A probabilistic fatigue model based on nonlinear Kohout-Věchet function: Application to 42CrMo4+QT steel

Abstract

This paper presents a fatigue model designed to provide probabilistic-stress-life (P-S-N) curves at any probability level. Grounded in the Weibull probabilistic model’s framework, the model describes two scenarios: P-Case A, which considers deviations in stress, and P-Case B, centered on deviations in cycles to failure from the median S-N curve. A significant aspect of the proposed model is the incorporation of the Kohout-Věchet function as the representative median S-N curve, allowing for the Kohout-Vechet P-S-N curves across any probability level. To demonstrate the model’s practical relevance, an experimental example focused on specimens made from 42CrMo4+QT steel and subjected to push-pull loading is explored. Not only do the results show the robustness of the model but they also emphasize the role of the characteristic P-S-N curves, especially at lower probability level, in assuring the safety of engineering components.