• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.60-63
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• 2007

The effect of process parameters on springback of AZ31B magnesium alloy sheet was investigated by performing 2D draw bending test at the elevated temperatures. And also the springback characteristics were studied different blank holding forces between 30 to 250 kgf. Springback was considerably reduced at higher temperatures than $200^{\circ}C$. The blank holding force in the range used, however, had little influence on springback in isothermal tests. For a given temperature, springback decreased with increasing blank holding force in non-isothermal tests.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.304-307
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• 2008

In order to evaluate the effect of permanent softening behavior on springback prediction, 2D-draw bending simulations were compared with experiments for friction stir welded DP590 steel sheets. To account fur the nonlinear hardening behavior, the combined isotropic-kinematic hardening law was utilized with and without considering the permanent softening behavior during reverse loading. Also, the non-quadratic orthotropic yield function, Yld2000-2d, was used to describe the anisotropic initial-yielding behavior of the base sheet while anisotropic properties of the weld zone were ignored for simplicity.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.329-335
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• 2009

In order to better predict the springback for friction stir welded DP590 steel sheet, the combined isotropic-kinematic hardening was formulated with considering the permanent softening behavior during reverse loading. As for yield function, the non-quadratic anisotropic yield function, Yld2000-2d, was used under plane stress condition. For the verification purposes, comparisons of simulation and experiments were performed here for the unconstrained cylindrical bending, the 2-D draw bending tests. For two applications, simulations showed good agreements with experiments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.330-333
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• 2009

The time-dependent constitutive law was developed based on viscoelastic-plasticity to describe the time-dependent spring-back behavior of aluminum alloy 6022-T4 sheets. Besides nonlinear viscoelasticity, non-quadratic anisotropic yield function, Yld2000-2d, was used to account for the anisotropic yield behavior, while the combined isotropic-kinematic hardening law was used to represent the Bauschinger effect and transient hardening. For verification purposes, finite element simulations were performed for the draw-bending and the results were compared with experimental results.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.494-499
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• 2009

The time-dependent constitutive law was utilized based on viscoelastic-plasticity to predict the time-dependent spring-back behavior of aluminum alloy 6022-T4 sheets. Besides nonlinear viscoelasticity, non-quadratic anisotropic yield function, Yld2000-2d, was used to account for the anisotropic yield behavior, while the combined isotropic-kinematic hardening law was used to represent the Bauschinger effect and transient hardening. For verification purposes, finite element simulations were performed for the draw-bending and the results were compared with experimental results.