Implicit elastoplastic finite element analysis of tube-bending with an emphasis on springback prediction

Implicit elastoplastic finite element (FE) analyses of rotary draw tube bending (RDTB) with a ball-and-socket-type mandrel were conducted with an emphasis on accurate prediction of bent tube springback. A multi-body treatment was employed to deal with the moving mandrel assembly as deformable bodies. Tetrahedral MINI-element mesh system was implemented for easy and flexible FE modeling of the RDTB system and its related theory and formulation were given. Numerical effects were investigated using various FE mesh systems with different numbers of tetrahedrons and different mesh densities, revealing the robustness and prediction accuracy of the model. It has also been shown that the number of FE mesh layers in the major deforming region does not give much effect on the springback prediction of the bent tube in RDTB. The predicted springback was also compared to the experimental data and other analytical and numerical predictions, revealing that the present method has acceptable accuracy with low percentage errors in predicting the springback.