Fracture statistics of ceramics – Weibull statistics and deviations from Weibull statistics

It is claimed in almost every experimental work on ceramics that the strength is Weibull distributed. The literature demonstrates that this is not valid in any case, but it is up to now the backbone in the design of brittle components. An overview on situations that deviate from Weibulls statistics is presented (multi-modal flaw distribution, R-curves, etc.). It is also shown that testing specimens with different volumes may help to understand the real strength distribution.Inaccuracies that arise from using the Weibull’s theory are presented. Monte Carlo simulations on the basis of the standardised testing procedure (30 specimens) clearly reveal that these deviations can be hardly detected on the basis of small samples.