Probabilistic fatigue assessment of notched components under size effect using critical distance theory

•Framework for probabilistic fatigue assessment of notched components under size effect.•Notch fatigue analysis by coupling Weibull model with the theory of critical distance.•Two strategies for characterizing the influence of size effect on critical distances of notched specimens.•Model predicted scatter band agree well with experimental data of En3B steel and Al 2024-T531 alloy. Notch features often raise critical influences on fatigue lives of engineering components, which deserve particular attentions for ensuring their structural integrity and reliability. The theory of critical distance provides a simple way to evaluate fatigue lives of notched components without extracting complicated stress fields within the notch vicinities. In this study, a probabilistic model for deducing fatigue life distribution of notched components is established by coupling the Weibull distribution with the theory of critical distance. In addition, the influence of size effect on critical distance values and predicting performance is characterized by two strategies, i.e. average approach and highly stressed volume-based approach. Experimental data of low carbon steel En3B and Al 2024-T351 were utilized for model validation and comparison. Predicted P–S–N curves indicate that the predicted scatter bands using highly stressed volume approach yield better correlations with experimental results than that by the average approach.