Recent developments in finite element simulations of the deep drawing process

Some new developments in a finite element code for the deep drawing process are presented\ud in this paper. First the phenomenon of friction is treated. A Stribeck friction model has been\ud developed which accounts for the dependency of the friction coefficient on the local contact\ud conditions. Secondly a new yield criterion has been developed by Vegter. This Vegter yield\ud criterion is based on multi-axial stress states. Finally attention will be paid to reduce the CPUtime\ud of a simulation when drawbeads are used. An equivalent drawbead model has been\ud developed to avoid an enormous increase in calculation time

The implementation of the vegter yield criterion and a physically based hardening rule in finite elements

A new material description for sheet metal forming using Finite Elements has been developed. The description consists of a yield criterion and a hardening rule. In contrast to most former criteria the new criterion is based on multi-axial stress states. The yield criterion is extended with a physically based hardening rule, in which the flow stress depends on the strain and strain rate. A Limiting Dome Height test is used to examine the material description