Prediction of the forming limit curves using GTN damage model
Keywords:sheet metals, GTN damage model, formability, anisotropy
In this paper, the forming limit curve of an AA6016-T4 sheet metal is constructed using Gurson-Tvergaard-Needleman (GTN), Marciniak-Kuczynski (M-K) and Modified Maximum Force Criterion (MMFC) models. The mechanical behavior of the matrix material is described using Hill’48 quadratic yield criterion and an isotropic hardening rule. The accuracy of the predicted forming limit curves is checked by comparison with an experimental forming limit curve. The forming limit curve obtained by the anisotropic GTN damage model is in better agreement with the experimental results especially in the biaxial tension region. While the M–K model predicts the left branch of the forming limit curve with high accuracy, it provides poor results with high overestimation along right branch of the forming limit curve. Also, the MMFC model overestimates the forming limits. These results indicate that the GTN model is a useful tool in analyzing the formability of anisotropic sheet metals.
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