Prediction of Forming Limit in Axisymmetric Deep Drawing of Steel/Aluminium Alloy Laminated Sheets Using a Simple Criterion for Ductile Fracture

摘要

Deep drawing processes of laminated sheets composed of mild steel and various aluminium alloy sheets are simulated by the rigid-plastic finite-element method. From the stress and strain histories of elements in each layer calculated by the finite-element simulation, the fracture initiation site and the forming limit are predicted using the ductile fracture criterion. The predictions so obtained are compared with experimental observations. The results show that the ductile fracture criterion is useful to predict fracture initiation in forming of laminated composite sheets. Furthermore it is found that the drawability is improved by setting the mild steel sheet on the punch side for the case of aluminium alloy sheet with comparatively high ductility, and by sandwiching the aluminium alloy sheet with the mild steel sheets for the case of low ductility.