A nonlinear fatigue damage accumulation model for block loading conditions considering the load interaction history

The increasing complexity of flight mission profiles complicates fatigue damage accumulation in aero-engine components, yet existing nonlinear models are often insufficient for accurate life prediction under such block loading conditions involving frequent transitions. To address this limitation, a new nonlinear damage accumulation model considering the load interaction history was developed. A historical reference parameter was introduced to modify the interaction factor, serving as a dynamic baseline to quantify the cumulative influence of historical loading transitions. The theoretical formulation of the model was initially established through mathematical derivation, and its performance was subsequently validated using experimental data on FGH96 alloy under three designed repeated block spectra of increasing complexity. The results demonstrated that the proposed model achieved prediction accuracy with mean absolute percentage errors within 25 %, outperforming other models that only consider the localized interaction effect. Further validation using published data for common engineering materials under multi-level loading conditions confirmed the model's robustness and generalization capability.