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

296

11

Figure 10: Contours of equivalent plastic strain showing details of two-scale void interaction and the resulting crack growth. Idealized linear clusters of initially elliptical ( =6) secondary voids are modelled at an angle Ɵ=45 with respect to the initial crack plane. Contours shown in (a) - (d) are extracted J = 0.476 σ 0 X 0 , J = 0.702 σ 0 X 0 , J= 0.851σ 0 X 0 and J = 1.116σ 0 X 0 , respectively. 4. Conclusion In this study, numerical results providing some details of the growth and coalescence of the two-scale voids and the influence of this complex void interaction, occurring ahead of the crack tip, on ductile crack propagation are presented. Only pure mode-I loading is considered. The salient conclusions of this study are as follows.  For the idealized configurations of voids modelled in this study, it seems that ductile crack propagation is not solely controlled by the larger primary voids. The pre-existing secondary voids may result in a complex two-scale void interaction that may influence ductile crack growth and, hence, the crack driving force.  For the initial configuration of primary voids modelled here, the small secondary voids lying in the crack plane ( Ɵ=0 ), requires lesser driving force for ductile crack extension compared to voids distributed in a plane oriented at Ɵ=45 relative to the initial crack plane. For such secondary void configuration ( Ɵ=0 ), the effect of initial void shape on crack driving force and ligament reduction ahead of crack tip is rather insignificant.  Clusters of favourably oriented initially elliptical ( =6) secondary voids may lead to strain localization in the plane ( Ɵ=45 ), containing these small voids, thus, leading to crack branching. Therefore, the driving force required for crack propagation is much higher compared to the cases where crack growth is coplanar. References Andersen, R. G., Nielsen, K. L., & Legarth, B. N. (2019). Void-by-void versus multiple void interaction under mode I-mode II or mode I-mode III loading conditions. Engineering Fracture Mechanics , 214 , 248 – 259. https://doi.org/10.1016/j.engfracmech.2019.02.031 Aravas, N., & Mcmeeking, R. M. (1985). Microvoid growth and failure in the ligament between a hole and a blunt crack tip. In International Journal of Fracture (Vol. 29). Benzerga, A. A., & Besson, J. (2001). Plastic potentials for anisotropic porous solids. European Journal of Mechanics, A/Solids , 20 (3), 397 – 434. https://doi.org/10.1016/S0997-7538(01)01147-0