Journal of Marine Science and Engineering

Editorial

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4 pages, 151 KiB

Open AccessEditorial

Advanced Analysis of Marine Structures

by Bin Liu, Kun Liu and Chenfeng Li

J. Mar. Sci. Eng. 2024, 12(7), 1111; https://doi.org/10.3390/jmse12071111 - 2 Jul 2024

Viewed by 873

Abstract

In the analysis and design of marine structures, one of the key issues is the accurate prediction of their strength under various load conditions, particularly impact and ultimate and fatigue strength [...] Full article

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

Research

Jump to: Editorial

22 pages, 5068 KiB

Open AccessArticle

A Novel Wave Energy Equivalence Based Lumping Block Method for Efficiently Predicting the Fatigue Damage of Mooring Lines

by Yuanzhi Guo, Shuqing Wang, Haiyan Guo and Xiancang Song

J. Mar. Sci. Eng. 2023, 11(9), 1679; https://doi.org/10.3390/jmse11091679 - 25 Aug 2023

Cited by 1 | Viewed by 1149

Abstract

The lumping block equivalent method (LBEM) is widely used to reduce the computational effort in the fatigue damage assessment of offshore structures, and the wave parameters of the representative sea states (RSSs) resulting from LBEM are of vital importance for the accurate prediction [...] Read more.

The lumping block equivalent method (LBEM) is widely used to reduce the computational effort in the fatigue damage assessment of offshore structures, and the wave parameters of the representative sea states (RSSs) resulting from LBEM are of vital importance for the accurate prediction of offshore structures’ fatigue damage. In this study, a novel wave energy equivalence (WEE)-based LBEM is proposed to determine the wave parameters of the RSS accurately. The novelty of the proposed method is that a compact relationship between the input wave energy component and mooring lines’ fatigue damage is derived, and the modified statistical relationships between the wave parameters and spectral moments are provided by incorporating the effects of the peak enhancement factor of the input wave spectrum, the number of original sea states (OSSs) and the equivalence bandwidth of the OSSs. Based on the compact relationship, the wave energy component of the RSS can be determined from the wave energy component of the OSSs for each wave frequency from the viewpoint of the fatigue damage equivalence criterion. The wave energy distribution of the RSS can be accurately characterized with the wave energy distribution of the OSSs, and the spectral moments of the RSS can be calculated by its energy distribution directly, without any approximation. Moreover, the wave parameters of the RSS can be determined from the modified statistical relationships easily. The effectiveness of the proposed WEE LBEM is numerically investigated with a moored semi-submersible platform. Results show that the proposed WEE LBEM is robust, efficient and accurate within engineering expectations, and it outperforms the conventional LBEMs both in accuracy and robustness. Full article

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

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21 pages, 8820 KiB

Open AccessArticle

Dynamic Response Analysis of Submarines Based on FEM-ALE Coupling Method in Floating Ice Conditions

by Zhongyu Chen, Weidong Zhao, Zhanyang Chen, Guoqing Feng, Huilong Ren and Hongbin Gui

J. Mar. Sci. Eng. 2023, 11(8), 1560; https://doi.org/10.3390/jmse11081560 - 7 Aug 2023

Cited by 3 | Viewed by 1374

Abstract

To address global challenges, research on the safety of polar navigation is indispensable. However, most of studies focus on traditional surface vessels, with few research studies on submarine. The dynamic response of submarine during surface navigation in floating ice channels under special conditions [...] Read more.

To address global challenges, research on the safety of polar navigation is indispensable. However, most of studies focus on traditional surface vessels, with few research studies on submarine. The dynamic response of submarine during surface navigation in floating ice channels under special conditions is studied in this work. Firstly, a model of the submarine incorporating an intact internal frame was established. Subsequently, the FEM-ALE coupled method was employed to simulate the structure-ice interaction, and the obtained results was verified by the Colbourne method. Then, the parametric study (navigation speed, ice thickness, and floating ice size) were analyzed from the perspectives of ice resistance, stress and plastic strain. Finally, an empirical equation suitable for the interaction between submarine and floating ice during surface navigation is improved based on the Colbourne method. Full article

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

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14 pages, 4694 KiB

Open AccessArticle

Experimental and Numerical Study on Crack Propagation of Cracked Plates under Low Cycle Fatigue Loads

by Dong Qin, Xu Geng, Zhao Jie and Hu Yaoyu

J. Mar. Sci. Eng. 2023, 11(7), 1436; https://doi.org/10.3390/jmse11071436 - 18 Jul 2023

Cited by 3 | Viewed by 1419

Abstract

The traditional study on fatigue strength for ship structures usually focuses on high cycle fatigue and ignores low cycle fatigue. However, given the recent trend towards large-scale ship development, the stress and deformation experienced by ship structures are becoming increasingly significant, leading to [...] Read more.

The traditional study on fatigue strength for ship structures usually focuses on high cycle fatigue and ignores low cycle fatigue. However, given the recent trend towards large-scale ship development, the stress and deformation experienced by ship structures are becoming increasingly significant, leading to greater attention being paid to low cycle fatigue damage. Therefore, experimental and numerical studies on crack propagation behavior of cracked plates under low cycle fatigue loads were carried out in this paper, in order to explain the fatigue crack propagation mechanism. The effect of the stress ratio and maximum applied load on the crack propagation behavior was investigated by conducting experimental research on the cracked plate of AH32 steel. The experimental results show that an increasing maximum applied load and decreasing stress ratio will shorten the fatigue life of the cracked plate. Meanwhile, based on the finite element method, the distribution of the stress–strain field at the crack tip and the effect of crack closure were evaluated. The influencing factors such as the stress ratio and crack length were considered in numerical studies, which provided a new way to study the low cycle fatigue crack propagation behavior. Full article

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

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14 pages, 3296 KiB

Open AccessArticle

Experimental Study of Hot Spot Stress for Spatial CHS KK-Joints

by Kang Wang, Yuhang Wang, Shan Gao, Bin Wang, Jinzhong Chen and Pengjun Luo

J. Mar. Sci. Eng. 2023, 11(7), 1432; https://doi.org/10.3390/jmse11071432 - 18 Jul 2023

Cited by 2 | Viewed by 1296

Abstract

In offshore structures such as offshore wind turbine jacket foundations, prolonged exposure to wind and wave loads can lead to fatigue failure, especially at the joint connections. Currently, international codes primarily evaluate the fatigue performance of tubular joints using the hot spot stress [...] Read more.

In offshore structures such as offshore wind turbine jacket foundations, prolonged exposure to wind and wave loads can lead to fatigue failure, especially at the joint connections. Currently, international codes primarily evaluate the fatigue performance of tubular joints using the hot spot stress (HSS) method, with stress concentration factor (SCF) being the most crucial parameter. Numerous studies have investigated the SCF of tubular joints and proposed corresponding calculation formulas. However, most of these studies have focused on simple basic loading cases. To comprehensively understand the distribution pattern of the HSS method at spatial tubular joints, this study selects the spatial CHS KK-joints as the research subject and performs the HSS testing on spatial KK-joints. The research indicates that, in CHS joints, the distribution of the HSS on the chord side remains consistent under tensile or compressive loading conditions along the brace axis. Additionally, within spatial joints, the loading conditions of neighboring braces near the reference brace significantly affect the distribution of HSS on the chord side and exhibit varying spatial effects on the SCF. Furthermore, this study applies recommended calculation formulas from codes to analyze the experimental results. The findings reveal significant discrepancies between the SCF calculation formulas recommended by CIDECT and the test results, rendering it inadequate for accurately calculating the SCF of spatial KK-joints. Therefore, further research is required to develop suitable calculation formulas for SCFs in spatial KK-joints. Full article

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

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22 pages, 12785 KiB

Open AccessArticle

Crashworthiness Optimization Method of Ship Structure under Multi-Working Conditions

by Weijian Qiu, Kun Liu, Hewei Liu, Shuai Zong, Jiaxia Wang and Zhenguo Gao

J. Mar. Sci. Eng. 2023, 11(7), 1335; https://doi.org/10.3390/jmse11071335 - 30 Jun 2023

Viewed by 1395

Abstract

Numerous collision conditions can occur during ship operations, resulting in various consequences that require specific consideration for optimizing crashworthiness design. Existing studies have investigated crashworthiness design in ship structures; however, they often focus on single working conditions and do not comprehensively consider the [...] Read more.

Numerous collision conditions can occur during ship operations, resulting in various consequences that require specific consideration for optimizing crashworthiness design. Existing studies have investigated crashworthiness design in ship structures; however, they often focus on single working conditions and do not comprehensively consider the diverse scenarios encountered during ship operations. To overcome this drawback, this paper proposes a novel method that addresses multi-working conditions and combines orthogonal testing with a backpropagation neural network (BPNN) to establish an efficient surrogate model for collision optimization. The accuracy of the BPNN was improved by introducing the genetic algorithm and Adam algorithm. The technique for order preference by similarity to ideal solution (TOPSIS) is introduced to formulate a multi-working condition optimization function. The crashworthiness of the ship structure is optimized using the sparrow search algorithm (SSA) while considering the constraint of lightweight design. The results demonstrate a substantial reduction in the objective functions for the optimized collision conditions. Moreover, the BPNN predicted values are in good agreement with the finite element simulation results, affirming the effectiveness of the proposed method in improving the crashworthiness of the ship structure and providing valuable guidance for engineering design. Full article

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

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16 pages, 6865 KiB

Open AccessArticle

Experimental Research on the Stiffness Step between the Main Hull and Superstructure of Cruise Ships

by Zhiyong Pei, Bin Yang, Guangwu Liu and Weiguo Wu

J. Mar. Sci. Eng. 2023, 11(7), 1264; https://doi.org/10.3390/jmse11071264 - 21 Jun 2023

Cited by 2 | Viewed by 1749

Abstract

The demand for larger passenger capacity and more entertainment facilities has led to the rapid growth of the cruise tourism market. The superstructure of cruise ships is designed to be plumper, with numerous decks and complex structural forms. To control the weight and [...] Read more.

The demand for larger passenger capacity and more entertainment facilities has led to the rapid growth of the cruise tourism market. The superstructure of cruise ships is designed to be plumper, with numerous decks and complex structural forms. To control the weight and the center of gravity, the bending stiffness of the superstructure is always designed to be weaker than that of the main hull, resulting in a stiffness step. Currently, there is no satisfactory method to accurately estimate the influence of the stiffness step between the main hull and superstructure on the structural response of cruise ships. In the present research, an experimental analysis is conducted to investigate the stiffness step between the main hull and superstructure of a typical cruise ship. By comparing the longitudinal stress distribution characteristics with and without the stiffness step with the theoretical results, the influence of the stiffness step on the longitudinal strength is investigated. Furthermore, the maximum stress and the bending efficiency of the superstructure are also discussed. The present research is of reference significance for the structural safety and reliability design of cruise ships. Full article

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

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22 pages, 10632 KiB

Open AccessArticle

Numerical and Experimental Analysis of Fire Resistance for Bulkhead and Deck Structures of Ships and Offshore Installations

by Shuai Zong, Kun Liu, Weijian Qiu, Zhenguo Gao and Jiaxia Wang

J. Mar. Sci. Eng. 2023, 11(6), 1200; https://doi.org/10.3390/jmse11061200 - 9 Jun 2023

Cited by 2 | Viewed by 1682

Abstract

Investigating the loss of integrity (E) in cabin walls and decks, as well as the role of insulation capabilities, holds significant implications for preventing serious human, economic and environmental damage caused by the ignition of cabins in ships and ocean platforms due to [...] Read more.

Investigating the loss of integrity (E) in cabin walls and decks, as well as the role of insulation capabilities, holds significant implications for preventing serious human, economic and environmental damage caused by the ignition of cabins in ships and ocean platforms due to fires and explosions. In this study, the fire resistance of A-60 class ship bulkheads and decks was evaluated through two groups of standard fire resistance tests. In the first test, the steel structure side of the bulkhead was exposed to the fire, while in the second test, the mineral wool and L-shaped stiffeners side of the deck was exposed to the fire. Numerical material models for steel and mineral wool were established based on standards, and the temperature distribution and structural deformation were simulated using Abaqus. The results showed a good correlation with the experimental data. The maximum and average temperature increases on the unheated surface of the bulkhead during the standard fire resistance test were 158 °C and 136 °C, respectively. The corresponding values for the deck were 176 °C and 138 °C. Upon the conclusion of the experiment, the maximum displacement deformation in the direction towards the furnace from the center of the cabin wall was 54 mm, and from the center of the deck, the maximum displacement deformation towards the furnace was 28 mm. This research can provide guidance for the design of fire-resistant ship compartment structures. Full article

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

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20 pages, 6940 KiB

Open AccessArticle

The Oscillating Behavior of Trawl Codends Including Various Geometric Configurations of Simulated Catch

by Feng Zhang, Hao Tang, Nyatchouba Nsangue Bruno Thierry, Wei Liu, Qiuyang Sun, Meixi Zhu, Can Zhang, Xuhao Guo, Chenxu Shan, Liuxiong Xu and Fuxiang Hu

J. Mar. Sci. Eng. 2023, 11(5), 1026; https://doi.org/10.3390/jmse11051026 - 11 May 2023

Cited by 1 | Viewed by 1444

Abstract

Codends are the posterior components of trawl nets that collect the catch and play a crucial role in the selectivity process. Due to the accumulation of catch and the variety of catch types, the quality of catch and trawl selectivity can be negatively [...] Read more.

Codends are the posterior components of trawl nets that collect the catch and play a crucial role in the selectivity process. Due to the accumulation of catch and the variety of catch types, the quality of catch and trawl selectivity can be negatively impacted. Therefore, this study aims to investigate the effects of various catch configurations on the hydrodynamic characteristics, geometrical profile, and fluttering motions of the codend in a flume tank. A codend structure was designed and tested using various catch configurations, including grooved-type configurations (canvas, green canvas, basketballs) and spherical configurations (table tennis balls filled with water, balloons filled with water, and balls made of twine) in the flume tank. The sea trial data were compared with the flume tank data. The results indicate that there were no significant differences in the codend profiles between the different catch configurations. The drag of the codend with a grooved-type configuration was 13.63% greater than that obtained using a spherical configuration as the catch. The wavelet coefficient obtained from the codend drag revealed that the oscillations of the codend with a grooved-type catch configuration began at a periodicity of 0.07 s and were more intense than that of the codend with the spherical catch configuration. Moreover, these amplitudes increased as the codend flow velocity increased. The wavelet analysis results showed that the dominant frequency of the periodic high-energy coherent structures for the codend drag and codend displacements was detected at a low-frequency. In terms of displacement oscillation characteristics, the table tennis ball filled with water was an approximate substitute for real catch during the sea trial because the difference in wavelet coefficients for the codend displacements in amplitude and the period between the model codend with the table tennis ball filled with water and the full-scale codend was 91% and 89%, respectively. The findings of this study confirm the feasibility of replacing real catch with simulated catch configurations with similar shapes in model testing. They can provide basic scientific data for improving the hydrodynamic characteristics and selectivity of the codend structure. Full article

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

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19 pages, 21315 KiB

Open AccessArticle

Experimental and Numerical Studies on Bending and Failure Behaviour of Inflated Composite Fabric Membranes for Marine Applications

by Yunling Ye, Jin Gan, Huabing Liu, Qingfei Guan, Zhongyi Zheng, Xiaolin Ran and Zi’ang Gao

J. Mar. Sci. Eng. 2023, 11(4), 800; https://doi.org/10.3390/jmse11040800 - 7 Apr 2023

Cited by 7 | Viewed by 1853

Abstract

Owing to their excellent physical characteristics of lightweightiness, compactness and rapid deployment, the inflated membrane structures satisfy the demands of maritime salvage and military transportation for long-distance delivery and rapid response. Exploring the failure behaviour of inflated membrane structures can greatly contribute to [...] Read more.

Owing to their excellent physical characteristics of lightweightiness, compactness and rapid deployment, the inflated membrane structures satisfy the demands of maritime salvage and military transportation for long-distance delivery and rapid response. Exploring the failure behaviour of inflated membrane structures can greatly contribute to their widespread applications in ocean engineering. In this research, the main objective is to comprehensively investigate the bending and failure behaviour of inflated membrane structures. Thus, the Surface-Based Fluid Cavity method is employed to set up the finite element model (FEM) which is compared to the experimental results to verify its reliability. In parallel, the effects of internal pressure and wrinkles are discussed. An empirical expression of the ultimate bending loading was fitted by face-centred composite designs of the Response Surface Methodology. The results of experiments and FEM show that the bearing capacity of the inflated membrane structure is positively correlated with the internal pressure but decreased obviously with the occurrence and propagation of wrinkles. The deformation behaviour and the stress distribution are similar to those of the traditional four-point bending beam, and the local instability induced by wrinkles will cause structural failure. In addition, the numerical model and the proposed expression showed deviations below 5% in relation to the experimental measures. Therefore, the FEM and proposed expression are high of reliability and have important engineering guiding significance for the application of inflated membrane structures in ocean engineering. Full article

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

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24 pages, 15125 KiB

Open AccessArticle

A CFD-FEA Method for Hydroelastic Analysis of Floating Structures

by Nan Gu, Deli Liang, Xueqian Zhou and Huilong Ren

J. Mar. Sci. Eng. 2023, 11(4), 737; https://doi.org/10.3390/jmse11040737 - 28 Mar 2023

Cited by 4 | Viewed by 2806

Abstract

The so-called large multi-body floating offshore structure is a new type of offshore structure with a huge and extremely flat deck area, which has a promising prospect as a floating port and also in applications in the area of marine space exploitation. Due [...] Read more.

The so-called large multi-body floating offshore structure is a new type of offshore structure with a huge and extremely flat deck area, which has a promising prospect as a floating port and also in applications in the area of marine space exploitation. Due to its unique structural form, the hydrodynamic and structural response characteristics are very complex. Specifically, due to the instantaneous position variation in the body surface, the nonlinearity of the free surface, the interactions between floating bodies, and the elastic deformation of floating bodies, the nonlinear factors are significant and cannot be neglected. For these kinds of problems, methods based on CFD-FEA (computation fluid dynamics–finite element analysis) coupling simulation have significant advantages over traditional methods. In the present paper, the hydrodynamic and structural response characteristics of a large multi-body floating offshore structure are studied using a CFD-FEA method, and the results are compared with those obtained by the potential-flow-based commercial code SESAM/WADAM, and a three-dimensional nonlinear hydroelastic analysis commercial code COMPASS-WALCS-NE. The comparison and the analysis of the results show that the CFD-FEA method presented in this study can well simulate the behavior of the hydroelastic responses of flexible floating structures and has the potential to capture complex nonlinear behaviors. Full article

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

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19 pages, 3016 KiB

Open AccessArticle

Fracture Prediction of Steel-Plated Structures under Low-Velocity Impact

by Burak Can Cerik and Joonmo Choung

J. Mar. Sci. Eng. 2023, 11(4), 699; https://doi.org/10.3390/jmse11040699 - 24 Mar 2023

Cited by 3 | Viewed by 2030

Abstract

In this paper, a validation study of a recently proposed rate-dependent shell element fracture model using quasi-static and dynamic impact tests on square hollow sections (SHS) made from offshore high-tensile strength steel was presented. A rate-dependent forming limit curve was used to predict [...] Read more.

In this paper, a validation study of a recently proposed rate-dependent shell element fracture model using quasi-static and dynamic impact tests on square hollow sections (SHS) made from offshore high-tensile strength steel was presented. A rate-dependent forming limit curve was used to predict the membrane loading-dominated failure, while a rate-dependent ductile fracture locus was applied for predicting failure governed by bend loading. The predicted peak force and fracture initiation using the adopted material and fracture model agreed well with the experimental results. The fracture mode was also captured accurately. Further simulations were performed to discuss the importance of the inclusion of dynamic effects and the separate treatment of failure modes. Finally, the shortcomings of the common practice of treatment of rate-effects in low-velocity impact simulations involving fracture were highlighted. Full article

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

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21 pages, 14102 KiB

Open AccessArticle

Low Temperature Effect on the Mechanical Properties of EH36 with Strain Rates

by Jing Zhang, Xuelei Kang, Xinghua Shi, C. Guedes Soares and Ming Song

J. Mar. Sci. Eng. 2023, 11(3), 678; https://doi.org/10.3390/jmse11030678 - 22 Mar 2023

Cited by 9 | Viewed by 2917

Abstract

With the expansion of the Arctic route, the safety of ship crossing the area in light of the low temperature and ice has become of focus, especially with regards to the ship’s structure. The mechanical properties of the material making up the ship’s [...] Read more.

With the expansion of the Arctic route, the safety of ship crossing the area in light of the low temperature and ice has become of focus, especially with regards to the ship’s structure. The mechanical properties of the material making up the ship’s structure may not be suitable for the Arctic environment. A series of quasi-static and dynamic tests were performed to investigate the behaviour of EH36 steel, which is used to build Arctic ships, at temperatures ranging from 20 °C to −60 °C. The yield and ultimate tensile stress increased more than 10% as the temperature decreased from 20 °C to −60 °C, whereas the toughness decreased as the temperature decreased. A formula was derived to illustrate the relationship between the temperature reduction and the yield strength by fitting the experimental data. Four common constitutive rigid-perfectly plastic, elastic-perfectly plastic, bilinear elastic-plastic, and multi-linear elastic plastic models were fitted to simulate the hull structure under static loading and low temperature. Additionally, the strain rate effect of EH36 steel at low temperatures was illustrated by quasi-static and high-speed impact tests. A constitutive model including the low temperature and strain rate was introduced based on a modified Cowper-Symonds model, in which the coefficients of the constitutive model are fitted by the test results. It is improved by an iterative numerical method used to obtain more accurate coefficients using a series of numerical analyses. Detailed finite element simulations of the experiment conditions revealed that the constitutive model accurately predicts the dynamic response at low temperatures. Full article

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

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23 pages, 8648 KiB

Open AccessArticle

Research on Bearing Characteristics of Gravity Anchor in Clay

by Jianxing Yu, Pengfei Liu, Yang Yu, Xin Liu, Haoda Li, Ruoke Sun and Xuyang Zong

J. Mar. Sci. Eng. 2023, 11(3), 505; https://doi.org/10.3390/jmse11030505 - 26 Feb 2023

Viewed by 1703

Abstract

The applications and studies of gravity anchors in the ocean are becoming more and more extensive. Most of the research, however, has been directed toward the bearing properties of sand. Relatively less attention has been paid to the bearing properties of gravity anchors [...] Read more.

The applications and studies of gravity anchors in the ocean are becoming more and more extensive. Most of the research, however, has been directed toward the bearing properties of sand. Relatively less attention has been paid to the bearing properties of gravity anchors in clay. Clay is widely distributed on the seabed. The research on the bearing capacity of gravity anchors in clay is of great significance for offshore oil exploitation. Therefore, the gravity anchor was investigated by conducting reduced-scale model tests, and the bearing process of gravity anchors in clay was simulated through a 3D finite element method. Model tests and numerical simulations were used to determine the capacity curve and the V-H failure envelope of gravity anchors in clay. The simulation results and the test results are in good agreement. The failure form of the gravity anchor in clay was revealed by 3D finite element analysis. The effect of cohesion, internal friction angle, and mooring point height on bearing capacity have been studied. The influence of the height of the mooring point on the V-H failure envelope curve was explored by changing the height of the mooring point. The formula of the V-H failure envelope curve suitable for different mooring point heights was obtained. Full article

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

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20 pages, 6644 KiB

Open AccessArticle

Coupling of Finite Element Method and Peridynamics to Simulate Ship-Ice Interaction

by Renwei Liu, Yanzhuo Xue and Xikui Lu

J. Mar. Sci. Eng. 2023, 11(3), 481; https://doi.org/10.3390/jmse11030481 - 23 Feb 2023

Cited by 6 | Viewed by 2128

Abstract

In this work, the finite element method (PD-FEM) coupling strategy is used to simulate ship-ice interaction. Two numerical benchmark tests are selected to validate the coupling approach and its program. During the ice-breaking process simulation, the generation and propagation of radial and circular [...] Read more.

In this work, the finite element method (PD-FEM) coupling strategy is used to simulate ship-ice interaction. Two numerical benchmark tests are selected to validate the coupling approach and its program. During the ice-breaking process simulation, the generation and propagation of radial and circular cracks in level ice are modeled and phenomena such as the shedding of wedge ice, flipping of brash ice, and cleaning of the channel are observed to be broadly consistent with experimental observation. The influence of ship speed and ice thickness on the ice load are investigated and analyzed. The ice load obtained from the numerical simulations is in general agreement with that given by Lindqvist’s empirical formula. The boundary effect on the crack path can also be avoid with the current coupling method. Full article

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

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18 pages, 5617 KiB

Open AccessArticle

On the Resistance of Cruciform Structures during Ship Collision and Grounding

by Hewei Liu, Kun Liu, Xiufei Wang, Zhenguo Gao and Jiaxia Wang

J. Mar. Sci. Eng. 2023, 11(2), 459; https://doi.org/10.3390/jmse11020459 - 20 Feb 2023

Cited by 2 | Viewed by 1745

Abstract

This paper presents an experimental, numerical, and analytical study of a novel specimen subjected to local in-plane load, to investigate its crushing deformation and resistance. The specimen was designed and fabricated to simplify the cruciform structure in double-hulled vessels subjected to external loads [...] Read more.

This paper presents an experimental, numerical, and analytical study of a novel specimen subjected to local in-plane load, to investigate its crushing deformation and resistance. The specimen was designed and fabricated to simplify the cruciform structure in double-hulled vessels subjected to external loads during collision and grounding incidents. The study results will provide reliable insights into grounding scenarios as well as side collision scenarios of double-hulled vessels. A quasi-static indentation test and related numerical research showed good agreement regarding deformation mode and force–displacement response. On the basis of the experimental and numerical results, an analytical method is proposed to derive the deformation energy, the instantaneous resistance, and the mean resistance of the deformed structure. The analytical method was verified with recorded test data and a nonlinear finite element analysis. It enables a rapid assessment of the response of the structure under accidental loads, which is a guideline for the design of crashworthy hull structures and the assessment of their crashworthiness. Full article

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

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15 pages, 4727 KiB

Open AccessArticle

Study on the Low-Frequency and Broadband Sound Absorption Performance of an Underwater Anechoic Layer with Novel Design

by Jinshun Hu, Yongshui Lin, Zhiwei Zhou, Xiaofei Cao, Qingjia Chi and Weiguo Wu

J. Mar. Sci. Eng. 2023, 11(2), 409; https://doi.org/10.3390/jmse11020409 - 13 Feb 2023

Cited by 5 | Viewed by 2420

Abstract

To further improve the low-frequency broadband sound absorption capability of the underwater anechoic layer (UAL) on the surface of marine equipment, a novel sound absorption structure with cavities (NSSC) is designed by adding resonators and honeycombs to the traditional sound absorption structure with [...] Read more.

To further improve the low-frequency broadband sound absorption capability of the underwater anechoic layer (UAL) on the surface of marine equipment, a novel sound absorption structure with cavities (NSSC) is designed by adding resonators and honeycombs to the traditional sound absorption structure with cavities (SSC). Based on the principle of shear dissipation, the original intention of the design is to allow more parts of the viscoelastic material to participate the dissipation of acoustic energy. The approximate multilayer sound absorption theoretical model based on the modified transfer matrix method is used to verify the accuracy of finite element calculations. In the frequency range of 1100 Hz–10,000 Hz, the sound absorption coefficient (α) of NSSC can reach 0.8. The effects of the presence and size of cylindrical oscillators and honeycomb structures on sound absorption are discussed in detail. The results show that expanding the effective sound absorption range of the damping area of the structure is the key to improve the wideband sound absorption effect. This design concept could guide the structural design of the UAL. Full article

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

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20 pages, 10468 KiB

Open AccessArticle

Analysis of Dynamic Response and Ultimate Strength for Box Girder under Bending Moment

by Gui-Jie Shi, De-Yu Wang, Fu-Hua Wang and Shi-Jian Cai

J. Mar. Sci. Eng. 2023, 11(2), 373; https://doi.org/10.3390/jmse11020373 - 8 Feb 2023

Cited by 3 | Viewed by 2181

Abstract

The box girder can be seen as a kind of simplified ship structure that can withstand a vertical bending moment. Dynamic loads play an important role in structural safety analysis, such as ship bow slamming during harsh sea conditions. In this paper, the [...] Read more.

The box girder can be seen as a kind of simplified ship structure that can withstand a vertical bending moment. Dynamic loads play an important role in structural safety analysis, such as ship bow slamming during harsh sea conditions. In this paper, the dynamic elastic–plastic response and ultimate strength of a box girder under a bending moment are analyzed. A box girder with the same cross-section scantlings and span length as the Nishihara experiment is selected as the analysis object. Based on the model experiment results, the non-linear FE analysis method is validated to capture the ultimate strength of a box girder under bending moment. Then, six box girders were designed to study the critical influence factors on the dynamic ultimate moment, including the model length, plate thickness, mass density and load excitation period. On the basis of structural dynamic response, an evaluation criterion of dynamic limit state for the box girder under a bending moment is proposed in this paper. Compared with the static ultimate moment, the change in the dynamic ultimate moment is discussed in detail to obtain the general principal method for dynamic strength analysis. The conclusions in this paper can provide guidance for dynamic ultimate strength evaluation. Full article

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

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28 pages, 22332 KiB

Open AccessArticle

Experimental Study of the Dynamic Performance of Steel Catenary Riser within the Touchdown Zone

by Yang Yu, Shengbo Xu, Jianxing Yu, Lixin Xu, Xin Liu and Pengfei Liu

J. Mar. Sci. Eng. 2023, 11(1), 151; https://doi.org/10.3390/jmse11010151 - 8 Jan 2023

Cited by 2 | Viewed by 2277

Abstract

This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser (SCR) within the touchdown zone (TDZ). The facilities of the platform, including a soil tank, a loading system, and a soil stirring system, were [...] Read more.

This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser (SCR) within the touchdown zone (TDZ). The facilities of the platform, including a soil tank, a loading system, and a soil stirring system, were introduced in detail. The parameters of the test were determined through the simulation of an in situ riser. A steel pipe was adopted as the model riser, with its outer diameter equaling that of the prototype SCR. Before executing the dynamic loadings, the model riser developed its static configuration under the submerged weight and applied bending moment. Subsequently, cyclic vertical and lateral displacement loads were applied to the truncated point. The test results showed that when the vertical loading amplitude increased from 200 mm to 300 mm, the stress ranges at the front of the model riser increased by more than 100%, whereas the stress range only differed by less than 5% under different loading periods. Numerical models of the SCR were built based on the vector form intrinsic finite element (VFIFE) method. High similarities between the test and simulation results proved the reliability of the nonlinear soil model and the numerical model. During the test, a seabed trench was developed with a depth of 0.71 D and a width of 0.48 D, and its shape was similar to the in situ trench. Full article

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

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20 pages, 10339 KiB

Open AccessArticle

Effectiveness of Sacrificial Shielding for Blast Mitigation of Steel Floating Pontoons

by Yasser A. Khalifa, Mohamed N. Lotfy and Elsayed Fathallah

J. Mar. Sci. Eng. 2023, 11(1), 96; https://doi.org/10.3390/jmse11010096 - 4 Jan 2023

Cited by 3 | Viewed by 1952

Abstract

Floating pontoons have played a supreme and indispensable role in crises and disasters for both civil and military purposes. Floating bridges and ferries are exposed to blast loadings in the case of wars or terrorist attacks. The protection effectiveness of sacrificial cladding subjected [...] Read more.

Floating pontoons have played a supreme and indispensable role in crises and disasters for both civil and military purposes. Floating bridges and ferries are exposed to blast loadings in the case of wars or terrorist attacks. The protection effectiveness of sacrificial cladding subjected to a blast was numerically investigated. In this study, a steel ferry has been simulated and exposed to side explosions with different explosive charges at certain stand-off distances, according to military standards from NATO and American standard TM5. In this simulation, nonlinear three-dimensional hydro-code numerical simulation ANSYS autodyn-3d has been used. The results reported that the ferry could withstand a charge of 5 kg TNT at a stand-off distance of 1 m without failure. The main objective of this research is to achieve a design that would increase the capacity against the blast loading with minimal plastic deformation in the absence of any failure in the ferry. Therefore, an innovative mitigation system has been proposed to dissipate the blast energy of the explosion based on the scientific theory of impedance using sacrificial cladding. The new mitigation system used a specific structural system in order to install the existing pontoon structure without any distraction. The response, elastic deformations, plastic deformations and plastic failure of the ferry were illustrated in this paper. Furthermore, the results revealed that the proposed mitigation system could mitigate more than 50% of the blast waves. The new design revealed promising results, which makes it suitable for mitigating blast waves. Finally, the results were provided with a reference for the preliminary design and application of sacrificial cladding for structural protection against blast waves. Full article

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

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