Strength of a Ceramic Sectored Flexural Test Specimen

A new test specimen, defined here as the “sectored flexural strength test specimen,” was developed to measure the strength of ceramic tubes specifically for circumstances when flaws located at the tube’s outer diameter are the strength-limiter when subjected to axial tension. The understanding of such strength-limitation is relevant when ceramic tubes are subjected to bending or when the internal temperature is hotter than the tube’s exterior (e.g., heat exchangers). The test specimen is both economically and statistically attractive because eight test specimens (eight in the case of this project—but the user is not necessarily limited to eight) were extracted out of each length of tube. An analytic expression for maximum (or failure) stress, and relationships portraying effective area and effective volume as a function of Weibull modulus were developed. Lastly, it was shown through the testing of two ceramics that the sectored flexural specimen was very effective; it produced failures caused by strength-limiting flaws located on the tube’s original outer diameter.