A nonlinear fatigue damage accumulation model under variable amplitude loading considering the loading sequence effect

•An exponential function based on load cycle ratio is proposed to characterize the load sequence effect.•Taking the static toughness of the material as the damage parameter, a damage evolution equation of the material in the fatigue process was proposed.•Based on the proposed damage evolution equation of materials under constant amplitude load and the damage equivalence principle, a residual life prediction model of materials under variable amplitude load is proposed, which can consider the effect of loading sequence.•The additional parameters used in the proposed life prediction model only involve the elastic modulus of the material. Compared to similar models, the application of the proposed model is simpler.