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

TLDR

The fatigue‑cracked‑beam method prescribed in ASTM E399 A2 is the standard for evaluating fracture toughness of ceramic materials. The authors applied a recently devised precracking method as a substitute for this standard. The test can be easily performed even at elevated temperatures, though its validity requires further examination. Straight‑through precracks were easily introduced into rectangular ceramic beams, yielding K_IC values nearly identical to the fatigue‑cracked‑beam method and remaining constant across a wide range of precrack lengths and loading rates, demonstrating the method’s reliability.

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 K ic values almost identical with those of the fatigue‐cracked‐beam method. The K ic 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.