Abstract
A concept is proposed to increase the matrix cracking stress of some brittle-matrix composites by taking advantage of the redistribution of internal stresses that occurs when a composite with phases that have dissimilar creep behavior is subjected to thermomechanical loading. The concept is elaborated through the stress analysis of a model unidirectional composite with constituents that exhibit linear viscoelastic behavior. It is shown that if a composite with a matrix that is less creep resistant than the fibers is subjected to a treatment involving both thermal and mehcanical loading (eg creep test), stresses can be transferred from the matrix to the fibers, resulting in the stress-relaxation of the matrix. Furthermore, it is also shown that by the elastic recovery of the fibers, the matrix can be subjected to large compressive residual stresses at the end of the treatment. The conditions for the viability of this concept and the implications of fiber overloading and potential loss of composite-like behavior are discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 270-278 |
| Number of pages | 9 |
| Journal | Materials Science and Engineering: A |
| Volume | 250 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jul 31 1998 |
Funding
C.M. Russ, a sophomore at Washington University, St. Louis, MO, acknowledges the financial support from the Oak Ridge Institute for Science and Education, through the Professional Internship Program, to spend the summer of 1996 at ORNL. The authors are grateful to their colleagues Peter F. Tortorelli and Ellen Sun of Oak Ridge National Laboratory for reviewing the manuscript and for providing valuable comments. This research sponsored by the US Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Industrial Technologies, Industrial Energy Efficiency Division and Continuous Fiber Ceramic Composites Program, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation.