Analysis of Strain Path-Dependent Damage and Microstructure Development for the Numerical Design of Sheet-Bulk Metal Forming Processes

Funding: German Research Foundation (DFG)
Project: CRC/TR 73 • Subproject C4
Contact: Florian Gutknecht M. Sc.

Sheet-Bulk Metal Forming (SBMF) enables the near-net-shape production of components directly from sheet metal.

The extent to which an increased strain rate, e.g. in case of sudden overload, has an influence on failure in service was investigated on a gear wheel manufactured by BMU (see Figure a). To this end, a test rig was developed by the Institute for Materials Science (IW) at Leibniz Universität Hannover to test the strength of the gearing at peripheral speeds of 0.012 mm/s and 25 mm/s (see Figure b). Numerically, the plastic behavior was represented with the Johnson-Cook approach and the damage development with a criterion according to Lemaitre. The numerical and microscopic investigations have shown that, regardless of the speed, the component fails at the same position and in the same way (see Figures c and d). At increased speed, however, the damage in the component is about 25% higher, although the plastic strains are almost identical.

a) Gear wheel, b) Test rig for gear wheel, c) Simulation result, d) Microscopic investigation