Tensile and uniaxial/multiaxial fatigue behavior of ceramic matrix composites at ambient and elevated temperatures

Increasing use of fiber reinforced ceramic matrix composites (CMC's) materials is needed, especially for hostile environments such as elevated temperatures. However, some fundamental issues regarding how these materials should be made for optimized performance are far from being settled. This study focuses on the modeling of the tensile behavior of unidirectional CMC using statistical methods and micro-mechanical analysis, based on laboratory observations. The model can be used to examine the effect of performance-influencing parameters on the strength of unidirectional CMC, thus shed light on how such material should be put together. The tensile strength model was then modified such that the behavior of unidirectioal CMC under cyclic tensile load can be studied. Results from the tensile strength model suggest that the Weibull modulus, <i>m</i>, of the strength of the reinforcing fibers and the fiber/matrix interfacial shear stress both have significant effect on the strength and toughness of the unidirectional composite: a higher <i>m</i> value and a lower interfacial shear stress result in a lower strength; a lower value of <i>m</i> and a higher interfacial shear stress results in a higher strength but lower toughness. Calculations from the tensile fatigue model suggest that a lower <i>m</i> value results in a longer fatigue life.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Materials Engineering Science

Department dc:contributor.department

Materials Engineering Science

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1994

Author dc:creator

• Liao, Kin

Chair dc:contributor.committeechair

• Reifsnider, Kenneth L.

Committee members dc:contributor.committeemember

• Hasselman, D.P.H.
• Kriz, Ronald D.
• Stinchcomb, Wayne W.
• Wilkes, Garth L.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-10202005-102839

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/40047