Investigation of Thick Sheet AHSS Springback in Combined Bending under Tension

This contribution investigates the springback behavior of several advanced high-strength sheet steels (TRIP, Dual-Phase, ferrite-bainite) with thicknesses up to 4 mm. Samples were tested by means of the bending-under-tension (BUT) test. This test proved very useful to discriminate constitutive models, while avoiding the interference of friction in the springback investigations [1,2]. However, the interpretation and numerical simulation of the test have to be carefully performed [3,4]. The applicability of several guidelines from the literature was investigated experimentally and numerically, in the context of thick AHS sheets. The monotonic decrease of springback as back force increased was confirmed for this category of sheet steels, and a general trend for the non-linear influence of the tool radius was observed. The influence of numerical factors on the predicted values of springback was investigated. Conclusions and simple guidelines are drawn from the analysis with industrial sheet forming applications in mind. References [1] T. Kuwabara, S. Takahashi, K. Akiyama, Y. Miyashita, SAE Technical paper 950691 (1995) 1-10. [2] I.N. Vladimirov, M.P. Pietryga, S. Reese, Prediction of springback in sheet forming by a new finite strain model with nonlinear kinematic and isotropic hardening, Journal of Materials Processing Technology 209 (2009) 4062-4075. [3] W.D. Carden, L.M. Geng, D.K. Matlock, R.H. Wagoner, Measurement of springback, International Journal of Mechanical Sciences 44 (2002) 79-101. [4] K.P. Li, W.P. Carden, R.H. Wagoner, Simulation of springback, International Journal of Mechanical Sciences 44 (2002) 103-122.