Fracture Strength Data Base and Reliability-based Design System for Ceramics

For application of ceramics to mechanical and structural components, a data base system for fracture strength of ceramics was developed. In this data base system, various fracture strength test data of ceramics are compiled with the data of their manufacturing process and the test environment, which are used to retrieve various fracture test data. The fracture strength of ceramics obtained by each test varies usually in spite of being same in material and test environment. For estimating the strength as a material constant independent of each testing method, this system performs a unified analysis for all the fracture strength test data retrieved. This unified analysis method can estimate the material constant expressed by the delayed fracture strength normalized in terms of cummulative effective hold time Nfteff=1sec and effective volume Veff=1mm3. Furthermore, a reliability design system was developed for analyzing the strength reliability of the structural components of ceramics against the actual service loads. It is possible by this system to determine the allowable design stress by applying the normalized strength properties to the probabilistic analysis. This system has a wide applicability in performing the reliability-based design of ceramic structural components as well as in developing ceramic materials.