Nicalon fibers are one of the most attractive ceramic fibers for reinforcing high temperature structural composites. Experimental results show that the diameter variation (from 8 to 22 mu m) in a tow of commercial Nicalon fibers has an effect on the statistical strength distribution of Nicalon fibers. Therefore, an appropriate characterization of the statistical distribution of fiber strength, capable of accounting for the effect of diameter variation, is required. The two-parameter single-modal Weibull distribution is found inadequate for characterizing the strength of Nicalon fibers. In this work, we demonstrate that a three-parameter modified-Weibull distribution can successfully characterize the strength of Nicalon fibers. The three-parameter modified-Weibull distribution yields a higher (5 value, which indicates less scatter in fiber strength than would be found using the two parameter single-modal Weibull distribution. It more accurately treats the strength variation caused by diameter variation. In addition, it is also much easier to use than the four-parameter bi-modal Weibull distribution. Moreover, it is seen to more accurately treat the strength variation caused by diameter variation than the single modal two parameter analysis.
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