Sheet Metal Forming Limit Predictions Based on Advanced Constitutive Equations

The present paper aims at analysing the strain and stress–based forming limits predicted by an advanced sheet metal forming limit model. The onset of localized necking is simulated through the Marciniak-Kuczinsky (MK ) analysis [1]., which connects the physically-based hardening model accounting for the evolution of the anisotropic work-hardening induced by the microstructural evolution at large strains of Teodosiu and Hu [2] with the phenomenological anisotropic yield criterion Yld2000-2d (Barlat et al., 2003) [3] Linear and complex strain paths are taken into account. The selected material is a DC06 steel sheet. The validity of the model is assessed by comparing the predicted and experimental forming limits. The remarkable accuracy of the developed software on predicting the forming limits is obviously due to the performance of the advanced constitutive equations applied on M-K theory, able to describe with great detail the material behaviour. The effect of the strain-induced anisotropy predicted by the microstructural hardening model on the evolution of formability under strain path changes is particularly aimed it.