A numerical and experimental investigation of temperature effects on the formability of AA6063 sheets using different ductile fracture criteria

Abstract

In this study, different ductile fracture criteria, such as Ayada, Equivalent plastic strain (PEEQ), Brozzo, Rice, Freudenthal, Cockroft–Latham, and Normalized Cockroft–Latham, were considered to predict the formability of AA6063 aluminum alloy sheets. The forming limit diagram (FLD) of the aluminum sheet was obtained through experimental testing; then, it was compared with the results obtained by predicting various fracture criteria (numerical results). Moreover, the effects of temperature (25 °C or room temperature and 200 °C) and lubrication (Vaseline and PTFE) on the formability were investigated. The results indicated that the Ayada criterion was more consistent with the experimental results compared to the other mentioned criteria. The consistency in the right side of diagram was not as good as that in the left side. Therefore, in predicting the FLD, according to the accuracy of the obtained results, the Ayada ductile fracture criterion was used for the left side of the FLD. In addition, both experimental and numerical results illustrated that, with the increase in the temperature, the FLD moved upward and depending on the increased temperature, the forming force also decreased.