Stress State Control by a Novel Bending Process and its Effect on Damage Evolution

The novel sheet metal bending process is designed to change the load path in order to control the damage evolution. The process superposes targeted radial stresses during bending and is therefore called radial stress superposed bending, short RSS-bending. As material damage is strongly dependent on the load path, the setting of this property becomes possible in this process. Hence, the process principle, its features and the tool setup are presented. Furthermore, numerical simulations are carried out with the aim to investigate the occurring deformation zone and the resulting radial stress superposition. Scanning electron micrographs prove that the evolution of voids is delayed. With the acquired knowledge to change the stress state during the bending process, the property ‘damage’ can be controlled and finally reduced. This enhances the microstructure and lifetime performance of the bent product.