Parameters Determination of GTN Model and Damage Analysis of Aluminum Alloy 6016 Sheet Metal

Taking the material of AA6016 (Aluminum Alloy 6016) which is widely used in automobiles as the object of this study, the mechanical properties based on GTN (Gurson-Tvergaard-Needleman) model had been investigated. The parameters of the GTN model which were used for simulation were identified by uni-axial tensile test, parameter fitting and the inverse finite element method. Then, the simulation of the uni-axial tensile test was done by developing subroutine of UMAT (User-Defined Material) based on LS-DYNA. The results show that the damage and fracture of AA6016 have good agreements with the experiment. Further, the influences of different damage parameters f(0) and f(n) on the mechanical properties were investigated, which verifies the rationality of the GTN parameters. It is of interest that in the results of both simulation and experiment, the direction of fracture on the plate tensile specimen is 60 degrees, instead of the 45 degrees or 90 degrees obtained in previous literatures.