STRENGTH PREDICTION OF CERAMIC COMPONENTS UNDER COMPLEX STRESS STATES

The capability to perform accurate fast-fracture strength predictions for ceramic components under complex stress states must be available i n order to transition the use of advanced, high-strength ceramic mater ials from the laboratory to the high-strength/high-temperature applica tions they are intended for. Multiaxial strength prediction theories h ave provided the prediction capabilities, but only limited testing of these theories under complex stares of stress and stress gradient cond itions has been performed previously. Presented here are comprehensive test results and strength predictions for ceramic components subjecte d to complex states olf stress and stress gradient conditions. The res ults show excellent agreement of the predictions from the multiaxial t heories with test results for volumetrically distributed flaws. An imp ortant finding of this work is the problem that arises in performing c omponent surface strength predictions from database-type specimens. Da tabase-type specimens and component surface properties are not necessa ry correlated, and in many cases it may be completely inaccurate to us e database-type specimen surface properties for component surface stre ngth predictions.