Design techniques for highly reliable ceramic components using lifetime predictions

摘要

In technological responses to the enhancement of emission regulations on the vehicle in recent years, the components used are required to meet such rigorous conditions regarding properties such as resistance to wear that conventional metal materials can no longer be used. This has led manufacturers to study the use of ceramic materials for these components. However, due to the scattering of strength that is characteristic of brittle materials such as ceramics, a major issue in automotive parts development is the establishment of design methods that achieve high levels of reliability. In the design of ceramic components, it is important to consider both catastrophic fractures and the fatigue life of the component. This report describes design techniques developed at Sumitomo Electric, with specific reference to the following three points: (1) Measurement of the ceramic fatigue parameters required for predicting the product life in terms of fracture mechanics and probability statistics. (2) Drawing of Strength-Probability-Time (SPT) diagrams for use in predicting the product life from the obtained fatigue parameters. (3) Prediction of the actual ceramic component life using the SPT chart in combination with finite element method (FEM).