TY - GEN
T1 - Effect of anisotropic yield function evolution on formability of sheet metal
AU - Choi, H. J.
AU - Choi, Y.
AU - Lee, Kyoung Jin
AU - Lee, J. Y.
AU - Bandyopadhyay, K.
AU - Lee, M. G.
N1 - Funding Information:
All authors appreciate the support from POSCO. MGL appreciates partial supports by the National Research Foundation of Korea (NRF) Grant funded by Korean government (NRF-2012R1A5A1048294) and (NRF-2014R1A2A2A11052889).
Publisher Copyright:
© 2017 Author(s).
PY - 2017/10/16
Y1 - 2017/10/16
N2 - For the evaluation of anisotropic yield functions and hardening models, formability has been often investigated in the forming of sheet metals. The formability has been investigated in many ways, but a common conclusion is that it is significantly influenced by sheet anisotropy, especially the directional differences in yield stress and r-value along the material direction. Therefore, numerous works have been presented in terms of the accurate modeling of anisotropic behavior of sheet metals and its implementation into the finite element simulations. The previous efforts include the effects of quadratic or non-quadratic yield functions, their associated or non-associated flow rules and isotropic or non-isotropic hardening laws on formability. However, most of these works assumed that the anisotropic yield functions maintain their initial shapes, while they evolve by isotropic expansion or kinematic translation. Then, they could not consider the anisotropic evolution under monotonic loading with different deformation modes. In the present work, various anisotropic constitutive models were comparatively evaluated for the performance in predicting the earing profile in the cup drawing and the forming limit diagram. The constitutive models include the Hill48 quadratic yield function with associated and non-associated flow rules, and the non-quadratic Yld2000-2d function with associated flow rule. For both yield functions, the evolution of anisotropy was employed by considering the anisotropic coefficients as a function of equivalent plastic strain. The influence of the anisotropy evolution was comparatively evaluated by the computational simulations.
AB - For the evaluation of anisotropic yield functions and hardening models, formability has been often investigated in the forming of sheet metals. The formability has been investigated in many ways, but a common conclusion is that it is significantly influenced by sheet anisotropy, especially the directional differences in yield stress and r-value along the material direction. Therefore, numerous works have been presented in terms of the accurate modeling of anisotropic behavior of sheet metals and its implementation into the finite element simulations. The previous efforts include the effects of quadratic or non-quadratic yield functions, their associated or non-associated flow rules and isotropic or non-isotropic hardening laws on formability. However, most of these works assumed that the anisotropic yield functions maintain their initial shapes, while they evolve by isotropic expansion or kinematic translation. Then, they could not consider the anisotropic evolution under monotonic loading with different deformation modes. In the present work, various anisotropic constitutive models were comparatively evaluated for the performance in predicting the earing profile in the cup drawing and the forming limit diagram. The constitutive models include the Hill48 quadratic yield function with associated and non-associated flow rules, and the non-quadratic Yld2000-2d function with associated flow rule. For both yield functions, the evolution of anisotropy was employed by considering the anisotropic coefficients as a function of equivalent plastic strain. The influence of the anisotropy evolution was comparatively evaluated by the computational simulations.
UR - http://www.scopus.com/inward/record.url?scp=85037674184&partnerID=8YFLogxK
U2 - 10.1063/1.5007980
DO - 10.1063/1.5007980
M3 - Conference contribution
AN - SCOPUS:85037674184
T3 - AIP Conference Proceedings
BT - Proceedings of the 20th International ESAFORM Conference on Material Forming, ESAFORM 2017
A2 - Brabazon, Dermot
A2 - Ul Ahad, Inam
A2 - Naher, Sumsun
PB - American Institute of Physics Inc.
T2 - 20th International ESAFORM Conference on Material Forming, ESAFORM 2017
Y2 - 26 April 2017 through 28 April 2017
ER -