1 Scope
This document covers the reporting of uniaxial strength data and the estimation of
probability distribution parameters for advanced ceramics which fail in a brittle
fashion. The failure strength of advanced ceramics is treated as a continuous random
variable. Typically, a number of test specimens with well-defined geometry are brought
to failure under well-defined isothermal loading conditions. The load at which each
specimen fails is recorded. The resulting failure stresses are used to obtain parameter
estimates associated with the underlying population distribution.
This document is restricted to the assumption that the distribution underlying the
failure strengths is the two-parameter Weibull distribution with size scaling. Furthermore, this document is restricted to test specimens (tensile,
flexural, pressurized ring, etc.) that are primarily subjected to uniaxial stress
states. Subclauses 6.4 and 6.5 outline methods of correcting for bias errors in the estimated Weibull parameters,
and to calculate confidence bounds on those estimates from data sets where all failures
originate from a single flawpopulation (i.e. a single failure mode). In samples where failures originate from multiple independent flawpopulations (e.g. competing failure modes), the methods outlined in 6.4 and 6.5 for bias correction and confidence bounds are not applicable.