• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.409-415
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• 2003

The purpose of this paper is to develop the 2-Dim Lagrangian Hydrocode for the analysis of large deformations of solids with implementation of the contact algorithm. First, th e governing equations are discretized into a system of algebraic equations. For more accurate and robust contact force computation. the defense node contact algorithm was adopted and implemented. For the verification of the code developed, two cases are carried out; the Taylor-Impact test and two bodies impact. The von -Mises criterion is implemented into the code with the Shock equation of state. The simulation results show a good agreement compared with the published experimental data and results from the commercial code. It is necessary to implement several material models and failure models for applications to different impact and penetration problems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1235-1241
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• 2006

A new hydrocode which is still under development using Lagrangian, Eulerian and arbitrary Lagrangian-Eulerian operators, has been described. The three operators are implemented into a single framework by incorporating the sequential three stages of Lagrangian, remesh and remap stages. Several numerical schemes used for each operator are discussed briefly in this paper. In order to evaluate the characteristics of each operator, the Taylor Impact Test has been simulated using each operator and the results are compared. Currently the code is 1st order accuracy in the material interface tracking algorithm and can not handle multimaterial in the mixed cell. The areas of possible enhancement of the code are also discussed.

• Computational Structural Engineering
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• v.24 no.1
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• pp.49-56
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• 2011

• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1041-1050
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• 1995

The deformed shape of rod specimen of copper alloys was measured after the high-velocity impact against a rigid anvil and analyzed with one-dimensional theory to determine dynamic yield stress and strain-rate sensitivity which is defined as the ratio of dynamic yield stress to static flow stress. The evvect of two-dimensional deformation on the determination of dynamic yield stress by the one-dimensional theory, was investigated through comparison with the analysis by hydrocode. It showed that the one-dimensional theory is relatively consistent with two-dimensional hydrocode in spite of its simplicity in analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.5
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• pp.116-123
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• 2008

Hydrocodes are large computer programs that can be used to solve a wide variety of highly transient problems such as high-speed impact and explosion events. This paper describes the recent activity to develop a Multi-material hydrocode in Korea. The code consists of two stages; Lagrangian, and remap stages. Although a sophisticated contact algorithm has been developed for Lagrangian calculations, a relatively simple mechanics at the interfaces of materials are used in the multi-material Eulerian code. Volume of fluid interface reconstruction methods are used to resolve the interfaces between different materials. For the advection stage of the cell centered properties, one-dimensional hyperbolic equation is used. Test problems demonstrated here are the high-speed impact/penetration and explosion problems.

• 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.

• Computational Structural Engineering
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• v.16 no.2
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• pp.13-29
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• 2003

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.235-237
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• 2008

A unified hydrocode, ExLO, in which Largrangian, ALE and Eulerian solvers are incorporated into a single framework, has recently been developed in Korea. It is based on the three dimensional explicit finite element method and written in C++. ExLO is mainly designed for the calculation of structural responses to highly transient loading conditions, such as high-speed impacts, high-speed machining, high speed forming and explosions. In this paper the numerical schemes are described. Some improvements of the material interface and advection scheme are included. Details and issues of the momentum advection scheme are provided. In this paper the modeling capability of ExLO has been described for two extreme loading events; high-speed impacts and explosions. Numerical predictions are in good agreement with the existing experimental data. Specific applications of the code are discussed in a separate paper in this journal. Eventually ExLO will be providing an optimum simulation environment to engineering problems including the fluid-structure interaction problems, since it allows regions of a problem to be modeled with Lagrangian, ALE or Eulerian schemes in a single framework.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5A
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• pp.369-378
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• 2011

In this paper, the response analysis of RC(Reinforced Concrete), SC(Steel-Plate Concrete) containment buildings subjected to a large aircraft impact is performed using Autodyn-3D as Hydrocode. Until now, the impact load in the analysis of aircraft impacts has been applied to target structures at the local area by using the impact load-time history function of Riera. However in this paper, the results of aircraft crash are analyzed by using an aircraft model similar to Boeing 767 and verified by comparing the generated history of the aircraft crash against the rigid target with another history by using the Riera's function. To estimate the resistivity of the impact, the response and safety of SC containment buildings, this study is performed by comparing the four cases of plane concrete, reinforced concrete, bonded containment liner plate at reinforced concrete, and SC structure. Thus, the different behaviors between SC and RC structures when they are subjected to the extreme impact load could be anticipated. Consequently, the improved safety is expected by replacing RC structure with SC structure for nuclear power plants.