PSI - Issue 60

A.K. Dwivedi et al. / Procedia Structural Integrity 60 (2024) 286–297 A.K.Dwivedi / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig.4:- Contours of equivalent plastic strain depicting details of crack extension. Only primary voids are modelled and the crack growth is observed to occur in the initial crack plane. Contours shown in (a) and (b) are extracted at J = 0.667σ 0 X 0 and J=0.934σ 0 X 0 , respectively.

3.2. Effect of spatial distribution and initial shape of secondary voids We now present some results showing the influence of initial shape and spatial distribution of secondary voids on the interaction between the crack tip and the nearest void and between the two-scale voids. Two different distributions of secondary voids are analyzed. In first case, a single secondary void is located in the matrix close to the primary void ( Ɵ=0 ) whereas in the other case the ligament between a secondary void and the neighboring primary void is oriented at an angle (Ɵ=0 ) with respect to the initial crack plane. Calculations are performed for initially circular and initially elliptical secondary voids ( =6 ). The volume fraction of the secondary voids is fixed ( =0.06% ) in all the cases.

Fig. 5: Effect of initial shape and spatial distribution of secondary voids on (a) normalized crack driving force J/(σ 0 X 0 ) versus crack extension, (b) variation of J/(σ 0 X 0 ) as a function of the reduction in the ligament between the crack tip and the nearest void. The initial volume fraction of primary and secondary voids is 1.6% and 0.06%, respectively.