Papers by Keyword: Non Quadratic Anisotropic Yield Functions

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Authors: Won Oh Lee, Dae Yong Kim, June Hyung Kim, Kwan Soo Chung, Seung Hyun Hong
Abstract: Formability and springback of the automotive aluminum alloy sheet, 6K21-T4, in the sheet forming process were numerically investigated utilizing the combined isotropic-kinematic hardening law based on the modified Chaboche model. To account for the anisotropic plastic behavior, the non-quadratic anisotropic yield stress potential, Yld2004-18p was considered. In order to characterize the mechanical properties, uni-axial tension tests were performed for the anisotropic yielding and hardening behavior, while uni-axial tension/compression tests were performed for the Bauschinger and transient behavior. The Erichsen test was carried out to partially obtain forming limit strains and FLD was also calculated based on the M-K theory to complete the FLD. The failure location during simulation was determined by comparing strains with FLD strains. For verification purposes, the automotive hood outer panel was stamped in real. After forming, the amount of draw-in, thinning and springback were measured and compared with numerical simulation results.
Authors: Han Sun Ryou, Myoung Gyu Lee, Chong Min Kim, Kwan Soo Chung
Abstract: Crash simulations were performed for automotive sheets. To understand the influence of crystal structures in sheet materials on crashworthiness, the effect of the yield function shape was studied by adopting the recently developed non-quadratic anisotropic yield surface, Yld2004-18p. The effect of the back-stress was also investigated by comparing simulation results obtained for the isotropic, kinematic and combined isotropic-kinematic hardening laws based on the modified Chaboche model. In addition, the effects of anisotropy and sheet thickness on crashworthiness were evaluated.
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