Stress intensity factor coefficients for chevron-notched flexure specimens and a comparison fracture toughness methods

摘要

For chevron-notch geometries with α{sub}1 = 1, the STCA is a good approximation of the SIFC. For geometries with α{sub}1 significantly less than 1, the slice is a better approximation, but neither model appears to provide a good, general approximation of the SIFC. More analyses would be beneficial. Stable crack extension was readily attained in a variety of ceramics by using chevron-notch flexure specimens. Crack extensions were detectable with an extensometer placed between the test specimen and the test fixture, but only marginally detectable with the test system extensometer, which was placed remotely at the end of the test system actuator. Back-face strain was excellent for detecting crack stability. Precracked beam specimens exhibited stable crack extension when reasonable crack configurations were tested, even for α-SiC, which is expected to exhibit little stress corrosion or crack growth resistance. Crack extension was marginally detectable using an extensometer placed in the test fixture. Back-face strain was excellent for detecting crack extension and stability. Twisted cracks tended to be unstable and resulted in elevated values of fracture toughness.