Sheet springback prediction based on non-linear combined hardening rule and Barlat89’s yielding function

A stress–strain constitutive equation of non-linear combined hardening rule has been proposed in this paper according to non-linear kinematic hardening theory of Lemaitre and Chaboche and Barlat89’s yielding function. The algorithm of elastic predicting, plastic correcting and radial returning is applied to calculate the stress increment. Taking a benchmark of NUMISHEET’93 2-D draw bending problem as an example, the effects of different hardening rules and yielding functions are investigated. Comparison with NUMISHEET’93 experiment data indicates that the isotropic hardening rule over-predicts springback since the predicted stress after forming is relatively larger, while the predicted springback by non-linear combined hardening rule coincides well with experimental data. In addition to that, the study indicates that Barlat89’s and Hill48’s yielding functions describe the practical material behavior better than Mise’s yielding function, and the predicted results by Barlat89’s and Hill48’s yielding criterion are very closer to experiment data.