An r-curve approach for fracture of quasi-brittle materials

Ouyang Chengsheng*, Mobasher Barzin, Shah Surendra P.

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


An R-curve approach for fracture of quasi-brittle materials is proposed in this paper. An R-curve is defined as an envelope of fracture energy release rate of specimens with different sizes but the same initial notch length. By assuming that an effective traction-free critical crack is the function of an initial crack length contained in a material, an expression of the R-curve with two parameters can be derived by solving a differential equation. The parameters of the R-curve can be uniquely determined according to KICS and CTODc for positive geometry specimens, and according to KICS and dK1/da = 0 for negative geometry specimens. Load-CMOD and loaddisplacement response can be predicted based on the proposed R-curve by requiring that the crack driving force and crack growth resistance are equal at every equilibrium crack length. The predicted curves show a good agreement with the wide range of experimental results. Pre-critical stable crack propagation of quasi-brittle materials can be well described by the present approach.

Original languageEnglish (US)
Pages (from-to)901-913
Number of pages13
JournalEngineering Fracture Mechanics
Issue number4
StatePublished - 1990

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering


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