• Title/Summary/Keyword: AutoMesh

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Numerical Simulation of Wind Pressures on a High-rise Building by Auto-mesh System

  • Tang, Yuanzhe;Cao, Shuyang
    • International Journal of High-Rise Buildings
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    • v.8 no.4
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    • pp.255-264
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    • 2019
  • This paper describes large eddy simulation of wind pressures on a square cylinder in a uniform flow and a high-rise building immersed in an atmospheric turbulent boundary layer. For the atmospheric boundary layer case, the inflow turbulence is generated by a numerical wind tunnel. In the numerical simulation, particular attention is devoted to the performance of an auto hexahedral non-structural mesh. Both simulations are performed for three grid systems: an auto hexahedral non-structured grid, a structured Cartesian grid and a non-structured triangular prism grid, and for three grid numbers. The present study shows that the auto hexahedral unstructured mesh achieves the best simulation results for wind pressures on the square cylinder and the high-rise building. When the grid number is sufficiently large, the differences among the results obtained from the three investigated grid systems are not significant. However, the advantage of the auto hexahedral unstructured mesh becomes clear when the grid number decreases, because it enables a balanced distribution of orthogonal grids. The results described in this paper demonstrate that the auto hexahedral non-structured mesh has good potential applicability to simulation of urban flows.

Application of Grid-based Approach for Auto Mesh Generation of Vacuum Chamber (자동 요소망 생성을 위한 격자구성기법 적용)

  • Lee J.S.;Park Y.J.;Chang Y.S.;Choi J.B.;Kim Y.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.844-847
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    • 2005
  • A seamless analysis of complex geometry is one of greatly interesting topic. However, there are still gaps between the industrial applications and fundamental academic studies owing to time consuming modeling process. To resolve this problem, an auto mesh generation program based on grid-based approach has been developed for IT-product in the present study. At first, base mesh and skin mesh are generated using the information of entities which extracted from IGES file. Secondly the provisional core mesh with rugged boundary geometry is constructed by superimposing the skin mesh as well as the base mesh generated from the CAD model. Finally, the positions of boundary nodes are adjusted to make a qualified mesh by adapting node modification and smoothing techniques. Also, for the sake of verification of mesh quality, the hexahedral auto mesh constructed by the program is compared with the corresponding tetrahedral free mesh and hexahedral mapped mesh through static finite element analyses. Thereby, it is anticipated that the grid-based approach can be used as a promising pre-processor for integrity evaluation of various IT-products.

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The Characterization of Electrolytic Ion Water Generator by Electrode (전극에 따른 전해 이온수 발생장치의 특성)

  • Han, Byung-Jo;Lee, Yeon;Ryu, Bong-Jo;Koo, Kyung-Wan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.10
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    • pp.1786-1791
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    • 2016
  • The damage has occurred inside the semiconductor pattern When using conventional wet station for semiconductor. It was used for electrolytic ion water generator in order to prevent damage to the semiconductor pattern. It was designed and developed a flow path electrode and the mesh electrode to check the efficiency of the electrode. And It confirmed the expected results through the simulation of the flow path. and ORP were measured in accordance with the current and voltage of mesh electrode and flow paht electrodes. Flow path electrode 22A is 3V, up to pH 9.8, the value of ORP-558mV was measured and the mesh electrode was measured up to pH 9.8, ORP -350mV.

An Algorithm of Automatic 2D Quadrilateral Mesh Generation with the Line Constraints (라인(line) 제약조건을 가지는 2차원 사각 메쉬의 자동 생성 알고리즘)

  • 김인일;이규열;조두연;김태완
    • Korean Journal of Computational Design and Engineering
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    • v.8 no.1
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    • pp.10-18
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    • 2003
  • FEM (Finite Element Method) is a fundamental numerical analysis technique in wide spread use in engineering application. As the solving time occupies small portion of entire FEM analysis time because of development of hardware, the relative lime to the whole analysis time to make mesh mod-els is growing. In particular, in the case of stiffeners such as features attached to plate in ship structure, the line constraints are imposed on mesh model together with other constraints such as holes. To auto-matically generate two dimensional quadrilateral mesh with the line constraints, an algorithm is pro-posed based on the constrained Delaunay triangulation and Q-Morph algorithm in which the line constraints are not considered. The performance of the proposed algorithm is evaluated. And some numerical results of our proposed algorithm ate presented.

Flaw Analysis Based Life Assessment of Welded Tubular Joint (결함해석에 기초한 배관용접부 수명평가)

  • Lee, Hyeong-Il;Han, Tae-Su;Jeong, Jae-Heon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.5 s.176
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    • pp.1331-1342
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    • 2000
  • In power generation systems a variety of structural components typically operate at high temperature and pressure. Therefore a life assessment methodology accounting for gradual creep fracture is increasingly needed for these components. The most critical defects in such structure are generally found in the form of semi-elliptical surface cracks in the welded tubular joints. Therefore the analysis of a semi-elliptical surface crack in a plate or a shell is an important problem in engineering fracture mechanics. On this background, via shell/line-spring finite element analyses of such surface cracks in the welded T and L joints under various loadings, we investigate J-integral along the crack front We first develop T and L joints auto mesh generation program providing ABAQUS input file composed of shell/line-spring finite elements. We then further develop a T and L joints life assessment program based on the experimental creep crack growth law and auto mesh generation program in a graphical user interface format Finally the remaining life of T and L joints for various analytical parameters are assessed using the developed life assessment program.

Finite Element Springback Analysis of Vertically-Walled Auto-Body Part (수직벽을 가진 자동차 부품 성형공정의 스프링백 유한요소 해석)

  • 이두환;윤치상;신철수;조원석;구본영;금영탁
    • Transactions of Materials Processing
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    • v.9 no.6
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    • pp.574-581
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    • 2000
  • A vertically-walled auto-body part is one of the most difficult stamping parts because of angle change, wall curl, and twisting of the blank after springback as well as fracture and wrinkle. In this study, computational simulations of the vertically-walled auto-body part are carried out focusing on angle change, wall curl, and twisting after springback. Binderwrap blank shape is used in forming analysis for precise initial contacts between punch and blank. An adaptive mesh method is used in springback analysis for precise calculation of bending moments. In springback analysis, the differences of 2 and 3 dimensional analysis are compared and the effects of blank holdig force and friction coefficient are evaluated. In order to verify the validity of simulation results, they are compared with measured ones. The predicted thickness distribution and formed shape are agreed well with those of the measurement. The Predicted springback amount is less than that of the measurement.

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Trimming Line Design of Auto-body Panel with Complex Shape Using Finite Element Inverse Method (유한요소 역해석을 이용한 복잡한 자동차 판넬의 트리밍 라인 설계)

  • Song, Y.J.;Hahn, Y.H.;Park, C.D.;Chung, W.J.
    • Transactions of Materials Processing
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    • v.15 no.6 s.87
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    • pp.459-466
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    • 2006
  • Trimming line design plays an important role in obtaining accurate edge profile after flanging. Compared to the traditional section-based method, simulation-based method can produce more accurate trimming line by considering deformation mechanics. Recently, the use of a finite element inverse method is proposed to obtain optimal trimming line. By analyzing flanging inversely from the final mesh after flanging, trimming line can be obtained from initial mesh on the drawing die surface. Initial guess generation fer finite element inverse method is obtained by developing the final mesh onto drawing tool mesh. Incremental development method is adopted to handle irregular mesh with various size and undercut. In this study, improved incremental development algorithm to handle complex shape is suggested. When developing the final mesh layer by layer, the algorithm which can define the development sequence and the position of developing nodes is thoroughly described. Flanging of front fender is analyzed to demonstrate the effectiveness of the present method. By using section-based trimming line and simulation-based trimming line, incremental finite element simulations are carried out. In comparison with experiment, it is clearly shown that the present method yields more accurate edge profile than section-based method.

A study on the two-dimensional automatic mesh generation programming (2차원 자동요소분할 프로그램 개발에 관한 연구)

  • 조명철;유형선
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.720-725
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    • 1991
  • This paper is concerned with the program of the automatic mesh generation for 2-dimensional domain which contains the curved boundaries and holes. This program treats a new vertical - line drawing method. This method starts with 4-subdivisions of problem domain and the classification of the cross points of grid lines and boundaries. And the new node is generated by the vertical line to the line connecting the two intersections of a boundary and two grid lines in general. The boundaries are piecewise-curves composed of lines, circles, arcs, and free curves. The free curves are generated by B-Spline form. Although there were some bad elements for the complex boundary, it was possible to obtain the acceptable elements for the given boundaries. The results of automatic mesh generation can be verified directly by drawing on the computer monitor in executing the program. And it is possible to add the processes - that is, editing, hard copying, etc - using the script file in Auto-CAD.

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C* Based Life Assessment of 3D Crack at High Temperature (C*에 기초한 3차원 고온균열 수명평가)

  • Han, Tae-Soo;Yoon, Kee-Bong;Lee, Hyung-Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.5
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    • pp.823-833
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    • 2001
  • In recent years, the subject of remaining life assessment has drawn considerable attention in chemical plants, where various structural components typically operate at high temperature an pressure. Thus a life prediction methodology accounting for high temperature creep fracture is increasingly needed for the components. Critical defects in such structures are generally found in the form of semi-elliptical surface crack, and the analysis of which is consequently an important problem in engineering fracture mechanics. On this background, we first develop an auto mesh generation program for detailed 3-D finite element analyses of axial and circumferential semi-elliptical surface cracks in a piping system. A high temperature creep fracture parameter C-integral is obtained from the finite element analyses of generated 3-D models. Post crack growth module is further appended here to calculate the amount of crack growth. Finally the remaining lives of surface cracked pipes for various analytical parameters are assessed using the developed life assessment program.

Development of a CAD-based Utility for Topological Identification and Rasterized Mapping from Polygonal Vector Data (CAD 수단을 이용한 벡터형 공간자료의 위상 검출과 격자도면화를 위한 유틸리티 개발)

  • 조동범;임재현
    • Journal of the Korean Institute of Landscape Architecture
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    • v.27 no.4
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    • pp.137-142
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    • 1999
  • The purpose of this study is to develope a CAD-based tool for rasterization of polygonal vector map in AutoCAD. To identity the layer property of polygonal entity with user-defined coordinates as topology, algorithm in processing entity data of selection set that intersected with scan line was used, and the layers were extracted sequentially by sorted intersecting points in data-list. In addition to the functions for querying and modifying topology, two options for mapping were set up to construct plan projection type and to change meshes' properties in existing DTM data. In case of plan projection type, user-defined cell size of 3DFACE mesh is available for more detailed edge, and topological draping on landform can be executed in case of referring DTM data as an AutoCAD's drawing. The concept of algorithm was simple and clear, but some unexpectable errors were found in detecting intersected coordinates that were AutoCAD's error, not the utility's. Also, the routines to check these errors were included in algorithmic processing. Developed utility named MESHMAP was written in entity data control functions of AutoLISP language and dialog control language(DCL) for the purpose of user-oriented interactive usage. MESHMAP was proved to be more effective in data handling and time comparing with GRIDMAP module in LANDCADD which has similar function.

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