• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.77-86
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• 2003

Dynamic response of baffled fuel-storage tank in turnaround motion is simulated using the ALE finite element method. Fuel-storage tank undergoes abrupt impact load caused by inertia force of internal fuel in turnaround motion. Also, large dynamic force and moment caused by this load influence structural stability and control system. In this paper, ring-type baffles are adopted to suppress the dynamic influence. Through the parametric analysis with respect to the baffle number and location, the effects of baffle on the dynamic response of baffled fuel-storage tank is analyzed. The ALE finite element method is adopted for the accurate and effective simulation of the hydrodynamic interaction between fluid and structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1073-1080
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• 2012

Incremental forming is a cold working process in which a small part of the material is being deformed and the area of local deformation is moving over the entire material. In this paper, we study description schemes to perform finite element analysis for the incremental forming. The selected description schemes to examine are the Lagrangian description and the arbitrary Lagrangian-Eulerian (ALE) description. The sliding boundary scheme coupled with ALE is also examined to overcome the distortion problems of elements on the contact surface. Results show that the ALE description with the sliding boundary scheme is most favorable in overcoming the distortion of elements. This description leads to make the simulation continued to the final stage of the incremental forming. On the other hand, the Lagrangian description as well as the original ALE description makes the elements much distorted and the analysis is stopped long before arriving at the final shape of deformation.

• Journal of Korean Association for Spatial Structures
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• v.8 no.5
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• pp.95-105
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• 2008

The objective of this study is find out the stressed condition, slipped direction and slipped dimension when some elements of cable-membrane structures are slipped from it's initially designed coordinates by external loads as wind or non uniform load and so on. In order to search the slipped behaviors of cable-membrane structures, a ALE finite element formulation is introduced. In these procedures, a stiffness matrix related with ALE concept is formulated and a FE analysis program for cable-membrane structures with slipped elements is developed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1082-1088
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• 2007

Demand for high speed sea transportation modes has been increased dramatically last few decades. The WIG(Wing-in-ground effect) is considered as next generation maritime transportation system. In the structural design of high speed marine vessels, an estimation of water impact loads is essential. The dynamic structural responses of the WIG excited by the water impact loads may bring an important contribution to their damage process. The work presented in this paper is focused on the numerical simulation of the water impact on the WIG craft when it lands. It is aimed to study the structural responses of the WIG craft subjected to the water impact loads. The Arbitrary Lagrangian-Eulerian (ALE) finite element method is used to simulate the water impact of the WIG craft during a landing phase. A full 3D shell element is used to model the WIG craft in carbon composites, and a developed FE model is used to investigate the effect of the water impact loads on the structural responses of the WIG craft. In the analysis, two different landing scenarios are considered and their effects on the structural responses are investigated.

• Journal of computational fluids engineering
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• v.4 no.2
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• pp.39-46
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• 1999

The FVM(Finite Volume Method) have been used mainly for the flow analyses in the piston-cylinder. The objective of the present study is to analyze numerically the piston-driven intake flows using the FEM(Finite Element Method). The FEM algorithm used in this study is 4-step time-splitting method which requires much less execution time and computer storage than the velocity-pressure integrated method and the penalty method. And the explicit Lax-Wendroff scheme is applied to nonlinear convective term in the momentum equations to prevent checkerboard pressure oscillations. Also, the ALE(arbitrary Lagrangian Eulerian) method is adopted for the moving grids. The calculated results show good agreement in comparison with those by the FVM and the experimental results by the LDA.

• Transactions of Materials Processing
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• v.7 no.1
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• pp.72-80
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• 1998

This study is concerned with the thermo-biscoplastic finite element analysis of hot tube extrusion through square dies with a mandrel. The problem is treated as a non-steady state and the ALE description is used due to abruptly turning flow at the die aperture. Since the contact heat transfer coefficient and the friction factor are required in the analysis experiments are also carried out to determine the values, In order to apply ceramics to an extrusion die the study is focussed on under-standing the characteristics of the process. The simulated results provide the useful informations such as metal flow temperature distribution stress state etc. The elastic analysis of the dies is carried out to obtain the stress state of the ceramic dies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.882-886
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• 1996

The use of ceramics for extrusion dies is limited since the modification of die design is difficult. In order to successfully apply the ceramic dies to extrusion dies, a better understanding of the process should be preceded. This study focuses on understanding the characteristics of the process. In the present study, a hot extrusion of tube with a mandrel is analyzed by ALE finite element method. In order to obtain the stress state of ceraminc dies, the elastic analysis of dies is also carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.247-250
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• 2007

Flexible media such as the paper, the film, etc. are thin, light and very flexible. They behave in geometrically nonlinear. Any of small force makes large deformation. So we must including aerodynamic effect when its behavior is predicted. Thus, it becomes fully coupled fluid-structure interaction(FSI) problem. In FSI problems, where the fluid mesh near the structure undergoes large deformations and becomes unacceptably distorted, which drive the time step to a very small value for explicit calculations, the arbitrary Lagrangian-Eulerian(ALE) methods or rezoning are used to create a new undistorted mesh for the fluid domain, which allows the calculations to continue. In this paper, FE sheet model considering geometric nonlinearity is formulated to simulate the behavior of the flexible media. Aerodynamic force to the media by surrounding air is calculated by solving the incompressible Navier-Stokes equations. Q2Q1(Taylor-Hood) element which means biquadratic for velocity and bilinear for pressure is used for fluid domain. Q2Q1 element satisfies LBB condition and any stabilization technique is not needed. In this paper, cantilevered sheet in the viscous incompressible Navier-Stokes flow is simulated to check the mesh motion and numerical integration scheme, and then falling paper in the air is simulated and the effects of some representative parameters are investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.43-57
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• 1999

The fluid flow and heat transfer in a thin liquid film are investigated numerically. The flow Is assumed to be two-dimensional laminar and surface tension is considered. The most important characteristics of this flow is the existence of a hydraulic jump through which the flow undergoes very sharp and discontinuous change. Arbitrary Lagrangian-Eulerian(ALE) method is used to describe moving free boundary and a modified SIMPLE algorithm based on streamline upwind Petrov-Galerkin(SUPG) finite element method is used for time marching iterative solution. The numerical results obtained by solving unsteady full Navier-Stokes equations are presented for planar and radial flows subject to constant wall temperature or constant wall heat flux, and compared with available experimental data. It Is discussed systematically how the inlet Reynolds and Froude numbers and surface tension affect the formation of a hydraulic jump. In particular, the effect of temperature dependent fluid properties is also discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1538-1551
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• 1997

Kinetic energy conservation for fixed and moving grids is examined in time-accurate finite element computation of fully unsteady inviscid flows. As numerical algorithms, fractional step method (FSM) and modified SIMPLE are used. To simulate the flow in moving grid system, arbitrary Lagrangian-Eulerian (ALE) method is adopted. In the present study, the energy conserving time integration rule for finite element algorithm is proposed and discussed schematically. It is shown that the discretization by Crank-Nicolson in time and Galerkin (central difference) in space must be used to ensure energy conservation. The developed code has been tested for a standing vortex in fixed or moving grid system, sloshing in a tank and propagation of a solitary wave, and has been shown to be a completely energy conserving algorithm.