Fatigue behavior, continuous fiber composites

Fatigue behavior of continuous fiber composites under multiaxial loading... 

The trend is similar to that discussed on page 345 for short fiber composites, but at the same time it is opposite to the general behavior of plain samples of both short fiber and continuous fiber composites, where the fatigue strength decreases when the biaxiality ratio A2 increases. However, on the basis of the limited amount of data available, it is impossible to justify the experimental evidence and further research is indeed needed to clarify the mechanisms responsible for this peculiar behavior. Results on [0/ 45]2s, [0/ 45/90]s, and [02/ 45]s graphite/epoxy cruciform laminates reported by Jones et al. [16] are less clear than those just discussed—in some cases increasing the biaxiality ratio Ai decreased the fatigue life, and for others the life was increased. 

Fatigue Behavior of Continuous Fiber-Reinforced Ceramic Matrix Composites... 

Experimental studies of the influence of stress ratio on elevated temperature fatigue life have been conducted by Suresh71 for whisker-reinforced AI2O3 (see Chapter 7 by Suresh for a discussion of the fatigue behavior of whisker-reinforced ceramics). In this section, the influence of stress ratio on the fatigue life of continuous fiber-reinforced ceramic matrix composites is discussed. 

L. P. Zawada and S. S. Lee, The effect of hold times on the fatigue behavior of an oxide/oxide ceramic composite, in Thermal and Mechanical Test Methods and Behavior of Continuous-Fiber Ceramic Composites, M. G. Jenkins, et al., Eds., American Society for Testing and Materials, West Conshohocken, PA, (1997). 

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