13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- to void coalescence starting at diverse equivalent plastic strain. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.3 0.6 0.9 1.2 1.5 Stress trixiality T Distance from the center point (mm) R6 R3 R1.5 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 2 4 6 8 R6 R3 Stress triaxiality T Equivalent plastic strain ⎯ε ef R1.5 Figure 5. (a)Variation in stress triaxiality along minimum section at crack intiation; (b) Different stress triaxialities at the center of specimens 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0.00 0.04 0.08 0.12 0.16 R6 R3 void volume fraction f Equivalent plastic strain ⎯ε ef R1.5 Figure 6. Void volume fraction versus equivalent plastic strain References [1] Z.L. Zhang, C. Thaulow, J. Odegard, A complete Gurson model approach for ductile fracture. Eng Fract Mech, 67(2000)155–168. [2] A.L. Gurson, Continuum theory of ductile rupture by void nucleation and growth: part I yield criteria and flow rules for porous ductile media. J Eng Mater Technol, 99(1977)2–15. [3] V. Tvergaard, Influence of voids on shear band instabilities under plane strain conditions. Int J Fract, 17(1981)389–407. [4] V. Tvergaard, On localization in ductile materials containing spherical voids. Int J Fract, 18(1982)237–252. [5] V. Tvergaard, A. Needleman, Analysis of the cup-cone fracture in a round tensile bar. Acta Metall, 32(1984)157–169.
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