Safety Assessment of Ship Launching Based on Airbags With the Nonlinear Rigidity of Airbags Being Considered

2009 ◽  
Author(s):  
Huilong Ren ◽  
Chenfeng Li ◽  
Guoqing Feng ◽  
Xiaobo Liu ◽  
Jian Zhang
Keyword(s):  
Calculation Method ◽  
Scientific Method ◽  
Safety Assessment ◽  
Ship Hull ◽  
Ship Motions ◽  
Equilibrium Conditions ◽  
Air Bags ◽  
Hull Structure ◽  
Comparison Of The Results ◽  
Force Equilibrium

Launching based on airbags is an important method of ship launching. However, there has not a scientific method for quantitative assessment on the strength of hull structure and safety of airbags at present. With the increases of tonnage of ships launching on airbags, this problem becomes increasingly apparent and important. With the nonlinear rigidity of air-bags and force equilibrium conditions of ship-hull beam being considered during launching, a method based on full ship FEA was put forward to assess the strength of ship structure and the safety of airbags in this paper. The main contents are as follows: Considering nonlinear rigidity of airbags, a calculation method of rigidity of airbags was studied; Based on the elastic launching calculation, a method of calculating ship motion and force on ship hull was studied with the nonlinear rigidity of elastic foundation being considered; Based on the above condition of ship motions and forces, the stress of hull structure and the force on airbags are calculated by full ship FEA; The safety of a real ship launching based on airbags was assessed, based on the comparison of the results with references, the safety of ship launching by airbags and the reliability of the calculation method in this paper are verified.

Residual Stress on Ship Hull Structure

1998 ◽  
Vol 14 (04) ◽  
pp. 277-286
Author(s):  
Yasuhisa Okumoto
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Ship Hull ◽  
Ship Structure ◽  
Heat Process ◽  
Steel Material ◽  
Hull Structure ◽  
Hull Strength

It is well known that ship structure experiences residual stresses due to heat process of steelmaking and assembly (cutting, bending, welding, straightening, etc.), and that these stresses affect ship hull strength. However, such stresses are usually not considered in strength calculations, because they are quantitatively ambiguous. This paper reviews the residual stresses in ship hull structure in accordance with each production step, including steel material, with reference to past measurements and analyses.

scholarly journals DEVELOPMENT OF STRUCTURAL SOLUTIONS FOR PREVENTION OF WAVE RUN-UP OF THE BOW

2017 ◽  
pp. 7-14
Author(s):  
Pavel Evgenievich Burakovskiy
Keyword(s):  
Hydrodynamic Force ◽  
Stability Loss ◽  
Critical Value ◽  
Ship Hull ◽  
Hydrodynamic Impact ◽  
Hull Structure ◽  
Run Up ◽  
Hull Damage ◽  
Structural Solutions ◽  
Navigation Safety

One of the most dangerous situations for seagoing ships is wave run-up in a head sea. In such a case, significant hydrodynamic forces appear resulting in stability loss or ship hull damage. The paper presents structural solutions that contribute towards navigation safety by means of decreasing probability of wave run-up of the ship bow in a head sea. A design has been developed of a ship stabilizer in the form of hinge-mounted stabilizing wings which deflect from the hull when the bow submerges in water and then cling to it when it emerges. The paper presents a new design of the bulwark with rotating sections able to rotate in the direction from the deck to the board. These designs can reduce dipping in a wave and reduce hydrodynamic impact on the bow. Apart from this, a hull structure has been proposed with a detachable bow to prevent capsizing of a ship. If the hydrodynamic force reaches a critical value, destruction of a permanent joint will happen in the proposed design, resulting in the situation when leak-proof aft and bow parts detach and remain afloat, which will allow the crew to evacuate. The proposed designs will increase navigation safety in storm conditions.

scholarly journals Force Equilibrium-Based Safety Assessment System for Cargo Securing of Car Ferries

2016 ◽  
Vol 2 (3) ◽  
pp. 112-128
Author(s):  
Younghun Kim ◽  
Joonmo Choung ◽  
Huisang Jo ◽  
Kyounghoon Lee
Keyword(s):  
Safety Assessment ◽  
Assessment System ◽  
Force Equilibrium

scholarly journals Structural Reliability Assessment of Corroded Tanker Ship Based on Experimentally Estimated Ultimate Strength

2019 ◽  
Vol 26 (2) ◽  
pp. 47-54 ◽  
Author(s):  
Krzysztof Woloszyk ◽  
Yordan Garbatov
Keyword(s):  
Carrying Capacity ◽  
Reliability Assessment ◽  
Ship Hull ◽  
Real Structure ◽  
Ultimate Limit State ◽  
State Function ◽  
Load Carrying Capacity ◽  
The Real ◽  
Hull Structure ◽  
Load Carrying

Abstract This work deals with the reliability assessment of a tanker ship hull structure subjected to a vertical bending moment and corrosion degradation. The progressive collapse and ultimate load carrying capacity are estimated based on experimentally tested scaled box-shaped-specimens. The translation of the strength estimate of the scaled specimen to the real tanker ship hull structure is performed based on the dimensional theory developing a step-wise linear stress-strain relationship. The load-carrying capacity is considered as a stochastic variable, and the uncertainties resulted from the scaled-specimen to the real-structure strength translation, and the subjected load of the real ship are also accounted for. A sensitivity analysis concerning the stochastic variables, included in the ultimate limit state function is performed. The partial safety factors, in the case of a scaled specimen and real structure, are also identified, and conclusions are derived.

scholarly journals RETROFITTING ANALYSIS OF TANKER SHIP HULL STRUCTURE SUBJECTED TO CORROSION

Brodogradnja ◽  
2019 ◽  
Vol 70 (2) ◽  
pp. 87-109
Author(s):  
Davide Chichi ◽  
◽  
Yordan Garbatov
Keyword(s):  
Ship Hull ◽  
Hull Structure

Model Experimental Research of Ship Section on Structural Ultimate Strength

2020 ◽  
Author(s):  
Chen Xianyin ◽  
Zeng Wenyuan ◽  
Li Cong ◽  
Wang Wei
Keyword(s):  
Bearing Capacity ◽  
Ultimate Strength ◽  
Ultimate Bearing Capacity ◽  
Ship Hull ◽  
Structural Safety ◽  
Hull Structure ◽  
Similarity Model ◽  
Large Ship ◽  
Section Structure ◽  
Classification Society

Abstract Focusing on the model design and experimental method research of ultimate strength of ship hull typical section, a large ship with complex section structure was taken in this paper as the research object. The nonlinear analysis on the failure mode and ultimate strength of the hull structure were carried out. The similarity model for ultimate strength experiment was designed, and the validity of the similarity model in reflecting the ultimate bearing capacity of the real ship was verified. According to the experimental results, the ultimate strength experimental value was obtained by numerical conversion. The ultimate bearing capacity of the example ship was then checked with reference to several classification society rules to verify the structural safety of the ship hull.

The Effect on Large Container Ships’ Fatigue due to Springing Loads Coupling Horizontal and Torsional Vibrations

2018 ◽  
Author(s):  
Hui Li ◽  
Huifen Xu ◽  
Huilong Ren ◽  
Xiaoxi Shen ◽  
Yubo Wang
Keyword(s):  
Fatigue Damage ◽  
Torsional Vibration ◽  
Calculation Method ◽  
Wave Loads ◽  
Analysis Method ◽  
Element Analysis ◽  
Hull Structure ◽  
Torsional Loads ◽  
Large Container ◽  
Simplified Calculation

The issue of hydroelasticity caused by hull vibration has become an unavoidable problem in the design and verification of large ships. Driven by environmental protection and economical efficiency, the size of ships are increasingly larger, and the resulting springing and whipping response and their effects on fatigue damage has been paid more and more attention especially for ultra large container ships (ULCS). Many classification societies typically check fatigue damage caused by vertical bending when considering springing, while it needs to be emphasized that large container ships can suffer severe torsional loads compared to other large ships due to wide breath and big hatch openings. In the existing stress calculation method, the finite element analysis method obviously has a high calculation accuracy. However, there are so much work to do with FEM model established, and partially refined, operated at all sea states etc., which not only requires much time, but also higher computing equipment. Therefore, in this paper, a simplified calculation method of fatigue damage considering the effect of bending and torsion is proposed, and a 21000TEU will be calculated by this method. The wave loads on the hull structure will be estimated based on the 3D linear hydroelastic theory coupling horizontal and torsional vibration, and the stress caused by bending and torsion will be obtained respectively. Finally, the fatigue damage is calculated by spectral analysis method considering high frequency springing loads. Then the effect on large container ships’ fatigue due to bending and torsional vibration is discussed.

Effect of Marine Nuclear Reactor Environment to Ship’s Structural Responses

2021 ◽  
Author(s):  
Han Koo Jeong ◽  
Soo Hyoung Kim
Keyword(s):  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Neutron Irradiation ◽  
Ship Hull ◽  
Propulsion System ◽  
Reactor Operation ◽  
Gas Emissions ◽  
Strength Assessment ◽  
Hull Structure ◽  
Structural Behaviors

Abstract As the regulations on greenhouse gas emissions at sea become strict, technology development to minimize environmental pollutants emitted from the propulsion system of ships is actively underway. Research on the use of renewable energy as a power source of ships propulsion system pursuing eco-friendliness is continuously carried out. However, considering the recent development of ships’ large-scale, and at the same time minimizing greenhouse gas emissions at sea, the interest in nuclear energy as the means of a stable supply of environmentally friendly large-capacity energy has been increased. In this study, the effect of marine reactor operation on the material properties of a ship hull material is reviewed, and from this, hull structural behaviors are investigated. Attention is paid to the neutron irradiation on the material in the reactor operation environment, and then the strength assessment of a hull structural member assumed in the neutron irradiation situation is performed. Considering the neutron irradiation effects, the Young’s modulus, poisson’s ratio and allowable stress of DH36, typical high tensile strength steel used in ship hull, are varied based on the research findings related with the topic of neutron irradiated steels. Rectangular stiffened plated structures, basic common structural members for ship hull, are exemplified for the strength assessment to understand their structural behaviors such as strength and stiffness. Results from this study provide information on the effect of neutron irradiation on the hull structural behaviors of the ship using nuclear power and possibly can supplement the hull structure part from classification societies’ rules and regulations.

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