A comparative study of forming limit diagram prediction of tailor welded blanks

The Forming Limit Diagram (FLD) is a useful method for characterizing the formability of sheet metals. In this paper, different numerical models were used to investigate the FLD of Tailor Welded Blanks (TWB). TWB were CO₂ laser-welded of interstitial-free (IF) steel sheets with difference in thickness. Numerical approaches of Müschenborn-Sonne Forming Limit Diagram (MSFLD), Forming Limit Diagram criterion (FLDcrt) and Ductile Fracture Criterion (DFCcrt), as well as new numerical method of Second Derivative of Thinning (SDT) were used for FLD prediction. The results of numerical models were compared with the experimental FLD, Limit Dome Height (LDH) and also load–displacement of samples. The emphasis of this investigation is to determine the performance of these different approaches in predicting the FLD. Results show that previous approaches are successful for the left side of FLD (drawing), but not so successful for the right side of the FLD (stretching). Influence of anisotropy on the forming behavior of TWB is investigated in this study and its results are compared with isotropic models and experimental data.