Springback prediction for rotary-draw bending of rectangular H96 tube based on isotropic, mixed and Yoshida–Uemori two-surface hardening models

Abstract

Based on the isotropic-hardening model, mixed-hardening model and Yoshida–Uemori two-surface model, the accuracy of springback prediction, such as section sag after springback, springback radius and springback angles, is researched for rotary-draw bending of thin-walled rectangular H96 tube to achieve a high precision of springback prediction. The material parameters of the three hardening models are obtained from the tensile and tension–compression tests of rectangular H96 tube specimen. The results show that, due to the tube undergoes reverse loading path in the bending process, and the Yoshida–Uemori model can well describe the transient Bauschinger effect and permanent softening of reverse loading, the Yoshida–Uemori model is more suitable for springback angle prediction than the other two hardening models, especially for the springback prediction with large deformation. Its average error is only 5.18%. The Yoshida–Uemori model also performs better on the prediction of section sag after springback, but the advantage is not obvious, and all of the three hardening models can accurately predict the springback radius with the average errors even smaller than 2.60%. It is also found the occurrence of tube reverse loading depends on the mandrel die, so if the tube is filled by the PVC mandrel, the three hardening models almost obtain the same prediction results; the filler of the tube determines whether the Yoshida–Uemori model should be considered.