• Title, Summary, Keyword: Element

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The use of the strain approach to develop a new consistent triangular thin flat shell finite element with drilling rotation

  • Guenfoud, Hamza;Himeur, Mohamed;Ziou, Hassina;Guenfoud, Mohamed
    • Structural Engineering and Mechanics
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    • v.68 no.4
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    • pp.385-398
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    • 2018
  • In the present paper, we offer a new flat shell finite element. It is the result of the combination of a membrane element and a bending element, both based on the strain-based formulation. It is known that $C^{\circ}$ plane membrane elements provide poor deflection and stress for problems where bending is dominant. In addition, they encounter continuity and compliance problems when they connect to C1 class plate elements. The reach of the present work is to surmount these problems when a membrane element is coupled with a thin plate element in order to construct a shell element. The membrane element used is a triangular element with four nodes, three nodes at the vertices of the triangle and the fourth one at its barycenter. Each node has three degrees of freedom, two translations and one rotation around the normal. The coefficients related to the degrees of freedom at the internal node are subsequently removed from the element stiffness matrix by using the static condensation technique. The interpolation functions of strain, displacements and stresses fields are developed from equilibrium conditions. The plate element used for the construction of the present shell element is a triangular four-node thin plate element based on Kirchhoff plate theory, the strain approach, the four fictitious node, the static condensation and the analytic integration. The shell element result of this combination is robust, competitive and efficient.

Defect-free 4-node flat shell element: NMS-4F element

  • Choi, Chang-Koon;Lee, Phill-Seung;Park, Yong-Myung
    • Structural Engineering and Mechanics
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    • v.8 no.2
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    • pp.207-231
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    • 1999
  • A versatile 4-node shell element which is useful for the analysis of arbitrary shell structures is presented. The element is developed by flat shell approach, i.e., by combining a membrane element with a Mindlin plate element. The proposed element has six degrees of freedom per node and permits an easy connection to other types of finite elements. In the plate bending part, an improved Mindlin plate has been established by the combined use of the addition of non-conforming displacement modes (N) and the substitute shear strain fields (S). In the membrane part, the nonconforming displacement modes are also added to the displacement fields to improve the behavior of membrane element with drilling degrees of freedom and the modified numerical integration (M) is used to overcome the membrane locking problem. Thus the element is designated as NMS-4F. The rigid link correction technique is adopted to consider the effect of out-of-plane warping. The shell element proposed herein passes the patch tests, does not show any spurious mechanism and does not produce shear and membrane locking phenomena. It is shown that the element produces reliable solutions even for the distorted meshes through the analysis of benchmark problems.

A mesh generation method using PC graphic editor (그래픽 에디터를 이용한 자동 요소 분할에 관한 연구)

  • 김동일;유형선
    • 제어로봇시스템학회:학술대회논문집
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    • pp.726-729
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    • 1991
  • In this paper it is discussed about the program which makes automatically the preprocessing data on the graphic editor of PC monitor. Three kinds of colors are used in order to make know a boundary_element, in_element, out_element. By initial mesh generation, three kinds of elements are made; the element with three nodes, four nodes, five nodes. The node of boundary element draw a vertical line to the boundary. At that time the element with three nodes is removed and the element with four nodes is changed to the element with four nodes. The domain graphic on this paper is compose of piecewise curves which has many lines and a hole. The data of element is written on the memory of PC computer. The program controls the memory address according to the change of element's quantity; disappearance and addition of element. All this work is operated on the PC computer.

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Selection of the Optimal Finite Element Type by Material Hardening Behavior Model in Elbow Specimen (엘보우 시편에서의 재료 경화 거동 모델에 따른 최적의 유한 요소 선정)

  • Heo, Eun Ju;Kweon, Hyeong Do
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.13 no.1
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    • pp.84-91
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    • 2017
  • This paper is proposed to select the optimal finite element type in finite element analysis. Based on the NUREG reports, static analyses were performed using a commercial analysis program, $ABAQUS^{TM}$. In this study, we used a nonlinear kinematic hardening model proposed by Chaboche. The analysis result of solid elements by inputting the same material constants was different from the results of the NUREG report. This is resulted from the difference between shell element and solid element. Therefore, the material constants that have similar result to the experimental result were determined and compared according to element type. In case of using solid element for efficient finite element analysis, we confirmed that the use of C3D8I element type(incompatible mode 8-node linear brick element) leads the accurate result while reducing the analysis time.

Construction of a macro plane stress triangle element with drilling d.o.f.'s (드릴링 자유도를 가진 매크로 삼각형 요소를 이용한 평면 응력 해석)

  • 엄재성;김영태;이병채
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.886-889
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    • 2004
  • A simple macro triangle with drilling d.o.f.'s is proposed for plane stress problems based on IET(Individual element test) and finite element template. Three-node triangular element has geometrical advantages in preprocessing but suffers from bad performance comparing to other shapes of elements -especially quadrilateral. Main purpose of this study is to construct a high-performance linear triangular element with limited supplementary d.o.f.'s. A triangle is divided by three sub-triangles with drilling d.o.f.'s. The sub-triangle stiffness come from IET passing force-lumping matrix, so this assures the consistency of the element. The macro element strategy takes care of the element‘s stability and accuracy like higher-order stiffness in the F.E. template. The resulting element fits on the uses of conventional three-node. Benchmark examples show proposed element in closed form stiffness from CAS (Computer algebra system) gives the improved results without more computational efforts than others.

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

  • 송하원;김형운;우승민
    • Journal of the Korea Concrete Institute
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    • v.11 no.3
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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.

Analysis of plane frame structure using base force element method

  • Peng, Yijiang;Bai, Yaqiong;Guo, Qing
    • Structural Engineering and Mechanics
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    • v.62 no.1
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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.

Stochastic finite element based reliability analysis of steel fiber reinforced concrete (SFRC) corbels

  • Gulsan, Mehmet Eren;Cevik, Abdulkadir;Kurtoglu, Ahmet Emin
    • Computers and Concrete
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    • v.15 no.2
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    • pp.279-304
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    • 2015
  • In this study, reliability analyses of steel fiber reinforced concrete (SFRC) corbels based on stochastic finite element were performed for the first time in literature. Prior to stochastic finite element analysis, an experimental database of 84 sfrc corbels was gathered from literature. These sfrc corbels were modeled by a special finite element program. Results of experimental studies and finite element analysis were compared and found to be very close to each other. Furthermore experimental crack patterns of corbel were compared with finite element crack patterns and were observed to be quite similar. After verification of the finite element models, stochastic finite element analyses were implemented by a specialized finite element module. As a result of stochastic finite element analysis, appropriate probability distribution functions (PDF's) were proposed. Finally, coefficient of variation, bias and strength reduction (resistance) factors were proposed for sfrc corbels as a consequence of stochastic based reliability analysis.

A simple method of stiffness matrix formulation based on single element test

  • Mau, S.T.
    • Structural Engineering and Mechanics
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    • v.7 no.2
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    • pp.203-216
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    • 1999
  • A previously proposed finite element formulation method is refined and modified to generate a new type of elements. The method is based on selecting a set of general solution modes for element formulation. The constant strain modes and higher order modes are selected and the formulation method is designed to ensure that the element will pass the basic single element test, which in turn ensures the passage of the basic patch test. If the element is to pass the higher order patch test also, the element stiffness matrix is in general asymmetric. The element stiffness matrix depends only on a nodal displacement matrix and a nodal force matrix. A symmetric stiffness matrix can be obtained by either modifying the nodal displacement matrix or the nodal force matrix. It is shown that both modifications lead to the same new element, which is demonstrated through numerical examples to be more robust than an assumed stress hybrid element in plane stress application. The method of formulation can also be used to arrive at the conforming displacement and hybrid stress formulations. The convergence of the latter two is explained from the point of view of the proposed method.

Evaluation of Probabilistic Finite Element Method in Comparison with Monte Carlo Simulation

  • 이재영;고홍석
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.32 no.E
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    • pp.59-66
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    • 1990
  • Abstract The formulation of the probabilistic finite element method was briefly reviewed. The method was implemented into a computer program for frame analysis which has the same analogy as finite element analysis. Another program for Monte Carlo simulation of finite element analysis was written. Two sample structures were assumed and analized. The characteristics of the second moment statistics obtained by the probabilistic finite element method was examined through numerical studies. The applicability and limitation of the method were also evaluated in comparison with the data generated by Monte Carlo simulation.

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