Experimental and Numerical Analysis of the Effect of Stress Triaxiality and Lode Angle Parameter on the Ductile Fracture of 321 Stainless Steel

Document Type : Research Article

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Mechanical Engineering Department, University of Tehran, Tehran, Iran

Abstract

In this study, the effect of stress triaxiality and the Lode angle parameter on the fracture strain of AISI 321 stainless steel was investigated. Although the influence of stress triaxiality has been extensively studied, the role of the Lode angle parameter remains unclear. This research was conducted with the aim of clarifying these effects in the ductile fracture of AISI 321 stainless steel. To this end, five specimens under tensile loading and two specimens under compressive loading, each with different geometries, were designed and simulated in the ABAQUS software. The specimens were also subjected to experimental tests, and the distributions of strain and stress were recorded up to the point of fracture. A power-law model was employed to define the stress–strain curve, and experimental data were used to calibrate the model. The extracted force–displacement results from both experimental and numerical approaches were found to be in good agreement. The results indicate that stress triaxiality has a direct effect on fracture strain, while the Lode angle parameter exhibits a nonlinear influence on fracture behavior. Moreover, slight changes in specimen geometry can lead to significant variations in the final fracture strain values. Overall, it was found that within a stress triaxiality range of −0.63 to 0.6 and a Lode angle parameter range of −0.78 to 1, the fracture strain varies from 0.6 to 0.9.

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Amirkabir Journal of Mechanical Engineering
Volume 57, Issue 5
August 2025
Pages 545-566

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