• 대한조선학회논문집
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• 제40권3호
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• pp.37-44
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• 2003

In rough seas, bow-flare regions of the sea-going ships are subject to high impact pressures due to the bow-flare slamming and panting. And many ships suffer structural damages in that region, even though they were built under the bow structure strengthening rules of the ship classes. So, a new design method for bow-flare structure is highly required. In this paper, bow-flare damage analysis is performed for 17 ships (total number of damage/non-damage data is 782). Based on this analysis, a new design standard and method for bow-flare structure (shell plate, frame and web frame) is proposed. 80.4% of the present damage/non-damage data were well-explained by this new design standard.

• 대한조선학회논문집
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• 제40권3호
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• pp.29-36
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• 2003

In rough seas, bow-flare regions of the fine ships (container ship and PCC) are subject to high impact pressures due to the bow-flare slamming. And many ships suffer structural damages in that region, even though they were built under the bow structure strengthening rules of the ship classes. So, a new design method for bow-flare structure is highly required. In this paper, a new prediction method of the bow-flare impact pressure (in terms of equivalent static pressure) acting on the fine ships' bow is presented. This method is based on the 11 fine ships' damage analysis and the mechanisms of water entry impact and breaking wave impact. Calculation results of the bow-flare impact pressure and the shell plate thickness are shown and discussed. Through the example calculations, it was found that the present method is useful for the structure design of the fine ships' bow.

• 대한조선학회논문집
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• 제40권3호
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• pp.22-28
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• 2003

In rough seas, bow-flare regions of the full ships (tanker and bulk carrier) are subiect to high impact pressures due to the on-coming breaking waves. And many ships suffer structural damages in that region, even though they were built under the bow structure strengthening rules of the ship classes. So, a new design method for bow-flare structure is highly required. In this paper, a new prediction method of the bow-flare impact pressure (in terms of equivalent static pressure) acting on the full ships' bow is presented. This method is based on the 6 full ships' damage analysis and the breaking wave impact mechanism. Calculation results of the bow-flare impact pressure and the shell plate thickness are shown and discussed. Through the example calculations, it was found that the present method is useful for the structure design of the full ships' bow.

• 대한조선학회논문집
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• 제49권1호
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• pp.79-86
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• 2012

It is very important to investigate and understand the motion of a FPSO on waves because green water phenomenon occurs owing to the relative motions between incident waves and a ship on them. In this research, both experimental and some numerical approaches have been performed in head sea conditions with regular waves. As an object model of this research, a FPSO model is set free to heave and pitch during the experiments. Also, the motions of the FPSO model which are the results of the experiments are used for the corresponding numerical computations. The purpose of this study is to clarify the effect of bow flare on green water load. In this research, it is found that the amount of green water entered from the side of bow is decreased by the increase of bow flare angle. Moreover, the relation between the green water on the bow upper deck and the impact load on the vertical wall located at turrethead is investigated. The results of this research could be used as one of the fundamental data to design bow flares. Also, an optimized bow flare angle is proposed in this study.

• Journal of Advanced Research in Ocean Engineering
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• 제4권4호
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• pp.204-216
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• 2018

A ship repeatedly face free surface under rough sea conditions owing to relative motion with wave encounter. The impact pressure is transferred to the hull structure and causes structural damage. In this study, the bow flare slamming load of a container ship is estimated using computations fluid dynamics (CFD) and prescript formula according to various classifications. It is found that the bow flare slamming load calculated by the formulas of the common structural rule and ABS tends to be similar to the CFD results.

• 대한조선학회논문집
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• 제44권3호
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• pp.279-284
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• 2007

As a container vessel becomes larger, the bow flare becomes larger. The large bow flare structures are often subjected to dynamic pressure loads due to bow flare slamming occurring in rough seas. The aim of this paper is to investigate the characteristics of bow flare slamming pressure measured in a real voyage through the North Pacific Ocean. The characteristics of impact pressure load caused by slamming is addressed in terms of the pressure pulse-time history which involves rising time, peak pressure, decaying time and type of pressure decay. The values were presented using non-dimensional parameters.

• Journal of Advanced Research in Ocean Engineering
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• 제4권4호
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• pp.195-203
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• 2018

The wave impact on ships could cause local damage to the ship's hull, which has been a concerning issue during the ship design process. In recent years, local structural damages of ships caused by slamming loads have been reported by accident; therefore, it is necessary to study the local slamming pressure loads and structural response assessment. In the present study, slamming loads around the ship's bow region in the presence of regular wave have been simulated by RANS equations discretized with a cell-centered finite volume method (FVM) in conjunction with the $k-{\Box}$ turbulence model. The dynamic structural response has been calculated using an explicit FE method. By adding the slamming pressure load of each time step to the finite element model, establishing the reasonable boundary conditions, and considering the material strain-rate effects, the dynamic response prediction of the bow flare structure has been achieved. The results and insights of this study will be helpful to design a container ship that is resistant enough to withstand bow flare slamming loads.

• 대한조선학회논문집
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• 제37권1호
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• pp.99-110
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• 2000

파랑충격하중에 의한 선수 구조부의 손상은 주로 충격압력역적과 파랑충격하중이 가한 면적에 의하여 크게 영향을 받는다. 본 연구에서는 세 번째 단계로서 LS/DYNA3D를 이용하여 파랑충격하중에 대한 DWT 300,000급 VLCC의 선수 구조부의 동적 구조해석을 수행하여 검증을 하고자 한다. 극치 6.5MPa, 후부높이 1.0MPa, 지속시간 5.0msec인 파랑충격압력 곡선을 강성이 작은 보강재로 보강된 선수 구조부에는 면적 $1.5s{\times}1.5s$, 대체로 강성이 큰 스트링거 등의 부재로 보강된 경우는 면적 $2.5s{\times}2.5s$에 가한다. 이상의 동적 구조해석을 통하여 넓은 간격의 보강재가 부착된 선수 구조부에는 외판과 보강재에 큰 손상변형이 발생한 것 이외는 고려 중인 유조선의 선수 구조부는 본 연구의 파랑충격하중에 대하여 충분한 강도를 지닌다고 사료된다.

• 한국해양공학회지
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• 제26권4호
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• pp.15-22
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• 2012

In this research, the relationship between the bow shape and green water phenomenon on the bow deck of an FPSO was studied using an experimental method. A 140,000 DWT FPSO was used as the objective hull form in the present research. The incident waves were regular types. The heights were 1.0 and 1.5 times the freeboard, and the length was equal in size to LBP. The wave heights and pressures on the deck were measured in experiments. Model tests were performed to determine the effects of bow flare angles, bow shapes, and a forecastle deck. The free heave and pitch conditions were applied to the models in these experiments. From the results of the model tests, an optimized bow shape was designed, which was found to decrease the green water impact loading. The results of this research could be used as fundamental data in the design of a bow shape.

• 해양환경안전학회지
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• 제25권4호
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• pp.489-497
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• 2019

거친 해상 조건에서 운항하는 선박은 파도와의 상대운동으로 인해 슬래밍 하중에 노출된다. 특히 선수가 자유수면으로 입수하는 과정에서 선체부는 일시적으로 큰 슬래밍 충격하중을 받게된다. 일반적으로 대형 컨테이너선박의 경우, 큰 플레어를 가지는 특징이 있으며, 이로 인해 플레어 슬래밍 충격하중으로 인한 구조적 손상이 발생할 수 있다. 본 연구에서는 슬래밍 수치시뮬레이션을 위해 먼저 신뢰할 만한 실험결과와의 비교검증을 수행하였으며, 선수 및 사파에서 선수플레어 슬래밍 하중을 추정하였다. 그 결과 슬래밍 하중이 발생되는 위치는 0.975st이며, 최대 충격 하중은 선수파 조건에서 약 475kPa임을 확인하였다.