• Title/Summary/Keyword: Barlat's strain-rate potential

Search Result 6, Processing Time 0.028 seconds

Sectional Forming Analysis of Stamping Processes for Luminum Alloy Sheet metals (알루미늄 합금 박판 스탬핑 공정의 단면 성형 해석)

  • 이광병;이승열;금영탁
    • Transactions of Materials Processing
    • /
    • v.6 no.4
    • /
    • pp.279-290
    • /
    • 1997
  • The sectional forming analysis of stamping pocesses for aluminum alloy sheet metals was investigated. For the modeling of the anomalous behavior of aluminum alloy sheet. the Barlat's strain rate potential and Hill's 1990 non-quadratic yield theory with an isotropic hardening rule were employed. The rigid-viscoplastic FEM formulation which solves equilibrium equation for plane-strain stage with mesh-normal geometric constraints was derived. A new method to determine the Barlat's anisotropic coefficients was also suggested. To verify the validity of the formulation, the stretch and draw forming processes of a square cup were simulated.

  • PDF

Prediction of Earings in the Deep Drawing Processes of a Cylindrical Cup (원통컵 디프드로잉 공정의 귀발생 예측)

  • 이승열;이승열;금영탁;정관수;박진무
    • Transactions of Materials Processing
    • /
    • v.4 no.3
    • /
    • pp.222-232
    • /
    • 1995
  • The planar anisotripic FEM analysis for predicting earing profiles and draw-in amounts in the deep-drawing process is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vector and normal contact pressure. The consistent full set of governing relations, which is comprising euilbrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameters. The linear triangular membrane elements are used for depicting the formed sheet. In the numerical simulations of deep drawing processes of a flat-top cylindrical cup for 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.

  • PDF

Earing Predictions in the Deep-Drawing Process of Planar Anisotropic Sheet-Metal (평면 이방성 박판 딥드로잉 공정의 귀발생 예측)

  • 이승열;금영탁;정관수;박진무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 1994.03a
    • /
    • pp.118-128
    • /
    • 1994
  • The planar anisotropic FEM analysis for predicting the earing profiles and draw-in amounts in the deep-drawing processes is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vectors and the normal contact pressure. the consistent full set of governing relations, comprising equilibrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameter. The linear triangular membrane elements are used for depicting the formed sheet. with the numerical simulations of deep drawing processes of flat-top cylindrical cup for the 2090-T3 aluminum effects on the earing behavior are examined. Earing predictions made for the 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.

  • PDF

Sectonal Forming Analysis of Stamping Processes of Aluminum Alloy Sheet Metals (알루미늄 합금 박판 스탬핑 공정의 단면 성형 해석)

  • 이광병;이승열;금영탁
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 1996.10a
    • /
    • pp.38-47
    • /
    • 1996
  • Sectional analysis program for plane strain or axisymmetric geometry of aluminum alloy sheet metals was developed. For modeling the anomalous behavior of aluminum alloy, Barlat's strain rate potential and Hill's 1990 non-quadratic yield theory arranged under the plane stress assumption were employed. 2-D rigid-viscoplastic FEM formulation based on the bending-augmented membrane theory was derived, solving simultaneously force equilibrium as well as non-penetration condition. Isotropic hardening law was also assumed for yielding behavior. To verify the validity and availability of the developed program, 2-D stretch/draw forming process for plane strain geometry and cylindrical cup deep drawing process for axisymmetric geometry were simulated.

  • PDF

Non-Quadratic Anisotropic Strain Rate Potential Defined in Plane Stress State (평면 응력 조건에서 정의된 비이차 비등방 변형률 속도 포텐셜)

  • Kim, D.;Kim, J.H.;Lee, Y.S.;Barlat, Frederic;Chung, K.
    • Transactions of Materials Processing
    • /
    • v.20 no.5
    • /
    • pp.369-376
    • /
    • 2011
  • A non-quadratic anisotropic strain rate potential was introduced as a conjugate potential of the yield stress potential Yld2000-2d to describe anisotropic behavior of sheet metals, in particular, aluminum alloy sheets under plane stress state. This strain-rate potential takes into account the anisotropic yield stresses and R-values measured along the directions measured at 0, 45 and 90 degrees from the rolling direction, as well as the balanced biaxial yield stress and strain-rate ratio. The convexity of the strain-rate potential was completely proven. The strain-rate potential was applied for two anisotropic aluminum alloy sheets, AA6022-T4 and AA2090-T3. The results verified that the strain rate potential properly described the anisotropic behavior of aluminum alloy sheets and was closely conjugate of Yld2000-2d under the plane stress state.

3-D FEM Analysis of Forming Processes of Planar Anisotropic Sheet Metal (평면이방성 박판성형공정의 3차원 유한요소해석)

  • 이승열;금영탁;박진무
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.18 no.8
    • /
    • pp.2113-2122
    • /
    • 1994
  • The 3-D FEM analysis for simulating the stamping operation of planar anisotropic sheet metals with arbitrarily-shaped tools is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The consistent full set of governing relations, comprising equilibrium equation and mesh-normal geometric constraints, is appropriately linearized. The linear triangular elements are used for depicting the formed sheet, based on membrane approximation. Barlat's non-quadratic anisotropic yield criterion(strain-rate potential) is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and non-quadratic function parameter. The planar anisotropic finite element formulation is tested with the numerical simulations of the stamping of an automotive hood inner panel and the drawing of a hemispherical punch. The in-plane anisotropic effects on the formability of both mild steel and aluminum alloy sheet metals are examined.