Effects of Elevated Temperatures and Thermal Cycling on Ceramic Composite Materials
Abstract
The need to determine the effects of elevated temperature and thermal cycling on the mode II fracture toughness of fiber reinforced ceramic composites was identified. The two materials chosen for this purpose in this thesis were CGW 1723 and CGW 7740. In addition to mode II fracture toughness, preliminary mode I fracture toughness values were determined in order to evaluate similarities or dissimilarities in fracture toughness trends with increasing temperature. A pre-cracking fixture was designed and built to allow for precise pre-cracking of the specimens. A test stand for subjecting specimens to thermal cycling was designed and constructed. CGW 1723 Mode II specimens were tested at room temperature, 600 F, 1000 F, after being cycled from 130 F to 600 F for 25 cycles, and after exposure to 600 F for 125 minutes. CGW 7740 mode II specimens were tested at room temperature. Compliance data was plotted as a function of non-dimensional crack length. 2nd and 3rd order polynomial curves were fitted to the data. These curve fits were compared to a theoretical compliance to crack length relationship. Critical loads were determined from the load-displacement curves by identifying the load at which the specimens compliance changed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA216242
Entities
People
- Michael A. Hoobler
Organizations
- Air Force Institute of Technology