A modified critical plane energy–energy gradient based multiaxial fatigue life prediction model for smooth/notched specimens

The energy-based critical plane method has gained considerable acceptance in multiaxial fatigue life prediction, but conventional implementations fundamentally limit accuracy through oversimplified strain energy density computations. By combining the modified strain energy computation approach and critical plane criterion, a general prediction model that applicable to both smooth and notched specimens is established, in which the critical plane is determined by the maximum damage parameter. In the proposed model, the concept of energy gradient influence coefficient in terms of the energy distribution on the critical plane is defined to account for the influence of the notch. For model verification and comparison, finite element analysis (FEA) and the experimental data of GH4169, TC4 and Al7050-T7451 alloys are utilized. Quantitative evaluation shows that the proposed model has superior prediction accuracy compared to conventional energy-based models (SWT, CXH and CCB), especially when the materials generate plastic strain energy . • An accurate fatigue damage parameter is established by modifying strain energy calculation on the critical plane. • The critical plane energy distribution curve is used to characterize the complex stress-strain field near the notch. • The energy gradient influence coefficient is defined to account for the notch effects on multiaxial fatigue life. • The model’s effectiveness is validated using fatigue data of GH4169, TC4 , and Al7050-T7451 alloys.