• Title, Summary, Keyword: Element

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FORMULATION OF SHELL RINITE ELEMENTS BASED ON A NEW METHOD OF ELEMENT DECOMPISITION (새로운 요소분해방법에 의한 쉘 유한요소의 개발)

  • 이재영
    • Computational Structural Engineering
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    • v.1 no.1
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    • pp.67-78
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    • 1988
  • A new method of element decomposition is suggested for simple, efficient, and generalized formulation of shell finite elements. The kernel of the method is to decompose conceptually the actual element into a translational element and a difference element. The actual element is obtained by combining the two component elements. The derived element can be classified into three basic types depending on how the element is decomposed. A few complementary measures, to remove locking phenomena and thus improve the performance of the elements, have been studied. They are reduced integration, addition of internal degrees of freedom, and mixed formulation. A rational method of controlling spurious zero energy modes has also been devised. Validity and efficiency of the element with or without complementary measures have been examined through a series of numerical studies.

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Finite Element Analysis of Sheet Metal Forming Process Using Shell Element (쉘 요소를 이용한 박판성형공정의 유한요소해석)

  • Ko Hyung-Hoon;Lee Chan-Ho;Kang Dong-Kyu;Sul Nam-Ki;Lee Kwang-Sik;Jung Dong-Won
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.122-125
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    • 2005
  • The AutoForm previously used the membrane element and it accomplished sheet metal forming analysis. The membrane analysis has been widely applied to various sheet metal forming processes because of its saving time effectiveness. However, it's well known that the membrane analysis can not provides correct information for the processes which considerable bending effects. From this time research it tried to compare the formation analysis result which uses the shell element which is applied newly in the AutoForm and actual products. The shell element is compromise method between continuum analysis and membrane analysis. The Finite element method by using shell element is the most economical numerical method. From analysis results, FEA by using shell element can estimate accurately the problems happened in actual auto-body panel.

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A Finite Element Analysis based on Higher-Order Zig-Zag Shell Theory for Laminated Composites Cylinderical Shell with Multiple Delaminations (다중 층간분리부가 있는 복합재 원통쉘의 지그재그 고차이론에 기초한 유한요소 진동해석)

  • Cho Maenghyo;Oh Jinho;Kim Heung-Soo
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.69-72
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    • 2004
  • A new three-node triangular shell element based on higher order zig-zag theory is developed for laminated composite shells with multiple delaminations. The present higher order zig-zag shell theory is described in a general curvilinear coordinate system and in general tensor notation. All the complicated curvatures of surface including twisting curvatures can be described in an exact manner in the present shell element because this element is based on geometrically exact surface representation. The displacement field of the proposed finite element includes slope of deflection, which requires continuity between element interfaces. Thus the nonconforming shape function of Specht's three-node triangular plate bending element is employed to interpolate out-of-plane displacement. The present element passes the bending and twisting patch tests in flat surface configurations. The developed element is evaluated through the eigenvalue problems of composite cylindrical shells with multiple delaminations. Through the numerical examples it is demonstrated that the proposed shell element is efficient because it has minimal degrees of freedom per node. The present shell element should serve as a powerful tool in the prediction of natural frequency and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

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Static Analysis of Two Dimensional Curbed Beam Structure by Finite Element-Transfer Stiffness Coefficent Method (유한요소-전달강성계수법에 의한 2차원 곡선 보 구조물의 정적해석)

  • Choi, Myung-Soo
    • Journal of the Korea Society For Power System Engineering
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    • v.21 no.6
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    • pp.40-45
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    • 2017
  • The objective of this study is the finite element-transfer stiffness coefficient method, which is the combination of the modeling technique of finite element method and the transfer technique of transfer stiffness coefficient method, is applied in the static analyses of two dimensional curved beam structures. To confirm the effectiveness of the applied method, two computational models are selected and analyzed by using finite element method, finite element-transfer stiffness coefficient method and exact solution. The computational results of the static analyses for two computational models using finite element-transfer stiffness coefficient method are equal to those using finite element method. When the element partition number of curved beam structure is increased, the computational results of the static analyses using both methods approach the exact solution. We confirmed that the finite element-transfer stiffness coefficient method is superior to finite element method when the number of the curved beam elements is increased from the viewpoints of the computational speed and the utility of computer memory.

Development of a Robot Element Design Program (로봇 요소품 설계 프로그램 개발)

  • Jung Il Ho;Kim Chang Su;Seo Jong Hwi;Park Tae Won;Kim Hee Jin;Choi Jae Rak;Byun Kyng Seok
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.4
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    • pp.113-120
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    • 2005
  • This paper presents the development of the design of the robot element. Robot element design is an important part of robot design since it decides the performance and life time of the robot. It is necessary that the robot kinematics and the robot dynamics are accomplished to design the robot elements. The robot kinematics and dynamics determine the design parameters of the element. We developed a robot element design program with which a designer can design the robot element with convenience and reliability. The program is composed of motor, harmonic driver and ball-screw design. The program is founded on the virtual robot design program. The virtual robot design program is the powerful software which may be used to solve various problems of the robot kinematics and dynamics. The robot element design program may be used to calculate the design parameters of the element that are necessary to design robot element. Therefore, the designer can decide upon the available robot elements available to perform the objective of the robot. The robot element design program is expected to increase the competitiveness and efficiency of the robot industry.

Pre-processing System for Converting Shell to Solid at Selected Weldment in Shell FE Model (선체 Shell FE 모델 내 용접부의 Solid 요소변환 자동화 시스템)

  • Yoo, Jinsun;Ha, Yunsok
    • Journal of Welding and Joining
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    • v.34 no.2
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    • pp.11-15
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    • 2016
  • FE analyses for weldment of ship structure are required for various reasons such as stress concentration for bead tow, residual stress and distortion after welding, and hydrogen diffusion for prediction of low temperature crack. These analyses should be done by solid element modeling, but most of ship structures are modeled by shell element. If we are able to make solid element in the shell element FE modeling it is easily to solve the requirement for solid elements in weld analysis of large ship structures. As the nodes of solid element cannot take moments from nodes of shell element, these two kinds of element cannot be used in one model by conventional modeling. The PSCM (Perpendicular shell coupling method) can connect shell to solid. This method uses dummy perpendicular shell element for transferring moment from shell to solid. The target of this study is to develop a FE pre-processing system applicable at welding at ship structure by using PSCM. We also suggested glue-contact technique for controlling element numbers and element qualities and applied it between PSCM and solid element in automatic pre-processing system. The FE weldment modeling through developed pre-processing system will have rational stiffness of adjacent regions. Then FE results can be more reliable when turn-over of ship-block with semi-welded state or ECA (Engineering critical assessment) of weldment in a ship-block are analyzed.

Function space formulation of the 3-noded distorted Timoshenko metric beam element

  • Manju, S.;Mukherjee, Somenath
    • Structural Engineering and Mechanics
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    • v.69 no.6
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    • pp.615-626
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    • 2019
  • The 3-noded metric Timoshenko beam element with an offset of the internal node from the element centre is used here to demonstrate the best-fit paradigm using function space formulation under locking and mesh distortion. The best-fit paradigm follows from the projection theorem describing finite element analysis which shows that the stresses computed by the displacement finite element procedure are the best approximation of the true stresses at an element level as well as global level. In this paper, closed form best-fit solutions are arrived for the 3-noded Timoshenko beam element through function space formulation by combining field consistency requirements and distortion effects for the element modelled in metric Cartesian coordinates. It is demonstrated through projection theorems how lock-free best-fit solutions are arrived even under mesh distortion by using a consistent definition for the shear strain field. It is shown how the field consistency enforced finite element solution differ from the best-fit solution by an extraneous response resulting from an additional spurious force vector. However, it can be observed that when the extraneous forces vanish fortuitously, the field consistent solution coincides with the best-fit strain solution.

An element-based 9-node resultant shell element for large deformation analysis of laminated composite plates and shells

  • Han, S.C.;Kim, K.D.;Kanok-Nukulchai, W.
    • Structural Engineering and Mechanics
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    • v.18 no.6
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    • pp.807-829
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    • 2004
  • The Element-Based Lagrangian Formulation of a 9-node resultant-stress shell element is presented for the isotropic and anisotropic composite material. The effect of the coupling term between the bending strain and displacement has been investigated in the warping problem. The strains, stresses and constitutive equations based on the natural co-ordinate have been used throughout the Element-Based Lagrangian Formulation of the present shell element which offers an advantage of easy implementation compared with the traditional Lagrangian Formulation. The element is free of both membrane and shear locking behavior by using the assumed natural strain method such that the element performs very well in thin shell problems. In composite plates and shells, the transverse shear stiffness is defined by an equilibrium approach instead of using the shear correction factor. The arc-length control method is used to trace complex equilibrium paths in thin shell applications. Several numerical analyses are presented and discussed in order to investigate the capabilities of the present shell element. The results showed very good agreement compared with well-established formulations in the literature.

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
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    • v.12 no.3
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    • pp.194-201
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    • 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.

Geometrical Nonlinear Analysis of Thin-walled Structures by Flat Shell Elements with Drilling D.O.F. (회전자유도를 갖는 평면쉘요소에 의한 박판구조물의 기하비선형해석)

  • 최창근;송명관
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.317-324
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    • 1998
  • A nonlinear anile element formulation of flat shell elements with drilling d.o.f, is presented for the geometrical nonlinear analysis of thin-walled structures. The shell element to be applied in finite element analysis was developed by combining a membrane element named as CLM with drilling rotation d.o.f, and plate bending element. The combined shell element possesses six degrees of freedom per node. The element showed the excellent performance in the linear analysis of the folded plate structures, in which the normal rotational rigidity of folded plates is considered, therefore, using this element geometrical nonlinear analysis of those structures is fulfilled in this study. An incremental total Larangian approach is adopted through out in which displacements are referred to the original configuration. Comparing the results with those of other researches shows the performance of this element and a folded plate structure is analyzed as an example.

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