• Title/Summary/Keyword: Kinematically Steady-state

Search Result 3, Processing Time 0.016 seconds

A Study on Material Characterization of Semi-Solid Materials (I) -Proposal of New Velocity Field for Upper Bound Analysis of Backward Extrusion- (반용융 재료의 물성치 평가에 관한 연구(I) -후방압출의 상계해석을 위한 동적 가용 속도장의 제안-)

  • 이주영;김낙수
    • Transactions of Materials Processing
    • /
    • v.8 no.4
    • /
    • pp.364-373
    • /
    • 1999
  • For material characterization of semi-solid materials, backward extrusion process, which has been used in forming of hollow-sectioned products, was analyzed by the upper bound analysis in the current study. The existing kinematically admissible velocity field was applied to steady state at which there was no change in the assumed regions of velocity field. For unsteady state, new velocity field, as a function of dead zone angle, was proposed. Through the whole analysis, fiction between die and workpiece was also considered. It has been studied how the process variables, such as friction factor and punch velocity, and material parameters, such as strength coefficient, strain rate sensitivity could affect on analysis results. Finally, by the comparison with the finite element analysis, the reliability and efficiency of the proposed velocity field were discussed.

  • PDF

Finite Element Analysis Simulation for Roll Forming Process (3차원 유한요소법에 의한 롤 포밍 공정 해석 시뮬레이션)

  • 김낙수
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 1999.03b
    • /
    • pp.207-212
    • /
    • 1999
  • A computational method based on the three-dimensional finite element method is developed for the deformation analysis of roll forming process. the method approximates the process as a kinematically steady state deformation of strip. For industrial usefulness of the simulation method several rolls with arbitrary shapes in one stand can be considered. The shapes and the thickness distributions of strip after roll forming were examined by comparing computation results with experiments It is concluded that the tool is useful enough to predict the process. The overall simulation method was integrated into a sorftware package to help the industrial roll-design.

  • PDF

A Finite Element Model for Predicting the Microstructural Evolution in Hot Rolling (열간압연시 미세조직 예측을 위한 유한요소 모델)

  • Cho, Hyunjoong;Kim, Naksoo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.14 no.9
    • /
    • pp.90-100
    • /
    • 1997
  • A full three-dimensional thermo-coupled rigid-viscoplastic finite element method and the currently developed microstructural evolution system which includes semi-empirical equations suggested by different research groups were used together to form an integrated system of process and micro- structure simulation of hot rolling. The distribution and time histroy of the momechanical variables such as temperature, strain, strain rate, and time during pass and between passes were obtained from the finite element analysis of multipass hot rolling processes. The distribution of metallurgical variables were calculated on the basis of instantaneous thermomechanical data. For the verification of this method the evolution of microstructure in plate rolling and shape rolling was simulated and their results were compared with the data available in the literature. Consequently, this approach makes it possible to describe the realistic evolution of microstructure by avoiding the use of erroneous average value and can be used in CAE of multipass hot rolling.

  • PDF