PSI - Issue 41

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Karolina Głowacka et al. / Procedia Structural Integrity 41 (2022) 232 – 240 Głowack K., Łagoda T./ Structural Int grity Procedia 00 ( 2019) 00 – 000

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Fig. 5. Set of equivalent stress amplitudes according to the hypothesis defined in the plane of the maximum normal stress as a function of the number of cycles depending on the specimen cut angle against the background of the characteristics at 0° . From the drawings themselves, it is difficult to interpret which model is the best. For this purpose, a model taken from work of Walat and Łagoda (2014) was used. This analysis was performed for equivalent stresses and referred to the stresses determined for the experi mental number of cycles in relation to the tests at the 0° axis, the same as it was done for the relevant drawings. The calculations were carried out in accordance with the dependencies: = √ ∑ 2 =1 (13) = 10 (14) The results of these calculations are presented in Table 3. The analysis of the calculations shows that the smallest dispersion was obtained according to the Norris criterion - formula (4), and the largest according to the ATH criterion - formula (3). The results of the calculations for the obtained equivalent amplitude according to the proposed model, considering the critical plane (11), give the values of the dispersion between the scatterings of these two models. However, it should be noted that such a solution has a wider application as it could be used for experimental or disproportionate loads.

Table 3. Determination of the dispersion (14) of the results of the equivalent amplitude calculations for different criteria. ATH (3) Norris (4) Critical plane (11) 1.142 1.067 1.130