Fracture Forming Limit Curve Prediction by Ductile Fracture Models T. A. Akşen1,∗, B. Şener2, E. Esener3, Ü. Kocabıçak4, M. Fırat4 1 Department of Mechanical Engineering, The University of Sakarya, Sakarya 54050, Turkey 2 Department of Mechanical Engineering, Yildiz Technical University, Istanbul 34349 Turkey 3 Department of Mechanical Engineering, Bilecik Şeyh Edebali University, Bilecik 11210, Turkey 4 Department of Computer Engineering, The University of Sakarya, Sakarya 54050, Turkey ∗ ardaaksen@sakarya.edu.tr Keywords: Ductile fracture model, Fracture locus, Forming limit curve. The fracture forming limit curve is an essential tool giving information about fracture initiation in metal forming applications. In order to obtain a fracture-forming limit curve, the Nakajima test should be carried out. However, these tests are costly and time-consuming processes. Therefore, companies in the automotive industry tended to use non-expensive numerical approaches to determine the material’s formability limits. In this work, an anisotropic polynomial yield criterion was implemented to calibrate the different ductile fracture models, including only or both the stress triaxiality and the Lode parameter’s effect. Analyses of different uniaxial tensile test geometries were carried out, and the two-dimensional fracture loci were constructed by different ductile fracture models. Correspondingly, the fractureforming limit curves were predicted by the two-dimensional fracture loci. The results showed that the ductile fracture models, including only the stress triaxiality effect, provide an acceptable performance covering the range from uniaxial tension and the plane strain tension lines, while the models, including the stress triaxiality and Lode parameter, provide a plausible prediction performance throughout the whole range for forming limit diagram. 121
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