Fatigue design criteria for ceramic components under cyclic loading

The investigations carried out and the results presented show clearly that for a fatigue design against cyclic loading the knowledge of conventional properties like tensile or compressive static stresses are not sufficient; they do not contain the information about endurable stresses, the effects of mean-stress and notch sensitivity as well as the size effect obviously reduced under cyclic loading. However, if cyclic fatigue properties are not available in dependency of stress-concentration, mean-stresses, and loading mode, a preliminary fatigue design can be carried out by applying the proposed uniform S-N curve, Fig. 7. The starting point is then the monotonic bending strength of the candidate ceramic material (Psubs is equal to 50 %) obtained from specimens having similar dimensions as the component to be designed. But this procedure requires subsequent verification tests with real components.