Probabilistic Life Estimation Framework for Mechanical Component

Within the field of structural integrity design, notch fatigue analysis holds critical significance. Nevertheless, the absence of efficient fatigue models capable of seamlessly incorporating both notch and size effects continues to present a considerable challenge. Addressing this gap, the present study introduces a modelling for service life evaluation. Grounded in strain energy theory, a fatigue life prediction model and a reliability evaluation equation for notched structures that incorporate size effects are proposed. These models effectively capture the combined influences of varying stress ratios and notch-size interactions under stochastic conditions, achieving high predictive accuracy and robust quantification of fatigue life dispersion. An equivalent variable energy density damage parameter is formulated by integrating total strain energy density, weight functions, and strain energy gradients. Furthermore, a correlation is established between fatigue test data obtained under symmetric cyclic loading and local strain energy density distributions under asymmetric cyclic loading, enabling life prediction for notched structural components considering size effects across different stress ratios, using only symmetric cyclic loading test data. Additionally, a new gap fatigue life prediction model is presented, explicitly accounting for both mean stress and size effects. This study delivers a comprehensive program framework mechanically structural components, offering improved representation of fatigue test data dispersion under varying stress ratios.