• Title/Summary/Keyword: Remeshing Criterion

Search Result 6, Processing Time 0.017 seconds

A Remeshing Criterion for Large Deformation Finite Element Analysis (대변형 유한요소해석에서 요소망의 재구성을 위한 기준)

  • Cho, Hae-Gyu;Chae, Soo-Won;Park, Jong-Jin
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.13 no.10
    • /
    • pp.78-87
    • /
    • 1996
  • In this paper, a remeshing criterion has been suggested in order to order to automate the remeshing decision during finite element analysis of metal forming. In order to use for the remeshing decision, two of remeshing criteria have been investigated. One is the use of error estimates based on errors in stresses and strain rate of the finite element solution and the other is the use of geometric characterisreics of distorted elements. As a result, the strain rate error estimate in power norm based on the former is found to give more valuable information about remeshing decision than the ones based on the latter. Examples are given to demon- strate the usefulness of the suggested eroor estimate as a remeshing criterion.

  • PDF

Remeshing Criterion for Large Deformation Finite Element Analyses Based on the Error Calculation (오차계산에 기초한 대변형 유한요소 해석에서의 요소망 재구성 기준)

  • 김형종;김낙수
    • Transactions of Materials Processing
    • /
    • v.4 no.1
    • /
    • pp.92-104
    • /
    • 1995
  • It often happens some elements are so largely distorted during a large-deformation finite element analysis that further calculation becomes impossible or the approximation error increases rapidly. This problem can be overcomed only by remeshing at several suitable stages. The present study aimed to establish the criterion based on the error estimators, and examined in the simulation and posterior error analysis of ring compression test to demonstrate the usefulness of them. The distribution of each error estimator and its variation during deformation were investigated. All the error estimators were increased monotonously with deformation and decreased rapidly at remeshing stage. It was shown that the error estimators suggested in this study are good measures as remeshing criterion for large deformation finite element analyses.

  • PDF

Mesh Reconstruction Using Redistibution of Nodes in Sub-domains and Its Application to the Analyses of Metal Forming Problems (영역별 절점재구성을 통한 격자재구성 및 소성가공해석)

  • Hong, Jin-Tae;Yang, Dong-Yol
    • Korean Journal of Computational Design and Engineering
    • /
    • v.12 no.4
    • /
    • pp.255-262
    • /
    • 2007
  • In the finite element analysis of forming process, objects are described with a finite number of elements and nodes and the approximated solutions can be obtained by the variational principle. One of the shortcomings of a finite element analysis is that the structure of mesh has become inefficient and unusable because discretization error increases as deformation proceeds due to severe distortion of elements. If the state of current mesh satisfies a certain remeshing criterion, analysis is stopped instantly and resumed with a reconstructed mesh. In the study, a new remeshing algorithm using tetrahedral elements has been developed, which is adapted to the desired mesh density. In order to reduce the discretization error, desired mesh sizes in each lesion of the workpiece are calculated using the Zinkiewicz and Zhu's a-posteriori error estimation scheme. The pre-constructed mesh is constructed based on the modified point insertion technique which is adapted to the density function. The object domain is divided into uniformly-sized sub-domains and the numbers of nodes in each sub-domain are redistributed, respectively. After finishing the redistribution process of nodes, a tetrahedral mesh is reconstructed with the redistributed nodes, which is adapted to the density map and resulting in good mesh quality. A goodness and adaptability of the constructed mesh is verified with a testing measure. The proposed remeshing technique is applied to the finite element analyses of forging processes.

Finite Element Analysis of a Roll Piercing Process Equipped with Diecher's Guiding Discs (원형디스크 지지 방식의 롤피어싱 공정의 유한요소해석)

  • Shim, S.H.;Cho, J.M.;Lee, M.C.;Joun, M.S.
    • Transactions of Materials Processing
    • /
    • v.21 no.1
    • /
    • pp.19-23
    • /
    • 2012
  • In this paper, a Mannesmann roll piercing process equipped with Diecher's guiding discs is investigated using a rigid-thermoviscoplastic finite elements method with intelligent remeshing capability and tetrahedral elements. The analysis model is presented and the approach is applied to a Mannesmann roll piercing process found in the literature. Details about the remeshing criterion as well as mesh density control are given. The present predictions are compared with the predictions found in the literature, showing that the two predictions are in close agreement in terms of the deformed shape. However, it is emphasized that the present approach has the distinct strength in predicting details of final shape.

A Study on the Optimal Stress Compensation to Dynamic Recrrystallization for the Estimation of Forming Loads (성형하중예측을 위한 재결저분율 보상의 최적조건 도출)

  • 장영원
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 1999.03b
    • /
    • pp.131.1-134
    • /
    • 1999
  • The effect of dynamic recrystallization during hot forming process was implemented to a commercial FEM code by conditioned remeshing and remapping of sate variables. A datum strain for stress compensation was determined as a strain for maximum softening rate and was able to be formulated as a function of critical strain f($\varepsilon$). The validity of remapping criterion was examined by a series of mechanical tests and microstructural observation. The application of suggested datum resulted in better estimation of load-stroke during forging processes.

  • PDF

Analysis of Stress Intensity Factors for Interacting Two Growing Cracks (2개의 성장 균열들의 상호작용에 관한 응력확대계수 해석)

  • 박성완
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.9 no.5
    • /
    • pp.47-57
    • /
    • 2000
  • In this study, a fundamental approach to make clear the mechanism of the mutual interference and coalescence of stress fields in the vicinity of two crack tips on the process of their slow growth, using boundary element method. Automatic generation of quadratic discontinuous elements along both of the crack boundaries which can be defined by an arbitrary piece-wise straight geometry. The direction of the crack-extension increment is predicted by the maximum principal stress criterion, corrected to account for the discreteness of the crack extension. Along the computed direction, the crack is extended one increment. Automatic incremental crack-extension analysis with no remeshing, computation of the stress intensity factors by J-integral. Numerical stress intensity factors for two growing cracks in plane-homogeneous regions were determined.

  • PDF