Cyclic fatigue in ceramics: A balance between crack shielding accumulation and degradation
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
Cyclic fatigue growth rates in R-curve ceramics have been observed to depend very strongly on the maximum applied stress intensity, K{sub max}, and only weakly on the stress intensity range, {Delta}K. This behavior is rationalized through measurement of crack wake shielding characteristics as a function of these fatigue parameters in a gas-pressure-sintered silicon nitride. In particular, evidence for a mechanical equilibrium between shielding accumulation by crack growth and shielding degradation by frictional wear of sliding interfaces is found for steady-state cyclic fatigue. This equilibrium gives rise to a rate law for cyclic fatigue. The data suggest that the accumulation process is the origin of the strong K{sub max} dependence, and that the degradation process is the origin of the weak {Delta}K dependence. These features are shown to be related to the ``cyclic`` R-curve and to the cyclic crack opening displacement, respectively.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 79760
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 3 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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