层流转化为湍流时产生的阻力。
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