• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 춘계학술대회 논문집
• /
• pp.235-237
• /
• 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.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.503-506
• /
• 2005

In this study, optimization design technique for control of solid-fluid coupled force (sloshing) using evolutionary method is suggested. Artificial neural networks(ANN) and genetic algorithm(GA) is employed as evolutionary optimization method. The ANN is used to analysis of the sloshing and the genetic algorithm is adopted as an optimization algorithm. In the creation of ANN learning data, the design of experiments is adopted to higher performance of the ANN learning using minimum learning data and ALE(Arbitrary Lagrangian Eulerian) numerical method is used to obtain the sloshing analysis results. The proposed optimization technique is applied to the minimization of sloshing of the water in the tank lorry with baffles under 2 second lane change.

• 대한기계학회논문집A
• /
• 제21권11호
• /
• pp.1912-1920
• /
• 1997

In the analysis of metal forming process, ALE(Arbitrary Lagrangian Eulerian) finite element methods have been increasingly used for the capability to control mesh independently from material flow. The methods can be divided into two groups i.e., coupled and split formulations. In the present work, the split ALE formulation is used for computational efficiency. A split ALE finite element method developed for rigid-viscoplastic materials and applied to the analysis of hot square die extrusion. Since thermal state greatly affects the product quality, an ALE scheme for temperature analysis is also presented. As computational examples, profile shapes as square and cross-like sections are chosen.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제8권2호
• /
• pp.137-152
• /
• 2016

This paper studied the dynamic response of a new gasbag-type floating bridge under the effect of a moving load. The arbitrary Lagrangian-Eulerian (ALE) method was used to simulate the movement of seawater and air, and the penalty-based method was used to study the coupling between gasbags and fluid. A three-dimensional finite element model of the floating bridge was established, and the numerical model was verified by comparing with the experimental results. In order to prevent resonance, the natural frequencies and flexural mode shapes were analyzed. Based on the initial state analysis, the dynamic responses of the floating bridge subjected to different moving loads were investigated. Vertical displacements and radial deformations of gasbags under different loads were compared, and principal stress distributions of gasbags were researched while driving. The hinge forces between adjacent modules were calculated to ensure the connection strength. Besides, the floating bridge under wave impacting was analyzed. Those results can provide references for the analysis and design of this new floating bridge.

• Structural Engineering and Mechanics
• /
• 제13권6호
• /
• pp.653-670
• /
• 2002

In order to ensure the structural dynamic stability of moving liquid-storage containers, the flow motion of interior liquid should be appropriately suppressed by means of mechanical devices such as the disc-type elastic baffle. In practice, the design of a suitable baffle requires a priori the parametric dynamic characteristics of storage containers, with respect to the design parameters of baffle, such as the installation location and inner-hole size, the baffle number, and so on. In this paper, we intend to investigate the parametric effect of the baffle parameters on the transient dynamic behavior of a cylindrical fuel-storage tank in an abrupt vertical acceleration motion. For this goal, we employ the ALE (arbitrary Lagrangian-Eulerian) kinematic description method incorporated with the finite element method.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.475-480
• /
• 2000

The transient dynamic-response analysis of fuel-storage tanks of flying vehicles accelerating in the vertical direction is achieved with finite element method. A fuel-storage tank is a representative example of the fluid-structure interaction problem, in which structure and fluid media interact strongly. For the accurate analysis of this complicated fluid-structure system, we employed ALE(arbitrary Lagrangian-Eulerian) coupling method. Two types of fuel-storage tanks, one with two baffles and the other without baffle, are considered to examine the effect of baffles. The fuel-storage tank with baffles shows more uniform hydrodynamic pressure distribution, resulting effective stress in structural region and faster convergence from transient to steady states. MSC/Dytran, a commercial FEM software for the 3D coupled dynamic analysis, is used for this analysis.

• 한국해양공학회지
• /
• 제7권1호
• /
• pp.33-55
• /
• 1993

선수충격파의 문제를 푸는데 있어서 Boundary Integral Method(BIM)의 여러가지 수치 해석방법이 검토되었으며, 특히 여러가지 Time stepping scheme, Green function, far-field 조건등에 따른 수치해석안정성과 정확성의 상관관계가 연구되었다. von Neumann 안정성해석과 matrix 안정성해석 등을 이용한 선형 안정성해석을 기초로하여, 수치해석방법의 안정성 여부를 체계적으로 조사할 수 있는 parameter(Free Surface Stability number)를 설정하고, 이 parameter의 변화에 따른 비선형 운동해석을 연구하였다. 그 결과 비선형성이 심하지 않은 기진파의 경우에서는 비선형 운동해석의 수치해석 안정성의 선형 수치해석 안정성과 큰 차이가 없음을 알 수 있게 된다.

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

• 대한기계학회논문집A
• /
• 제20권11호
• /
• pp.3441-3453
• /
• 1996

A finite element anlaysis is performed for large deformations of a felxible beam. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. The finite elements results are confirmed for several cases of deformations through comparison to a first order elasticity solution obtained by numerical integration, and the agreement between the two is found to be excellent. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformation in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement.

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