Dispersion of strength

Fig. 18.1. If small samples are cut from a large block of o brittle ceramic, they will show o dispersion of strengths because of the dispersion of flaw sizes. The average strength of the small samples is greater than that of the large sample.

The fibers taken from the same bundle showed a wide range of diameters, which is a typical drawback of natural fibers, justifying the need for the use of a more accurate statistical distribution function. In fact, all the fibers showed wide dispersion of strength with respect to diameter data, indicated by the dimensionless shape parameter of the Weibull equation. By contrast, the advanced statistical approach based on neural network algorithms (PDF estimation technique) mentioned above resulted in asymmetric curves of diameter distributions of four lignocellulosic fibers mentioned above (Fig. 8.7). 

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