A Damage Accumulation Model Based on Load Interaction Effects

Aiming at the fatigue failure of mechanical components of rail vehicles subjected to complex variable amplitude loading loads, a cumulative damage model considering load interaction effects and a life prediction theory are developed in this paper. Firstly, the load loading sequence effect is described and it is proved that the inseparability of fatigue damage and stress level is the main cause of the load sequence effect. Secondly, considering the load interaction effects and the fatigue limit of the structure, a load interaction effects factor is defined and introduced, and a fatigue damage equivalence law is established. Finally, the fatigue damage equivalence rule proposed in this paper is combined with the material toughness dissipation model to construct an improved cumulative damage model under multi-stage variable amplitude loading. Based on steel 45, 16Mn, and Cr41r, which are the materials used in railroad vehicles, by comparing with Miner's rule and the original material toughness dissipation model, it is verified that the improved model proposed in this paper improves the validity and accuracy of fatigue life prediction, which shows that the cumulative damage model proposed in this paper considering the load interaction effects is reasonable and feasible.