• 제목/요약/키워드: Quadrilateral Element

Search Result 162, Processing Time 0.032 seconds

Automatic Quadrilateral Element Mesh Generation Using Boundary Normal Offsetting In Various Two Dimensional Objects (다양한 2차원 형상에서의 외부 경계 절점 오프셋 방법을 이용한 자동 사각 요소 및 요소망 생성)

  • 김도헌;양현익
    • Korean Journal of Computational Design and Engineering
    • /
    • v.8 no.4
    • /
    • pp.270-277
    • /
    • 2003
  • In two dimensional mechanical design analysis, quadrilateral element mesh is preferred because it provides more accurate result than triangular element mesh. However, automation of quadrilateral element mesh generation is much more complex because of its geometrical complexities. In this study, an automatic quadrilateral element mesh generation algorithm based on the boundary normal offsetting method and the boundary decomposition method is developed. In so doing, nodes are automatically placed using the boundary normal offsetting method and the decomposition method is applied to decompose the designed domain into a set of convex subdomains. The generated elements are improved by relocation of the existing nodes based on the four criteria - uniformity, aspect ratio, skewness and taper degree. The developed algorithm requires minimal user inputs such as boundary data and the distance between nodes.

Analysis of Anisotropic Folded Structures using Triangular and Quadrilateral Elements (3절점 및 4절점 요소를 이용한 비등방성 절판 구조물의 해석)

  • Yoo, Yong-Min;Yhim, Sung-Soon;Chang, Suk-Yoon
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.20 no.1
    • /
    • pp.29-37
    • /
    • 2007
  • This study deals with displacement analysis of anisotropic folded structures with triangular elements and quadrilateral elements. When folded plates are analyzed, triangular elements as well as quadrilateral elements are needed for conveniences of modelling. However, using triangular elements is not a simple problem. A simple formulation is presented which allows a quadrilateral element to degenerate into a triangular element. Therefore it can easily be used for computational simplicity and avoided complexities on mixed use of triangular element and quadrilateral element. In this paper, a high-order shear deformation theory using only Lagrangian interpolation functions and drilling degrees of freedom for folded plates are utilized for more accurate analysis. Especially, various results of anisotropic laminated and folded composite structures with triangular element and quadrilateral element show the structural behavior characteristics of them.

Automatic Quadrilateral Mesh Generation Using Updated Paving Technique in Various Two Dimensional Objects (다양한 2차원 영역에서의 향상된 Paving법을 이용한 자동 사각 요소 생성)

  • Yang, Hyun-Ik;Kim, Myung-Han
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.27 no.10
    • /
    • pp.1762-1771
    • /
    • 2003
  • In part of mechanical design analysis, quadrilateral mesh is usually used because it provides less approximate errors than triangular mesh. Over the decades, Paving method has been considered as the most robust method among existing automatic quadrilateral element mesh generation methods. However, it also has some problems such as unpredictable node projection and relatively large element generation. In this study, the aforementioned problems are corrected by updating the Paving method. In so doing, a part of node projection process is modified by classifying nodes based on the interior angles. The closure check process is also modified by adding more nodes while generating elements. The result shows well shaped element distribution in the final mesh without any aforementioned problems.

Automatic Quadrilateral Mesh Generation for Large Deformation Finite Element Analysis (대변형 유한요소해석을 위한 요소망 자동 생성기법)

  • 김동준;최호준;장동환;임중연;이호용;황병복
    • Transactions of Materials Processing
    • /
    • v.12 no.3
    • /
    • pp.194-201
    • /
    • 2003
  • An automatic quadrilateral mesh generator for large deformation finite element analysis such as metal forming simulation was developed. The NURBS interpolation method is used for modeling arbitrary 2-D free surface. This mesh generation technique is the modified paving algorithm, which is an advancing front technique with element-by-element resolving method for paving boundary intersection problem. The mesh density for higher analysis accuracy and less analysis time can be easily controlled with high-density points, maximum and minimum element size. A couple of application to large deformation finite element analysis is given as an example, which shows versatility and applicability of the proposed approach and the developed mesh generator for large deformation finite element analysis.

Variable-node axisymmetric solid element and its application to adaptive mesh refinement

  • Choi, Chang-Koon;Lee, Eun-Jin;Lee, Wan-Hoon
    • Structural Engineering and Mechanics
    • /
    • v.11 no.4
    • /
    • pp.443-460
    • /
    • 2001
  • This paper presents an effective application of a variable-node axisymmetric solid element designated as AQV (Axisymmetric Quadrilateral Variable-node element). The variable-node element with physical midside nodes helps to overcome some problems in connecting the different layer patterns on a quadrilateral mesh in the adaptive h-refinement. This element alleviates the necessity of imposing displacement constraints on irregular (hanging) nodes in order to enforce the inter-element compatibility. Therefore, the elements with variable mid-side nodes can be used effectively in the local mesh refinement for the axisymmetric structures which have stress concentrations. A modified Gaussian quadrature should be adopted to evaluate the stiffness matrices of the variable-node elements mainly because of the slope discontinuity of assumed displacement within the elements. Some numerical examples show the usefulness of variable-node axisymmetric elements in the practical application.

Two Dimensional Automatic Quadrilateral Mesh Generation for Metal Forming Analysis (소성 가공 공정 해석을 위한 2차원 사각 요소망 자동 생성)

  • Kim, Sang-Eun;Yang, Hyun-Ik
    • Korean Journal of Computational Design and Engineering
    • /
    • v.14 no.3
    • /
    • pp.197-206
    • /
    • 2009
  • In a finite element analysis of the metal forming processes having large plastic deformation, largely distorted elements are unstable and hence they influence upon the result toward negative way so that adaptive remeshing is required to avoid a failure in the numerical computation. Therefore automatic mesh generation and regeneration is very important to avoid a numerical failure in a finite element analysis. In case of generating quadrilateral mesh, the automation is more difficult than that of triangular mesh because of its geometric complexity. However its demand is very high due to the precision of analysis. Thus, in this study, an automatic quadrilateral mesh generation and regeneration method using grid-based approach is developed. The developed method contains decision of grid size to generate initial mesh inside a two dimensional domain, classification of boundary angles and inner boundary nodes to improve element qualities in case of concave domains, and boundary projection to construct the final mesh.

A Study on the Comparison of Triangular and Quadrilateral Elements for the Analysis of 3 Dimensional Plate Structures (3차원 판구조물 해석을 위한 삼각형요소와 사각형 요소의 비교에 관한 연구)

  • 왕지석;김유해;이우수
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.26 no.3
    • /
    • pp.344-352
    • /
    • 2002
  • In the analysis of the 3 dimensional plate structures by the finite element method, the triangular elements are generally used for the global stiffness matrix of the analyzed system. But the triangular elements of the plates have some problems in the process of formulation and in the precision of analysis. The formulation of the finite element method to analyze 3 dimensional plate structures using quadrilateral elements is presented in this paper. The degree of freedom off nodal point is 6, that is, the displacements in the direction off-y-z is and the rotations about x-y-z axis and then the degree of freedom off element is 24. For the comparison of the analysis using triangular elements and quadrilateral elements, the rectangular plates subjected to the uniform load and a concentrated load on the centroid of the plate, for which the theoretical solutions have been obtained, are analyzed. The calculated deflections of the rectangular plates using the finite element method by the triangular elements and the quadrilateral elements are also compared with the deflections of the plates calculated by theoretical solutions. The defections of the rectangular plates calculated by the finite element method using the quadrilateral elements are closer to the theoretical solutions than the defections calculated by the finite element method using the triangular elements. The deflection of the centroid of plate, calculated by the finite element method, converges to that of theoretical solution as the number of elements is increased. This convergence is much more rapid for the case of using the quakrilateral elements than fir the case of using triangular elements.

THE GRADIENT RECOVERY FOR FINITE VOLUME ELEMENT METHOD ON QUADRILATERAL MESHES

  • Song, Yingwei;Zhang, Tie
    • Journal of the Korean Mathematical Society
    • /
    • v.53 no.6
    • /
    • pp.1411-1429
    • /
    • 2016
  • We consider the nite volume element method for elliptic problems using isoparametric bilinear elements on quadrilateral meshes. A gradient recovery method is presented by using the patch interpolation technique. Based on some superclose estimates, we prove that the recovered gradient $R({\nabla}u_h)$ possesses the superconvergence: ${\parallel}{\nabla}u-R({\nabla}u_h){\parallel}=O(h^2){\parallel}u{\parallel}_3$. Finally, some numerical examples are provided to illustrate our theoretical analysis.

Level set method for the simulation of rising bubble based on triangular and Quadrilateral elements (삼각형 요소와 사각형 요소에 기초한 상승기포의 모사를 위한 Level set 방법)

  • Cho, M.H.;Choi, H.G.;Jeon, B.J.;Yoo, J.Y.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2011.05a
    • /
    • pp.10-13
    • /
    • 2011
  • A level set method is proposed to simulate the incompressible two-phase flow considering the effect of surface tension. For reinitialization of level set junction, a direct approach method is employed, instead of solving hyperbolic type equation. A mixed element is adopted, so that the continuity mid Navier-Stokes equations are solved by using the quadratic elements (six-node triangular element mid nine-node quadrilateral element), mid the level set function is solved by using the linear elements (three-node triangular element mid four-node quadrilateral element). In order to verify the accuracy mid robustness of the codes, the present methods are applied to a few benchmark problems. It is confirmed that the present results are in good qualitative mid quantitative agreements with the existing studies.

  • PDF

Higher Order Quadrilateral Plate Bending Finite Element (고차(高次) 판(板) 사각형(四角形) 유한요소(有限要素))

  • Shin, Young Shik;Shin, Hyun Mook;Kim, Myung Chul
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.8 no.2
    • /
    • pp.25-32
    • /
    • 1988
  • A formulation of an isoparametric quadrilateral higher-order plate bending finite element is presented. The 8-noded 28-d.o.f. plate element has been degenerated from the three-dimensional continuum by introducing the plate assumptions and considering higher-order in-plane displacement profile. The element characteristics have been derived by the Galerkin's weighted residual method and computed by using the selective reduced integration technique to avoid shear-locking phenomenon. Several numerical examples are given to demonstrate the accuracy and versatility of the proposed quadrilateral higher-order plate bending element over the other existing plate finite elements in both static and dynamic analyses.

  • PDF