• 대한기계학회논문집A
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• 제30권12호
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• pp.1518-1525
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• 2006

Finite element analyses of structures made of the fiber reinforced composites require an adequate method to characterize the high anisotropic behavior induced by one or several layers of fiber cords with different spatial orientation embedded in a rubber matrix. This paper newly proposes a continuum based rebar element considering change of the orientation of the fiber during deformation of the composite. The mechanical behavior of the embedded fiber is modeled using two-node bar elements in order to consider the relative deformation and spatial orientation of the embedded fiber. For improvement of the analysis accuracy, the load-displacement curve of fiber is applied to the stiffness matrix of fiber. A finite element program is constructed based on the total Lagrangian formulation considering both geometric and material nonlinearity. Finite element analyses of the tensile test are carried out in order to evaluate the validity of the proposed method. Analysis results obtained with the proposed method provides realistic representation of the fiber reinforced rubber composite compared to results of other two models by the Halpin-Tsai equation and a rebar element in ABAQUS/Standard.

• 전기학회논문지
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• 제61권8호
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• pp.1123-1129
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• 2012

This paper presents the fast steady state analysis using time-stepping finite element method for a high power three-phase transformer. The high power transformer spends huge computational cost of the time-stepping finite element method. It is because that the high power transformer requires a lot of time to reach steady state by its large inductance component. In order to reduce computational cost, in this paper, the adaptive time-step control algorithm combined with the embedded 2nd 4th singly diagonally implicit Runge-Kutta method and the analysis strategy using variation of the winding resistance are studied, and their numerical results are compared with those from the typical time-stepping finite element method.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1730-1740
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• 2006

A nodeless variables finite element method for analysis of two-dimensional, steady-state viscous incompressible flow is presented. The finite element equations are derived from the governing Navier-Stokes differential equations and a corresponding computer program is developed. The proposed method is evaluated by solving the examples of the lubricant flow in journal bearing and the flow in the lid-driven cavity. An adaptive meshing technique is incorporated to improve the solution accuracy and, at the same time, to reduce the analysis computational time. The efficiency of the combined adaptive meshing technique and the nodeless variables finite element method is illustrated by using the example of the flow past two fences in a channel.

• Structural Engineering and Mechanics
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• 제62권1호
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• pp.11-20
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• 2017

The base force element method (BFEM) is a new finite element method. In this paper, a degenerated 4-mid-node plane element from concave polygonal element of BFEM was proposed. The performance of this quadrilateral element with 4 mid-edge nodes in the BFEM on complementary energy principle is studied. Four examples of linear elastic analysis for plane frame structure are presented. The influence of aspect ratio of the element is analyzed. The feasibility of the 4 mid-edge node element model of BFEM on complementary energy principles researched for plane frame problems. The results using the BFEM are compared with corresponding analytical solutions and those obtained from the standard displacement finite element method. It is revealed that the BFEM has better performance compared to the displacement model in the case of large aspect ratio.

• 한국해안·해양공학회논문집
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• 제24권2호
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• pp.84-88
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• 2012

본 연구에서는 완경사 방정식을 이용한 유한요소모형에서 경사 경계면을 효율적으로 처리할 수 있는 수치기법을 소개하였다. 유한요소법은 다른 수치기법과 다르게 불규칙한 지형에도 적용이 가능하다는 장점을 가지고 있어 복잡한 지형 형태를 갖는 연안에서 발생하는 수리현상을 해석하기 위하여 빈번히 사용되었다. 그러나 유한요소모형에 사용된 지배방정식이 타원형 미분방정식인 경우에는 연직방향으로 경사진 경계면에서의 경계처리가 쉽지 않다는 단점이 있다. 본 연구에서는 Bessel 함수를 이용하여 경사진 경계면을 처리하는 방법을 소개하고 얻어진 결과를 해석해와 비교하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.258-261
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• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.

• Structural Engineering and Mechanics
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• 제29권5호
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• pp.469-488
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• 2008

Finite element methods have often been used for structural analyses of various mechanical problems. When finite element analyses are utilized to resolve mechanical systems, numerical uncertainties in the initial data such as structural parameters and loading conditions may result in uncertainties in the structural responses. Therefore the initial data have to be as accurate as possible in order to obtain reliable structural analysis results. The typical finite element method may not properly represent discrete systems when using uncertain data, since all input data of material properties and applied loads are defined by nominal values. An interval finite element analysis, which uses the interval arithmetic as introduced by Moore (1966) is proposed as a non-stochastic method in this study and serves a new numerical tool for evaluating the uncertainties of the initial data in structural analyses. According to this method, the element stiffness matrix includes interval terms of the lower and upper bounds of the structural parameters, and interval change functions are devised. Numerical uncertainties in the initial data are described as a tolerance error and tree graphs of uncertain data are constructed by numerical uncertainty combinations of each parameter. The structural responses calculated by all uncertainty cases can be easily estimated so that structural safety can be included in the design. Numerical applications of truss and frame structures demonstrate the efficiency of the present method with respect to numerical analyses of structural uncertainties.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.765-772
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• 1996

Objectives of this study were to develop an application method of a numerical retina using the finite element model and to investigate the performance of image features extraction in comparison to the textural analysis. Using a plant community of radish sprouts, excellent resolution of the finite element retina was revealed. The sensitivity analysis of the finite element retina from engineering point of view was discussed. The importance of sensitivity analysis of the finite element retina was pointed out in terms of extraction of effective image features of plant community . Technical details of maximizing the sensitivity of the finite element retina to populated plant canopy were also discussed.

• 한국방재학회 논문집
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• 제9권1호
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• pp.9-13
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• 2009

본 연구는 적응적 요소망을 사용한 유한요소법으로 해석된 2차원 문제를 전산을 활용한 구조공학 교육의 중요한 부분으로 활용하는 대요를 제시한다. 적응적 요소망 형성방법에서는 비교적 간단한 요소의 대표 변형률 값을 사용하였고 유한요소법으로는 광범위하게 활용되고 있는 변위법을 사용하였다. 적용한 예제는 기본 역학의 대표적인 문제인 집중 하중을 받는 캔틸레버보와 중앙에 원형 구멍을 갖은 평판 인장 문제이다. 교육 대요와 예제는 적응적 요소망을 사용한 유한요소법이 전산을 활용한 구조공학 교육에 중요한 부분이 될 수 있는 것을 보여준다.

• Structural Engineering and Mechanics
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• 제43권6호
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• pp.761-769
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• 2012

In this paper the Modified Finite Element-Transfer Matrix Method, which is the combination of Transfer Matrix Method and Finite Element Method, is applied to the static analysis of the structures. In the method, the structure is divided into substructures thus the number of unknowns that need to be worked out is reduced due to the transformation process. The static analysis of the structures can be performed easily and speedily by the proposed method. At the end of the study examples are presented for ensuring the agreement between the proposed method and classic Finite Element Method.