Through analyzing the characteristics of the Miner’s rule and the Manson-Halford (M-H) model, a nonlinear fatigue damage accumulation model is established based on the damage curve method under combined high and low cycle fatigue loading. In this model, an interaction factor related to the maximum stress and high cycle stress range is proposed to consider the loading interaction effect. Furthermore, the proposed model does not require any additional material parameters except for the S-N curve parameters. The experimental data of five materials, including TC11 alloy, 2024-T3 aluminum alloy, 45 steel, LY12-CZ aluminum alloy, and GH4033 Ni-based alloy, are introduced to verify the proposed model. Compared with the Miner’s rule and the M-H model, most of the prediction results by the proposed model are within the life factor range of 2, implying the established model has higher prediction accuracy.

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Based on the analysis of the test data and Miner's rule, a combined high and low cycle fatigue (CCF) life prediction model considering the loading interaction is established by introducing coupled damage. The coupled damage is determined by multiplying the high cycle fatigue damage and the low cycle fatigue damage by a coupled damage coefficient K. According to the analysis of the test data, the coupled damage coefficient K is positively correlated with the high cycle stress ratio R. In addition, an interaction factor, which reflects the loading interaction effect, is introduced to correct the coefficient K. The CCF experimental data of four materials are employed for model verification and comparison among the proposed model, Miner's rule, and Trufyakov-Kovalchuk model (T-K model). The proposed model exhibits a relatively higher prediction accuracy and is more suitable for predicting the fatigue life of CCF. K E Y W O R D S combined high and low cycle fatigue, coupled damage, fatigue life, loading interaction Highlights 1. A combined fatigue life prediction model is proposed considering loading interaction.2. Coupled damage coefficient is determined through analysis of the test data. 3. The proposed model exhibits a relatively higher prediction accuracy.

It is very important to establish a life prediction model that evaluates the combined high and low cycle fatigue (CCF) damage of materials. Based on the toughness exhaustion, this paper develops a CCF life prediction model considering loading interaction effect. The loading interaction factor is proposed to reflect the interaction effect between high cycle fatigue and low cycle fatigue. The proposed model does not require any additional material parameters and is convenient for application. The experimental data of four materials including GH4033 Ni-basis alloy, TC11 titanium alloy, LY12-CZ aluminum alloy, and 45 steel are applied to verify the proposed model. Comparing the prediction results of the proposed model with the Miner’s rule and the T-K model, the results show that the predicted results of the proposed model are more satisfactory.