• Title, Summary, Keyword: Element

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Finite Element Modeling and Mechanical Analysis of Orthodontics (치아교정의 역학적 해석을 의한 유한요소 모델링 및 치아의 거동해석)

  • Heo, Gyeong-Heon;Cha, Gyeong-Seok;Ju, Jin-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4
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    • pp.907-915
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    • 2000
  • The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element models by considering the measuring factors such as angulation, crown inclination, rotation and translations. The finite element analysis for the wire activation with a T-loop arch wire was carried out. Mechanical behavior on the movement and the initial stress for the malocclusion finite element model was shown to agree with the objectives of the actual treatment. Finite element models and procedures of analysis developed in this study would be suitably utilized for the design of initial shape of the wire and determination of activation displacements.

A Study on the Improvement of Shape Optimization associated with the Modification of a Finite Element (유한요소의 개선에 따른 형상최적화 향상에 관한 연구)

  • Sung, Jin-Il;Yoo, Jeong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1408-1415
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    • 2002
  • In this paper, we investigate the effect and the importance of the accuracy of finite element analysis in the shape optimization based on the finite element method and improve the existing finite element which has inaccuracy in some cases. And then, the shape optimization is performed by using the improved finite element. One of the main stream to improve finite element is the prevention of locking phenomenon. In case of bending dominant problems, finite element solutions cannot be reliable because of shear locking phenomenon. In the process of shape optimization, the mesh distortion is large due to the change of the structure outline. So, we have to raise the accuracy of finite element analysis for the large mesh distortion. We cannot guarantee the accurate result unless the finite element itself is accurate or the finite elements are remeshed. So, we approach to more accurate shape optimization to diminish these inaccuracies by improving the existing finite element. The shape optimization using the modified finite element is applied to a two and three dimensional simple beam. Results show that the modified finite element has improved the optimization results.

Development of triangular flat-shell element using a new thin-thick plate bending element based on semiLoof constrains

  • Chen, Yong-Liang;Cen, Song;Yao, Zhen-Han;Long, Yu-Qiu;Long, Zhi-Fei
    • Structural Engineering and Mechanics
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    • v.15 no.1
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    • pp.83-114
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    • 2003
  • A new simple 3-node triangular flat-shell element with standard nodal DOF (6 DOF per node) is proposed for the linear and geometrically nonlinear analysis of very thin to thick plate and shell structures. The formulation of element GT9 (Long and Xu 1994), a generalized conforming membrane element with rigid rotational freedoms, is employed as the membrane component of the new shell element. Both one-point reduced integration scheme and a corresponding stabilization matrix are adopted for avoiding membrane locking and hourglass phenomenon. The bending component of the new element comes from a new generalized conforming Kirchhoff-Mindlin plate element TSL-T9, which is derived in this paper based on semiLoof constrains and rational shear interpolation. Thus the convergence can be guaranteed and no shear locking will happen. Furthermore, a simple hybrid procedure is suggested to improve the stress solutions, and the Updated Lagrangian formulae are also established for the geometrically nonlinear problems. Numerical results with solutions, which are solved by some other recent element models and the models in the commercial finite element software ABAQUS, are presented. They show that the proposed element, denoted as GMST18, exhibits excellent and better performance for the analysis of thin-think plates and shells in both linear and geometrically nonlinear problems.

A 4-Node Non-conforming Flat Shell Element with Drilling DOF (면내회전자유도를 가지는 4절점 비적합 평면쉘의 개발)

  • 최창근;이필승
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.27-34
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    • 1998
  • A versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. This element is formulated by the enhanced displacement field with the additional non-conforming displacement modes. Thus the element possesses six degrees-of-freedom (DOF) per node which permits an easy connection to other six DOF elements as well as the improvement of the element behavior. In plate bending part, this element is established by the combined use of the addition of non-conforming modes, the reduced (or selective) integration scheme, and the construction of the substitute shear strain fields. The achieved improvement may be attributable to the fact that the merits of these individual techniques are merged into the new element in a complementary manner. In membrane part, this element shows better membrane behavior as the nonconforming displacement mode is added to drilling mode.

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Study on the dynamic behaviors of curved beam structure using spectral element (스펙트럴 요소를 이용한 곡선 보 구조물의 동적거동 해석)

  • 이준근;이우식;박철희
    • Journal of KSNVE
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    • v.6 no.1
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    • pp.83-88
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    • 1996
  • The significance of spectral element method is that it can treat the mass and stiffness distribution exactly in contrast to the conventional finite element method, and therefore the dynamic behaviors within each spectral element can be obtained exactly. The present study provides the derivation of the spectral element of a curved beam, while the previous ones presented that of a straight structure. Further, in order to verify the derived spectral element, the natural frequencies of a ring by the spectral element method are compared with those by the analytical method and those by the FEM. From the verification, derived spectral element is admissible. And the dynamic behaviors of curved beam are simulated by using the derived spectral element of a curved beam.

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The Free Vibration Analyses by Using Two Dimensional 6-Node Element and Three Dimensional 16-Node element with Modification of Gauss Sampling Point (가우스 적분점을 수정한 2차원 6-절점 요소 및 3차원 16-절점 요소에 의한 자유진동해석)

  • 김정운;경진호;권영두
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.11
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    • pp.2922-2931
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    • 1994
  • We propose a modified 6-node element, where the sampling point of Gauss quadrature moved in the thickness direction. The modified 6-node element has been applied to static problems and forced motion analyses. In this study, this method is extended to the finite element analysis of the natural frequencies of two dimensional problems. We also propose a modified 16-node element for three dimensional problems, which behaves much like a 20-node element with smaller degree of freedom. The modified 6-node and 16-node elements have been applied to the modal analyses of beams and plates, respectively. The results agree well with the results of the 8-node or 20-node element models.

Mixed formulated 13-node hexahedral elements with rotational degrees of freedom: MR-H13 elements

  • Choi, Chang-Koon;Chung, Keun-Young;Lee, Eun-Jin
    • Structural Engineering and Mechanics
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    • v.11 no.1
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    • pp.105-122
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    • 2001
  • A new three-dimensional 13-node hexahedral element with rotational degrees of freedom, which is designated as MR-H13 element, is presented. The proposed element is established by adding five nodes to one of the six faces of basic 8-node hexahedral element. The new element can be effectively used in the connection between the refined mesh and the coarser mesh. The derivation of the current element in this paper is based on the variational principles in which the rotation and skew-symmetric stress are introduced as independent variables. Numerical examples show that the performance of the new element is satisfactory.

Assumed strain quadrilateral C0 laminated plate element based on third-order shear deformation theory

  • Shi, G.;Lam, K.Y.;Tay, T.E.;Reddy, J.N.
    • Structural Engineering and Mechanics
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    • v.8 no.6
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    • pp.623-637
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    • 1999
  • This paper presents a four-noded quadrilateral $C^0$ strain plate element for the analysis of thick laminated composite plates. The element formulation is based on: 1) the third-order shear deformation theory; 2) assumed strain element formulation; and 3) interrelated edge displacements and rotations along element boundaries. Unlike the existing displacement-type composite plate elements based on the third-order theory, which rely on the $C^1$-continuity formulation, the present plate element is of $C^0$-continuity, and its element stiffness matrix is evaluated explicitly. Because of the third-order expansion of the in-plane displacements through the thickness, the resulting theory and hence elements do not need shear correction factors. The explicit element stiffness matrix makes the present element more computationally efficient than the composite plate elements using numerical integration for the analysis of thick layered composite plates.

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

  • Jo, Seong-Su;Ha, Seong-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.11
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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.

Dynamically Adaptive Finite Element Mesh Generation Schemes

  • Yoon, Chong-Yul;Park, Joon-Seok
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.6
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    • pp.659-665
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    • 2010
  • The finite element method(FEM) is proven to be an effective approximate method of structural analysis if proper element types and meshes are chosen, and recently, the method is often applied to solve complex dynamic and nonlinear problems. A properly chosen element type and mesh yields reliable results for dynamic finite element structural analysis. However, dynamic behavior of a structure may include unpredictably large strains in some parts of the structure, and using the initial mesh throughout the duration of a dynamic analysis may include some elements to go through strains beyond the elements' reliable limits. Thus, the finite element mesh for a dynamic analysis must be dynamically adaptive, and considering the rapid process of analysis in real time, the dynamically adaptive finite element mesh generating schemes must be computationally efficient. In this paper, a computationally efficient dynamically adaptive finite element mesh generation scheme for dynamic analyses of structures is described. The concept of representative strain value is used for error estimates and the refinements of meshes use combinations of the h-method(node movement) and the r-method(element division). The shape coefficient for element mesh is used to correct overly distorted elements. The validity of the scheme is shown through a cantilever beam example under a concentrated load with varying values. The example shows reasonable accuracy and efficient computing time. Furthermore, the study shows the potential for the scheme's effective use in complex structural dynamic problems such as those under seismic or erratic wind loads.