Void-by-void versus multiple void interaction under mode I-mode II or mode I-mode III loading conditions

R. G. Andersen*, K. L. Nielsen, B. N. Legarth

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Ductile crack initiation, governed by void growth to coalescence, is controlled by two distinct mechanisms, namely: (i) void-by-void growth, where substantial growth of the void closest to the crack tip precedes growth of other voids, and (ii) multiple void interaction, where the voids grow simultaneously and interact in the vicinity of the crack tip prior to crack advance. Tvergaard and Hutchinson (2002) [Int. J. Solids and Struct, 39: 3581-3597] studied the two mechanisms in detail under far-field mode I loading conditions and demonstrated their interference by changing the size and spacing of discretely modeled voids. The present numerical work focuses on mixed mode loading conditions rather than limiting the study to mode I and takes up the question; how will a change in the far-field loading conditions affect the shift between the two mechanisms? A pre-existing straight crack with nearby discretely modeled voids in an elastic-plastic material is considered by a specialized 2D plane strain setting capable of out-of-plane displacements to allow for combinations of mode I, mode II, and mode III. Details of the void-by-void growth versus the multiple void interaction mechanisms are laid out for a range of load cases and geometrical void configurations, and increasing the mode mixity is found to favor void-by-void growth accompanied by a higher load intensity required on the far-field boundary to initiate the crack. The change between the two mechanisms is tied to a change in the deformation field that surrounds the voids, and the study reveals significant deformation that stretches above (and below) the row of discrete voids for increasing shear mode contributions yielding an increase in the void rotation.
Original languageEnglish
JournalEngineering Fracture Mechanics
Volume214
Pages (from-to)248-259
Number of pages12
ISSN0013-7944
DOIs
Publication statusPublished - 2019

Keywords

  • Ductile fracture
  • Fracture toughness
  • Void interaction
  • Mode mixity

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