Stress and strain histories of multiple bending-unbending springback process

A drawbead model with sheet metal passing through multiple bending-unbendin g processes was employed in this study to understand the springback phenome non and to develop a numerical simulation technique for more accurate predi ction of the springback process. The deformation process is simulated using an implicit finite element modeling code. The predicted results were compa red with the physically measured ones, including clamping and restraining f orces, thickness strains, and the curvatures of the deformed sheets. Consid eration of the Bauschinger effect and employment of a combined isotropic an d kinematic hardening models greatly improve the prediction accuracy. Stres s and strain histories under various conditions during the drawing process are studied in detail in an attempt to provide a better basis for compariso n for dynamic explicit solutions.