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Description
Abstract: Uncoupled ductile fracture models have gained popularity for accurate prediction of fracture in ductile metallic sheets due to their ease of implementation. Accurate description of anisotropic fracture behavior is an active research field for sheet metal forming. In the present study, three isotropic ductile fracture models, i.e., modified Mohr-Coulomb, Hosford-Coulomb and DF2016 model are evaluated for an O-tempered aluminum alloy (AA1050-O) sheet. The plastic anisotropy is modeled with a non-associated Hill48 plasticity model. In order to verify the models, experiments are conducted for a 1.2 mm thick AA1050-O sheet under various loading conditions, such as uniaxial tension, in-plane shear, and plane strain tension at room temperature. For evaluating the anisotropic ductile fracture, tensile tests are carried out in 15° intervals to the rolling direction using digital image correlation technique. The experimental results show that loading histories of low to mid-range stress triaxialities show larger anisotropy in fractured displacements, as shown by in-plane shear and uniaxial tension tests, than high range stress triaxialities as shown by notch tests. The predicted fracture limit strains by the three uncoupled fracture models are compared with experimental results to evaluate the accuracy of these models.
Keywords: Ductile fracture, Stress triaxiality, Lode angle, Uncoupled damage model, anisotropy