Forming Limit Diagram Prediction of AISI 304–St 12 Tailor Welded Blanks Using GTN Damage Model

Abstract

Abstract Because of weight and manufacturing cost decrease, tailor welded blanks (TWBs) have great usage in different industries such as the automotive and aircraft industries. Despite the wide use of TWBs in various industries, there are some drawbacks in the formability of these blanks. Using a forming limit diagram (FLD) enables one to prevent necking and fracture of these blanks by correct selection of forming parameters. There are different numerical methods to predict the FLD of sheet metals, but the Gurson–Tvergaard–Needleman (GTN) model is a useful ductile fracture model in this field. In this study, the GTN model was used for FLD prediction of AISI 304–St 12 TWBs. An anti-inference method and a numerical simulation of the tensile test by ABAQUS software (Dassault Systèmes, Vélizy-Villacoublay, France) were firstly used for GTN parameter identification of AISI 304 and St 12 blanks. Proper parameters of the GTN model were imported to the numerical tests of FLD, which was done based on the Nakazima standard test. In the experimental part of this study, carbon dioxide laser welding was used for TWBs welding, which consists of AISI 304 and St 12 blanks with equal thicknesses of 1 mm. The numerical results were compared for FLD prediction, punch’s load-displacement curve, and the fracture position of samples with experimental ones. The results showed that there was a good agreement between the numerical prediction and the experimental results.