Study on the Ductile Fracture Rule of 6061-T6 Aluminum Alloy Sheet Under Different Strain Conditions

In recent years, some ductile fracture criteria, such as Cockcroft–Latham (C–L) criterion, Brozzo criterion, Oyane criterion, and Gurson–Tveergard–Needleman (GNT) criterion, have been proposed to analyze various material damage behaviors in the plastic deformation process. However, the first three criteria do not consider the effect of shear stress on ductile fracture, and the GNT criterion is a complex structure and a high computational cost due to the consideration of micromechanics. Therefore, Mohr–Coulomb criterion (M–C) has been proposed to describe material damage behaviors with the sample structure and the consideration of shear and principal stress. In this study, the effect of the thickness and the strain rate on the fracture strain is carefully analyzed based on uniaxial tensile tests of sheet metal, and the M–C model of coupled thickness factor is established to predict the ductile fracture of various thickness and strain conditions with 6061-T6 aluminum alloy sheet. Meanwhile, the fracture process of various strain conditions is predicted based on Abaqus/Vusdfld, and the relevant rule of ductile fracture is obtained using the numerical simulation analysis of coupled fracture criterion.