• 제목/요약/키워드: Finite Element technique

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EXTRAPOLATED EXPANDED MIXED FINITE ELEMENT APPROXIMATIONS OF SEMILINEAR SOBOLEV EQUATIONS

  • Ohm, Mi Ray;Lee, Hyun Young;Shin, Jun Yong
    • East Asian mathematical journal
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    • 제30권3호
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    • pp.327-334
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    • 2014
  • In this paper, we construct extrapolated expanded mixed finite element approximations to approximate the scalar unknown, its gradient and its flux of semilinear Sobolev equations. To avoid the difficulty of solving the system of nonlinear equations, we use an extrapolated technique in our construction of the approximations. Some numerical examples are used to show the efficiency of our schemes.

콘크리트의 변형률 국소화 및 진행성 파괴에 관한 연구 (Study on Strain Localization and Progressive Failure of Concrete)

  • 송하원;김형운;우승민
    • 콘크리트학회논문집
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    • 제11권3호
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    • pp.181-192
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    • 1999
  • The progressive failure following strain localization in concrete can be analyzed effectively using finite element modeling of fracture process zone of concrete with a finite element embedded discontinuity. In this study, a finite element with embedded discontinuous line is utilized for the analysis of progressive failure in concrete. The finite element with embedded discontinuity is a kind of discrete crack element, but the difficulties in discrete crack approach such as remeshing or adding new nodes along with crack growth can be avoided. Using a discontinuous shape function for this element, the displacement discontinuity is embedded within an element and its constitutive equation is modeled from the modeling of fracture process zone. The element stiffness matrix is derived and its dual mapping technique for numerical integration is employed. Then, a finite element analysis program with employed algorithms is developed and failure analysis results using developed finite element program are verified through the comparison with experimental data and other analysis results.

Strong formulation finite element method for arbitrarily shaped laminated plates - Part I. Theoretical analysis

  • Fantuzzi, Nicholas;Tornabene, Francesco
    • Advances in aircraft and spacecraft science
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    • 제1권2호
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    • pp.125-143
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    • 2014
  • This paper provides a new technique for solving the static analysis of arbitrarily shaped composite plates by using Strong Formulation Finite Element Method (SFEM). Several papers in literature by the authors have presented the proposed technique as an extension of the classic Generalized Differential Quadrature (GDQ) procedure. The present methodology joins the high accuracy of the strong formulation with the versatility of the well-known Finite Element Method (FEM). The continuity conditions among the elements is carried out by the compatibility or continuity conditions. The mapping technique is used to transform both the governing differential equations and the compatibility conditions between two adjacent sub-domains into the regular master element in the computational space. The numerical implementation of the global algebraic system obtained by the technique at issue is easy and straightforward. The main novelty of this paper is the application of the stress and strain recovery once the displacement parameters are evaluated. Computer investigations concerning a large number of composite plates have been carried out. SFEM results are compared with those presented in literature and a perfect agreement is observed.

LHS기법을 이용한 불연속암반구조물의 확률유한요소해석기법개발 (Development of Stochastic Finite Element Model for Underground Structure with Discontinuous Rock Mass Using Latin Hypercube Sampling Technique)

  • 최규섭;정영수
    • 전산구조공학
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    • 제10권4호
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    • pp.143-154
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    • 1997
  • 본 연구에서는 지하암반구조물의 구조해석시 불연속암반체의 물성변이를 고려할 수 있는 확률론적 해석기법을 개발하였다. 수치해석적 접근은 몬테칼로모사기법의 단점을 보완한 LHS기법을 사용하였고, 불연속면의 영향은 단층, 벽개 등과 같이 불연속성이 뚜렷한 지역에서 적용성이 높은 절리유한요소모델을 사용하였다. 재료특성에 대한 확률변수는 불연속면의 수직강성과 전단강성을 다확률변수로 사용하였으며, 이들은 확률공간에서 정규분포를 갖는 경우에 대하여 고려하였다. 본 연구에서 개발된 수치해석프로그램은 검증예제를 통하여 타당성을 확인하였으며, 가상의 불연속면군이 존재하는 지하원형공동에 대한 해석을 통하여 프로그램의 적용성을 확인하였다.

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대류확산문제의 유한요소해석을 위한 Line-by-Line 해법 (A Line-by-Line Technique for Convection-diffusion Problem Implementing Finite Element Method)

  • 유재석
    • 설비공학논문집
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    • 제3권2호
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    • pp.97-102
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    • 1991
  • Finite element method has been developed recently for the solution of the convection-diffusion problems. Finite element method has several advantages over finite difference method, but its requirement of the larger memory size of the computer has prevented from wide application. In the present study, line-by-line technique has been implemented to finite element method to overcome this disadvantage. Two dimensional laminar natural convection in square cavity was chosen as an example in this study. The numerical result shows good agreement with bench mark solution and the size of the coefficient marix has been reduced drastically.

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열 및 응력 해석용 3차원 적층 유한요소의 개발 (Development of Three-Dimensional Layered Finite Element for Thermo-Mechanical Analysis)

  • 조성수;하성규
    • 대한기계학회논문집A
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    • 제25권11호
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    • pp.1785-1795
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    • 2001
  • A multi-layered brick element fur the finite element method is developed for analyzing the three-dim-ensionally layered composite structures subjected to both thermal and mechanical boundary conditions. The element has eight nodes with one degree of freedom for the temperature and three for the display-ements at each node, and can contain arbitrary number of layers with different material properties with-in the element; the conventional element should contain one material within an element. Thus the total number of nodes and elements, which are needed to analyze the multi-layered composite structures, can be tremendously reduced. In solving the global equation, a partitioning technique is used to obtain the temperature and the displacements which are caused by both the mechanical boundary conditions and temperature distributions. The results by using the developed element are compared wish the commercial package, ANSYS and the conventional finite element methods, and they are in good agreement. It is also shown that the Number of nodes and elements can be tremendously reduced using the element without losing the numerical accuracies.

Direct frequency domain analysis of concrete arch dams based on FE-(FE-HE)-BE technique

  • Lotfi, Vahid
    • Computers and Concrete
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    • 제1권3호
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    • pp.285-302
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    • 2004
  • A FE-(FE-HE)-BE procedure is presented for dynamic analysis of concrete arch dams. In this technique, dam body is discretized by solid finite elements, while the reservoir domain is considered by a combination of fluid finite elements and a three-dimensional fluid hyper-element. Furthermore, foundation rock domain is handled by three-dimensional boundary element formulation. Based on this method, a previously developed program is modified, and the response of Morrow Point arch dam is studied for various conditions. Moreover, the effects of canyon shape on response of dam, is also discussed.

혼합 유한요소법을 사용한 H-평면의 도파관 접합 해석 (Analysis of Waveguide Junction in H-Plane Using Finite Element-Boundary Element Method)

  • 정진교;천창열;정현교;한송엽
    • 대한전기학회논문지
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    • 제43권4호
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    • pp.666-672
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    • 1994
  • An H-Plane waveguide component with arbitrary shape is analyzed using finite element method(FEM) Cooperated with boundary element method(BEM). For the application of BEM in the waveguide structure, a ray representation of the waveguide Green's function is used. This technique is applied to the analysis of the waveguide inductive junction. The results are compared with the results of the mode matching technique. The comparison shows good agreement.

Reliability-based stochastic finite element using the explicit probability density function

  • Rezan Chobdarian;Azad Yazdani;Hooshang Dabbagh;Mohammad-Rashid Salimi
    • Structural Engineering and Mechanics
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    • 제86권3호
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    • pp.349-359
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    • 2023
  • This paper presents a technique for determining the optimal number of elements in stochastic finite element analysis based on reliability analysis. Using the change-of-variable perturbation stochastic finite element approach, the probability density function of the dynamic responses of stochastic structures is explicitly determined. This method combines the perturbation stochastic finite element method with the change-of-variable technique into a united model. To further examine the relationships between the random fields, discretization of the random field parameters, such as the variance function and the scale of fluctuation, is also performed. Accordingly, the reliability index is calculated based on the explicit probability density function of responses with Gaussian or non-Gaussian random fields in any number of elements corresponding to the random field discretization. The numerical examples illustrate the effectiveness of the proposed method for a one-dimensional cantilever reinforced concrete column and a two-dimensional steel plate shear wall. The benefit of this method is that the probability density function of responses can be obtained explicitly without the use simulation techniques. Any type of random variable with any statistical distribution can be incorporated into the calculations, regardless of the restrictions imposed by the type of statistical distribution of random variables. Consequently, this method can be utilized as a suitable guideline for the efficient implementation of stochastic finite element analysis of structures, regardless of the statistical distribution of random variables.

유한요소법을 이용한 2차원 절삭가공면의 소성스트레인에 관한 연구 (A Study on Plastic Strain after Orthogonal Machining using Finite Element Analysis)

  • 김기환;문상돈;신형곤;김태영
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2001년도 춘계학술대회 논문집
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    • pp.988-991
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    • 2001
  • Plastically deformed layer influences the mechanical property of the mechanical element such as creep hardening, microscopical crack and stress corrosion destruction. Therefore, the property so called the surface integrity has to be considered, and the machined surface including plastic deformation, distribution of stress has to be conducted quantitatively. This paper explains the orthogonal cutting, and made an orthogonal cutting model using the finite element method, then analyzed cutting power, plastic deformation of workpiece. It introduces the developed subsequent recrystallizations technique for measurement of the plastic strain of machined surface, and verified the technique.

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