The performance of Yld96 and BBC2000 yield functions in forming limit prediction

The objective of the work presented here is to assess the performance of two non-quadratic yield functions for orthotropic sheet metals under plane stress conditions, namely Yld96 and BBC2000, on forming limit prediction. The similitude and the differences between both of them are discussed. The Newton–Raphson numerical method respectively the minimisation of an error-function has been used for the numerical identification of the Yld96 and BBC2000 coefficients. The necking phenomenon was modelled by using the Marciniack–Kuczinsky (M–K) theory. In the present study an aluminium alloy sheet metal AA5XXX is considered. Yield surface shapes, yield stress and r-value directionalities of Yld96 and BBC2000 were investigated and compared with the experimental data. A successful correlation is observed between the experimental FLDs and the computed limit strains when, the shape of yield locus is described by Yld96 criterion respectively BBC2000 criterion and the hardening law represented by Voce equation.