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This paper presents the structural assessment of a 500-cbm liquefied natural gas bunker ship, which is operated as a ship-to-ship transporter in the coastal area of South Korea, under collision accidents by a numerical approach. Based on marine traffic data, it was assumed that an oil tank is the colliding ship and the bunker ship is the struck ship. A non-linear finite element analysis was conducted under credible scenarios to consider the hydrodynamic response on the struck ship. It was compared to the structural response of the struck ship in bunkering which does not consider the hydrodynamic effect. In addition, major collision parameters that lead to severe damage on the struck ship was observed, and the specific values for ship speed and displacement of a third-party colliding ship during bunkering were suggested to minimise the risk of structural failure. [ABSTRACT FROM AUTHOR]

As ship collisions and grounding accidents lead to human injury and damage to the environment and property, more accurate predictions of structural damage to ships under impact loads are needed. Currently, to determine structural behaviors, finite element analysis (FEA) is frequently adopted. However, it is recommended to pay attention to material properties in FEA because structural damage is sensitive to material properties such as yield strength, fracture strain, etc. While the strain rate (impact speed) is automatically considered for dynamic yield stress using the Cowper–Symonds equation or other methods, the pre-defined fracture strain is generally used as the dynamic fracture strain (DFS), which is not dependent on strain rate during the simulation. This assigned value of fracture strain may affect the extent of damage and structural response. In this study, the effect of the DFS on the structural damage from collisions was investigated to determine the relationship between the DFS and damage. Empirical formulas based on predictions of damage by various events were developed as a function of the DFS and initial impact speed. The results of this study explained the effect of the DFS on the structural damage and determined the upper and lower bounds of damage by collisions. [ABSTRACT FROM AUTHOR]

The growing demand for liquefied natural gas (LNG)-fueled ships necessitates the establishment of an LNG bunkering facility. Ship-to-ship (STS) is one of the most practical forms of LNG bunkering systems. Although there are benefits to the LNG bunkering of ships, risk and safety issues are a concern due to the volatile cargo. Ship collision could result in accidental LNG release. The purpose of this study was to build LNG leakage scenarios, establish critical zones based on gas concentrations, and estimate the temperature reduction in a bunkering ship's structure resulting from the use of cryogenic fluid. The condition of a target ship's structure, both intact and when damaged due to collision, was considered. Leak size, leak direction, leak position, release rate, and reservoir pressure were included as leak parameters, and environmental parameters, such as the wind direction, wind speed, and ambient temperature, were also included. The release duration was set based on the shutdown duration of the emergency shutdown valve (ESD). A total of 72 leakage scenarios were generated for the main CFD analysis. Convergence tests were conducted to determine the appropriate grid and iteration numbers for a computational fluid dynamics (CFD) simulation. The gas dispersion characteristics and the cryogenic flow impact on the LNG bunkering ship's structure are discussed through a parametric study. [ABSTRACT FROM AUTHOR]

Abstract The occurrence of impact needs to be predicted for various cases as it mostly delivers negative to target object and environment. In marine structure, this phenomenon has distributed numerous damages to involved objects, such as can be found in tragedy of the Estonia in 1994. This disaster led to a reassessment of the safety of passenger ships in many country. During impact both of structural and material aspects contributes to responses in form of energy, force, and damage. In present work, consideration of the both aspects would be considered in preparation, analysis, and discussion, to evaluate contribution of considered aspects on failure characteristic. A target subjected to impact load in form of collision so called struck ship which had different hull configuration would be used in analysis as structural behaviour during and after hull structure of the struck ship was penetrated by the striking ship would be observed. In material level, analyses were conducted with applying different mechanical properties on the side structure. The results indicated that the tearing of inner hull was avoided due to size of double hull structure. This condition provided better safety but lower ship capacity. In other hand, strength characteristic of material was proofed dominate difference of internal energy. Finally, the influences of material strength, failure strain, and hardening parameter were evaluated and summarized. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to review and examine the effects of the selected collision parameter values on the characteristics of collision energy in several ship collision scenarios. The benchmarking particulars were taken from the ship-to-ship collision case on Sunda Strait in 2014, while the collision process was modeled with non-linear simulations using the finite element (FE) method to determine the predicted damage and internal energy in the collision process. In the first phase, the verified model for the numerical simulation was built based on the benchmarks and other previous findings by researchers. The study of parameters during the collision process was performed in a later stage. The location of the target point in the vertical axis and the effect of the collision angle were the primary main focuses. The characteristics of damage and energy tendencies will be presented. One remarkable findings was that the structure of the car deck showed a better resistance and was more difficult to destroy than the other proposed locations. The angle position between the two objects during the impact process significantly contributed to the damage pattern on the side hull. The final results also indicated that the cross-section of the target point's location influenced the observed parameters. [ABSTRACT FROM AUTHOR]

Roll on-roll off (Ro-Ro) ship is the preferable vessel for public transportation and also as a medium to distribute several commodities. Its operations are a straightforward process but traffic management is quite delicate, especially for cross-route. Moreover, maritime incidents sometimes occur, causing significant casualties and in the case of the Ro-Ro, collision with other ship is a possible threat with the ability to trigger immense damages. This research, therefore, was conducted to assess the structural casualties of a Ro-Ro vessel under collision. This was modelled with respect to a ship involved in a certain incident in Indonesia in the latest decade, and the designed collision problems were calculated using the finite element approach. The collision angle was selected as the main input parameter with the straight collision of angle 90° and oblique collision with different angles applied to the scenario. The results found the collision energy due to structural destruction to have distinct pattern and peak value under oblique cases with lower values observed for straight collision for all scenarios. It is, however, recommended that energy should be taken as an initial parameter in further investigation of structural damage and response contour. [ABSTRACT FROM AUTHOR]