Degradation of residual strength in SCS-6/Ti-15-3 due to fully reversed fatigue

Little attention has been given to residual strength degradation in titaniu m matrix composites (TMCs) after exposure to fatigue loading. To address th is problem, fatigue tests on SCS-6/Ti-15-3 were performed to investigate th e fatigue life and residual strength behavior of TMCs with different fiber volume fractions. Results indicate that fiber volume fraction seems to have an effect on both of these quantities. Lower fiber percentages result in a material where the characteristics of the matrix, such as hardening or cra cking, play a much larger role in the composite response. Fatigue lives wer e not affected by fiber volume fraction at higher strain ranges, but lower fiber volume fractions resulted in shorter fatigue lives at lower strain va lues. Also, a slight increase in residual strength occurred up to 75 pet of fatigue life, for the lower-fiber volume fraction material. Despite these distinctions between specimens with different fiber contents, all specimens tested retained the majority of their strength prior to failure.