Issue 41

M. Kurek et alii, Frattura ed Integrità Strutturale, 41 (2017) 24-30; DOI: 10.3221/IGF-ESIS.41.04 27 Figure 2 : The methodology of presented calculations. Figure 3 : Relationship between scatter values T and the angle β for D30. In addition, calculations were performed with regard to the relation of the ratio of normal stress to shear one depending on angle β. The study took into consideration the level of error of 10%. Accordingly, it was adopted that the ratio is established with the probability level of ± 5% 0.95 1.05 a a a a a a         . One of the characteristics of fatigue tests is that the results demonstrate a considerable degree of scatter. This paper is based on an assumption that the error is at a level of 10%, which is sufficient during calculations of fatigue life with regard to loads. The results that were gained, were subsequently plotted onto the diagram representing the relation of angle β depending on the ratio of normal to shear stresses (Fig. 4).