Statistical Analysis of Fracture of Silicon Nitride (RBSN) Using the Short Span Bending Technique

Abstract

The short-span bending technique, pionneered with rod specimens of porcelain for the separation of the respective influences of surface and volume flaw populations upon strength, was applied to reaction bonded silicon nitride, prime candidate for use in advanced gas turbine systems. General approach for the statistical analysis of brittle fracture under tensile multiaxial stress states was extended to square specimens, and used to interpret experimental results. Surface and volume flaw populations appeared to exhibit different characteristics, and thus exert different influences upon the reliability of RBSN. Implications for the interpretation of bending tests and some important trends in the failure strength with specimen size are discussed.