Development of a Model to Describe Springback and Residual Stresses Resulting from Bending at Elevated Temperatures

Funding: German Research Foundation (DFG)
Project: TE 508/59-1
Contact: Dr.-Ing. Christian Löbbe
Status: Completed

In order to model sheet metal bending at elevated temperatures, a process description was developed according to an experimental study.

The analysis finally reveals two different models for the two process variants air and die bending. In the air bending process a closed solution of the bending line in an isothermal state is not possible when a non-linear elasto-viscoplastic material behavior is taken into account. Thus, the derived semi-analytical approach is based on the discretization along the curved line. The figure exemplarily shows overbending and springback-ratios in relation to the Cowper-Symonds parameter c compared to the FEM simulation. In addition, the die bending process was investigated for different process parameters. For a given component geometry during coining the changing elastic, plastic, and thermal strains during cooling were covered by an analytical approach which allows a qualitative description of the springback ratio (see figure).

Analysis and description of the bending angle deviation after bending at elevated temperatures