COMPARISON OF THE FORMING - LIMIT DIAGRAM (FLD) MODELS FOR DRAWING QUALITY (DQ) STEEL SHEETS

In this paper a comparative investigation of three mathematical models (Marciniak-Kuczynski model, Hill-Swift model and Sing-Rao model) as well as an empirical model proposed by the North American Deep Drawing Research Group (NADDRG) has been carried out. The yield criterion (1993), recently proposed by Hill, is used for the calculation of the limit strains in connection with the Swift's instability condition for diffuse necking and with the Marciniak-Kuczynski analysis. The emphasis of this investigation is to consider these different approaches to predicting the FLD. Experimental results have been obtained for different low carbon steel sheets of drawing quality - FeP06 G and ZStE 220P as well as rephosphorised and micro-alloyed steel. It was compared, which theoretical model showing good correlation with experiment is suitable for materials mentioned above.