• Title, Summary, Keyword: Element

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A Finite Element Analysis based on Higher-Order Zig-Zag Shell Theory for Laminated Composites with Multiple Delamination (다중 층간 분리부가 내재된 복합재 쉘 고차 지그재그 모델의 유한요소 해석)

  • 오진호;조맹효
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.229-236
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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 buckling 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 accuracy of the present element is demonstrated in the prediction of buckling loads and buckling modes of shells with multiple delaminations. The present shell element should serve as a powerful tool in the prediction of buckling loads and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

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Prediction evaluation of problems happened of Sheet Metal Forming Process Using Shell Element (쉘 요소를 이용한 박판성형공정의 불량 예측 평가)

  • Ko Hyung-Hoon;Lee Chan-Ho;Kang Dong-Kyu;Sul Nam-Ki;Lee Kwang-Sik;Jong Dong-Won
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.481-484
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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 time effectiveness. However, it's well known that the membrane analysis can not provide correct information for the processes which have considerable bending effects. In this research it tried to compare the analysis results which use the shell element which is applied newly in the AutoForm commercial software with actual experimental results. The shell element is compromise element between continuum element and membrane element. The Finite element method by using shell element is the most efficient numerical method. From this research, it is known that FEA by using shell element can predict accurately the problems happened in actual experimental auto-body panel.

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Zoogeography of Taiwanese Fishes

  • Nakabo, Tetsuji
    • Korean Journal of Ichthyology
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    • v.21 no.4
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    • pp.311-321
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    • 2009
  • Three categories (freshwater, amphidromous, and marine fishes) of Taiwanese fishes are analyzed on the basis of zoogeographic elements, viz. China element, Indo-China element, Indo-West Pacific element, Indo-Pacific element, North-Pacific element, Japan-Oregon element, and circumtropical element. Freshwater fishes, which include the China and Indo-China elements, are distributed on part of the boundary area between the Palaearctic and Oriental regions of Wallace (1876). Diadromous fishes include the North-Pacific, Indo-China and Indo-West Pacific elements. Taiwanese salmon, a landlocked (initially diadromous) species that became established in Taiwan between 0.5 my B.P. and the early Pleistocene, is recognized as a distinct taxon included within the Oncorhynchus masou complex, which comprises here three species and two subspecies, viz. Oncorhynchus masou masou (Sancheoneo, Songeo, Sakura-masu or Yamame), O. masou ishikawae (Satsuki-masu or Amago), O. sp. (Biwa-masu), and O. formosanus (Taiwanese salmon), based on molecular, morphological and biological studies. Marine fishes are discussed under the following headings, brackish-water fishes (fishes of brackish waters and seas adjacent to continental coastlines, North Pacific and Indo-West Pacific elements; fishes of brackish waters and seas primarily around islands, Indo-West Pacific element), reef fishes (fishes of inshore reefs along continental coastlines from 0 to ca.100 m depth, Indo-West Pacific element; fishes of inshore reefs primarily around islands from 0 to ca.100 m depth, Indo-West Pacific element; fishes of offshore reefs along continental shelf edges from ca.150 to 300 m depth, circumtropical and Indo-Pacific elements; fishes of offshore reefs primarily around islands from ca.150 to 300 m depth, Indo-Pacific element), demersal fishes (fishes on continental shelves shallower than ca.150 m depth, Indo-West Pacific and Japan-Oregon elements; fishes on edges and upper continental slopes from ca.150 m to 500 m depth, Indo-West Pacific, Indo-Pacific, and circumtropical elements; fishes on lower continental slopes to abyssal plains from ca.500 m to 6,000 m depth, circumtropical element and rarely Indo-Pacific element), pelagic fishes (epipelagic fishes from 0 to ca.150 m depth, Indo-West Pacific, Indo-Pacific or circumtropical elements; meso- and bathypelagic fishes from ca.150 to 3,000 m depth, circumtropical element). The distribution of Taiwanese marine fishes are influenced by the Kuroshio Current, low-salinity and low-temperature waters from mainland China, and sea-bottom topography.

Electrical Characteristics of ZnO element to Surge protector for 154kC Underground Cable (154kV 지중케이블 서지 보호장치용 ZnO 소자의 전기적 특성)

  • 조한구;한동희;김석수;이종혁;장태봉
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.1054-1056
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    • 2001
  • This paper deals with underground transmission system of present and ZnO element of newly developed. in the characteristics of ZnO element of newly developed, an newly developed ZnO element compared with previous ZnO element that electrical characteristics and external characteristics. In result, characteristics of newly developed ZnO element is improved than previous one.

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An Improved Quadratic Finite Element with Modified Integration Order (수정된 적분차수를 이용한 평면유한요소의 개선)

  • 김선훈;김주일;이창원;신재철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.42-49
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    • 2001
  • In this paper the efficient finite element for stress analysis of plane stress/strain problems is proposed. This element is achieved by adding the bubble-mode function to 8-node element. The stiffness matrix of the element is calculated by using modified numerical integration order to avoid spurious zero energy mode. In order to demonstrate the performance of this element numerical tests for various verification problems are carried out. The results of numerical tests show accuracy and reliability of the element presented in this paper.

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Static and free vibration behaviour of orthotropic elliptic paraboloid shells

  • Darilmaz, Kutlu
    • Steel and Composite Structures
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    • v.23 no.6
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    • pp.737-746
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    • 2017
  • In this paper the influence of aspect ratio, height ratio and material angle on static and free vibration behaviour of orthotropic elliptic paraboloid shells is studied by using a four-node hybrid stress finite element. The formulation of the element is based on Hellinger-Reissner variational principle. The element is developed by combining a hybrid plane stress element and a hybrid plate element. A parametric study is carried out for static and free vibration response of orthotropic elliptic paraboloid shells with respect to displacements, internal forces, fundamental frequencies and mode shapes by varying the aspect and height ratios, and material angle.

Dynamic behaviour of orthotropic elliptic paraboloid shells with openings

  • Darilmaz, Kutlu
    • Structural Engineering and Mechanics
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    • v.63 no.2
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    • pp.225-235
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    • 2017
  • In this paper a vibration study on orthotropic elliptic paraboloid shells with openings is carried out by using a hybrid stress finite element. The formulation of the element is based on Hellinger-Reissner variational principle. The element is developed by combining a hybrid plane stress element and a hybrid plate element. Natural frequencies of orthotropic elliptic paraboloid shells with and without openings are presented. The influence of aspect ratio, height ratio, opening ratio and material angle on the frequencies and mode shapes are investigated.

Problems with a popular thick plate element and the development of an improved thick plate element

  • Cheng, Y.M.;Law, C.W.
    • Structural Engineering and Mechanics
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    • v.29 no.3
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    • pp.327-349
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    • 2008
  • Some unreasonable results from the use of a popular thick plate element are discovered from the analysis of a raft foundation and a pile cap in Hong Kong. To overcome the problems, the authors have developed a new shear deformable beam which can be extended to a general quadrilateral shear deformable plate. The behaviour of this new element under several interesting cases is investigated, and it is demonstrated that the new element possesses very high accuracy under different depth/span ratios, and the results from this new element are good even for a coarse mesh.

The Prediction Modelling on the Stress Intensity Factor of Two Dimensional Elastic Crack Emanating from the Hole Using Neural Network and Boundary element Method (신경회로망과 경계요소법을 이용한 원공에서 파생하는 2차원 탄성균열의 응력세기계수 예측 모델링)

  • Yun, In-Sik;Yi, Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.3
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    • pp.353-361
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    • 2001
  • Recently the boundary element method has been developed swiftly. The boundary element method is an efficient and accurate means for analysis of two dimensional elastic crack problems. This paper is concerned with the evaluation and the prediction of the stress intensity factor(SIF) for the crack emanating from the circular hole using boundary element method-neural network. The SIF of the crack emanating from the hole was calculated by using boundary element method. Neural network is used to evaluate and to predict SIF from the results of boundary element method. The organized neural network system (structure of four processing element) was learned with the accuracy 99%. The learned neural network system could be evaluated and predicted with the accuracy of 83.3% and 71.4% (in cases of SIF and virtual SIF). Thus the proposed boundary element method-neural network is very useful to estimate the SIF.

Finite Element Analysis and Experiments of Milli-Part Forming of Strip Bending Using Grain Element (입자요소계를 이용한 유한요소 해석)

  • Ku T.W.;Kim D.J.;Kang B.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.266-273
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    • 2002
  • Milli-structure components are classified as a component group whose size is between macro and micro scales, that is, about less than 20mm and larger than 1mm. The bending of these components of thin sheets has a typical phenomenon of bulk deformation because of the forming size. The recent trend towards miniaturization causes an increased demand for parts with very small dimensions. The conceptual miniature bending process enables the production of such parts with high productivity and accuracy. The stress values of the flow curve decrease with miniaturization, which means that coarse grained materials show a higher resistance against deformation, when the grain size is in the range of the sheet thickness. In this paper, a new numerical approach is proposed to simulate intergranular milli-structure in forming by the finite element method. The grain element and grain boundary element are introduced to simulate the milli-structure of strip in the bending. The grain element is used to analyze the deformation of individual grain while the grain boundary element is for the investigation on the movement of the grain boundary. Also, the result of the finite element analysis is confirmed by a series of milli-sized forming experiments.

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