Probabilistic Aspects of Designing with Ceramics

The paper reviews the design methodology for brittle materials which is being developed under the Ford/ARPA contract. Theoretical aspects of designing with high-temperature ceramics are discussed and demonstrated on a turbine rotor system. Statistical treatment of brittle behavior, based on Weibull’s model, is reviewed and relations for predicting probability of failure and material strength requirements for complex ceramic structures are presented. Reliability considerations, uncertainty of predictions, and need for proof testing are discussed. Similarly, a probabilistic treatment of time to failure of a typical turbine structure in the presence of slow crack growth is presented using fracture mechanics and Weibull relations.