(Dr. Richard Neu, advisor)

"Mechanical Behavior of Transversely-Loaded Titanium Matrix Composites at Elevated Temperatures"

Abstract

This study is aimed at improving the understanding of influence of damage-state on the transverse behavior of a unidirectional silicon carbide/titanium matrix composite.  The objective is to determine the effect of different mechanical loading and temperature histories on the damage state and the influence of damage state on the effective coefficient of thermal expansion (CTE).  It is important to make this correlation because unidirectional titanium matrix composites are typically exposed to thermal cycling conditions and the transverse behavior often controls the damage state.

Experiments are conducted on SCS-6/Timetal 21S with six plies at room temperature, 400?C, 500?C, and 650?C.  The damage state is then determined by taking edge replicas and performing residual strength tests with loadings and unloadings taken at different stages of deformation.  The relationship between damage state and the effective CTE is determined by performing stress-free thermal cycling tests after different loading and temperature exposures.