Damage in Sheet Metal Bending of Lightweight Profiles

Funding: German Research Foundation (DFG)
Project: SFB/TRR188 • Subproject A05
Contact: Rickmer Meya M. Sc.

Profiles made of high-strength and ultra-high-strength steel materials are often produced by classic bending processes such as air and die bending.

Characteristic for these bending processes is the inhomogeneous plastic strain distribution over the sheet thickness. The performance of bent components in use is determined by the strain hardening, the residual stresses, and the damage evolution. Damage develops at the outer tensile fibers depending on the loading condition during the plastic deformation. In order to influence the load path during bending, stress superposition must be used since conventional process parameters do not lead to a change in the stress state. For compressive stress superposition during bending a new bending process is being developed. The so-called bending with radial stress superposition (RSS bending) is able to initiate predetermined and controlled compressive stresses during bending. This leads to a delayed damage development (see figure) and, thus, to increased performance.

 

 

Influence of RSS bending on the damage evolution