• Title/Summary/Keyword: 비적합 변위형

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Improved Nonconforming 8-node Solid Element with Rotational Degrees of Freedom (회전자유도를 갖는 비적합 8-절점 입체요소의 개선)

  • 최창근;정근영;이태열
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.4
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    • pp.475-484
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    • 2000
  • In this paper, new additional nonconforming modes for the improvement of bending behavior in the distorted 8 node hexahedral element and their effective modification method are studied. The rotational degrees of freedom are introduced by using a functional in which the rotations are independent variables. In an element formulation, the same interpolations are used in displacement and rotation fields, but nonconforming modes we applied only in displacement fields. To verify the developed element various numerical tests are carried out and test results show good behavior.

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A Four-node General Shell Element with Drilling DOFs (면내회전자유도를 갖는 4절점 곡면 쉘요소)

  • Chung, Keun-Young;Kim, Jae-Min;Lee, Eun-Haeng
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.4
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    • pp.37-52
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    • 2012
  • In this study, a new 4-node general shell element with 6 DOFs per node is presented. Drilling rotational degrees of freedom are introduced by the variational principle with an independent rotation field. In formulation of the element, substitute transverse shear strain fields are used to avoid shear locking, while four nonconforming modes are applied in the in-plane displacement fields as a remedy for membrane locking. In addition, a direct modification method for nonconforming modes is employed in the numerical implementation of nonconforming modes to represent constant strain states. A 9-points integration rule is adopted for volume integration in the computation of the element stiffness matrix. With the combined use of these techniques, the developed shell element has no spurious zero energy modes, and can represent a constant strain state. Several numerical tests are carried out to evaluate the performance of the new element developed. The test results show that the behavior of the elements is satisfactory.

Development of the Plate Element Using Combination of Reduced Integration and Nonconforming Modes (감차적분(減次積分) 비적합변위형(非適合變位形)을 혼합사용한 평판요소(平板要素)의 개발(開發))

  • Bang, Myung Suk;Choi, Chang Kuen
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.5 no.2
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    • pp.19-25
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    • 1985
  • By the combined use of reduced integration and addition of nonconforming displacement modes, a highly effective new plate element has been established. The displacement field of this element was formed by adding nonconforming modes only to transverse displacement component of Ahmad-Irons' element and the element matrices are computed by the numerical integrations with modified orders. Comparing with other elements, the superiority of the both NC 8-4.1 and NC 8-5.1 elements over the elements previously studied has been observed. The solutions with these elements converge to the true solutions very rapidly as the mesh is refined. These elements are also shown to be applicable to the wide range of thick and very thin plate problems.

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Static and Dynamic Analysis of Plate Structures using a High Performance Finite Element (고성능 유한요소를 이용한 평판구조물의 정적 및 동적해석)

  • Han In-Seon;Kim Sun-Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.3
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    • pp.311-320
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    • 2005
  • In this paper an enhanced quadratic finite element for static and dynamic analysis of plate structures is presented. The performance of a proposed plate element is improved by the coupled use of non conforming displacement modes, the selective integration scheme, and the assumed shear strain fields. An efficient direct modification method is also applied to this element to solve the problem such as failure of the patch test due to the adoption of non conforming modes. The proposed quadratic finite element does not show any spurious mechanism and does not produce shear locking phenomena even with distorted meshes. It is shown that the results obtained by this element converged to analytical solutions very rapidly tough numerical tests for standard benchmark problems. It is also noted that this element is applicable to transient dynamic analysis of Mindlin plates.

Estimation of the Moving Load Velocity Using Micro Genetic Algorithm (마이크로 유전 알고리즘을 이용한 교통하중의 속도추정)

  • Tak, Moon-Ho;Noh, Myung-Hyun;Park, Tae-Hyo;Park, In-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2009.04a
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    • pp.292-295
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    • 2009
  • 본 논문에서는 평판구조물의 정적 및 동적해석에 사용할 목적으로 성능이 향상된 평판유한요소를 제시하였다. 이 요소는 비적합변위형과 선택적 감차적분방법 그리고 대체전단변형률장을 복합적으로 적용하여 각각의 장점들을 포함하는 향상된 거동을 보여주고 있다. 또한 비적합변위형의 적용으로 발생되는 조각시험의 실패 문제점을 해결하기 위하여 직접수정법을 평판유한요소의 개선에 사용하였다. 대표적인 검증문제에 대한 수치해석작업을 통하여 본 연구에서 개발한 요소는 가상적인 제로에너지모드 및 전단잠김현상의 발생과 같은 문제를 나타내지 않음을 알 수 있었다. 특히 찌그러진 형상으로 모형화 한 경우에 있어서도 전단잠김현상이 발생하지 않았다. 본 연구에서 수행한 동적반응해석 시험에 있어서도 이론해와 잘 일치하는 결과를 보여주었다.

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Improved Finite Element Models for Analysis of Plate Structures (평판구조물의 해석을 위한 개선된 유한요소모델의 개발)

  • Choi, Chang Koon;Kim, Sun Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.4
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    • pp.83-90
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    • 1987
  • The applications of reduced integration technique, addition of nonconforming modes, and their coupling to the Mindlin plate elements to improve their basic behavior are reviewed and the establishment of a series of new plate elements by combined use of these schemes are presented in this paper. The element formulation is based upon quadratic Mindlin plate concept. The results obtained by new elements converged to the exact solutions very rapidly as the mesh is refined and showed reliable solutions even for severely distorted meshes. The new elements have the requisite numbers of zero eigenvalues associated with rigid body modes to avoid the spurious zero energy modes. These elements are shown to be applicable to the wide range of plate problems, giving a high accuracy for both thick and thin plates.

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Improved Degenerated Shell Finite Elements for Analysis of Shell Structures (쉘구조 해석을 위한 개선된 Degenerated 쉘유한요소)

  • 최창근;유승운
    • Computational Structural Engineering
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    • v.3 no.1
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    • pp.97-107
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    • 1990
  • The development of an improved degenerated shell element is presented in this paper. In the formulation of this element, an enhanced interpolation of transverse shear strains in the natural coordinate system is used to overcome the shear locking problem ; the reduced integration technique in in-plane strains is applied to avoid the membrane locking behavior ; and selective addition of the nonconforming displacement modes improve the element performances. This element is free of serious locking problems and undesirable compatible or commutable spurious kinematic deformation modes, and passes the patch tests. To illustrate the performance of this improved degenerated shell element, some benchmark problems are presented. Numerical results indicate that the new element shows fast convergence and reliable solutions.

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Improvement of Finite Element for Mindlin Plate Bending (Mindlin 평판 유한요소의 개선)

  • 김선훈;최창근
    • Computational Structural Engineering
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    • v.1 no.2
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    • pp.83-90
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    • 1988
  • The present work is concerned with the improvement of finite element for the analysis of plate bending structures. The element formulation is based upon Mindlin plate concept. The displacement field of this element is formed by adding nonconforming modes to two rotational displacement components of a 'heterosis plate element. The element has the requisite numbers of zero eigenvalues associated with rigid body modes to avoid the spurious zero energy mode. It is shown that the results obtained by the element converged to the exact solutions very rapidly as the mesh is refined and exhibited reliable solutions through numerical studies for standard benchmark problems. This element is shown to overcome the shear locking problem completely in very thin plate situation even for irregular meshes.

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An Improved Degenerated Shell Element for Analysis of Laminated Composite Structures (복합적층구조 해석을 위한 개선된 쉘요소)

  • Choi, Chang Koon;Yoo, Seung Woon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.11 no.3
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    • pp.1-10
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    • 1991
  • The paper is concerned with the analysis of laminated composite shell structures using an improved degenerated shell element. In the formulation of the element stiffness, the combined use of three different techniques was made. They are; 1) an enhanced interpolation of transverse shear strains in the natural coordinate system to overcome the shear locking problem; 2) the reduced integration technique in in-plane strains to avoid the membrane locking behavior; and 3) selective addition of the nonconforming displacement modes to improve the element performances. This element is free of serious shear/membrane locking problems and undesirable compatible/commutable spurious kinematic deformation modes. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements. The resulting non-linear equilibrium equations are solved by the Newton-Raphson method. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.

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Nonlinear Analysis of Improved Degenerated Shell Finite Element (개선된 Degenerated 쉘 유한요소의 비선형 해석)

  • 최창근;유승운
    • Computational Structural Engineering
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    • v.3 no.3
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    • pp.113-123
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    • 1990
  • The paper is concerned with the elasto-plastic and geometrically nonlinear analysis of shell structures using an improved degenerated shell element. In the formulation of the element stiffness, the combined use of three different techniques was made. They are; 1) an enhanced interpolation of transverse shear strains in the natural coordinate system to overcome the shear locking problem ; 2) the reduced integration technique in in-plane strains to avoid the membrane locking behavior ; and 3) selective addition of the nonconforming displacement modes to improve the element performances. This element is free of serious shear/membrane locking problems and undesirable compatible/commutable spurious kinematic deformation modes. In the formulation for plastic deformation, the concept of a layered element model is used and the material is assumed von Mises yield criterion. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements and rotations. The resulting non-linear equilibrium equations are solved by the Netwon-Raphson method combined with load or displacement increment. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.

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