Numerical simulation of sheet metal forming using anisotropic strain-rate potentials

For numerical simulation of sheet metal forming, more and more advanced phenomenological functions are used to model the anisotropic yielding. The latter can be described by an adjustment of the coefficients of the yield function or the strain-rate potential to the polycrystalline yield surface determined using crystal plasticity and X-ray measurements. Several strain-rate potentials were examined by the present authors and compared in order to analyze their ability to model the anisotropic behavior of materials using the methods described above to determine the material parameters. Following that, a specific elastic-plastic time integration scheme was developed and the strain-rate potentials were implemented in the FE code. Comparison of the previously investigated potentials is continued in this paper in terms of numerical predictions of cup drawing, for different b.c.c. and f.c.c. materials. The identification procedure is shown to have an important impact on the accuracy of the FE predictions.