The size dependence of micro-toughness in ductile fracture

Kartik Srinivasan, Yonggang Huang, Otmar Kolednik, Thomas Siegmund*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Micro-toughness in ductile fracture is defined as the plastic work dissipated per unit fracture surface area in the material separation processes of void growth and coalescence. A micromechanics model for the estimation of the size dependence of micro-toughness in ductile fracture is presented. Size effects are incorporated in the model using the conventional mechanism-based strain gradient plasticity (CMSG) theory. A finite element model of an axisymmetric representative unit cell with an initial spherical void is used to validate model predictions. Two characteristic length scales emerge from the model. The initial void radius sets the scale for the initial spherical void growth. For the subsequent void coalescence, the scale is set by the width of the intervoid ligament. Energy dissipation in ductile fracture is found to be dominated by the mechanisms of coalescence, and the micro-toughness in ductile fracture is found to be size dependent for dimple sizes approximately one order of magnitude larger than the material length scale.

Original languageEnglish (US)
Pages (from-to)2707-2726
Number of pages20
JournalJournal of the Mechanics and Physics of Solids
Issue number8
StatePublished - Aug 2008


  • Ductility
  • Fractography
  • Fracture toughness
  • Metallic materials
  • Voids and inclusions

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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