Progressive fracture mechanism of CCNSCB rock fracture toughness specimens and calibration of wide-range dimensionless stress intensity factors

Feng Dai, Mingdong Wei, Nu Wen Xu*, Yuan Xu, Tao Zhao

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)

Abstract

International Society for Rock Mechanics has suggested four methods for measuring Mode-I fracture toughness (KIC) of rocks. By combining the suggested semi-circular bend specimen and cracked chevron notched Brazilian disc, the cracked chevron notched semi-circular bend (CCNSCB) specimen is produced, which inherits many merits from previous methods. The CCNSCB method has recently received much attention by researchers for testing KIC of rocks, but has not been numerically assessed. Thus, the method is numerically studied and the progressive fracture process is presented via meso-damage mechanical analysis. Considering different span to diameter ratios β, the results show that the real fracture is more aligned with the measuring principle while β is greater. Therefore, β=0.8 is suggested. The minimum dimensionless stress intensity factor Ymin *, which is critical to determine the KIC value, is calibrated by finite element method (FEM) with a sub-modelling technique for diversified CCNSCB geometries in terms of β=0.8. The calibrated Ymin * values are conveniently obtained for other relevant researches. The critical crack corresponding to the peak load simulated by microscopic damage mechanics is quite consistent with that corresponding to the calibrated Ymin * via FEM. It is indicated that the CCNSCB method is appropriate to measure KIC of rocks and the numerical simulations as well as the calibration of Ymin * values are effective.

Original languageEnglish
Pages (from-to)3215-3223
Number of pages9
JournalYantu Lixue
Volume37
Issue number11
DOIs
Publication statusPublished - 10 Nov 2016
MoE publication typeA1 Journal article-refereed

Keywords

  • Cracked chevron notched semi-circular bend (CCNSCB)
  • Critical dimensionless stress intensity factor
  • Fracture toughness
  • Numerical assessment
  • Numerical calibration

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