1988 Volume 54 Issue 503 Pages 1445-1450
Plane strain fracture toughness (K/<IC>) measurements were made on ceramics (graphite, engineering ceramics) using short bar and bend bar chevron notched specimens previously calculated by optimum specimen geometry, to enable precracking, by means of 3-dimensional finite element and Bluhm's slice model analysis. Acoustic emission (AE) signals were also measured for detecting precracking and successive crack growth. AE signals due to precracking and crack growth were obtained for all short bar and bend bar specimens of graphite ; and deviations of KIC values were relatively small with variations in chevron notch angle and the width of the slot from 0.2 mm to 0.5 mm. In most engineering ceramics, unstable fracture immediately occurred after popin. About 20% higher KIC values were obtained in comparison to another testing device (fractometer-Terratek Co.), except for one commercial hot-pressed Si3N4. It means that the width of the slot should be less than 0.2 mm in highly brittle solids, and confirmation of precracking is actually important to evaluate KIC value.
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A
Transactions of the Japan Society of Mechanical Engineers Series C
Transactions of the Japan Society of Mechanical Engineers Series B
