Volume 14, Issue 2 (March 1986)
Determination of Fracture Toughness for Brittle Nonmetallic Materials at the Subcritical Crack Growth Stage
In addition to the KIc characteristics of such brittle materials as glass-like and ceramic ones, it is proposed to determine the values of KIo and KIi, corresponding to the crack onset and the beginning of the accelerated stage of its subcritical growth. An experimental method has been developed: to grow a given edge crack in a flat specimen, to determine the values of KIo and KIi by loading this specimen in transverse compression and then, in the course of eccentric tension (wedging) of the same specimen, to evaluate the KIc characteristics. The validity of the KIo, KIi and KIc values obtained for glass and polymethyl methacrylate (PMMA) is confirmed by their comparison with the data published.