• Title, Summary, Keyword: Nonsteady Ideal Bulk Forming

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Nonsteady Plane-strain ideal forming with elastic dead zone (탄성 변형 영역을 고려한 비정상 평면 변형 이상 공정 이론)

  • Lee W.;Chung K.;Richmond Owen
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.190-193
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    • 2004
  • Ever since the ideal forming theory has been developed fur process design purposes, application has been limited to sheet forming and, for bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was performed under the plane-strain condition based on the theory previously developed. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-strain flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, for a prescribed final part shape, schemes to optimize a preform shape out of a class of initial configurations and also to define the evolution of shapes and boundary tractions were developed. Discussions include the two problematic issues on internal tractions and the non-monotonous straining. For demonstration purposes, numerical calculations were made for a bulk part under forging.

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Nonsteady Plane-strain Ideal Forming without Elastic Dead-zone

  • Chung, Kwansoo;Lee, Wonoh;Kang, Tae Jin;Youn, Jae Ryoun
    • Fibers and Polymers
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    • v.3 no.3
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    • pp.120-127
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    • 2002
  • Ever since the ideal forming theory has been developed for process design purposes, application has been limited to sheet forming and, for bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was made under the plane-strain condition. In the ideal flow, material elements deform fellowing the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-strain flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, schemes to optimize preform shapes for a prescribed final part shape and also to define the evolution of shapes and frictionless boundary tractions were developed. Discussions include numerical calculations made for a real automotive part under forging.

Nonsteady Plane-strain Ideal Forming with Elastic Dead Zone (탄성 변형 영역을 고려한 비정상 평면 변형 이상 공정 이론)

  • Lee W.;Chung K.;Alexandrov S.;Kang T.J.
    • Transactions of Materials Processing
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    • v.13 no.6
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    • pp.540-545
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    • 2004
  • Ever since the ideal forming theory has been developed for process design purposes, application has been limited to sheet forming and, fur bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was performed under the plane-strain condition based on the theory previously developed. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-stram flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, fur a prescribed final part shape, schemes to optimize a preform shape out of a class of initial configurations and also to define the evolution of shapes and boundary tractions were developed. Discussions include the two problematic issues on internal tractions and the non-monotonous straining. For demonstration purposes, numerical calculations were made for a bulk part under forging.

Plane-strain bending based on ideal flow theory (이상 유동 이론에서의 평면 변형 벤딩)

  • Alexandrov Sergei;Lee W.;Chung K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.233-236
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    • 2004
  • The major objective of this paper is to clarify the effect of constitutive laws on bulk forming design based on the ideal flow theory. The latter theory is in general applicable for perfectly/plastic materials. However, its kinematics equations constitute a closed-form system, which are valid for any incompressible materials, therefore enabling us to extend design solutions based on the perfectly/plastic constitutive law to more realistic laws with rate sensitive hardening behavior. In the present paper, several constitutive laws commonly accepted for the modeling of cold and hot metal forming processes are considered and the effect of these laws on one particular plane-strain design is demonstrated. The closed form solution obtained describes a non-trivial nonsteady ideal process. The design solutions based on the ideal flow theory are not unique. To achieve the uniqueness, the criterion that the plastic work required to deform the initial shape of a given class of shapes into a prescribed final shape attains its minimum is adopted. Comparison with a non-ideal process is also made.

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