Possibilities, Challenges and Risks in Creating Material Cards for Forming Simulations

Abstract

The fit of complex yield locus models with different experiments is often not unique and the quality of modeling can not be derived directly. To overcome this problem a set of simple material tests are proposed, one is discussed in detail. This test allows the individual estimation how realistic yield locus results are and is also adequate to calibrate the free yield locus exponent. The in literature given exponent of M=6.0 for steels can not be confirmed here. Better is a range of M=4.5 to M=5.0 in combination with a strain rate depending material hardening for some steels, but not in general. With the help of an optimization strategy in combination with an inverse model calibration the yield locus exponent, friction and material hardening are automatically determined for a mild steel grade. Finally the results of the validation experiments are confirmed in a study for a side wall frame produced with the same material grade.