Evaluation of Fracture Toughness for Ceramic Materials by a Single‐Edge‐Precracked‐Beam Method

Abstract
As a substitute for the fatigue‐cracked‐beam method prescribed in ASTM E399 A2, a recently devised precracking method was applied to the evaluation of fracture toughness of ceramic materials. Straight‐through precracks proved to be easily introduced into rectangular beams of several ceramic materials. This method gives Kic values almost identical with those of the fatigue‐cracked‐beam method. The Kic values are almost constant over wide ranges of the pop‐in precrack length and the loading rate of the three‐point bend test. The test can be easily performed even at elevated temperatures although its validity should be further examined.