Finite Element Analysis of Size Effect for Forming-Limit Curves

Nowadays, finite element (FE) methods are widely used for the analysis of Body in White parts production. An FE software applies the forming-limit diagram to predict the failure of the sheet metal. There are many new materials for weight reduction; for these new materials, the determination of forming-limit curves (FLC) is important to studying formability issues. There are some cases where the available material for the measurements is not enough or due to some specific measurement parameter, the standard test specimen cannot be used. In these cases, the geometry of the test pieces and the testing equipment should be reduced. In this paper, the material card for DC05 (1.0312) steel was determined based on a tensile test and the Nakajima test. With the material card, simulations were performed to investigate the size effect of the hemispherical punch used for Nakajima forming method. Based on the simulations, the difference between the FLC-s (determined with different equipment) was found to be negligible