Mechanics of Elevated Temperature Fatigue Damage in Fiber-Reinforced Ceramics
Abstract
The focus of the research conducted under Grant No. 91-0106 (a two year effort) was to identifying the fundamental mechanisms of fatigue damage that occur in fiber-reinforced ceramics. Several new findings were made during the research effort: (1) the fatigue life of fiber-reinforced ceramics decreased markedly during high frequency fatigue loading, (2) fiber-reinforced ceramics undergo significant internal heating during cyclic loading, (3) because of frictional wear along the fiber-matrix interface, the frictional shear stress in fiber-reinforced ceramics decreases sharply under cyclic loading. Based upon insight gained from the analytical and experimental parts of the investigation, we developed a novel approach to estimate the level of frictional shear stress that exists along the fiber-matrix interface during fatigue. Since this technique allows confirmation of other techniques for estimating frictional shear stress (e.g., fiber pushout technique developed by Marshall at Rockwell Science Center). Moreover, it is the only approach that allows determination of the in-situ change in frictional shear stress during cyclic loading (note that the level of frictional shear stress controls many mechanical properties such as strength, toughness and mechanical damping as well as thermophysical properties such as thermal diffusivity). The analysis that was developed to estimate frictional shear stress can also be used to understand the relationship between composite microstructure and cyclic energy dissipation in fiber-reinforced ceramics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1993
- Accession Number
- ADA262403
Entities
People
- John W. Holmes
Organizations
- University of Michigan