Numerical research on springback law of tension-compression yield asymmetry sheet in multi-point forming

Abstract

Springback of SUS430/AA1050/TA1 (SAT) laminated sheet in multi-point forming (MPF) is difficult to predict due to its complex microstructure. In this work, the polycrystalline texture and crystal structure of the three materials were measured firstly by electron backscatter diffraction (EBSD). Crystal plasticity finite element method (CPFEM) considering twinning and slip was used to predict the anisotropy and tension-compression yield asymmetry (TCYA) of the materials. The data obtained by virtual simulation are validated and used to calibrate the phenomenological yield criteria. In the springback prediction model, the three materials were modeled using the layered modeling method. The anisotropic yield criteria were implemented into finite element software ABAQUS via a user-defined material subroutine VUMAT to fully consider the anisotropy of the SAT laminated sheet. The comparison between the forming experiment and simulation results shows that the model can predict the springback accurately. Finally, the effect of plastic deformation, strain path, and TA1 layer thickness on springback were discussed.

Component specific elastic cushion design to enhance the accuracy with the usage of reconfigurable tools in stretch forming

“…2,4,6 Reconfigurable die consists of discrete pins, and each pin is adjustable to desired height based on the component geometry. 4,6,10 An elastic cushion (Figure 1(b)) is placed between the sheet metal and pin heads to avoid direct contact between them, thereby reducing the possibility of dimple formation on the formed components. The reconfigurable tooling concept was started by Nakajima, 11 and a considerable amount of work has been carried out by Hardt et al 4,12–14 on the mechanical design of pins.…”