• Journal of the Korean Society of Marine Environment & Safety
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• v.3 no.1
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• pp.1-14
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• 1997

This paper describes a series of numerical simulations of colision between a 310, 000 DWT double hull VLCC (struck ship) and three 35, 000, 70, 000 and 105, 000 DWT tankers (striking ships) using LS/DYNA3D. Collisions are assumed to occur at the middle of the VLCC with the striking ships moving at right angle to the VLCC centerline. Striking ship speeds are varied to find a critical speed without failure of inner side shell, and the informations of collision force and absorption energy of each case are also reported. The validation of LS/DYNA3D in this study was made by comparing the result of numerical simulation of LS/DYNA3D with that of double hull tanker grounding experiment by the Carderock Division of Navla Surface Warfare Center (CDNSWC).

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.932-940
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• 2011

This study describes computational simulation results in 2-dimensional and 3-dimensional space concerning large scale gap test(LSGT) by using commercial hydrocode such as AUTODYN and LS-DYNA to analyze the detonation phenomenons of high explosives. To consider the possibilities of LSGT simulation, we used Lee - Tarver reaction rate model of PBX-9404 and Comp-B which were implemented AUTODYN's material library. Also we have tried the diverse numerical schemes such as Lagrangian, Eulerian and ALE(Arbitary Lagrangian Eulerian), SPH(Smoothed Particle Hydrodynamics) in LSGT simulations. After LSGT simulations, we compared the simulation results with published results to verify the LSGT simulations. According to the LSGT simulations, we have concluded as follows. In 2-dimensional and 3-dimensional space, Lagrangian solver provided the most reliable results based on analysis time and accuracy. When using two hydrocodes in 2-dimensional space, the simulation results are almost same except one explosive model. We have verified the modeling method and simulation results of the LSGT by using the commenrcial hydrocode in this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1174-1179
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• 2000

In recent years, the structural shock response to underwater explosion has been studied as much, or more, through numerical simulations than through testing for several reasons. Very high costs and sensitive environmental concerns have kept destructive underwater explosion testing to a minimum. Increase of simulation capabilities and sophisticated simulation tools has made numerical simulations more efficient analysis methods as well as more reliable testing aids. For the simulation of underwater explosions against, surface ships or submerged structures one has to include the effects of the explosive shock wave, the motion of the gaseous reactive products, the local cavitation collapse, the different nonlinear structural properties and the complex fluid-structure interaction phenomena. In this study, as benchmark step for the validation of hydrocode LS/DYNA3D and of technology of fluid-structure interaction problems, two kinds of cavitation problems are analyzed and structural shock response of floating ship model are compared with experimental result.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.89-99
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• 2003

Smoothed particle hydrodynamics, SPH, is a gridless Lagrangian technique which is a useful alternative numerical analysis method to simulate high velocity deformation problems as well as astrophysical and cosmological problems. The SPH method brings about some difficulties such as tensile Instability and stress oscillation. A new SPH method, so called normalized algorithm, was introduced to overcome these difficulties. In this paper we aimed to estimate this method and have developed an one-dimensional normalized SPH program. The high velocity impact model of an aluminum bar has been analysed by using the developed program and a commercial hydrocode, LS-DYNA. The obtained numerical results showed good agreement with the results of the same model in reference. The program also showed more stable results than those of LS-DYNA in stress oscillation. We hopefully expect that the developed one-dimensional normalized SPH program can be used to solve hydrodynamic problems especially for explosive detonation analysis.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.36-37
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• 2014

It is necessary to develop highly sophisticated Modeling & Simulation (M&S) system for the scientific investigation of marine accident causes and for the systematic reproduction of accidental damage procedure. To ensure an accurate and reasonable prediction of marine accidental causes, such as collision, grounding and flooding, full-scale ship M&S simulations would be the best approach using hydrocode, such as LS-DYNA code, with its Fluid-Structure Interaction (FSI) analysis technique. The objectivity of this paper is to present three full-scale ship collision, grounding and flooding simulation results of marine accidents, and to show the possibility of the scientific investigation of marine accident causes using highly sophisticated M&S system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.2
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• pp.99-111
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• 1999

The object of this study is to get the superior double hull structure to its crashworthiness against collision comparing absorbed energy capacities of its various types with each other, varying material properties, collision positions and velocities, and structural arrangements such as double hull width, web and stringer spaces, etc. Local absorbed energy capacities, failure behaviors and damage extents of their members are also considered during collision in addition to the estimations of their global ones. This paper describes a series of numerical simulations of collisions between DWT 45,000 oil tanker(struck ship) and DWT 10,500 rigid one(striking ships) using Hydrocode LS/DYNA3D. Collisions are assumed to occur at the middle of struck ship with striking one moving at right angle to its centerline. The following remarks were obtained through this study: More flexible the double hull structure is, much superior its crashworthiness against collision is. The increment of double hull width does not give much influence than other factors do. The exact use of material property such as failure strain is also important on the numerical simulation of collision.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.166-173
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• 2007

Collision analysis problems between ship to ship can be generally classified into the external mechanics(outer dynamics) and internal mechanics(inner dynamics). The former can be also dealt with the concept of fluid-structure interaction and the use of rigid body dynamic program, depending on the ways handling the hydrodynamic pressure due to surrounding water. In this study, full scale ship collision simulation was carried out, such as a DWT 75,000 ton striking ship collided at right angle to the middle of a DWT 150,000 struck ship with 10 knots velocity, coupling MCOL, a rigid body mechanics program for modeling the dynamics of ships, to hydrocode LS-DYNA. It could be confirmed that more suitable damage estimation would be performed in the case of the collision simulations with consideration of surrounding water through the comparison with the collision simulation results of fixed struck ships without it. Through this study, the opportunity could be obtained to establish a more effective ship collision simulation technique between ship to ship.