Earing predictions for strongly textured aluminum sheets

Yoon, Jonghun; Cazacu, Oana; Yoon, Jeong Whan; Dick, Robert E.

doi:10.1016/j.ijmecsci.2010.07.005

Cited by 72 publications

(26 citation statements)

References 34 publications

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“…Figure 3 shows the yield surface associated with equivalent strain increment of 0.02 predicted by the new anisotropic and isotropic hardening model. As expected, results showed the better agreement between the experiments [9] and the new anisotropic hardening model compared with conventional isotropic hardening model. …”

Section: Scheme Of Stress Integration Proceduressupporting

confidence: 75%

A numerical scheme of convex yield function with continuous anisotropic hardening based on non-associated flow rule in FE analysis of sheet metal

Liu¹,

Chen²

2018

J. Phys.: Conf. Ser.

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Section: Scheme Of Stress Integration Proceduressupporting

confidence: 75%

A numerical scheme of convex yield function with continuous anisotropic hardening based on non-associated flow rule in FE analysis of sheet metal

Liu¹,

Chen²

2018

J. Phys.: Conf. Ser.

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“…Thus, only the anisotropy coefficients corresponding to a converged state were calculated. Further details concerning the integration algorithm can be found in Yoon et al (2010). It is shown that even if anisotropy evolution is neglected, this yield function predicts a cup with eight ears as was observed experimentally.…”

Section: Resultsmentioning

confidence: 62%

New distortional hardening model capable of predicting eight ears for textured aluminum sheet

Yoon¹,

Cazacu²,

Yoon³

et al. 2011

AIP Conference Proceedings

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The effects of the anisotropy evolution and of the directionality in hardening on the predictions of the earing profile of a strongly textured aluminum alloy are investigated using a new distortional hardening model that incorporates multiple hardening curves corresponding to uniaxial tension along several orientations with respect to the rolling direction, and to biaxial tension. Yielding is described using a form of CPB06ex2 yield function (Plunkett et al. (2008)) which is tailored for metals with no tension-compression asymmetry. It is shown that even if directional hardening and its evolution are neglected, this yield function predicts a cup with eight ears as was observed experimentally. However, directional hardening can be of considerable importance for improved accuracy in prediction of the non-uniformity of the cup height profile.

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“…Also, it is emphasized that in the most published studies mentioned above, the CPB06 yield function was reduced to 2-D stress states with shell elements (e.g., [11,21,48]), whereas the current implementation accounts for a general 3-D stress state. Shell elements are not suitable for the evaluation of local fields after the onset of necking while solids elements can provide more accurate predictions of localized deformation and through-thickness gradients of stress and strain fields.…”

Section: Implementation Into a Finite Element Codementioning

confidence: 99%

Application of an Evolving Non-Associative Anisotropic-Asymmetric Plasticity Model for a Rare-Earth Magnesium Alloy

Abedini

Butcher

Worswick

2018

Metals

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Magnesium sheet metal alloys have a hexagonal close packed (hcp) crystal structure that leads to severe evolving anisotropy and tension-compression asymmetry as a result of the activation of different deformation mechanisms (slip and twinning) that are extremely challenging to model numerically. The low density of magnesium alloys and their high specific strength relative to steel and aluminum alloys make them promising candidates for automotive light-weighting but standard phenomenological plasticity models cannot adequately capture the complex plastic response of these materials. In this study, the constitutive plastic behavior of a rare-earth magnesium alloy sheet, ZEK100 (O-temper), was considered at room temperature, under quasi-static conditions. The CPB06 yield criterion for hcp materials was employed along with a non-associative flow rule in which the yield function and plastic potential were calibrated for a range of plastic deformation levels to account for evolving anisotropy under proportional loading. The non-associative flow rule has not previously been applied to magnesium alloys which require the use of flexible constitutive models to capture the severe anisotropy and its evolution with plastic deformation. The non-associative flow rule can provide the required flexibility by decoupling the yield function and plastic potential. For the associative flow rule, such flexibility can only be achieved by multiple linear transformations of the stress tensor resulting in expensive models for calibration and simulations. The constitutive model was implemented as a user material subroutine (UMAT) within the commercial finite element software, LS-DYNA, for general 3-D stress states along with an interpolation technique to consider the evolution of anisotropy based upon the plastic work. To evaluate the accuracy of the implemented model, predictions of a single-element model were compared with the experimental results in terms of flow stresses and plastic flow directions under various proportional loading conditions and along different test directions. Finally, to assess the predictive capabilities of the model, full-scale simulations of coupon-level formability experiments were performed and compared with experimental results in terms of far-field load-displacement and local strain paths. Using these experiments, the constitutive model was evaluated across the full range of representative stress states for sheet metal forming operations. It was shown that the predictions of the model were in very good agreement with experimental data.

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Earing predictions for strongly textured aluminum sheets

Cited by 72 publications

References 34 publications

A numerical scheme of convex yield function with continuous anisotropic hardening based on non-associated flow rule in FE analysis of sheet metal

A numerical scheme of convex yield function with continuous anisotropic hardening based on non-associated flow rule in FE analysis of sheet metal

New distortional hardening model capable of predicting eight ears for textured aluminum sheet

Application of an Evolving Non-Associative Anisotropic-Asymmetric Plasticity Model for a Rare-Earth Magnesium Alloy

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