• Title, Summary, Keyword: computational node

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The Phantom-node Method for Cracked Problems in Shell Structures

  • Zi, Goang-Seup;Chau-Dinh, Thanh;Lee, Phill-Seung;Kim, Ji-Hwan
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.207-210
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    • 2010
  • This paper presents an method, called the phantom-node method, for representing discontinuities in shell structures. By decomposing an element completely cut by a crack into two overlapped elements special treatment of the MITC3 shell element to overcome "locking phenomenon" is straightforward. Two numerical examples are provided.

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Performance evaluation of EMI interface and multi-channel wireless impedance sensor node for bolted connection monitoring (볼트 연결부 모니터링을 위한 다채널 무선 임피런스 센서노트와 EMI 인터페이스의 성능 분석)

  • Nguyen, Khac-Duy;Lee, Po-Young;Kim, Jeong-Tae
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.36-39
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    • 2011
  • In this paper, performance of EMI interface and multi-channel wireless impedance sensor node is evaluated for SHM on bolted connection. To achieve the objective, following approaches are implemented. Firstly, an interface washer is designed to monitor loosened bolt through the variation in EMI of interface washer due to change in preload in bolt. Secondly, a multi-channel wireless impedance sensor node based on Imote2 platform is designed for automated and cost-efficient impedance-based SHM on bolted connections. Finally, performance of the multi-channel wireless impedance sensor node and the interface washer are experimentally validated for a lab-scale bolted connection model. A damage monitoring method using RMSD index of EMI signatures is utilized to examine the strength of each individual bolted connection.

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The Development of the Automatic Triangular Mesh Generation Software Using Modified Lo's Algorithm (수정된 Lo의 요소망 생성 알고리즘은 이용한 자동 삼각 요소망 생성 소프트웨어의 개발)

  • 김병옥;양현익
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.1
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    • pp.95-101
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    • 2000
  • For last two decades numerous automatic mesh generation algorithms for various two dimensional objects have been introduced continuously and among them triangular mesh generation schemes have been majority because of efficiency and controllability. In our study, an existing triangular mesh generation algorithm developed by Lo is totally modified to more improve node distribution, element shape, and objects shape independency. ft is composed of node generation part and element generation part. In order to find a suitable node position within geometry, the suggested algorithm searches desirable positions of points within boundary and optimizes node position to generate comparatively well-shaped elements. More over, the suggested algorithm handles various complex two dimensional objects and its meshing speed shows superiority to those of the existing triangulation mesh generation algorithms. It is fully automated in a sense of constructing object boundary and hence can be directly used as an independent meshing software.

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Higher Order Elements by Delaunay Triangulation (드로네이기법에 의한 고차 유한요소 생성)

  • 송영준
    • Computational Structural Engineering
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    • v.9 no.4
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    • pp.141-154
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    • 1996
  • Delaunay triangulation is a very powerful method of mesh generation for its versatility such as handling complex geometries, element density control, and local/global remeshing capability, The limit of generating simplex elements(3-node elements in 2-D) only is resolved by adding generation module of 6-node quadratic elements. Since proposed adjacency does not change from 3-node element mesh to 6-node mesh, generation module can utilize the original simplex element generator. Therefore, versatility of the Delaunay triangulation is preserved. A simple upsetting problem is employed to show the possibility of the algorithm.

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Development of 8-node Flat Shell Element for the Analysis of Folded Plate Structures (절판 구조물의 해석을 위한 8절점 평면 첼 요소의 개발)

  • 최창근;한인선
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.234-241
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    • 1999
  • In this study, an improved 8-node flat shell element is presented for the analysis of shell structure, by combining 8-node membrane element with drilling degree-of-freedom and 8-node plate bending element based on the recently presented technique. Firstly, 8-node membrane element designated as CLM8 is presented in this paper. The element has drilling degree-of.freedom in addition to transitional degree-of-freedom. Therefore the element possesses 3 degrees-of-freedom per each node which as well as the improvement of the element behavior, permits an easy connection to other element with rotational degree-of -freedom. Secondly. 8-node flat shell element was composed by adding 8-node Mindlin plate bending element to the membrane element. The behavior of the introduced plate bending element is further improved by combined use of nonconforming displacement modes, selectively reduced integration scheme and assumed shear strain fields. The element passes in the patch test, doesn't show spurious mechanism and doesn't produce shear locking phenomena. Finally, Numerical examples are presented to show the performance of flat shell element developed in the present study.

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Nano-continuum multi scale analysis using node deactivation techniques (절점 비활성화 기법을 적용한 나노-연속체 멀티스케일 해석 기법)

  • Rhee Seung-Yun;Cho Maeng-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.395-402
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    • 2006
  • In analyzing the nano-scale phenomena or behaviors of nano devices or materials, it is often desirable to deal with more atoms than can be treated only with a full atomistic simulation. However, even now, it is advisable to apply the atomistic simulation to the narrow region where the deformation field changes rapidly but to apply the conventional continuum model to the region far from that region. This equivalent continuum model can be formulated by applying the Cauchy-Born rule to the exact atomistic potential as in the quasicontinuum method. To couple the atomistic model with the equivalent continuum model, continuum displacements are conformed to the molecular displacements at the discrete positions of the atoms within the bridging domain. To satisfy the coupling constraints, we apply the Lagrange multiplier method. The continuum model in the bridging model should be applied on the region where the deformation field changes gradually. Then we can make the nodal spacing in the continuum model be much larger than the atomic spacing. In the first step, we generate the atomic-resolution mesh with the nodal spacing equal to the atomic spacing, and then we eliminate the nodal degrees of freedom adaptively using the node deactivation techniques. We eliminate more DOFs as the regions are more far from the atomistic region. Computing time and computational resources can be greatly reduced by the present node deactivation technique in multi scale analysis.

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Variable-node-flat shell element for adaptive mesh refinement (적응적체눈세분화를 위한 변절점 평면 쉘 요소)

  • 최창근;이완훈
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.1-8
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    • 1994
  • A variable-node-flat shell element designated as CLS which has variable mid-side nodes with drilling freedom has been presented in this paper. The shell element to be applied in finite element analysis has been developed by combining a membrane element named as CLM with drilling rotation d.o.f. and plate bending element. The combined shell element possess six degrees of freedom per node. By introducing the variable-node elements which have physical midside nodes, some difficulties associated with imposing displacement constraints on irregular nodes to enforce interelement compatibility in common adaptive h-refinement on quadrilateral mesh are easily overcome. Detailed numerical studies show the excellent performance of the new shell elements developed in this study.

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Triangular Plate-Bending Element by Combined node (절점 병합에 의한 삼각형 평판휨 요소)

  • 최창근;강윤숙;이태열
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.104-111
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    • 2002
  • A new triangular element fur the finite element analysis of plate-bending problems is presented. For the purpose of sharing the program code of 4 node plate-bending element, two nodes of the 4-node element are combined to form a triangular element. Thus, the presented element would bring about great deal of efficiency of the computer program. The proposed variable-node elements pass the patch tests, do not show spurious zero-energy modes, and do not produce shear locking phenomena. It is also shown that the elements produce reliable solutions through numerical tests for standard benchmark problems.

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Automatic Mesh Generation for Three-Dimensional Structures Consisting of Free-Form Surfaces (자유 곡면으로 구성되는 3차원 구조물에 대한 자동 요소 분할)

  • ;Yagawa, Genki
    • Korean Journal of Computational Design and Engineering
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    • v.1 no.1
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    • pp.65-75
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    • 1996
  • This paper describes an automatic finite element(FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid and shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid and shell structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

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Parametric Design on Bellows of Piping System Using Fuzzy Knowledge Processing

  • Lee Yang-Chang;Lee Joon-Seong;Choi Yoon-Jong
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.6 no.2
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    • pp.144-149
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    • 2006
  • This paper describes a novel automated analysis system for bellows of piping system. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy theory and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes and one of commercial solid modelers. In this system, a geometric model, i.e. an analysis model, is first defined using a commercial solid modelers for 3-D shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation technique is introduced as a basic tool for element generation. The triangular elements are converted to quadrilateral elements. Practical performances of the present system are demonstrated through several analysis for bellows of piping system.