• Title/Summary/Keyword: Rezoning

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대변형 해석에서 평활화를 이용한 사면체 요소망의 재조성

  • Gwon, Gi-Hwan;Chae, Su-Won;Sin, Sang-Yeop
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2397-2405
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    • 2000
  • The remeshing is a method to replace a distorted mesh by a new mesh without interrupting the finite element calculation. The remeshing procedure in this paper refers to the rezoning, for which a sm oothing process is developed to alleviate the distortions of mesh. In the paper, an automatic finite element rezoning system with tetrahedral elements for large deformation analysis has been developed. Our smoothing process is composed of two steps, a surface smoothing and a volume smoothing. In the surface smoothing, checking the dihedral angle and projection on surface patch reduced the change of shape and nodes penetrating die. The constrained Laplacian smoothing has been employed for the volume smoothing process. The state variables are mapped from old mesh to new mesh by using volume coordinates within a tetrahedral element. All these procedures have been linked to the NIKE3D program As illustrated in the examples the overall strategy ensures a robust and efficient rezoning scheme for finite element simulation of metal-forming processes.

Coupled Analysis of Structure and Surface Ablation in Solid Rocket Nozzle (삭마반응을 고려한 고체 추진기관 노즐 조립체의 열반응 및 구조해석)

  • Kim, Yun-Chul;Doh, Young-Dae;Hahm, Hee-Cheol;Moon, Soon-Il
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.565-569
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    • 2011
  • A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermo-structural analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem are solved by remeshing-rezoning method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code.

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Thermal decomposition and ablation analysis of solid rocket propulsion (삭마 및 열분해 반응을 고려한 고체 추진기관의 열해석)

  • Kim, Yun-Chul
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.113-122
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    • 2010
  • A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem are solved by remeshing-rezoning method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.

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Thermal decomposition and ablation analysis of solid rocket nozzle using MSC.Marc (상용해석 코드(MSC-Marc)를 활용한 노즐 내열부품의 숯/삭마 해석 기법)

  • Kim, Yun-Chul
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.05a
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    • pp.311-314
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    • 2009
  • A two-dimensional thermal response and ablation simulation code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem and endothermic reaction in thermal decomposition are solved by rezoning and effective specific heat method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.

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Thermal Decomposition and Ablation Analysis of Solid Rocket Propulsion (삭마 및 열분해 반응을 고려한 고체 추진기관의 열해석)

  • Kim, Yun-Chul
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.5
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    • pp.32-44
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    • 2010
  • A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. The thermogravimetric analysis (TGA) techniques have been used to characterize the thermal decomposition constants for Arrhenius parameters. Two heterogeneous reactions involving carbon and the oxidizing species of $H_2O$ and $CO_2$ are considered and determined by Zvyagin's ablation model and kinetic constants. The moving boundary problem and mesh moving are solved by remeshing-rezoning method in MSC-Marc-ATAS program. The difference between the calculated and experimental value of char and ablation thickness is up to 20%. For the performance prediction of thermal protection systems, this method will be integrated with a three-dimensional finite-element thermal and structure analysis code through the real time sensing of in-depth temperature and heat flux.

FINITE ELEMENT ANALYSIS AND MEASUREMENT ON THE RELEASE OF RESIDUAL STRESS AND NON-LINEAR BEHAVIOR IN WELDMENT BY MECHANICAL LOADING(I) -FINITE ELEMENT ANALYSIS-

  • Jang, Kyoung-Bok;Kim, Jung-Hyun;Cho, Sang-Myoung
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.378-383
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    • 2002
  • In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non-coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

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Landscape Evaluation Based on Ecological and Visual Characteristics of Moodeungsan Natural Park (생태 및 시각특성을 기초로 한 무등산도립공원의 경관평가)

  • 황국웅;이규완
    • Korean Journal of Environment and Ecology
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    • v.12 no.1
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    • pp.14-21
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    • 1998
  • Landscape has two side, ecological structure and visual characteristics. And Landscape evaluation should be implemented from this viewpoint. In this study, landscape of the Moodeungsan natural park was evaluated based on ecological and visual characteristics, and the results was compared with the existing zoning. And it was recognized that the areas having high preserbability are located in the nature environmental zone. For the purpose of natural park management planning, in this study, rezoning method of natural park based on landscape evaluation is proposed.

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Finite Element Analysis and Measurement on the Release of Residual Stress and Non-linear Behavior in Weldment by Mechanical Loading(I) -Finite Element Analysis-

  • Jang, K.B.;Kim, J.H.;Cho, S.M.
    • International Journal of Korean Welding Society
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    • v.2 no.1
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    • pp.29-32
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    • 2002
  • In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non- coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

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Analysis of Two-Dimensional Sloshing Problems by a Lagrangian FEM (Lagrangian 유한요소법을 이용한 2차원 탱크내 유동해석)

  • P.M.,Lee;S.W.,Hong;S.Y.,Hong
    • Bulletin of the Society of Naval Architects of Korea
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    • v.27 no.2
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    • pp.21-30
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    • 1990
  • Theoretical and experimental techniques to analyze the two-dimensional liquid motion in a tank are discussed. A Lagrangian FEM with a velocity correction procedure is introduced to describe incompressible free surface fluid flow. A mesh rezoning technique is used to prevent strong distortion of finite elements in the Lagrangian description. Model test technique for sloshing tank is developed using a hydraulic type bench tester. The influence of the variation in the exciting frequency and amplitude are observed for various fill depths. The results of theoretical calculations are compared with those of experiments.

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Analysis of Flexible Media Using ALE Finite Element Method (ALE 유한요소법을 이용한 유연매체의 거동해석)

  • Jee, Jung-Geun;Jang, Yong-Hoon;Park, No-Cheol;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.247-250
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    • 2007
  • Flexible media such as the paper, the film, etc. are thin, light and very flexible. They behave in geometrically nonlinear. Any of small force makes large deformation. So we must including aerodynamic effect when its behavior is predicted. Thus, it becomes fully coupled fluid-structure interaction(FSI) problem. In FSI problems, where the fluid mesh near the structure undergoes large deformations and becomes unacceptably distorted, which drive the time step to a very small value for explicit calculations, the arbitrary Lagrangian-Eulerian(ALE) methods or rezoning are used to create a new undistorted mesh for the fluid domain, which allows the calculations to continue. In this paper, FE sheet model considering geometric nonlinearity is formulated to simulate the behavior of the flexible media. Aerodynamic force to the media by surrounding air is calculated by solving the incompressible Navier-Stokes equations. Q2Q1(Taylor-Hood) element which means biquadratic for velocity and bilinear for pressure is used for fluid domain. Q2Q1 element satisfies LBB condition and any stabilization technique is not needed. In this paper, cantilevered sheet in the viscous incompressible Navier-Stokes flow is simulated to check the mesh motion and numerical integration scheme, and then falling paper in the air is simulated and the effects of some representative parameters are investigated.

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