Strength measurements with a broad spectrum (from less than 2 GPa to more than 5 GPa), at different stress-rates have been analyzed. The number of samples for each stress-rate was large (200). For each stress-rate, two straight lines, one for high and the other for low fracture strength can fit the strength data in a Weibull diagram. Intersection of both lines depends strongly on stress-rate. In order to obtain the strength and fatigue behavior for several strengths, the data for each stress-rate were divided in six group of data points by considering different ranges of probability (i.e., inert strength). Good linear fittings are obtained in Weibull diagrams for most groups. The fatigue parameter n is larger for the lowest and highest strength groups (n equals 22) and decreases for the middle groups (lowest n equals 15). In the lowest strength group, a large deviation from the linear fitting is observed, mainly for the lowest strength points. This behavior suggests the operation of some random mechanism.
Ricardo E. Medrano,
"Mechanical properties of weak optical fibers", Proc. SPIE 3848, Optical Fiber Reliability and Testing, (29 December 1999); doi: 10.1117/12.372782; https://doi.org/10.1117/12.372782