• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.641-645
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• 2002

In case of aluminum-cased battery, The ratio of height and base of square is generally above the ten times, square-shaped and problem of non-axis symmetry. It is typical model to set up the analysis method of finite element. The reliable analysis of finite element method is suggested, which is used to investigate the possibility that multi-stage deep drawing and ironing used currently is replaced by backward impact extrusion favorable in the respect of cost production and productivity. The influence of parameter was analyzed and compared, which was considered to analyze the process of large deformation plasticity such as extrusion. Die and billet was made as the same shape of finite element model. The results of experiment show good forming without the rupture and wrinkles with the optimum velocity 100mm/sec obtained by analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2410-2414
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• 2008

Human heart valves diseased by congenital heart defects, rheumatic fever, bacterial infection, cancer may cause stenosis or insufficiency in the valves. Treatment may be with medication but often involves valve repair or replacement (insertion of an artificial heart valve). Bileaflet mechanical heart valves (BMHVs) are widely implanted to replace the diseased heart valves, but still suffer from complications such as hemolysis, platelet activation, tissue overgrowth and device failure. These complications are closely related to both flow characteristics through the valves and leaflet dynamics. In this study, the physiological flow interacting with the moving leaflets in a bileaflet mechanical heart valve (BMHV) is simulated with a strongly coupled implicit fluid-structure interaction (FSI) method which is newly organized based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in FLUENT. The simulated results are in good agreement with previous experimental studies. This study shows the applicability of the present FSI model to the complicated physics interacting between fluid flow and moving boundary.

• 한국전산구조공학회논문집
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• 제35권6호
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• pp.333-342
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• 2022

경험식에 기반한 폭발 해석방법은 폭압-시간 이력곡선을 하중으로 적용하여 해석하는 방법이다. 이 방법은 모델링이 간단하고 해석시간이 짧아 효율적이지만, 일부 연구에 따르면 근거리 폭발 해석에는 적합하지 않음이 보고되고 있다. 본 연구에서는 예로써 환산거리 0.4~1.0의 근거리 폭발조건에 있는 RC 보에 대해 해석방법에 따른 결과의 차이 및 원인을 분석하였고, 이를 통해 경험식 방법을 이용한 해석의 적용 범위를 구체적으로 검토 및 확인할 수 있었다. 사용된 유한요소해석 프로그램은 LS-DYNA이다. 해석결과에 따르면, 원거리 폭발 실험 데이터를 근거로 하는 경험식 해석방법은 충격량을 과소평가하고 있었다. 이로 인해 RC 보의 처짐은 측정된 처짐 또는 ALE(Arbitrary Lagrangian Eulerian) 해석결과에 비해 작게 계산되었다. 구조체의 응답이 크게 나타나는 근거리 폭발에 대해서는 ALE 해석방법을 사용하는 것이 더 적합할 것으로 사료된다.

• Wind and Structures
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• 제18권3호
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• pp.215-233
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• 2014

This paper presents a method to extract flutter derivatives of bridge decks based on a combination of the computational fluid dynamics (CFD), system simulations and system identifications. The incompressible solver adopts an Arbitrary Lagrangian-Eulerian (ALE) formulation with the finite volume discretization in space. The imposed sectional motion in heaving or pitching relies on exponential time series as input, with aerodynamic forces time histories acting on the section evaluated as output. System identifications are carried out to fit coefficients of the inputs and outputs of ARMA models, as to establish discrete-time aerodynamic models. System simulations of the established models are then performed as to obtain the lift and moment exerting on the sections to a sinusoidal displacement. It follows that flutter derivatives are identified. The present approaches are applied to a hexagon thin plate and a real bridge deck. The results are compared to the Theodorsen closed-form solution and those from wind tunnel tests. Satisfactory agreements are observed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.597-602
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• 2006

Many researches have been studied several vibration control device such as TMD and TLD to reduce the influence of wind or seismic waves for high-rise buildings. TLD provides some advantages such as easy installation and low maintenance cost. However, because of the difficulties in evaluating the characteristics of TLD, the dynamic characteristics of TLD must be investigated by experiment or analysis. In this study, the dynamic response analysis of structure with TLD was carried out to verify the vibration control ability of the proposed TLD for high-rise building with about 60 stories. A real seismic wave was used, and the parameter of interest was chosen by the height of water level in the same shape of water tank. From the numerical results, the responses of structure with water tank were confirmed to be safer than those of structure without water tank.

• Structural Engineering and Mechanics
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• 제16권4호
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• pp.423-440
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• 2003

Arbitrary Lagrangian Eulerian finite element methods gain interest for the capability to control mesh geometry independently from material geometry, the ALE methods are used to create a new undistorted mesh for the fluid domain. In this paper we use the ALE technique to solve fuel slosh problem. Fuel slosh is an important design consideration not only for the fuel tank, but also for the structure supporting the fuel tank. "Fuel slosh" can be generated by many ways: abrupt changes in acceleration (braking), as well as abrupt changes in direction (highway exit-ramp). Repetitive motion can also be involved if a "sloshing resonance" is generated. These sloshing events can in turn affect the overall performance of the parent structure. A finite element analysis method has been developed to analyze this complex event. A new ALE formulation for the fluid mesh has been developed to keep the fluid mesh integrity during the motion of the tank. This paper explains the analysis capabilities on a technical level. Following the explanation, the analysis capabilities are validated against theoretical using potential flow for calculating fuel slosh frequency.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.783-788
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• 2007

Many researches have been studied several vibration control device such as TMD and TLD to reduce the influence of wind or seismic waves for high-rise buildings. TLD provides some advantages such as easy installation and low maintenance cost. However, because of the difficulties in evaluating the characteristics of TLD, the dynamic characteristics of TLD must be investigated by experiment or analysis. In this study, the dynamic response analysis of structure with TLD was carried out to verify the vibration control ability of the proposed TLD for high-rise building. The parameter of interest was chosen by the height of the water level and the frequency of input seismic wave in the same shape of water tank.

• 항공우주시스템공학회지
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• 제15권6호
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• pp.10-18
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• 2021

A flame deflector prevents a launch system from thermal damage by deflecting the exhaust flame of the launch vehicle. During the deflection of the flame, the flame deflector is subjected to a high-temperature and high-pressure flow, which results in thermal ablation damage at the surface. Predicting this ablation damage is an essential requirement to ensure a reliable design. This paper introduces a numerical method for predicting the ablation damage phenomena based on a one-way fluid-structure interaction (FSI) analysis. In the proposed procedure, the temperature and convective heat transfer coefficient of the exhaust flame are calculated using a fluid dynamics analysis, and then the ablation is calculated using a finite element analysis (FEA) based on the user-subroutine UMESHMOTION and Arbitrary Lagrangian-Eulerian (ALE) adaptive mesh technique in ABAQUS. The result of such an analysis was verified by comparison to the ablation test result for a flame deflector.

• 한국전산유체공학회지
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• 제5권1호
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• pp.1-7
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• 2000

In general, FDM(finite difference method) and FVM(finite volume method) are used for analyzing the fluid flow numerically. However it is difficult to apply them to problems involving complex geometries, multi-connected domains, and complex boundary conditions. On the contrary, FEM(finite element method) with coordinates transformation for the unstructured grid is effective for the complex geometries. Most of previous studies have used commercial codes such as KIVA or STAR-CD for the flow analyses in the engine cylinder, and these codes are mostly based on the FVM. In the present study, using the FEM for three-dimensional, unsteady, and incompressible Navier-Stokes equation, the velocity and pressure fields in the engine cylinder have been numerically analyzed. As a numerical algorithm, 4-step time-splitting method is used and ALE(arbitrary Lagrangian Eulerian) method is adopted for moving grids. In the Piston-Cylinder, the calculated results show good agreement in comparison with those by the FVM and the experimental results by the LDA.

• Korea-Australia Rheology Journal
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• 제18권2호
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• pp.109-118
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• 2006

A finite-element method was employed to analyze axisymmetric unsteady motion of a deformable bubble near the wall. In the present study a deformable bubble in a Newtonian medium near the wall was considered. In solving the governing equations a structured mesh generator was used to describe the collapse of highly deformed bubbles with the Arbitrary Lagrangian Eulerian (ALE) method being employed in order to capture the transient bubble boundary effectively. In order to check the accuracy of the present FE analysis we compared the results of our FE solutions with the result of the collapse of spherical bubbles in a large body of fluid in which solutions can be obtained using a 1D FE analysis. It has been found that 1D and 2D bubble deformations are in good agreement for spherically symmetric problems confirming the validity of the numerical code. Non-spherically symmetric problems were also solved for the collapse of bubble located near a plane solid wall. We have shown that a microjet develops at the bubble boundary away from the wall as already observed experimentally. We have discussed the effect of Reynolds number and distance of the bubble center from the wall on the transient collapse pattern of bubble.