PSI - Issue 38

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Robin Hauteville et al. / Procedia Structural Integrity 38 (2022) 507–518 Robin Hauteville, Xavier Hermite, Fabien Lefebvre / Structural Integrity Procedia 00 (2021) 000 – 000

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Figure 3: Stromeyer model

A second hypothesis can, however, be established on this parameter C by assuming that it is an integer belonging to an interval defined either by the literature or by feedback. Nevertheless, the same problem remains to be solved as for the Basquin model regarding the consideration of censored data if the least square method is used. 3.3. Bastenaire model In 1960, Bastenaire proposed a new type of doubly asymptotic model to consider the transition between the field of limited and unlimited endurance (as for Stromeyer's model) but also with the oligocyclic domain. This model is found in the literature in two formulations: • The original one resulting from the thesis of F. Bastenaire (1974) [5]: = − ( − ) − • The one more commonly found in the literature today [9]: = − − ( ( − ) ) (6) This model has the particularity of being composed of 4 parameters which implies an even greater complexity for the identification of these during the post-processing of experimental data. As with the Stromeyer model, the parameter C can be defined as an integer on an interval defined either by the literature or by feedback. This parameter has an influence on the level of inflection of the S-N curve during transitions between the three lifetime domains as it could be seen in the Figure 4. Indeed, the higher this parameter will be, the more brutal the asymptotic double character of the curve will be. (5)