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Sensitivity Analysis on Triaxiality Factor and Lode Angle in Ductile Fracture

  • R. Ghajar (a1), G. Mirone (a2) and A. Keshavarz (a1)

Abstract

Accuracy of numerical analysis is always important but it is much more important in failure analysis of ductile materials. In ductile materials, the process of removing the effects of necking to obtain stress-strain curve usually need reverse identification methods which are based on iterative finite element analysis. Moreover, triaxiality factor and Lode angle (two parameters that control failure of ductile materials) are obtained from finite element analysis.

In this article based on some experiments, the effect of triaxiality factor and Lode angle on the failure strain of X100 pipeline steel is studied. In order to gain a better understanding of the response of triaxiality and Lode angle to deviations of stress, a sensitivity analysis is done on these two parameters before the start of finite elements (FE) analysis. This sensitivity analysis shows that the two parameters are really sensitive to stress deviations in some areas. Three geometries are selected and their FE analysis shows that it is necessary to reduce the element size lower than what is reported in literature in order to get convergence in triaxiality factor and Lode angle in critical areas.

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Corresponding author

*Corresponding author (a_keshavarz@dena.kntu.ac.ir)

References

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1. Bridgman, P. W., Studies in Large Plastic Flow and Fracture with Special Emphasis on the Effects of Hydrostatic Pressure, First Edition, McGraw-Hill, New York (1952).
2. Lemaitre, J., “A Continuous Damage Mechanics Model for Ductile Fracture,” Journal of Engineering Materials Technology, 107, pp. 8389 (1985.).
3. Lemaitre, J., Desmorat, R. and Sausay, M., “Anisotropic Damage Laws of Evolution,” European Journal of Mechanics, 19, pp. 187208 (2000).
4. Chaboche, J. L., “Continuous Damage Mechanics: A Tool to Describe Phenomena Before Crack Initiation,” Nuclear Engineering and Design, 64, pp. 233247 (1981).
5. Bao, Y., “Prediction of Ductile Crack Formation in Uncracked Bodies,” Ph.D Thesis, Department of Mechanics Engineering, MIT, U.S.A. (2003).
6. Xue, L. and Wierzbicki, T., “Ductile Fracture Initiation and Propagation Modeling Using Damage Plasticity Theory,” Engineering Fracture Mechanics, 75, pp. 32763293 (2008).
7. Bai, Y. and Wierzbicki, T., “A New Model of Metal Plasticity and Fracture with Pressure and Lode Dependence,” International Journal of Plastics, 24, pp. 10711096 (2008).
8. Gao, X., Zhang, T., Hayden, M. and Roe, C., “Effects of the Stress State on Plasticity and Ductile Failure of an Aluminum 5083 Alloy,” International Journal of Plastics, 25, pp. 23662382 (2009).
9. Mirone, G. and Corallo, D., “A Local Viewpoint for Evaluating the Influence of Stress Triaxiality and Lode Angle on Ductile Failure and Hardening,” International Journal of Plastics, 26, pp. 348371 (2010).
10. Wierzbicki, T., Bao, Y., Lee, Y. W. and Bai, Y., “Calibration and Evaluation of Seven Fracture Models,” International Journal of Mechanical Sciences, 47, pp. 719743 (2005).
11. Barsoum, I. and Faleskog, J., “Micromechanical Analysis on the Influence of the Lode Parameter on Void Growth and Coalescence,” International Journal of Solids and Structures, 48, pp. 925938.
12. Barsoum, I. and Faleskog, J., “Rupture Mechanisms in Combined Tension and Shear– Micromechanics,” International Journal of Solids and Structures, 44, pp. 54815498.
13. Coppola, T., Corallo, D. and Mirone, G., “Determinazione Della Curva Costitutiva Postnecking Per Metalli Duttili,” Proceedings of 38th National Conference of AIAS – Italian Association for Stress Analysis, Italy (2009).
14. Mirone, G., Keshavarz, A. and Ghajar, R., “An Experimental Failure Model Based on Triaxiality Factor and Lode Angle for X-100 Pipeline Steel,” Proceedings of X-Mech-2012, Iran (2012).
15. Broggiato, G. B., Coppola, T. and Cortese, L., “Caratterizzazione Sperimentale Del Legame Elasto-Plastico Ad Elevate Deformazioni Mediante La Prova Di Torsione,” Proceedings of 39th Conference of AIAS – Italian Association for Stress Analysis, Italy (2010).
16. Mirone, G., “A New Model for the Elastoplastic Characterization and the Stress–Strain Determination on the Necking Section of a Tensile Specimen,” International Journal of Solids and Structures, 41, pp. 35453564 (2004).
17. Bai, Y., “Effect of Loading History on Necking and Fracture,” Ph. D. Thesis, Department of Mechanics Engineering, MIT, U.S.A. (2008).
18. Coppola, T., Cortese, L. and Folgarati, P., “The Effect of Stress Invariants on Ductile Fracture Limit in Steels,” Engineering Fracture Mechanics, 76, pp. 12881302 (2009).
19. Hashemi, S. H., Howard, I. C., Yates, J. R. and Andrews, R. M., “The Transferability of Micro Mechanical Damage Parameters in Modern Pipeline Steel,” 15th Europian Conference on Fracture, Sweden (2004).
20. Hashemi, S. H., Howard, I. C., Yates, J. R. and Andrews, R. M., “Micromechanical Damage Modelling of Notched Bar Testing of Modern Line Pipe Steel,” 15th Europian Conference on Fracture, Sweden (2004).

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