Effect of stress triaxiality on fracture failure of 6061 aluminium alloy

  • L. Y. Kou School of Mechanical Engineering, Ningxia University, 750021 Yinchuan, Ningxia, China
  • W. Y. Zhao School of Mechanical Engineering, Ningxia University, 750021 Yinchuan, Ningxia, China
  • X. Y. Tuo School of Mechanical Engineering, Ningxia University, 750021 Yinchuan, Ningxia, China
  • G. Wang School of Mechanical Engineering, Ningxia University, 750021 Yinchuan, Ningxia, China
  • C. R. Sun State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, College of Mechanical and Vehicle Engineering, Hunan University, 410082 Changsha, Hunan, China
Keywords: 6061 aluminium alloy, stress triaxiality, digital image correlation, Johnson-Cook failure model, fracture analysis

Abstract

The effect of stress triaxiality on mechanical properties of 6061 aluminium alloy extruded profiles with different specimens was studied. Macroscopic mechanical property of the various specimen was got through universal testing machine. At the same time, stress triaxiality of different specimens was obtained using the method of finite element simulation. And then the fracture strain of each specimen was outputted by DIC. Fracture modes of 6061 aluminium alloy with different stress triaxiality were studied by SEM. The results show that taking tensile samples as comparison, the cross-sectional area of some notched specimens decreases and the peak load increases. Among them, the minimum cross-sectional area of the R5 central hole specimen is 20% smaller than that of the tensile sample, and the peak load is 28% larger. The fracture strain of the alloy increased with the decrease of stress triaxiality. For the same notch specimens, along the path direction, stress triaxiality of R5 notch specimens, R5 Center-hole specimens and R20 Arc notched specimens increased 47%, 17.8%, 25% respectively. According to the analysis of fracture morphology, the main fracture of 6061 aluminium alloy was ductile fracture. When the stress triaxiality is large, the dimples are small and sparsely distributed, and when the stress triaxiality is small, the dimple is large and evenly distributed. Finally, the Johnson-Cook model material parameters of 6061 aluminum alloy are fitted based on the tensile test results of different shapes of specimens, which can accurately simulate the elastic-plastic deformation and fracture instability of 6061 aluminum alloy under different stress states.

Published
2020-06-23
How to Cite
Kou, L. Y., Zhao, W. Y., Tuo, X. Y., Wang, G., & Sun, C. R. (2020). Effect of stress triaxiality on fracture failure of 6061 aluminium alloy. Journal of Mechanical Engineering and Sciences, 14(2), 6961 - 6970. https://doi.org/10.15282/jmes.14.2.2020.33.0545
Section
Article