Journal of Marine Science and Engineering

Research

21 pages, 33618 KiB

Open AccessArticle

Research on a Real-Time Prediction Method of Hull Girder Loads Based on Different Recurrent Neural Network Models

by Qiang Wang, Lihong Wu, Chenfeng Li, Xin Chang and Boran Zhang

J. Mar. Sci. Eng. 2024, 12(5), 746; https://doi.org/10.3390/jmse12050746 (registering DOI) - 29 Apr 2024

Real-time prediction of hull girder loads is of great significance for the safety of ship structures. Some scholars have used neural network technology to investigate hull girder load real-time prediction methods based on motion monitoring data. With the development of deep learning technology, [...] Read more.

Real-time prediction of hull girder loads is of great significance for the safety of ship structures. Some scholars have used neural network technology to investigate hull girder load real-time prediction methods based on motion monitoring data. With the development of deep learning technology, a variety of recurrent neural networks have been proposed; however, there is still a lack of systematic comparative analysis on the prediction performance of different networks. In addition, the real motion monitoring data inevitably contains noise, and the effect of data noise has not been fully considered in previous studies. In this paper, four different recurrent neural network models are comparatively investigated, and the effect of different levels of noise on the prediction accuracy of various load components is systematically analyzed. It is found that the GRU network is suitable for predicting the torsional moment and horizontal bending moment, and the LSTM network is suitable for predicting the vertical bending moment. Although filtering has been applied to the original noise data, the prediction accuracy still decreased as the noise level increased. The prediction accuracy of the vertical bending moment and horizontal bending moment is higher than that of the torsional moment. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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24 pages, 7759 KiB

Open AccessArticle

Experimental and Numerical Prediction of Slamming Impact Loads Considering Fluid–Structure Interactions

by Tao Lu, Jiaxia Wang, Kun Liu and Xiaochao Zhao

J. Mar. Sci. Eng. 2024, 12(5), 733; https://doi.org/10.3390/jmse12050733 (registering DOI) - 28 Apr 2024

Viewed by 216

Abstract

Slamming impacts on water are common occurrences, and the whipping induced by slamming can significantly increase the structural load. This paper carries out an experimental study of the water entry of rigid wedges with various deadrise angles. The drop height and deadrise angle [...] Read more.

Slamming impacts on water are common occurrences, and the whipping induced by slamming can significantly increase the structural load. This paper carries out an experimental study of the water entry of rigid wedges with various deadrise angles. The drop height and deadrise angle are parametrically varied to investigate the effect of the entry velocity and wedge shape on the impact dynamics. A two-way coupled approach combing CFD method software STAR-CCM+12.02.011-R8 and the FEM method software Abaqus 6.14 is presented to analyze the effect of structural flexibility on the slamming phenomenon for a wedge and a ship model. The numerical method is validated through the comparison between the numerical simulation and experimental data. The slamming pressure, free surface elevation, and dynamic structural response, including stress and strain, in particular, are presented and discussed. The results show that the smaller the inclined angle at the bottom of the wedge-shaped body, the faster the entry speed into the water, resulting in greater impact pressure and greater structural deformation. Meanwhile, studies have shown that the bottom of the bow is an area of concern for wave impact problems, providing a basis for the assessment of ship safety design. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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21 pages, 14444 KiB

Open AccessArticle

Experimental and Numerical Studies on the Ultimate Bending Strength of Welded Plated Grillage with Combined Openings

by Chen Chen, Hong Zhou, Zhengda Lv and Ziqiu Li

J. Mar. Sci. Eng. 2024, 12(2), 295; https://doi.org/10.3390/jmse12020295 - 07 Feb 2024

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Abstract

Plated grillage with combined openings was susceptible to complex failure behaviors as the main load-bearing structure of the superstructure on passenger ships subjected to deck loads. Additionally, the deformation and stresses generated during the welding of the plated grillage complicated the prediction of [...] Read more.

Plated grillage with combined openings was susceptible to complex failure behaviors as the main load-bearing structure of the superstructure on passenger ships subjected to deck loads. Additionally, the deformation and stresses generated during the welding of the plated grillage complicated the prediction of its failure behavior. In this case, a new partitioned inherent strain method and nonlinear finite element method were used to simulate the welding and loading process, and experiments were designed and carried out to make comparisons, unveiling the influence regulations between the failure behavior of the structure and the loading condition, the initial welding state. This research on the failure mode analysis of plated grillages could provide references for the optimization of the structural form of plated grillages and the cargo loading scheme on the deck of a real ship. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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18 pages, 9116 KiB

Open AccessArticle

Real-Time Digital Twin of Ship Structure Deformation Field Based on the Inverse Finite Element Method

by Pengyu Wei, Chuntong Li, Ze Jiang and Deyu Wang

J. Mar. Sci. Eng. 2024, 12(2), 257; https://doi.org/10.3390/jmse12020257 - 31 Jan 2024

Viewed by 706

Abstract

Digital twins, an innovative technology propelled by data and models, play a seminal role in the digital transformation and intelligent upgrade of ships. This study introduces a digital twin methodology for the real-time monitoring of ship structure deformation fields, based on finite discrete [...] Read more.

Digital twins, an innovative technology propelled by data and models, play a seminal role in the digital transformation and intelligent upgrade of ships. This study introduces a digital twin methodology for the real-time monitoring of ship structure deformation fields, based on finite discrete strain data, and a visualization tool framework is developed using virtual reality technology. First, the inverse Finite Element Method (iFEM) is employed to derive the deformation field of the ship structure in real time using sensor strain data. Secondly, the deformation field data obtained based on the iFEM algorithm is converted into general visualization data conducive to interpretation within virtual reality (VR) applications. Lastly, a digital twin software tool is built to enable synchronous responses and interactions between the virtual scene and the physical scene, directly superposing particular virtual objects (data acquired by sensors, computer-aided design (CAD) virtual models, and deformation field cloud images) onto the physical scene in real time. The digital twin tool embodies a virtual reality visualization system framework integrating the physical data measurement, reconstruction, analysis, expression, storage, rendering, and interaction of deformation field data. Through practical application, the flexibility, effectiveness, and compatibility of the developed prototype tool are verified. According to the results, the system can enhance the efficiency of scientific communication, model validation, and interdisciplinary sharing during the analysis and evaluation of the mechanical properties of ship structures. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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17 pages, 4944 KiB

Open AccessArticle

Stress Concentration Factors Due to Misalignment at Girth Welds in Bi-Layer Pipes

by Ruili Guo, Hongyang Hu, Haisheng Zhao and Yao Zhang

J. Mar. Sci. Eng. 2024, 12(2), 231; https://doi.org/10.3390/jmse12020231 - 28 Jan 2024

Viewed by 624

Abstract

In recent years, bi-layer pipes, composed of an inner layer and an outer layer, have been widely used in offshore engineering. In this study, the governing equation for a bi-layer pipe subjected to axisymmetric loadings is derived based on classical shell theory. Then, [...] Read more.

In recent years, bi-layer pipes, composed of an inner layer and an outer layer, have been widely used in offshore engineering. In this study, the governing equation for a bi-layer pipe subjected to axisymmetric loadings is derived based on classical shell theory. Then, the equation is used to develop stress concentration factor formulations for girth welds in bi-layer pipes with fabrication tolerances and thickness transitions. Axisymmetric finite element analysis is carried out to verify the accuracy of the proposed formulations. It is noted that these formulations can be well suited for determining the stress concentration factors for a wide range of thickness ratios (ratio of the inner layer thickness to the total thickness in a bi-layer pipe) varying from 0.0 to 1.0. They can also obtain accurate stress concentration factors whether the elastic modulus of the inner layer is smaller or larger than that of the outer layer. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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24 pages, 28071 KiB

Open AccessArticle

A Two-Step Approach for Evaluating the Dynamic Ultimate Load Capacity of Ship Structures

by Weilong Zhang, Jinju Cui and Deyu Wang

J. Mar. Sci. Eng. 2024, 12(2), 219; https://doi.org/10.3390/jmse12020219 - 25 Jan 2024

Viewed by 645

Abstract

One important parameter for evaluating the safety and reliability of a ship is o the dynamic ultimate load capacity of ship structures. Because of the importance of this parameter, its determination is essential. In this paper, a novel “two-step” approach for determining the [...] Read more.

One important parameter for evaluating the safety and reliability of a ship is o the dynamic ultimate load capacity of ship structures. Because of the importance of this parameter, its determination is essential. In this paper, a novel “two-step” approach for determining the dynamic ultimate load capacity of ship structures is proposed. The main idea of two-step approach is to determine the dynamic ultimate load capacity based on the static ultimate load capacity after accounting for impacts that cause strain on the ship structures. This approach is based on nonlinear finite element method. Here, taking stiffened plate as a case study, the practical application of thus two-step approach is discussed in detail. The results of this approach reveal that the static ultimate load capacity decreases by less than 3% after a stiffened plate is subjected to an impact load whose amplitude corresponds to the dynamic ultimate load capacity. Then, the influence of the impact duration on the failure mode and the effect of the impact load cycles and the impact load sequence on the dynamic ultimate load capacity of the stiffened plate were investigated. Finally, the applicability of the two-step approach to a hull girder is demonstrated. The two-step approach and the conclusions presented in this paper can provide guidance for the evaluation of dynamic ultimate load capacity. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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16 pages, 6885 KiB

Open AccessArticle

XFEM-Based Study of Fatigue Crack Propagation in Rocket Deflector Troughs under Coupled High-Temperature and Impact Conditions

by Zhixin Xiong, Chengyuan Zhu, Yue Yang, Tong Lin and Ruoxuan Li

J. Mar. Sci. Eng. 2024, 12(2), 207; https://doi.org/10.3390/jmse12020207 - 23 Jan 2024

Viewed by 580

Abstract

This research investigated fatigue crack propagation on the lower surface of rocket deflector troughs in offshore rocket launch platforms. Initially, a numerical model of an offshore rocket launch platform was established using ABAQUS based on the Extended Finite Element Method (XFEM). Subsequently, two [...] Read more.

This research investigated fatigue crack propagation on the lower surface of rocket deflector troughs in offshore rocket launch platforms. Initially, a numerical model of an offshore rocket launch platform was established using ABAQUS based on the Extended Finite Element Method (XFEM). Subsequently, two variable parameters—the initial crack length and initial tilt angle—were introduced. This research systematically analysed the impact of these parameters on the fatigue crack propagation patterns in both the maximum stress and maximum deformation regions of the deflector channels under the combined conditions of high temperature and impact. Finally, the research indicated that the propagation length of surface cracks in the deflector trough exhibited an initial increase followed by a decrease with the rise in the pre-set inclination angle. Notably, the stable propagation rate of the crack in the region of maximum deformation surpassed that observed in the region of maximum stress. Through meticulous comparative analysis, it was evident that temperature loading significantly exacerbated the initiation and propagation of cracks, particularly in the upper region of the deflector channel’s lower surface. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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23 pages, 15187 KiB

Open AccessArticle

Experimental and Numerical Analysis of Supporting Forces and Lashing Forces in a Ship Cargo Securing Scheme

by Mengxiang Li, Guo Wang, Kun Liu, Yue Lu and Jiaxia Wang

J. Mar. Sci. Eng. 2024, 12(1), 158; https://doi.org/10.3390/jmse12010158 - 12 Jan 2024

Viewed by 677

Abstract

The safety assessment of ship cargo securing systems is of significant importance in preventing casualties, vessel instability, and economic losses resulting from the failure of securing systems during transportation in adverse sea conditions. In this study, an independently designed cylindrical cargo securing scheme [...] Read more.

The safety assessment of ship cargo securing systems is of significant importance in preventing casualties, vessel instability, and economic losses resulting from the failure of securing systems during transportation in adverse sea conditions. In this study, an independently designed cylindrical cargo securing scheme with supporting structures was adopted for investigation. Utilizing a sway device, three-degree-of-freedom coupled motion encountered during ship transportation was obtained, and data regarding changes in the support forces at the foundations and tension forces in the lashing ropes were collected. Subsequently, numerical simulations were conducted using the multibody dynamics software ADAMS 2020. The results obtained from the simulations were compared with the experimental data. The overall tendencies were accurately predicted in the numerical analysis. It was observed that the difference of the peak support forces between the numerical simulation results and the experimental data were within a 10% margin. In terms of the lashing ropes, the difference was limited, within 9%. These findings demonstrate that numerical simulation techniques can provide valuable insights for verifying the safety of practical cargo securing systems. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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23 pages, 20731 KiB

Open AccessArticle

Experimental and Numerical Analysis of Ultimate Carrying Capacity of a Funnel Structure with Opening under Wind Pressure

by Lei Ao, Ziqi Ding, Bin Liu, Zhiyong Pei, Qin Tang and Weiguo Wu

J. Mar. Sci. Eng. 2024, 12(1), 41; https://doi.org/10.3390/jmse12010041 - 23 Dec 2023

Viewed by 680

Abstract

This study presents experimental and finite element investigations on the ultimate strength of the funnel structure of a large passenger ship subjected to wind pressure. An experimental test is conducted using a similar model to analyze the failure characteristics of the funnel structure. [...] Read more.

This study presents experimental and finite element investigations on the ultimate strength of the funnel structure of a large passenger ship subjected to wind pressure. An experimental test is conducted using a similar model to analyze the failure characteristics of the funnel structure. The model is designed based on similar theories to simulate the progressive collapse behavior of an actual ship’s funnel under wind load. Additionally, a simplified wind loading device is also developed to apply large wind loads. Practical insights are provided in the research to assess the opening’s influence on reducing the ultimate strength of funnel structures when suffering wind pressure. Results represent the failure initiated at the edges of the large opening, with stress concentration primarily occurring at the stiffener end, showing good agreement with the simulated results performed using the finite element method. Furthermore, the effects of different parameters on the ultimate strength of the funnel structure are discussed by using the numerical method. This analysis provides an important guide for the design of funnel structures of passenger ships with openings. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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