Observation of mixed mode fracture with center notched disk specimens

Z. Jia*, A. Castro-Montero, S. P. Shah

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Center notched disk (CND) specimens were loaded diametrically under Brazilian test configuration. By changing the notch inclination angle with respect to the loading direction the mode of fracture was varied from mode I (tensile) to mixed mode (tension-shear and compression-shear). The tests were conducted at two rates of loading. First, a quasi-static rate of loading was used under closed loop testing conditions. High rate of loading was applied using an instrumented Charpy machine. The selected impact rate of loading did not modify the failure mode. Failure was still the result of propagation of a single crack. At quasi-static rate, both laser holographic interferometry and reflection photoelasticity with conventional TV imaging were used to observe mixed mode fracture in the center notched disk specimens. Reflection photoelasticity and high speed photography were used to monitor the crack growth at impact rate. Laser holographic interferometry was also used to calibrate reflection photoelasticity recordings on similar specimens at comparable rates of loading. For all notch inclination angles, the peak load increased by a constant factor relative to the peak loads at quasi-static rate of loading. However, the increase of apparent stress intensity factor at crack initiation for tensile cracking is almost double that corresponding to shear cracking.

Original languageEnglish (US)
Pages (from-to)125-137
Number of pages13
JournalCement and Concrete Research
Issue number1
StatePublished - Jan 1996

ASJC Scopus subject areas

  • Building and Construction
  • Materials Science(all)

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