Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics


This study investigated the fatigue life and damage mechanisms of a [0]8, SCS-6/Ti-15-3, metal matrix composite at 427°C for three different stress/strain ratios, R = -1, 0 and 0.5. Fatigue life and damage mechanism comparisons were made for the varying R ratios and between the load and strain control modes. Fatigue life comparisons show that on a maximum stress/strain basis as R is increased fatigue life increases while on a stress/strain range basis as R increases fatigue life decreases. Similar damage mechanisms were found between the R = -1 and R = 0 tests conducted at the same maximum stress/strain level. However, comparisons between R = 0 or R = -1 and R = 0.5 show that the decreased stress/strain range at R = 0.5 results in increased fatigue life and the onset of matrix damage at the same maximum stress/strain level.

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DTIC Accession Number