Abstract: The effect of proof testing on the fatigue strength of ceramic specimens is analyzed by means of the fracture mechanics approach. It is shown that the damage during proof testing is hard to avoid and the minimum specimen strength after the testing can be assessed by the proof stress, the unloading rate in the proof test and the subcritical crack growth parameters of material in the environment where the test is carried out. Higher minimum strength can be obtained by adopting the inert testing environment and the high unloading rate.

Key words: cer amics, fatigue, st rengt h, proof-t est