Issue 9

An. Carpinteri et alii, Frattura ed Integrità Strutturale, 9 (2009) 46 - 54; DOI: 10.3221/IGF-ESIS.09.05 52 For each data set presented above, the relative frequency of the error index is shown in Fig.5. The values of I , ranging from %100  to %100  , have been separated in 20 classes of 10% range. Such a relative frequency represents the number of experimental tests whose error index falls in the interval considered, normalised with respect to the total number of tests. Note that a positive value of I represents a conservative prediction. Figure 4 : Experimental fatigue life exp N vs predicted fatigue life cal N for each experimental data set analysed [11, 19–21]. Figure 5 : Error index distribution for each experimental data set analysed [11,19–21].