A nonlinear cumulative fatigue damage life prediction model under combined cycle fatigue loading considering load interaction

In the present work, combined high and low cycle fatigue (CCF) tests were performed on GH4169 nickel-based alloy under stress-controlled conditions. The interaction between high cycle fatigue (HCF) and low cycle fatigue (LCF) results in a complex process of fatigue damage evolution under CCF loading. Based on the fatigue damage curve and the theory of equivalent damage, considering the interaction between HCF and LCF loading, a nonlinear cumulative damage model is proposed under CCF loading. The proposed model is deduced from the fatigue damage curve under CCF loading, which establishes a connection between the LCF and HCF damage curve. Three materials, including the other two materials, namely TC11 and Al 2024-T3, published in the relevant literature, are used to verify the proposed model. The experimental results demonstrate that the proposed model has better prediction results than those for Miner’s rule and the Trufyakov-Kovalchuk (T-K) model. The validation of the proposed model shows its superior performance.