Chapter 23. Influence of R-Ratio on the Fatigue Behavior of a Woven SiC/SiC Composite
- Rajan Tandon,
- Andrew Wereszczak and
- Edgar Lara-Curzio
Published Online: 27 MAR 2008
Copyright © 2007 The American Ceramics Society
Mechanical Properties and Performance of Engineering Ceramics II: Ceramic Engineering and Science Proceedings, Volume 27, Issue 2
How to Cite
Kalluri, S., Calomino, A. M. and Brewer, D. N. (2006) Influence of R-Ratio on the Fatigue Behavior of a Woven SiC/SiC Composite, in Mechanical Properties and Performance of Engineering Ceramics II: Ceramic Engineering and Science Proceedings, Volume 27, Issue 2 (eds R. Tandon, A. Wereszczak and E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291313.ch23
- Published Online: 27 MAR 2008
- Published Print: 1 JAN 2006
Print ISBN: 9780470080528
Online ISBN: 9780470291313
- chemical vapor infiltrated (CVI);
- melt infiltration process (MI).
Fatigue behavior of a woven SiC/SiC composite (CMC), manufactured by slurry–cast, melt–infiltration process, was determined at 1038 and 1204°C by conducting tests on specimens machined from CMC plates. Cyclic fatigue tests were conducted in air with a frequency of 20cpm at both temperatures. Two different R–ratios (minimum stress/maximum stress of 0.05 & 0.5) and a maximum stress of 179 MPa were used during the investigation. Five fatigue tests were conducted at each test condition to obtain representative fatigue durability at that condition. Geometric mean cyclic fatigue lives generated at both temperatures and R–ratios were compared. At both temperatures, the geometric mean cyclic lives of the R = 0.5 fatigue tests were higher than those from the R = 0.05 fatigue tests. Results from this investigation suggest that for this material, fatigue durability is primarily governed by the tensile stress range rather than the tensile mean stress. Cumulative fatigue tests, with a maximum stress of 179 MPa and R = 0.05 followed by R = 0.5 on the same specimen, were subsequently conducted on the same CMC at 1038 and 1204°C. At least two cumulative fatigue tests were conducted for each initial life fraction and temperature combination. Summations of life fractions from these tests were used to evaluate applicability of the linear damage rule, which was originally developed for metallic alloys, to the woven CMC. For the conditions investigated, the linear damage rule served as a lower bound for a majority of the cases.