Fracture toughness estimation of small diameter fibers

S. Ochiai, K. Morishita, S. Kuboshima, H. Okuda, T. Inoue, T. Ishikawa, M. Sato

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In estimation of fracture toughness of small diameter (5∼15 um) fibers, the difficulty arises from the small physical dimensions, due to which proper method to introduce small notches is limited. Also, the diameter is usually different among the fiber test specimens. Accordingly, a proper method to introduce an artificial notch in the specimens is required, and the fracture toughness value shall be estimated for each fiber test specimen. In the present work, as the method to introduce artificial notch, focused-ion (Ga +)-beam was used, with which a mode I type straight-fronted edge notch was introduced in the fiber specimens. The notch-tip radius was around 25 nm. The fracture strength (af), notch depth (a) and fiber diameter (D) were measured for each fiber test specimen. The correction factor Y for the present straight-fronted edge notch, which is a function of a relative notch depth a/D was calculated by the finite element method. The fracture toughness KIc was estimated for each fiber specimen by substituting the measured values of a, D and σf and calculated value of Y into KIc=Yσf (πa)1/2. Such an approach was applied to the polycrystalline SiC fiber (Tyranno-SA® with diameter 5∼11μm) and amorphous SiC fiber (Tyranno-ZMI® with diameter 9∼14 um). The fracture toughness values of the polycrystalline and amorphous SiC fibers were estimated to be 2.7±0.4 and 1.8±0.3 Mpa *m1/2, respectively. The fracture toughness value was almost independent of the fiber diameter and notch depth in both fibers.

Original languageEnglish
Title of host publication12th International Conference on Fracture 2009, ICF-12
Number of pages7
Publication statusPublished - 2009
Externally publishedYes
Event12th International Conference on Fracture 2009, ICF-12 - Ottawa, ON, Canada
Duration: Jul 12 2009Jul 17 2009

Publication series

Name12th International Conference on Fracture 2009, ICF-12


Other12th International Conference on Fracture 2009, ICF-12
CityOttawa, ON

All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology


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