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The Effect of Notches on the Fatigue Life of SCS-6/Ti3Al Composite

Published online by Cambridge University Press:  21 February 2011

Kenneth R. Bain
Affiliation:
Materials Behavior Research Corporation, 421 Wards Corner Road, Loveland, Ohio 45140
Mary Lee Gambone
Affiliation:
Materials Behavior Research Corporation, 421 Wards Corner Road, Loveland, Ohio 45140
Richard D. Zordan
Affiliation:
Allison Gas Turbine Division, GMC, P.O. Box 420, Indianapolis, Indiana, 46206–0420
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Abstract

Low cycle fatigue tests were performed on Ti-24Al-11Nb titanium aluminide composite unidirectionally reinforced with SCS-6 fiber. (SCS-6 is a SiC-based fiber manufactured by Textron-SMD in Lowell, Massachusetts.) The effect of circular holes onthe fatigue life of this composite system was measured with respect to fiber orientation, temperature, and frequency. Longitudinal and transverse specimens with and without holes were tested at 26°C and 649°C at 0.33 Hz. In addition, longitudinal specimens were also tested at 30 Hz and 649°C to determine the effect of frequency.

A degradation in fatigue life due to the presence of holes was observed in specimens loaded in the fiber direction (longitudinally). This effect is independent of frequency. The notch sensitivity factor, Q, associated with the reduction in life ranges from 0.33 to 0.50 over the range of temperature tested.

The specimens oriented with the load axis perpendicular to the fiber direction (transverse) demonstrated no sensitivity of fatigue life to the presence of holes at room temperature but did possess a finite sensitivity at 649°C with a Q=0.45.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

1. Gambone, M. L. Fatigue and Fracture of Titanium Aluminides. Phase II, Final Report. Contract No. F33615–85-C-5111. Not yet published.Google Scholar
2. Dieter, G. E. Mechanical Metallurgy. McGraw-Hill, Inc., New York, NY 1976, pp. 422426 Google Scholar