• Title/Summary/Keyword: mesh deformation

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A New 3D Mesh Regeneration Method in the Shape Optimal Design of (전자소자의 형상최적화를 위한 3차원 요소의 재생성법)

  • Yao, Yingying;Koh, Chang-Seop;Xie, Dexin
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.841-843
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    • 2002
  • A novel and simple method, which can be used to automatically regenerate 3D finite element meshes, is presented in the paper. This technique based on the structural deformation analysis. It is problem independent and can be used to renew the mesh of any kind of 3D shape design system whether the geometric surface is parameterized or not. The mesh deformation degree can be adjusted by choosing suitable subregion and giving proper parameters. It is sufficient to obtain a smooth contour with proper mesh quality. Application to the optimum design of shielding plate shows the effectiveness of the proposed technique.

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DEVELOPMENT OF SPECIALIZED GRID GENERATION PROGRAM FOR MULTI-ELEMENT AIRFOIL AERODYNAMIC ANALYSIS (다중익형 공력 계산을 위한 특화 격자생성 프로그램 개발)

  • Nam, D.W.;Lee, Y.J.;Lee, J.Y.;Kim, B.S.
    • Journal of computational fluids engineering
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    • v.21 no.4
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    • pp.85-89
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    • 2016
  • Wing is the most important part of aircraft which produces lift. In general when aircraft takes off or lands, high lift is required and additional devices are adopted in front and aft-side of wing, which constitute so-called multi element airfoils. The objective of this research is to develop a specialized grid generation program to help engineers in reducing human labor and eliminating time-consuming process for mesh regeneration by deforming the initially-given grid system with efficient deforming method. This paper describes briefly about the mesh deformation methods, and provides some results to verify the quality of deformed mesh and eventually correctness of current approach.

3D Optimal Design of Transformer Tank Shields using Design Sensitivity Analysis

  • Yingying Yao;Ryu, Jae-Seop;Koh, Chang-Seop;Dexin Xie
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.3B no.1
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    • pp.23-31
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    • 2003
  • A novel 3D shape optimization algorithm is presented for electromagnetic devices carry-ing eddy current. The algorithm integrates the 3D finite element performance analysis and the steepest descent method with design sensitivity and mesh relocation method. For the design sensitivity formula, the adjoint variable vector is defined in complex form based on the 3D finite element method for eddy current problems. A new 3D mesh relocation method is also proposed using the deformation theory of the elastic body under stress to renew the mesh as the shape changes. The design sensitivity f3r the sur-face nodal points is also systematically converted into that for the design variables for the parameterized optimization application. The proposed algorithm is applied to the optimum design of the tank shield model of the transformer and the effectiveness is proved.

ANALYSIS OF TWO-DIMENSIONAL FLOW AROUND AN OSCILLATING CYLINDER USING MOVING MESH TECHNIQUES (격자 변형 기법을 사용한 운동하는 2차원 실린더 주위의 유동 해석)

  • Lee, Hee-Bum;Rhee, Shin-Hyng
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.542-547
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    • 2010
  • Recently, thanks to advanced computational power and numerical techniques, it is made possible to analyze the flow around moving bodies using computational fluid dynamics techniques. In those simulations, moving mesh techniques should be able to represent both the body motion and boundary deformation which are frequently encounterd in fluid-structure interaction and/of six degree-of-freedom problems. There are several moving mesh techniques such as the Laplacian operator based, tension spring based and elastic deformation based methods. In the present study, the Laplacian operator based method was utilized and the results were validated. For the validation, the flow around an oscillating two-dimensional cylinder was simulated and analyzed.

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3-D Analysis of Hot Forging Processes using the Mesh Compression Method (격자압축법을 이용한 3차원 열간단조공정해석)

  • 홍진태;양동열;이석렬
    • Transactions of Materials Processing
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    • v.11 no.2
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    • pp.179-186
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    • 2002
  • In the finite element analysis of metal forming Processes using general Lagrangian formulation, element nodes in the mesh move and elements are distorted as the material is deformed. The excessive degeneracy of mesh interrupts finite element analysis and thus increases the error of plastic deformation energy, In this study, a remeshing scheme using so-called mesh compression method is proposed to effectively analyze the flash which is generated usually in hot forging processes. In order to verify the effectiveness of the method, several examples are tested in two-dimensional and three-dimensional problems.

Two Dimensional Automatic Quadrilateral Mesh Generation for Metal Forming Analysis (소성 가공 공정 해석을 위한 2차원 사각 요소망 자동 생성)

  • Kim, Sang-Eun;Yang, Hyun-Ik
    • Korean Journal of Computational Design and Engineering
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    • v.14 no.3
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    • pp.197-206
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    • 2009
  • In a finite element analysis of the metal forming processes having large plastic deformation, largely distorted elements are unstable and hence they influence upon the result toward negative way so that adaptive remeshing is required to avoid a failure in the numerical computation. Therefore automatic mesh generation and regeneration is very important to avoid a numerical failure in a finite element analysis. In case of generating quadrilateral mesh, the automation is more difficult than that of triangular mesh because of its geometric complexity. However its demand is very high due to the precision of analysis. Thus, in this study, an automatic quadrilateral mesh generation and regeneration method using grid-based approach is developed. The developed method contains decision of grid size to generate initial mesh inside a two dimensional domain, classification of boundary angles and inner boundary nodes to improve element qualities in case of concave domains, and boundary projection to construct the final mesh.

A Coarse Mesh Model for Numerical Analysis of Lead Frame Deformation Due to Blanking Residual Stress (블랭킹 잔류응력에 의한 리드프레임 변형 수치해석을 위한 대격자 모델)

  • Kim Yong Yun
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.2
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    • pp.133-138
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    • 2005
  • The deformation of sheet metal due to the residual stress during blanking or piercing process, is numerically simulated by means of a commercial finite element code. Two dimensional plain strain problem is solved and then its result is applied to the deformation analysis of the lead frame. The plain strain element is applied to the 2D problem to observe the Von Mises equivalent stress concentration at the both shearing edges. As the punch penetrates into the sheet material, the stress concentration generated on both edges is getting increased to be the shearing surface. The limits of the punching depth applied to the simulation is 16% and 24% of the sheet thickness for the plain strain element and the hexahedral element, respectively. The hexahedral element and the limit of punching depth were applied to the deformation analysis of the lead frame for the blanking process. The FEM results for the lead deformation were very good agreement with the experimental ones. This paper shows that the coarse mesh has enabled to analyze the lead deformation generated due to the blanking mechanism. This simple approach to save the calculation time will be very effective to the design of the blanking tools in industries.

Application of mesh-free smoothed particle hydrodynamics (SPH) for study of soil behavior

  • Niroumand, Hamed;Mehrizi, Mohammad Emad Mahmoudi;Saaly, Maryam
    • Geomechanics and Engineering
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    • v.11 no.1
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    • pp.1-39
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    • 2016
  • The finite element method (FEM), discrete element method (DEM), and Discontinuous deformation analysis (DDA) are among the standard numerical techniques applied in computational geo-mechanics. However, in some cases there no possibility for modelling by traditional finite analytical techniques or other mesh-based techniques. The solution presented in the current study as a completely Lagrangian and mesh-free technique is smoothed particle hydrodynamics (SPH). This method was basically applied for simulation of fluid flow by dividing the fluid into several particles. However, several researchers attempted to simulate soil-water interaction, landslides, and failure of soil by SPH method. In fact, this method is able to deal with behavior and interaction of different states of materials (liquid and solid) and multiphase soil models and their large deformations. Soil indicates different behaviors when interacting with water, structure, instrumentations, or different layers. Thus, study into these interactions using the mesh based grids has been facilitated by mesh-less SPH technique in this work. It has been revealed that the fast development, computational sophistication, and emerge of mesh-less particle modeling techniques offer solutions for problems which are not modeled by the traditional mesh-based techniques. Also it has been found that the smoothed particle hydrodynamic provides advanced techniques for simulation of soil materials as compared to the current traditional numerical methods. Besides, findings indicate that the advantages of applying this method are its high power, simplicity of concept, relative simplicity in combination of modern physics, and particularly its potential in study of large deformations and failures.

A meshfree method based on adaptive refinement method and its application for deformation analysis (변형해석을 위한 적응적 세분화방법에 기초한 무요소법)

  • Han, Kyu-Taek
    • Design & Manufacturing
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    • v.7 no.1
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    • pp.34-39
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    • 2013
  • The finite element method(FEM) presents some limitations when the mesh becomes highly distorted. For analysis of metal forming processes with large deformation, the conventional finite element method usually requires several remeshing operations due to severe mesh distortion. The new computational method developed in the recent years, usually designated by meshfree method, offers an attractive approach to avoid those time-consuming remeshing efforts. This new method uses a set of points to represent the problem domain with no need of an additional mesh. Also this new generation of computational method provides a higher rate of convergence than that of the conventional finite element methods. One of the promising applications of meshfree methods is the adaptive refinement for problems having multi-scale nature. In this study, an adaptive node generation procedure is proposed and also to illustrate the efficiency of proposed method, several numerical examples are presented.

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A Study on the Room Temperature Properties of Molding Sand with different Sand Grain Size (규사(硅砂)의 입도(粒度)에 따른 주물사(鑄物砂)의 상온성질(常溫性質)에 관(關)한 연구(硏究))

  • Choi, Dong-Soo;Lee, Kye-Won
    • Journal of Korea Foundry Society
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    • v.3 no.3
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    • pp.167-173
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    • 1983
  • The effect of sand grain size on the various properties of mold is not only basic but important interest which we have to deal with.And the relation among the various properties of mold (strength, permeability, flowability, compactability, hardness, deformation, toughness etc.) is very complicated and inaccurate, so we can delineate the behavior of mixture (sand+water+bentonite) with experience only. Within recent years a so-called rigid-water theory has been accepted as a means of advancing logical explanations for the research aimed at delineating sand-clay-water relationships. By changing grain size or mesh no. of grain, specimens have been subjected to green compressive strength, permeability, deformation, flowability, compactablity, toughness at room temperature. Under constant mulling energy and ratio of water/bentonite, the results obtained were as follows: 1. With decreasing grain size green compressive strength of the specimen increased. 2. With decreasing grain size permeability decreased. 3. With decreasing grain size flowability and bulk density decreased but compactability increased. 4. With decreasing grain size deformation decreased but toughness increased. 5. At 60 mesh no., the properties of specimen are conspicuously changed. The reason is that the total surface area of sand grain which affects the type of bonding between sand grains is more changed at 60 mesh number.

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