Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 9 2024 11 21 The effect of negative stress triaxiality and lode angle on ductile fracture of ST-37 The effect of negative stress triaxiality and lode angle on ductile fracture of ST-37 1303 1326 5677 10.22060/mej.2025.23401.7756 FA Mohsen Mansouri Mechanical Engineeringو University of Tehran Mehdi Ganjiani Faculty of Mechanical Engineering, University of Tehran 0000-0001-9839-7795 Journal Article 2024 08 01 In this article, the effect of negative stress triaxiality on the fracture strain has been studied. First, the geometric model was obtained for samples with three negative stress triaxialities. To obtain negative stress triaxialities in the uniaxial compression test, the geometry of samples was designed somehow that prevent multiaxial tests. Samples were manufactured from ST-37 steel. Then tensile and compression tests were performed on them in order to obtain the fracture strain. Tensile and compression tests were simulated by Abaqus software. The digital image correlation method was used to obtain the strain values and validate the simulation results. The shape and damage mode of different samples were compared after the test and simulation in which the mode of fracture was the same in both methods. The strain contours of the finite element method and digital image correlation were compared and it was observed that the strain values of both methods match each other. The fracture strains were depicted in terms of stress triaxialities, the normalized Lode angle, and the third invariant. In both experimental and numerical methods, by decreasing the amount of negative stress triaxiality, the amount of fracture strain first decreases and then increases. In this article, the effect of negative stress triaxiality on the fracture strain has been studied. First, the geometric model was obtained for samples with three negative stress triaxialities. To obtain negative stress triaxialities in the uniaxial compression test, the geometry of samples was designed somehow that prevent multiaxial tests. Samples were manufactured from ST-37 steel. Then tensile and compression tests were performed on them in order to obtain the fracture strain. Tensile and compression tests were simulated by Abaqus software. The digital image correlation method was used to obtain the strain values and validate the simulation results. The shape and damage mode of different samples were compared after the test and simulation in which the mode of fracture was the same in both methods. The strain contours of the finite element method and digital image correlation were compared and it was observed that the strain values of both methods match each other. The fracture strains were depicted in terms of stress triaxialities, the normalized Lode angle, and the third invariant. In both experimental and numerical methods, by decreasing the amount of negative stress triaxiality, the amount of fracture strain first decreases and then increases. https://mej.aut.ac.ir/article_5677_cca8f108b55ec9e39d7885e24f7da0af.pdf