• Journal of the Society of Naval Architects of Korea
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• v.40 no.3
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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.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.3
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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.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.3
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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.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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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 the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.99-110
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• 2000

The damages due to wave impact loads are largely affected by impact pressure impulse and impact load area. The objective of this study is, as the third step, to perform dynamic structural analysis of bow flare structure of 300,000 DWT VLCC using LS/DYNA3D code, and to verify its dynamic structural behaviors. The impact load areas of stiffener space $1.5s{\times}1.5s$ and $2.5s{\times}2.5s$ are applied to bow flare structure part with relatively flexible stiffeners, and with stiff members such as stringers, webs etc., respectively, under the wave impact load with peak height 6.5MPa, tail 1.0MPa, and duration time 5.0msec. Through the dynamic structural analysis in this study, it might be thought that the structural strength of bow flare structure is generally sufficient for these wave impact load and areas, except that large damages were found at bow flare structure area with flexible wide span stiffeners.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.4
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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.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.4
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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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.489-497
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• 2019

A ship operating under rough sea conditions is exposed to a slamming load due owing to its motion relative to encountered waves. In the process of reentering the water, the ship's structure is temporarily subjected to an impact pressure. In particular, bow flare slamming often occurs in large container ships with a large flare angle, and can cause structural damage. Numerical simulations were performed in this study, and the results were compared with reliable experimental results. The simulation results were also used to estimate the bow flare slamming pressures on a container ship under head sea and oblique sea conditions. It was found that a maximum impact pressure of 475 kPa was generated near the 0.975 station of the container ship under a head sea condition.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.2
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• pp.117-124
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• 1983

In rough seas, actual behaviours of a ship may not be estimated by the linear strip theory, because of Nonlinearities due to the hull shape, bottom slamming and bottom and/or bow-flare slamming. In case of slamming, impulsive hydrodynamic pressure occurs on the fore body surface of the ship, resulting hull vibration called whipping, by which the ship may suffer from serious structural damages and the impact pressure, depends critically on the relative velocity at re-entry. In this paper, the Time history of impact froce at each station, the longitudinal distribution of impact force at critical time, the Time history of acceleration at F.P. and the Time history of Bending moment at midship are illustrated. That is, authors analyzed Dynamic response of container ship to be subjected slamming impact force.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.87-94
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• 1999

Empirical design is still used to avoid a structural damage because impact phenomenon and structural behaviour due to wave impact load can not examined accurately. The damage due to wave impact load is largely affected by impact pressure impulse and impact load area. The objective of this study is, as the second step, to develop an efficient scantling program of bow flare structure, and to predict its impact load area by comparing maximum dented deformations at center of idealized panel structure model of bow flare structure of 300k DWT VLCC using LS/DYNA3D code, which will be used for its verification of dynamic structural analysis, as the next step. Through this study, the impact load area was estimated as $1.5s{\times}1.5s$ stiffener space(s) in the case of panel with stiffeners and as $2.5s{\times}2.5s$, with stringers, under impact pressure curve with peak height 6.5MPa, tail height 1.0MPa, and duration time 5.0msec.