Application of ductile fracture criterion to manufacture of aluminium liner by drawing and ironing processes

Abstract

In order to manufacture a long cylinder to be used as a seamless aluminium liner using a four‐stage deep drawing process followed by a two‐stage ironing process, finite element simulations based on the normalised Cockroft‐Latham ductile fracture criterion and experimental studies were carried out. The critical damage value indicating fracture initiation during the forming process was obtained from comparison of simulation and experimental results of tensile tests. Since the strain‐hardening of the material continuously increases during deep drawing and ironing processes, annealing of the strain‐hardened material should be done to relieve the stress and to reduce the material flow resistance. For this, finite element simulation was carried out to investigate the effect of annealing treatment on ductile fracture. The optimum taper angle of the ironing die was also investigated to minimise the damage value and to eliminate the possibility of fracture generation during ironing processes.

Keywords:

• Aluminium liner
• Deep drawing and ironing
• Ductile fracture
• Optimum die design
• FE analysis

This work was supported by the Technology Innovation Program (Project No. S1058689) funded by the Ministry of Knowledge Economy (MKE, Korea).