Papers by Author: Liana Paraianu

Abstract: The accuracy of the forming limit curves reported by the Marciniak-Kuczynski model as well as the quality of the predictions provided by the FE programs depend on the yield criterion that describes the anisotropic plastic behavior of the sheet metal. Two identification procedures of Barlat89 and BBC2005 are used in this paper. The first procedure is a conventional one well described in the literature [, while the second approach is developed by adding an experimental parameter determined in plane-strain state that allows establishing the exponent of the yield criteria. The mechanical response of the IF steel shows that the limit strains are strongly influenced by a small alteration of the yield surface. The influence of the yield criterion on the thickness predictions obtained in the simulation of a square cup deep drawing simulation is also studied.

Abstract: The accuracy of the forming limit curves predicted by the Marciniak-Kuczynski model depends on the type and flexibility of the constitutive equations used to describe the mechanical response of the sheet metal. From this point of view, the yield criterion has the most significant influence. The paper presents a comparative analysis referring to the quality of the forming limit curves predicted by the Marciniak-Kuczynski model for the case when the plastic anisotropy of a DC04 sheet metal is described by the BBC2005 yield criterion. The coefficients included in the expression of the BBC2005 equivalent stress are evaluated using different identification strategies (with 4, 6, 7, and 8 mechanical parameters). The forming limit curves predicted by the Marciniak-Kuczynski model in each of the cases previously mentioned are compared with experimental data.