The effect of negative stress triaxiality and Lode angle on ductile fracture of ST-37

Document Type : Research Article

Authors

1 Mechanical Engineeringو University of Tehran

2 Faculty of Mechanical Engineering, University of Tehran

Abstract

In this article, the effect of negative stress triaxiality on the fracture strain has been studied. At first, the geometric model was obtained for samples with three negative stress triaxialities from ST-37 steel. A dog-bone sample was made for positive stress triaxiality and rectangular samples with an elliptical cavity for negative stress triaxiality. Then tensile and compression tests were performed on them in order to obtain the fracture strain. Tensile and compression tests were simulated by Abaqus finite element software. In addition to the tensile testing machine results, 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. To investigate the effect of negative stress triaxiality, the fracture strain values obtained from experimental tests and numerical simulations were drawn in terms of stress triaxialities, the normalized Lode angle, and the third invariant. It was observed that in both experimental and numerical methods, by decreasing the amount of negative stress triaxiality, the amount of fracture strain first decreases and then increases.

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Amirkabir Journal of Mechanical Engineering
Volume 56, Issue 9
2024
Pages 1303-1326

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